National Library of Energy BETA

Sample records for laser plasma wakefield

  1. Giga-electronvolt electrons due to a transition from laser wakefield acceleration to plasma wakefield acceleration

    SciTech Connect (OSTI)

    Masson-Laborde, P. E. Teychenné, D.; Mo, M. Z.; Ali, A.; Fedosejevs, R.; Fourmaux, S.; Lassonde, P.; Kieffer, J. C.; Rozmus, W.

    2014-12-15

    We show through experiments that a transition from laser wakefield acceleration (LWFA) regime to a plasma wakefield acceleration (PWFA) regime can drive electrons up to energies close to the GeV level. Initially, the acceleration mechanism is dominated by the bubble created by the laser in the nonlinear regime of LWFA, leading to an injection of a large number of electrons. After propagation beyond the depletion length, leading to a depletion of the laser pulse, whose transverse ponderomotive force is not able to sustain the bubble anymore, the high energy dense bunch of electrons propagating inside bubble will drive its own wakefield by a PWFA regime. This wakefield will be able to trap and accelerate a population of electrons up to the GeV level during this second stage. Three dimensional particle-in-cell simulations support this analysis and confirm the scenario.

  2. Probing the laser wakefield in underdense plasmas by induced terahertz emission

    SciTech Connect (OSTI)

    Hu, Z. D.; Wang, W. M.; Chen, L. M.; Li, Y. T.; Sheng, Z. M.; Zhang, J.; Key Laboratory for Laser Plasmas and Department of Physics, Shanghai Jiao Tong University, Shanghai 200240

    2013-08-15

    Terahertz (THz) radiation can be produced from a laser wakefield driven in underdense plasmas in the presence of a transverse DC magnetic field. It is shown that the radiation usually contains a component at the electron plasma frequency and its harmonics when the wakefield is excited at high amplitudes. In the highly nonlinear bubble/blowout regime, the radiation contains a smooth component peaked at the reduced electron plasma frequency and an irregular spectrum extending to tens of the electron plasma frequency. The latter is due to the broken-wave structure behind the bubble. A theoretical model is presented and validated via two-dimensional particle-in-cell simulations. The measurement of such THz emission may provide a diagnostic of the laser wakefield structure.

  3. Injection and acceleration of electron bunch in a plasma wakefield produced by a chirped laser pulse

    SciTech Connect (OSTI)

    Afhami, Saeedeh; Eslami, Esmaeil

    2014-06-15

    An ultrashort laser pulse propagating in plasma can excite a nonlinear plasma wakefield which can trap and accelerate charged particles up to GeV. One-dimensional analysis of electron injection, trapping, and acceleration by different chirped pulses propagating in plasma is investigated numerically. In this paper, we inject electron bunches in front of the chirped pulses. It is indicated that periodical chirped laser pulse can trap electrons earlier than other pulses. It is shown that periodical chirped laser pulses lead to decrease the minimum momentum necessary to trap the electrons. This is due to the fact that periodical chirped laser pulses are globally much efficient than nonchirped pulses in the wakefield generation. It is found that chirped laser pulses could lead to much larger electron energy than that of nonchirped pulses. Relative energy spread has a lower value in the case of periodical chirped laser pulses.

  4. Laser-seeded modulation instability in a proton driver plasma wakefield accelerator

    SciTech Connect (OSTI)

    Siemon, Carl; Khudik, Vladimir; Austin Yi, S.; Shvets, Gennady; Pukhov, Alexander

    2013-10-15

    A new method for initiating the modulation instability (MI) of a proton beam in a proton driver plasma wakefield accelerator using a short laser pulse preceding the beam is presented. A diffracting laser pulse is used to produce a plasma wave that provides a seeding modulation of the proton bunch with the period equal to that of the plasma wave. Using the envelope description of the proton beam, this method of seeding the MI is analytically compared with the earlier suggested seeding technique that involves an abrupt truncation of the proton bunch. The full kinetic simulation of a realistic proton bunch is used to validate the analytic results. It is further used to demonstrate that a plasma density ramp placed in the early stages of the laser-seeded MI leads to its stabilization, resulting in sustained accelerating electric fields (of order several hundred MV/m) over long propagation distances (∼100–1000 m)

  5. High-efficiency acceleration in the laser wakefield by a linearly increasing plasma density

    SciTech Connect (OSTI)

    Dong, Kegong; Wu, Yuchi; Zhu, Bin; Zhang, Zhimeng; Zhao, Zongqing; Zhou, Weimin; Hong, Wei; Cao, Leifeng; Gu, Yuqiu

    2014-12-15

    The acceleration length and the peak energy of the electron beam are limited by the dephasing effect in the laser wakefield acceleration with uniform plasma density. Based on 2D-3V particle in cell simulations, the effects of a linearly increasing plasma density on the electron acceleration are investigated broadly. Comparing with the uniform plasma density, because of the prolongation of the acceleration length and the gradually increasing accelerating field due to the increasing plasma density, the electron beam energy is twice higher in moderate nonlinear wakefield regime. Because of the lower plasma density, the linearly increasing plasma density can also avoid the dark current caused by additional injection. At the optimal acceleration length, the electron energy can be increased from 350 MeV (uniform) to 760 MeV (linearly increasing) with the energy spread of 1.8%, the beam duration is 5 fs and the beam waist is 1.25 μm. This linearly increasing plasma density distribution can be achieved by a capillary with special gas-filled structure, and is much more suitable for experiment.

  6. Two GeV Electrons Achieved by Laser Plasma Wakefield Acceleration | U.S.

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    DOE Office of Science (SC) Two GeV Electrons Achieved by Laser Plasma Wakefield Acceleration High Energy Physics (HEP) HEP Home About Research Facilities Science Highlights Benefits of HEP Funding Opportunities Advisory Committees Community Resources Contact Information High Energy Physics U.S. Department of Energy SC-25/Germantown Building 1000 Independence Ave., SW Washington, DC 20585 P: (301) 903-3624 F: (301) 903-2597 E: Email Us More Information » 07.01.13 Two GeV Electrons Achieved

  7. Demonstration of passive plasma lensing of a laser wakefield accelerated electron bunch

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kuschel, S.; Hollatz, D.; Heinemann, T.; Karger, O.; Schwab, M. B.; Ullmann, D.; Knetsch, A.; Seidel, A.; Rodel, C.; Yeung, M.; et al

    2016-07-20

    We report on the first demonstration of passive all-optical plasma lensing using a two-stage setup. An intense femtosecond laser accelerates electrons in a laser wakefield accelerator (LWFA) to 100 MeV over millimeter length scales. By adding a second gas target behind the initial LWFA stage we introduce a robust and independently tunable plasma lens. We observe a density dependent reduction of the LWFA electron beam divergence from an initial value of 2.3 mrad, down to 1.4 mrad (rms), when the plasma lens is in operation. Such a plasma lens provides a simple and compact approach for divergence reduction well matchedmore » to the mm-scale length of the LWFA accelerator. The focusing forces are provided solely by the plasma and driven by the bunch itself only, making this a highly useful and conceptually new approach to electron beam focusing. Possible applications of this lens are not limited to laser plasma accelerators. Since no active driver is needed the passive plasma lens is also suited for high repetition rate focusing of electron bunches. As a result, its understanding is also required for modeling the evolution of the driving particle bunch in particle driven wake field acceleration.« less

  8. Plasma wakefields driven by an incoherent combination of laser pulses: A path towards high-average power laser-plasma accelerators

    SciTech Connect (OSTI)

    Benedetti, C.; Schroeder, C. B.; Esarey, E.; Leemans, W. P.

    2014-05-15

    The wakefield generated in a plasma by incoherently combining a large number of low energy laser pulses (i.e., without constraining the pulse phases) is studied analytically and by means of fully self-consistent particle-in-cell simulations. The structure of the wakefield has been characterized and its amplitude compared with the amplitude of the wake generated by a single (coherent) laser pulse. We show that, in spite of the incoherent nature of the wakefield within the volume occupied by the laser pulses, behind this region, the structure of the wakefield can be regular with an amplitude comparable or equal to that obtained from a single pulse with the same energy. Wake generation requires that the incoherent structures in the laser energy density produced by the combined pulses exist on a time scale short compared to the plasma period. Incoherent combination of multiple laser pulses may enable a technologically simpler path to high-repetition rate, high-average power laser-plasma accelerators, and associated applications.

  9. Laser wakefield acceleration of electrons with ionization injection in a pure N{sup 5+} plasma waveguide

    SciTech Connect (OSTI)

    Goers, A. J.; Yoon, S. J.; Elle, J. A.; Hine, G. A.; Milchberg, H. M.

    2014-05-26

    Ionization injection-assisted laser wakefield acceleration of electrons up to 120?MeV is demonstrated in a 1.5?mm long pure helium-like nitrogen plasma waveguide. The guiding structure stabilizes the high energy electron beam pointing and reduces the beam divergence. Our results are confirmed by 3D particle-in-cell simulations.

  10. Electron acceleration by laser wakefield and x-ray emission at moderate intensity and density in long plasmas

    SciTech Connect (OSTI)

    Ferrari, H. E.; Lifschitz, A. F.; Maynard, G.; Cros, B.

    2011-08-15

    The dynamics of electron acceleration by laser wakefield and the associated x-rays emission in long plasmas are numerically investigated for parameters close to the threshold of laser self-focusing. The plasma length is set by the use of dielectric capillary tubes that confine the gas and the laser energy. Electrons self-injection and acceleration to the 170 MeVs are obtained for densities as low as 5 x 10{sup 18} cm{sup -3} and a moderate input intensity (0.77 x 10{sup 18} W/cm{sup 2}). The associated x-ray emission at the exit of the capillary tube is shown to be an accurate diagnostic of the electrons self-injection and acceleration process.

  11. Wakefield generation in magnetized plasmas

    SciTech Connect (OSTI)

    Holkundkar, Amol; Brodin, Gert; Marklund, Mattias

    2011-09-15

    We consider wakefield generation in plasmas by electromagnetic pulses propagating perpendicular to a strong magnetic field, in the regime where the electron cyclotron frequency is equal to or larger than the plasma frequency. Particle-in-cell simulations reveal that for moderate magnetic field strengths previous results are reproduced, and the wakefield wave number spectrum has a clear peak at the inverse skin depth. However, when the cyclotron frequency is significantly larger than the plasma frequency, the wakefield spectrum becomes broadband, and simultaneously the loss rate of the driving pulse is much enhanced. A set of equations for the scalar and vector potentials reproducing these results are derived, using only the assumption of a weakly nonlinear interaction.

  12. Latest Plasma Wakefield Acceleration Results from the FACET Project...

    Office of Scientific and Technical Information (OSTI)

    Latest Plasma Wakefield Acceleration Results from the FACET Project Citation Details In-Document Search Title: Latest Plasma Wakefield Acceleration Results from the FACET Project...

  13. Analysis of radial and longitudinal force of plasma wakefield generated by a chirped pulse laser

    SciTech Connect (OSTI)

    Ghasemi, Leila; Afhami, Saeedeh; Eslami, Esmaeil

    2015-08-15

    In present paper, the chirp effect of an electromagnetic pulse via an analytical model of wakefield generation is studied. Different types of chirps are employed in this study. Our results show that by the use of nonlinear chirped pulse the longitudinal wakefield and focusing force is stronger than that of linear chirped pulse. It is indicated that quadratic nonlinear chirped pulses are globally much efficient than periodic nonlinear chirped pulses. Our calculations also predict that in nonlinear chirped pulse case, the overlap of focusing and accelerating regions is broader than that achieved in linear chirped pulse.

  14. Laser wakefield accelerator based light sources: potential applications and requirements

    SciTech Connect (OSTI)

    Albert, F; Thomas, A G; Mangles, S P; Banerjee, S; Corde, S; Flacco, A; Litos, M; Neely, D; Viera, J; Najmudin, Z; Bingham, R; Joshi, C; Katsouleas, T

    2015-01-15

    In this article we review the prospects of laser wakefield accelerators as next generation light sources for applications. This work arose as a result of discussions held at the 2013 Laser Plasma Accelerators Workshop. X-ray phase contrast imaging, X-ray absorption spectroscopy, and nuclear resonance fluorescence are highlighted as potential applications for laser-plasma based light sources. We discuss ongoing and future eff orts to improve the properties of radiation from plasma betatron emission and Compton scattering using laser wakefi eld accelerators for these specifi c applications.

  15. A Meter-Scale Plasma Wakefield Accelerator (Conference) | SciTech...

    Office of Scientific and Technical Information (OSTI)

    Conference: A Meter-Scale Plasma Wakefield Accelerator Citation Details In-Document Search Title: A Meter-Scale Plasma Wakefield Accelerator No abstract prepared. Authors:...

  16. Study of electron acceleration and x-ray radiation as a function of plasma density in capillary-guided laser wakefield accelerators

    SciTech Connect (OSTI)

    Ju, J.; Döpp, A.; Cros, B.; Svensson, K.; Genoud, G.; Wojda, F.; Burza, M.; Persson, A.; Lundh, O.; Wahlström, C.-G.; Ferrari, H.

    2013-08-15

    Laser wakefield electron acceleration in the blow-out regime and the associated betatron X-ray radiation were investigated experimentally as a function of the plasma density in a configuration where the laser is guided. Dielectric capillary tubes were employed to assist the laser keeping self-focused over a long distance by collecting the laser energy around its central focal spot. With a 40 fs, 16 TW pulsed laser, electron bunches with tens of pC charge were measured to be accelerated to an energy up to 300 MeV, accompanied by X-ray emission with a peak brightness of the order of 10{sup 21} ph/s/mm{sup 2}/mrad{sup 2}/0.1%BW. Electron trapping and acceleration were studied using the emitted X-ray beam distribution to map the acceleration process; the number of betatron oscillations performed by the electrons was inferred from the correlation between measured X-ray fluence and beam charge. A study of the stability of electron and X-ray generation suggests that the fluctuation of X-ray emission can be reduced by stabilizing the beam charge. The experimental results are in good agreement with 3D particle-in-cell (PIC) simulation.

  17. A table-top x-ray FEL based on a laser wakefield accelerator-undulator system

    SciTech Connect (OSTI)

    Nakajima, K.; Kawakubo, T.; Nakanishi, H.

    1995-12-31

    Ultrahigh-gradient electron acceleration has been confirmed owing to the laser wakefield acceleration mechanism driven by an intense short laser wakefield acceleration mechanism driven by an intense short laser pulse in an underdense plasma. The laser wakefield acceleration makes it possible to build a compact electron linac capable of producing an ultra-short bunched electron beam. While the accelerator is attributed to longitudinal wakefields, transverse wakefields simultaneously generated by a short laser pulse can serve as a plasma undulator with a very short wavelength equal to a half of the plasma wavelength. We propose a new FEL concept for X-rays based on a laser wakefield accelerator-undulator system driven by intense short laser pulses delivered from table-top terawatt lasers. The system is composed of the accelerator stage and the undulator stage in a table-top size. A low energy electron beam is accelerated an bunched into microbunches due to laser wakefields in the accelerator stage. A micro-bunched beam travelling to the opposite direction of driving laser pulses produces coherent X-ray radiation in the undulator stage. A practical configuration and its analyses are presented.

  18. Demonstration of a positron beam-driven hollow channel plasma wakefield accelerator

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gessner, Spencer; Adli, Erik; Allen, James M.; An, Weiming; Clarke, Christine I.; Clayton, Chris E.; Corde, Sebastien; Delahaye, J. P.; Frederico, Joel; Green, Selina Z.; et al

    2016-06-02

    Plasma wakefield accelerators have been used to accelerate electron and positron particle beams with gradients that are orders of magnitude larger than those achieved in conventional accelerators. In addition to being accelerated by the plasma wakefield, the beam particles also experience strong transverse forces that may disrupt the beam quality. Hollow plasma channels have been proposed as a technique for generating accelerating fields without transverse forces. In this study, we demonstrate a method for creating an extended hollow plasma channel and measure the wakefields created by an ultrarelativistic positron beam as it propagates through the channel. The plasma channel ismore » created by directing a high-intensity laser pulse with a spatially modulated profile into lithium vapour, which results in an annular region of ionization. A peak decelerating field of 230 MeV m-1 is inferred from changes in the beam energy spectrum, in good agreement with theory and particle-in-cell simulations.« less

  19. Physics of beam self-modulation in plasma wakefield accelerators

    SciTech Connect (OSTI)

    Lotov, K. V.

    2015-10-15

    The self-modulation instability is a key effect that makes possible the usage of nowadays proton beams as drivers for plasma wakefield acceleration. Development of the instability in uniform plasmas and in plasmas with a small density up-step is numerically studied with the focus at nonlinear stages of beam evolution. The step parameters providing the strongest established wakefield are found, and the mechanism of stable bunch train formation is identified.

  20. A Beam Driven Plasma-Wakefield Linear Collider: From Higgs Factory...

    Office of Scientific and Technical Information (OSTI)

    A Beam Driven Plasma-Wakefield Linear Collider: From Higgs Factory to Multi-TeV Citation Details In-Document Search Title: A Beam Driven Plasma-Wakefield Linear Collider: From Higgs ...

  1. 9 GeV energy gain in a beam-driven plasma wakefield accelerator...

    Office of Scientific and Technical Information (OSTI)

    9 GeV energy gain in a beam-driven plasma wakefield accelerator Citation Details In-Document Search Title: 9 GeV energy gain in a beam-driven plasma wakefield accelerator An ...

  2. Angular Dependence of Betatron X-Ray Spectra from a Laser Wakefield...

    Office of Scientific and Technical Information (OSTI)

    X-Ray Spectra from a Laser Wakefield Accelerator Citation Details In-Document Search Title: Angular Dependence of Betatron X-Ray Spectra from a Laser Wakefield Accelerator ...

  3. BELLA World Record Sets Stage for Laser Experiments in Novel...

    Office of Science (SC) Website

    as laser plasma wakefield acceleration. Unlike conventional particle accelerators that use RF fields to accelerate charged particles over long distances, the plasma wakefield ...

  4. Observation of laser multiple filamentation process and multiple electron beams acceleration in a laser wakefield accelerator

    SciTech Connect (OSTI)

    Li, Wentao; Liu, Jiansheng; Wang, Wentao; Chen, Qiang; Zhang, Hui; Tian, Ye; Zhang, Zhijun; Qi, Rong; Wang, Cheng; Leng, Yuxin; Li, Ruxin; Xu, Zhizhan

    2013-11-15

    The multiple filaments formation process in the laser wakefield accelerator (LWFA) was observed by imaging the transmitted laser beam after propagating in the plasma of different density. During propagation, the laser first self-focused into a single filament. After that, it began to defocus with energy spreading in the transverse direction. Two filaments then formed from it and began to propagate independently, moving away from each other. We have also demonstrated that the laser multiple filamentation would lead to the multiple electron beams acceleration in the LWFA via ionization-induced injection scheme. Besides, its influences on the accelerated electron beams were also analyzed both in the single-stage LWFA and cascaded LWFA.

  5. Modeling laser wakefield accelerators in a Lorentz boosted frame

    SciTech Connect (OSTI)

    Vay, J.-L.; Geddes, C.G.R.; Cormier-Michel, E.; Grote, D.P.

    2010-09-15

    Modeling of laser-plasma wakefield accelerators in an optimal frame of reference [1] is shown to produce orders of magnitude speed-up of calculations from first principles. Obtaining these speedups requires mitigation of a high frequency instability that otherwise limits effectiveness in addition to solutions for handling data input and output in a relativistically boosted frame of reference. The observed high-frequency instability is mitigated using methods including an electromagnetic solver with tunable coefficients, its extension to accomodate Perfectly Matched Layers and Friedman's damping algorithms, as well as an efficient large bandwidth digital filter. It is shown that choosing theframe of the wake as the frame of reference allows for higher levels of filtering and damping than is possible in other frames for the same accuracy. Detailed testing also revealed serendipitously the existence of a singular time step at which the instability level is minimized, independently of numerical dispersion, thus indicating that the observed instability may not be due primarily to Numerical Cerenkov as has been conjectured. The techniques developed for Cerenkov mitigation prove nonetheless to be very efficient at controlling the instability. Using these techniques, agreement at the percentage level is demonstrated between simulations using different frames of reference, with speedups reaching two orders of magnitude for a 0.1 GeV class stages. The method then allows direct and efficient full-scale modeling of deeply depleted laser-plasma stages of 10 GeV-1 TeV for the first time, verifying the scaling of plasma accelerators to very high energies. Over 4, 5 and 6 orders of magnitude speedup is achieved for the modeling of 10 GeV, 100 GeV and 1 TeV class stages, respectively.

  6. Spectral diagnostics of laser wakefield in capillary tubes

    SciTech Connect (OSTI)

    Andreev, N.E.; Chegotov, M.V.; Cros, B.; Mora, P.; Vieux, G.

    2006-05-15

    The modification of the spectrum of a probe pulse traveling in a linear plasma wave created in the wake of a pump pulse guided inside a capillary tube is analyzed for the cases of narrow or broad chirped probe spectra. It is shown that in both cases the measurement of the spectrum can be used as a diagnostic for the amplitude of the plasma wave. The results of full-scale numerical modeling confirm the developed analytical theory of wake-field diagnostics.

  7. The phase-lock dynamics of the laser wakefield acceleration with an intensity-decaying laser pulse

    SciTech Connect (OSTI)

    Li, Wentao; Liu, Jiansheng Wang, Wentao; Zhang, Zhijun; Chen, Qiang; Tian, Ye; Qi, Rong; Yu, Changhai; Wang, Cheng; Li, Ruxin Xu, Zhizhan; Tajima, T.

    2014-03-03

    An electron beam with the maximum energy extending up to 1.8?GeV, much higher than the dephasing limit, is experimentally obtained in the laser wakefield acceleration with the plasma density of 3.5??10{sup 18}?cm{sup ?3}. With particle in cell simulations and theoretical analysis, we find that the laser intensity evolution plays a major role in the enhancement of the electron energy gain. While the bubble length decreases due to the intensity-decay of the laser pulse, the phase of the electron beam in the wakefield can be locked, which contributes to the overcoming of the dephasing. Moreover, the laser intensity evolution is described for the phase-lock acceleration of electrons in the uniform plasma, confirmed with our own simulation. Since the decaying of the intensity is unavoidable in the long distance propagation due to the pump depletion, the energy gain of the high energy laser wakefield accelerator can be greatly enhanced if the current process is exploited.

  8. Parameter sensitivity of plasma wakefields driven by self-modulating proton beams

    SciTech Connect (OSTI)

    Lotov, K. V.; Minakov, V. A.; Sosedkin, A. P.

    2014-08-15

    The dependence of wakefield amplitude and phase on beam and plasma parameters is studied in the parameter area of interest for self-modulating proton beam-driven plasma wakefield acceleration. The wakefield phase is shown to be extremely sensitive to small variations of the plasma density, while sensitivity to small variations of other parameters is reasonably low. The study of large parameter variations clarifies the effects that limit the achievable accelerating field in different parts of the parameter space: nonlinear elongation of the wakefield period, insufficient charge of the drive beam, emittance-driven beam divergence, and motion of plasma ions.

  9. Beam Matching to a Plasma Wakefield Accelerator Using a Ramped Density

    Office of Scientific and Technical Information (OSTI)

    Profile at the Plasma Boundary (Conference) | SciTech Connect Conference: Beam Matching to a Plasma Wakefield Accelerator Using a Ramped Density Profile at the Plasma Boundary Citation Details In-Document Search Title: Beam Matching to a Plasma Wakefield Accelerator Using a Ramped Density Profile at the Plasma Boundary An important aspect of plasma wake field accelerators (PWFA) is stable propagation of the drive beam. In the under dense plasma regime, the drive beam creates an ion channel

  10. Numerical modeling of multi-GeV laser wakefield electron acceleration inside a dielectric capillary tube

    SciTech Connect (OSTI)

    Paradkar, B. S.; Cros, B.; Maynard, G.; Mora, P.

    2013-08-15

    Numerical modeling of laser wakefield electron acceleration inside a gas filled dielectric capillary tube is presented. Guiding of a short pulse laser inside a dielectric capillary tube over a long distance (∼1 m) and acceleration of an externally injected electron bunch to ultra-relativistic energies (∼5-10 GeV) are demonstrated in the quasi-linear regime of laser wakefield acceleration. Two dimensional axisymmetric simulations were performed with the code WAKE-EP (Extended Performances), which allows computationally efficient simulations of such long scale plasma. The code is an upgrade of the quasi-static particle code, WAKE [P. Mora and T. M. Antonsen, Jr., Phys. Plasmas 4, 217 (1997)], to simulate the acceleration of an externally injected electron bunch (including beam loading effect) and propagation of the laser beam inside a dielectric capillary. The influence of the transverse electric field of the plasma wake on the radial loss of the accelerated electrons to the dielectric wall is investigated. The stable acceleration of electrons to multi-GeV energy with a non-resonant laser pulse with a large spot-size is demonstrated.

  11. AWAKE -- A Proton-driven Plasma Wakefield Experiment at

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AWAKE -- A Proton-driven Plasma Wakefield Experiment at CERN Swapan Chattopadhyay Fermilab March 9, 2016 4:00 p.m. - Wilson Hall, One West High energy intense proton beams such as the in the 7 TeV x 7 TeV Large Hadron Collider at CERN have sufficient energy stored per proton bunch to power and accelerate an electron beam to an energy of 600 GeV if a suitable mechanism could be found to transform all the stored proton beam energy into the electrons. A suitably designed plasma column could be such

  12. Plasma Wakefield Acceleration: How it Works

    SciTech Connect (OSTI)

    2014-11-05

    This animation explains how electrons can be efficiently accelerated to high energy using wakes created in a plasma.

  13. Experimental validation of a radio frequency photogun as external electron injector for a laser wakefield accelerator

    SciTech Connect (OSTI)

    Stragier, X. F. D.; Luiten, O. J.; Geer, S. B. van der; Wiel, M. J. van der; Brussaard, G. J. H.

    2011-07-15

    A purpose-built RF-photogun as external electron injector for a laser wakefield accelerator has been thoroughly tested. Different properties of the RF-photogun have been measured such as energy, energy spread and transverse emittance. The focus of this study is the investigation of the smallest possible focus spot and focus stability at the entrance of the plasma channel. For an electron bunch with 10 pC charge and 3.7 MeV kinetic energy, the energy spread was 0.5% with a shot-to-shot stability of 0.05%. After focusing the bunch by a pulsed solenoid lens at 140 mm from the middle of the lens, the focal spot was 40 {mu}m with a shot-to-shot stability of 5 {mu}m. Higher charge leads to higher energy spread and to a larger spot size, due to space charge effects. All properties were found to be close to design values. Given the limited energy of 3.7 MeV, the properties are sufficient for this gun to serve as injector for one particular version of laser wakefield acceleration, i.e., injection ahead of the laser pulse. These measured electron bunch properties were then used as input parameters for simulations of electron bunch injection in a laser wakefield accelerator. The arrival time jitter was deduced from measurements of the energy fluctuation, in combination with earlier measurements using THz coherent transition radiation, and is around 150 fs in the present setup. The bunch length in the focus, simulated using particle tracking, depends on the accelerated charge and goes from 100 fs at 0.1 pC to 1 ps at 50 pC. When simulating the injection of the 3.7 MeV electron bunch of 10 pC in front of a 25 TW laser pulse with a waist of 30 {mu}m in a plasma with a density of 0.7 x 10{sup 24} m{sup -3}, the maximum accelerated charge was found to be 1.2 pC with a kinetic energy of {approx}900 MeV and an energy spread of {approx}5%. The experiments combined with the simulations show the feasibility of external injection and give a prediction of the output parameters that can

  14. Measurements of the critical power for self-injection of electrons in a laser wakefield accelerator

    SciTech Connect (OSTI)

    Froula, D H; Clayton, C E; Doppner, T; Fonseca, R A; Marsh, K A; Barty, C J; Divol, L; Glenzer, S H; Joshi, C; Lu, W; Martins, S F; Michel, P; Mori, W; Palastro, J P; Pollock, B B; Pak, A; Ralph, J E; Ross, J S; Siders, C; Silva, L O; Wang, T

    2009-06-02

    A laser wakefield acceleration study has been performed in the matched, self-guided, blow-out regime where a 10 J, 60 fs laser produced 720 {+-} 50 MeV quasi-monoenergetic electrons with a divergence of {Delta}{theta} = 2.85 {+-} 0.15 mRad. While maintaining a nearly constant plasma density (3 x 10{sup 18} cm{sup -3}), a linear electron energy gain was measured from 100 MeV to 700 MeV when the plasma length was scaled from 3 mm to 8 mm. Absolute charge measurements indicate that self-injection occurs when P/P{sub cr} > 4 and saturates around 100 pC for P/P{sub cr} > 12. The results are compared with both analytical scalings and full 3D particle-in-cell simulations.

  15. Enhancement of x-rays generated by a guided laser wakefield accelerator inside capillary tubes

    SciTech Connect (OSTI)

    Ju, J.; Doepp, A.; Cassou, K.; Neveu, O.; Cros, B.; Svensson, K.; Genoud, G.; Wojda, F.; Burza, M.; Persson, A.; Lundh, O.; Wahlstroem, C.-G.; Ferrari, H. E.

    2012-05-07

    Electrons accelerated in the nonlinear regime in a laser wakefield accelerator experience transverse oscillations inside the plasma cavity, giving rise to ultra-short pulsed x-rays, also called the betatron radiation. We show that the fluence of x-ray can be enhanced by more than one order of magnitude when the laser is guided by a 10 mm long capillary tube instead of interacting with a 2 mm gas jet. X-rays with a synchrotron-like spectrum and associated critical energy {approx}5 keV, with a peak brightness of {approx}1x10{sup 21} ph/s/mm{sup 2}/mrad{sup 2}/0.1%BW, were achieved by employing 16 TW laser pulses.

  16. A Beam Driven Plasma-Wakefield Linear Collider: From Higgs Factory...

    Office of Scientific and Technical Information (OSTI)

    A Beam Driven Plasma-Wakefield Linear Collider: From Higgs Factory to Multi-TeV Summarized for CSS2013 E. Adli, J.P.Delahaye, S.J.Gessner, M.J. Hogan, T. Raubenheimer (SLAC) W.An,...

  17. Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhang, C. J.; Hua, J. F.; Xu, X. L.; Li, F.; Pai, C. -H.; Wan, Y.; Wu, Y. P.; Gu, Y. Q.; Mori, W. B.; Joshi, C.; et al

    2016-07-11

    A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of themore » wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. As a result, the capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method.« less

  18. Ultrafast pulse radiolysis using a terawatt laser wakefield accelerator

    SciTech Connect (OSTI)

    Oulianov, Dmitri A.; Crowell, Robert A.; Gosztola, David J.; Shkrob, Ilya A.; Korovyanko, Oleg J.; Rey-de-Castro, Roberto C.

    2007-03-01

    We report ultrafast pulse radiolysis transient absorption (TA) spectroscopy measurements from the Terawatt Ultrafast High Field Facility (TUHFF) at Argonne National Laboratory. TUHFF houses a 20 TW Ti:sapphire laser system that generates 2.5 nC subpicosecond pulses of multi-mega-electron-volt electrons at 10 Hz using laser wakefield acceleration. The system has been specifically optimized for kinetic TA measurements in a pump-probe fashion. This requires averaging over many shots which necessitates stable, reliable generation of electron pulses. The latter were used to generate excess electrons in pulse radiolysis of liquid water and concentrated solutions of perchloric acid. The hydronium ions in the acidic solutions react with the hydrated electrons resulting in the rapid decay of the transient absorbance at 800 nm on the picosecond time scale. Normalization of the TA signal leads to an improvement in the signal to noise ratio by a factor of 5 to 6. Due the pointing instability of the laser this improvement was limited to a 5 to 10 min acquisition period, requiring periodic recalibration and realignment. Time resolution, defined by the rise time of TA signal from hydrated electron in pulse radiolysis of liquid water, of a few picoseconds, has been demonstrated. The current time resolution is determined primarily by the physical dimensions of the sample and the detection sensitivity. Subpicosecond time resolution can be achieved by using thinner samples, more sensitive detection techniques, and improved electron beam quality.

  19. Wakefields generated by collisional neutrinos in neutral-electron-positron plasma

    SciTech Connect (OSTI)

    Tinakiche, Nouara

    2013-02-15

    A classical fluid description is adopted to investigate nonlinear interaction between an electron-type neutrino beam and a relativistic collisionless unmagnetized neutral-electron-positron plasma. In this work, we consider the collisions of the neutrinos with neutrals in the plasma and study their effect on the generation of wakefields in this plasma.

  20. Laser Plasma Interactions

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Laser Plasma Interactions Laser Plasma Interactions Understanding and controlling laser produced plasmas for fusion and basic science Contact David Montgomery (505) 665-7994 Email ...

  1. Automatic Beam Path Analysis of Laser Wakefield Particle Acceleration Data

    SciTech Connect (OSTI)

    Rubel, Oliver; Geddes, Cameron G.R.; Cormier-Michel, Estelle; Wu, Kesheng; Prabhat,; Weber, Gunther H.; Ushizima, Daniela M.; Messmer, Peter; Hagen, Hans; Hamann, Bernd; Bethel, E. Wes

    2009-10-19

    Numerical simulations of laser wakefield particle accelerators play a key role in the understanding of the complex acceleration process and in the design of expensive experimental facilities. As the size and complexity of simulation output grows, an increasingly acute challenge is the practical need for computational techniques that aid in scientific knowledge discovery. To that end, we present a set of data-understanding algorithms that work in concert in a pipeline fashion to automatically locate and analyze high energy particle bunches undergoing acceleration in very large simulation datasets. These techniques work cooperatively by first identifying features of interest in individual timesteps, then integrating features across timesteps, and based on the information derived perform analysis of temporally dynamic features. This combination of techniques supports accurate detection of particle beams enabling a deeper level of scientific understanding of physical phenomena than hasbeen possible before. By combining efficient data analysis algorithms and state-of-the-art data management we enable high-performance analysis of extremely large particle datasets in 3D. We demonstrate the usefulness of our methods for a variety of 2D and 3D datasets and discuss the performance of our analysis pipeline.

  2. A Beam Driven Plasma-Wakefield Linear Collider: From Higgs Factory to

    Office of Scientific and Technical Information (OSTI)

    Multi-TeV (Conference) | SciTech Connect Conference: A Beam Driven Plasma-Wakefield Linear Collider: From Higgs Factory to Multi-TeV Citation Details In-Document Search Title: A Beam Driven Plasma-Wakefield Linear Collider: From Higgs Factory to Multi-TeV Authors: Adli, E ; Delahaye, J.P. ; Gessner, S.J. ; Hogan, M.J. ; Raubenheimer, T. ; /SLAC ; An, W. ; Joshi, C. ; Mori, W. ; /UCLA, Los Angeles Publication Date: 2013-09-30 OSTI Identifier: 1074154 Report Number(s): SLAC-PUB-15426 DOE

  3. Dynamics of ionization-induced electron injection in the high density regime of laser wakefield acceleration

    SciTech Connect (OSTI)

    Desforges, F. G.; Paradkar, B. S. Ju, J.; Audet, T. L.; Maynard, G.; Cros, B.; Hansson, M.; Senje, L.; Persson, A.; Lundh, O.; Wahlström, C.-G.; Dobosz-Dufrénoy, S.; Monot, P.; Vay, J.-L.

    2014-12-15

    The dynamics of ionization-induced electron injection in high density (∼1.2 × 10{sup 19} cm{sup −3}) regime of laser wakefield acceleration is investigated by analyzing the betatron X-ray emission. In such high density operation, the laser normalized vector potential exceeds the injection-thresholds of both ionization-injection and self-injection due to self-focusing. In this regime, direct experimental evidence of early on-set of ionization-induced injection into the plasma wave is given by mapping the X-ray emission zone inside the plasma. Particle-In-Cell simulations show that this early on-set of ionization-induced injection, due to its lower trapping threshold, suppresses the trapping of self-injected electrons. A comparative study of the electron and X-ray properties is performed for both self-injection and ionization-induced injection. An increase of X-ray fluence by at least a factor of two is observed in the case of ionization-induced injection due to increased trapped charge compared to self-injection mechanism.

  4. Plasma Wakefield Acceleration and FACET - Facilities for Accelerator Science and Experimental Test Beams at SLAC

    ScienceCinema (OSTI)

    Andrei Seryi

    2010-01-08

    Plasma wakefield acceleration is one of the most promising approaches to advancing accelerator technology. This approach offers a potential 1,000-fold or more increase in acceleration over a given distance, compared to existing accelerators.  FACET, enabled by the Recovery Act funds, will study plasma acceleration, using short, intense pulses of electrons and positrons. In this lecture, the physics of plasma acceleration and features of FACET will be presented.  

  5. Wakefields generated by collisional neutrinos in neutral-electron-positron-ion plasma

    SciTech Connect (OSTI)

    Tinakiche, Nouara

    2015-12-15

    A classical fluid description is adopted to investigate nonlinear interaction between an electron-type neutrino beam and a relativistic collisionless unmagnetized neutral-electron-positron-ion plasma. In this work, we consider the collisions of the neutrinos with neutrals in the plasma and study their effect on the generation of wakefields in presence of a fraction of ions in a neutral-electron-positron plasma. The results obtained in the present work are interpreted and compared with previous studies.

  6. Dual effects of stochastic heating on electron injection in laser wakefield acceleration

    SciTech Connect (OSTI)

    Deng, Z. G.; Wang, X. G.; Yang, L.; Zhou, C. T.; Yu, M. Y.; Ying, H. P.

    2014-08-15

    Electron injection into the wakefield of an intense short laser pulse by a weaker laser pulse propagating in the opposite direction is reconsidered using two-dimensional (2D) particle-in-cell simulations as well as analytical modeling. It is found that for linearly polarized lasers the injection efficiency and the quality of the wakefield accelerated electrons increase with the intensity of the injection laser only up to a certain level, and then decreases. Theory and simulation tracking test electrons originally in the beat region of the two laser pulses show that the reduction of the injection efficiency at high injection-laser intensities is caused by stochastic overheating of the affected electrons.

  7. Tailoring the laser pulse shape to improve the quality of the self-injected electron beam in laser wakefield acceleration

    SciTech Connect (OSTI)

    Upadhyay, Ajay K.; Samant, Sushil A.; Krishnagopal, S.

    2013-01-15

    In laser wakefield acceleration, tailoring the shape of the laser pulse is one way of influencing the laser-plasma interaction and, therefore, of improving the quality of the self-injected electron beam in the bubble regime. Using three-dimensional particle-in-cell simulations, the evolution dynamics of the laser pulse and the quality of the self-injected beam, for a Gaussian pulse, a positive skew pulse (i.e., one with sharp rise and slow fall), and a negative skew pulse (i.e., one with a slow rise and sharp fall) are studied. It is observed that with a negative skew laser pulse there is a substantial improvement in the emittance (by around a factor of two), and a modest improvement in the energy-spread, compared to Gaussian as well as positive skew pulses. However, the injected charge is less in the negative skew pulse compared to the other two. It is also found that there is an optimal propagation distance that gives the best beam quality; beyond this distance, though the energy increases, the beam quality deteriorates, but this deterioration is least for the negative skew pulse. Thus, the negative skew pulse gives an improvement in terms of beam quality (emittance and energy spread) over what one can get with a Gaussian or positive skew pulse. In part, this is because of the lesser injected charge, and the strong suppression of continuous injection for the negative skew pulse.

  8. Multiple quasi-monoenergetic electron beams from laser-wakefield acceleration with spatially structured laser pulse

    SciTech Connect (OSTI)

    Ma, Y.; Li, M. H.; Li, Y. F.; Wang, J. G.; Tao, M. Z.; Han, Y. J.; Zhao, J. R.; Huang, K.; Yan, W. C.; Ma, J. L.; Li, Y. T.; Chen, L. M.; Li, D. Z.; Chen, Z. Y.; Sheng, Z. M.; Zhang, J.

    2015-08-15

    By adjusting the focus geometry of a spatially structured laser pulse, single, double, and treble quasi-monoenergetic electron beams were generated, respectively, in laser-wakefield acceleration. Single electron beam was produced as focusing the laser pulse to a single spot. While focusing the laser pulse to two spots that are approximately equal in energy and size and intense enough to form their own filaments, two electron beams were produced. Moreover, with a proper distance between those two focal spots, three electron beams emerged with a certain probability owing to the superposition of the diffractions of those two spots. The energy spectra of the multiple electron beams are quasi-monoenergetic, which are different from that of the large energy spread beams produced due to the longitudinal multiple-injection in the single bubble.

  9. Measuring the angular dependence of betatron x-ray spectra in a laser-wakefield accelerator

    SciTech Connect (OSTI)

    Albert, F.; Pollock, B. B.; Shaw, J. L.; Marsh, K. A.; Ralph, J. E.; Chen, Y. -H.; Alessi, D.; Pak, A.; Clayton, C. E.; Glenzer, S. H.; Joshi, C.

    2014-07-22

    This paper presents a new technique to measure the angular dependence of betatron x-ray spectra in a laser-wakefield accelerator. Measurements are performed with a stacked image plates spectrometer, capable of detecting broadband x-ray radiation up to 1 MeV. It can provide measurements of the betatron x-ray spectrum at any angle of observation (within a 40 mrad cone) and of the beam profile. A detailed description of our data analysis is given, along with comparison for several shots. As a result, these measurements provide useful information on the dynamics of the electrons are they are accelerated and wiggled by the wakefield.

  10. Laser Plasma Interactions

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Laser Plasma Interactions Laser Plasma Interactions Understanding and controlling laser produced plasmas for fusion and basic science Contact David Montgomery (505) 665-7994 Email John Kline (505) 667-7062 Email Thomson scattering is widely used to measure plasma temperature, density, and flow velocity in laser-produced plasmas at Trident, and is also used to detect plasma waves driven by unstable and nonlinear processes. A typical configuration uses a low intensity laser beam (2nd, 3rd, or 4th

  11. Electron self-injection in the proton-driven-plasma-wakefield acceleration

    SciTech Connect (OSTI)

    Hu, Zhang-Hu; Wang, You-Nian

    2013-12-15

    The self-injection process of plasma electrons in the proton-driven-plasma-wakefield acceleration scheme is investigated using a two-dimensional, electromagnetic particle-in-cell method. Plasma electrons are self-injected into the back of the first acceleration bucket during the initial bubble formation period, where the wake phase velocity is low enough to trap sufficient electrons. Most of the self-injected electrons are initially located within a distance of the skin depth c/ω{sub pe} to the beam axis. A decrease (or increase) in the beam radius (or length) leads to a significant reduction in the total charges of self-injected electron bunch. Compared to the uniform plasma, the energy spread, emittance and total charges of the self-injected bunch are reduced in the plasma channel case, due to a reduced injection of plasma electrons that initially located further away from the beam axis.

  12. Beam Matching to a Plasma Wakefield Accelerator Using a Ramped...

    Office of Scientific and Technical Information (OSTI)

    ... Sponsoring Org: USDOE Country of Publication: United States Language: English Subject: 43 PARTICLE ACCELERATORS; ACCELERATORS; BETATRON OSCILLATIONS; FOCUSING; PLASMA; STANFORD ...

  13. Beam Matching to a Plasma Wakefield Accelerator Using a Ramped...

    Office of Scientific and Technical Information (OSTI)

    Sponsoring Org: USDOE Country of Publication: United States Language: English Subject: 43 PARTICLE ACCELERATORS; ACCELERATORS; BETATRON OSCILLATIONS; FOCUSING; PLASMA; STANFORD ...

  14. Correlation of Beam Parameters to Decelerating Gradient in the E-167 Plasma Wakefield Acceleration Experiment

    SciTech Connect (OSTI)

    Blumenfeld, I.; Berry, M.; Decker, F.-J.; Hogan, M.J.; Ischebeck, R.; Iverson, R.; Kirby, N.; Siemann, R.; Walz, D.; Clayton, C.E.; Huang, C.; Joshi, C.; Lu, W.; Marsh, K.A.; Mori, W.B.; Zhou, M.; Katsouleas, T.C.; Muggli, P.; Oz, E.; /Southern California U.

    2007-06-27

    Recent experiments at SLAC have shown that high gradient acceleration of electrons is achievable in meter scale plasmas [1,2]. Results from these experiments show that the wakefield is sensitive to parameters in the electron beam which drives it. In the experiment the bunch length and beam waist location were varied systematically at constant charge. Here we investigate the correlation of peak beam current to the decelerating gradient. Limits on the transformer ratio will also be discussed. The results are compared to simulation.

  15. Multi-gigaelectronvolt acceleration of positrons in a self-loaded plasma wakefield

    SciTech Connect (OSTI)

    Corde, Sebastien; Adli, E.; Allen, J. M.; An, W.; Clarke, C. I.; Delahaye, J. P.; Frederico, J.; Gessner, S.; Green, S. Z.; Hogan, M. J.; Joshi, C.; Lipkowitz, N.; Litos, M.; Lu, W.; Marsh, K. A.; Mori, W. B.; Schmeltz, M.; Vafaei-Najafabadi, N.; Walz, D.; Yakimenko, V.; Yocky, G.; Clayton, C. E.

    2015-08-26

    New accelerator concepts must be developed to make future particle colliders more compact and affordable. The Plasma Wakefield Accelerator (PWFA) is one such concept, where the electric field of a plasma wake excited by a charged-particle bunch is used to accelerate a trailing bunch of particles. To apply plasma acceleration to particle colliders, it is imperative that both the electrons and their antimatter counterpart, the positrons, are efficiently accelerated at high fields using plasmas1. While substantial progress has recently been reported on high-field, high-efficiency acceleration of electrons in a PWFA powered by an electron bunch 2, such an electron-driven wake is unsuitable for the acceleration and focusing of a positron bunch. Here we demonstrate a new regime of PWFA where particles in the front of a single positron bunch transfer their energy to a substantial number of those in the rear of the same bunch by exciting a wakefield in the plasma. In the process, the accelerating field is altered – self-loaded – so that about a billion positrons gain five gigaelectronvolts (GeV) of energy with a narrow energy spread in a distance of just 1.3 meters. They extract about 30% of the wake’s energy and form a spectrally distinct bunch with as low as a 1.8% r.m.s. energy spread. This demonstrated ability of positron-driven plasma wakes to efficiently accelerate a significant number of positrons with a small energy spread may overcome the long-standing challenge of positron acceleration in plasma-based accelerators.

  16. Modeling Laser Wakefield Accelerators in a Lorentz Boosted Frame

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Lorentz Boosted Frame VayBoost.gif An image showing the "boosted frame," in which the observer moves at near light speed. The laser pulse is represented in blue and red; the...

  17. Analytic model of electron self-injection in a plasma wakefield accelerator in the strongly nonlinear bubble regime

    SciTech Connect (OSTI)

    Yi, S. A.; Khudik, V.; Siemon, C.; Shvets, G.

    2012-12-21

    Self-injection of background electrons in plasma wakefield accelerators in the highly nonlinear bubble regime is analyzed using particle-in-cell and semi-analytic modeling. It is shown that the return current in the bubble sheath layer is crucial for accurate determination of the trapped particle trajectories.

  18. Controlling the spectrum of x-rays generated in a laser-plasma accelerator by tailoring the laser wavefront

    SciTech Connect (OSTI)

    Mangles, S. P. D.; Kneip, S.; Dover, N. P.; Najmudin, Z.; Schreiber, J.; Genoud, G.; Burza, M.; Kamperidis, C.; Persson, A.; Wahlstroem, C.-G.; Cassou, K.; Cros, B.; Wojda, F.

    2009-11-02

    By tailoring the wavefront of the laser pulse used in a laser-wakefield accelerator, we show that the properties of the x-rays produced due to the electron beam's betatron oscillations in the plasma can be controlled. By creating a wavefront with coma, we find that the critical energy of the synchrotronlike x-ray spectrum can be significantly increased. The coma does not substantially change the energy of the electron beam, but does increase its divergence and produces an energy-dependent exit angle, indicating that changes in the x-ray spectrum are due to an increase in the electron beam's oscillation amplitude within the wakefield.

  19. 9 GeV energy gain in a beam-driven plasma wakefield accelerator

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Litos, M.; Adli, E.; Allen, J. M.; An, W.; Clarke, C. I.; Corde, S.; Clayton, C. E.; Frederico, J.; Gessner, S. J.; Green, S. Z.; et al

    2016-02-15

    An electron beam has gained a maximum energy of 9 GeV per particle in a 1.3 m-long electron beam-driven plasma wakefield accelerator. The amount of charge accelerated in the spectral peak was 28.3 pC, and the root-mean-square energy spread was 5.0%. The mean accelerated charge and energy gain per particle of the 215 shot data set was 115 pC and 5.3 GeV, respectively, corresponding to an acceleration gradient of 4.0 GeV m-1 at the spectral peak. Moreover, the mean energy spread of the data set was 5.1%. Our results are consistent with the extrapolation of the previously reported energy gainmore » results using a shorter, 36 cm-long plasma source to within 10%, evincing a non-evolving wake structure that can propagate distances of over a meter in length. Wake-loading effects were evident in the data through strong dependencies observed between various spectral properties and the amount of accelerated charge.« less

  20. Shielding effect and wakefield pattern of a moving test charge in a non-Maxwellian dusty plasma

    SciTech Connect (OSTI)

    Ali, S.; Khan, S.; Department of Physics, Gomal University, Dera Ismail Khan 29050

    2013-07-15

    By using the Vlasov-Poisson equations, we calculate an expression for the electrostatic potential caused by a test charge in an unmagnetized non-Maxwellian dusty plasma, whose constituents are the superthermal hot-electrons, the mobile cold-electrons with a neutralizing background of cold ions, and charge fluctuating isolated dust grains. The superthermality effects due to hot electrons not only modify the dielectric constant of the electron-acoustic waves but also significantly affect the electrostatic potential. The latter can be decomposed into the Debye-Hckel and oscillatory wake potentials. Analytical and numerical results reveal that the Debye-Hckel and wakefield potentials converge to the Maxwellian case for large values of superthermality parameter. Furthermore, the plasma parameters play a vital role in the formation of shielding and wakefield pattern in a two-electron temperature plasma. The present results should be important for laboratory and space dusty plasmas, where hot-electrons can be assumed to follow the non-Maxwellian distribution function.

  1. Laser Wakefield Acceleration: Structural and Dynamic Studies. Final Technical Report ER40954

    SciTech Connect (OSTI)

    Downer, Michael C.

    2014-12-19

    Particle accelerators enable scientists to study the fundamental structure of the universe, but have become the largest and most expensive of scientific instruments. In this project, we advanced the science and technology of laser-plasma accelerators, which are thousands of times smaller and less expensive than their conventional counterparts. In a laser-plasma accelerator, a powerful laser pulse exerts light pressure on an ionized gas, or plasma, thereby driving an electron density wave, which resembles the wake behind a boat. Electrostatic fields within this plasma wake reach tens of billions of volts per meter, fields far stronger than ordinary non-plasma matter (such as the matter that a conventional accelerator is made of) can withstand. Under the right conditions, stray electrons from the surrounding plasma become trapped within these “wake-fields”, surf them, and acquire energy much faster than is possible in a conventional accelerator. Laser-plasma accelerators thus might herald a new generation of compact, low-cost accelerators for future particle physics, x-ray and medical research. In this project, we made two major advances in the science of laser-plasma accelerators. The first of these was to accelerate electrons beyond 1 gigaelectronvolt (1 GeV) for the first time. In experimental results reported in Nature Communications in 2013, about 1 billion electrons were captured from a tenuous plasma (about 1/100 of atmosphere density) and accelerated to 2 GeV within about one inch, while maintaining less than 5% energy spread, and spreading out less than ½ milliradian (i.e. ½ millimeter per meter of travel). Low energy spread and high beam collimation are important for applications of accelerators as coherent x-ray sources or particle colliders. This advance was made possible by exploiting unique properties of the Texas Petawatt Laser, a powerful laser at the University of Texas at Austin that produces pulses of 150 femtoseconds (1 femtosecond is 10

  2. A broadband gamma-ray spectrometry using novel unfolding algorithms for characterization of laser wakefield-generated betatron radiation

    SciTech Connect (OSTI)

    Jeon, Jong Ho Nakajima, Kazuhisa Pathak, Vishwa Bandhu; Cho, Myung Hoon; Yoo, Byung Ju; Shin, Kang Woo; Kim, Hyung Taek; Sung, Jae Hee; Lee, Seung Ku; Choi, Il Woo; Rhee, Yong Joo; Shin, Jung Hun; Jo, Sung Ha; Hojbota, Calin; Cho, Byeoung Ick; Nam, Chang Hee

    2015-12-15

    We present a high-flux, broadband gamma-ray spectrometry capable of characterizing the betatron radiation spectrum over the photon energy range from 10 keV to 20 MeV with respect to the peak photon energy, spectral bandwidth, and unique discrimination from background radiations, using a differential filtering spectrometer and the unfolding procedure based on the Monte Carlo code GEANT4. These properties are experimentally verified by measuring betatron radiation from a cm-scale laser wakefield accelerator (LWFA) driven by a 1-PW laser, using a differential filtering spectrometer consisting of a 15-filter and image plate stack. The gamma-ray spectra were derived by unfolding the photostimulated luminescence (PSL) values recorded on the image plates, using the spectrometer response matrix modeled with the Monte Carlo code GEANT4. The accuracy of unfolded betatron radiation spectra was assessed by unfolding the test PSL data simulated with GEANT4, showing an ambiguity of less than 20% and clear discrimination from the background radiation with less than 10%. The spectral analysis of betatron radiation from laser wakefield-accelerated electron beams with energies up to 3 GeV revealed radiation spectra characterized by synchrotron radiation with the critical photon energy up to 7 MeV. The gamma-ray spectrometer and unfolding method presented here facilitate an in-depth understanding of betatron radiation from LWFA process and a novel radiation source of high-quality photon beams in the MeV regime.

  3. Study of electron trapping by a transversely ellipsoidal bubble in the laser wake-field acceleration

    SciTech Connect (OSTI)

    Cho, Myung-Hoon; Kim, Young-Kuk; Hur, Min Sup

    2013-09-15

    We present electron trapping in an ellipsoidal bubble which is not well explained by the spherical bubble model by [Kostyukov et al., Phys. Rev. Lett. 103, 175003 (2009)]. The formation of an ellipsoidal bubble, which is elongated transversely, frequently occurs when the spot size of the laser pulse is large compared to the plasma wavelength. First, we introduce the relation between the bubble size and the field slope inside the bubble in longitudinal and transverse directions. Then, we provide an ellipsoidal model of the bubble potential and investigate the electron trapping condition by numerical integration of the equations of motion. We found that the ellipsoidal model gives a significantly less restrictive trapping condition than that of the spherical bubble model. The trapping condition is compared with three-dimensional particle-in-cell simulations and the electron trajectory in test potential simulations.

  4. Role of stochastic heating in wakefield acceleration when optical injection is used

    SciTech Connect (OSTI)

    Rassou, S.; Bourdier, A.; Drouin, M.

    2014-08-15

    The dynamics of an electron in two counterpropagating waves is investigated. Conditions for stochastic acceleration are derived. The possibility of stochastic heating is confirmed when two waves interact with low density plasma by performing PIC (Particle In Cell) code simulations. It is shown that stochastic heating can play an important role in laser wakefield acceleration. When considering low density plasma interacting with a high intensity wave perturbed by a low intensity counterpropagating wave, stochastic heating can provide electrons with the right momentum for trapping in the wakefield. The influence of stochastic acceleration on the trapping of electrons is compared to the one of the beatwave force which is responsible for cold injection. To do so, several polarizations for the colliding pulses are considered. For some value of the plasma density and pulse duration, a transition from an injection due to stochastic acceleration to a cold injection dominated regime—regarding the trapped charge—has been observed from 2D and 3D PIC code simulations. This transition is ruled by the ratio of the interaction length of the pulses to the longitudinal size of the bubble. When the interaction length of the laser pulses reaches the radius of the accelerating cavity stochastic heating becomes dominant, and might be necessary to get electrons trapped into the wakefield, when wakefield inhibition grows with plasma density.

  5. Generation of 500 MeV-1 GeV energy electrons from laser wakefield acceleration via ionization induced injection using CO{sub 2} mixed in He

    SciTech Connect (OSTI)

    Mo, M. Z.; Ali, A.; Fedosejevs, R.; Fourmaux, S.; Lassonde, P.; Kieffer, J. C.

    2013-04-01

    Laser wakefield acceleration of 500 MeV to 1 GeV electron bunches has been demonstrated using ionization injection in mixtures of 4% to 10% of CO{sub 2} in He. 80 TW laser pulses were propagated through 5 mm gas jet targets at electron densities of 0.4-1.5 Multiplication-Sign 10{sup 19}cm{sup -3}. Ionization injection led to lower density thresholds, a higher total electron charge, and an increased probability of producing electrons above 500 MeV in energy compared to self-injection in He gas alone. Electrons with GeV energies were also observed on a few shots and indicative of an additional energy enhancement mechanism.

  6. Operational plasma density and laser parameters for future colliders based on laser-plasma accelerators

    SciTech Connect (OSTI)

    Schroeder, C. B.; Esarey, E.; Leemans, W. P.

    2012-12-21

    The operational plasma density and laser parameters for future colliders based on laser-plasma accelerators are discussed. Beamstrahlung limits the charge per bunch at low plasma densities. Reduced laser intensity is examined to improve accelerator efficiency in the beamstrahlung-limited regime.

  7. Observation of a strong correlation between electromagnetic soliton formation and relativistic self-focusing for ultra-short laser pulses propagating through an under-dense plasma

    SciTech Connect (OSTI)

    Zhu Bin; Wu Yuchi; Dong Kegong; Hong Wei; Teng Jian; Zhou Weimin; Cao Leifeng; Gu Yuqiu

    2012-10-15

    A strong correlation is observed between the formation of electromagnetic solitons, generated during the interaction of a short intense laser pulse (30 fs, {approx}10{sup 18} W/cm{sup 2}) with a rarefied (<0.1n{sub c}) plasma, and pulse self-focusing. Pulse defocusing, which occurs after soliton generation, results in laser-pulse energy depletion. The role of stimulated Raman scattering in soliton generation is analyzed from 2D particle-in-cell simulations. An observed relationship between initial plasma density and soliton generation is presented that might have relevance to wake-field accelerators.

  8. Proton Radiography of Magnetic Fields in a Laser Produced Plasma...

    Office of Scientific and Technical Information (OSTI)

    Proton Radiography of Magnetic Fields in a Laser Produced Plasma Citation Details In-Document Search Title: Proton Radiography of Magnetic Fields in a Laser Produced Plasma ...

  9. Laser Ionized Preformed Plasma at FACET (Conference) | SciTech...

    Office of Scientific and Technical Information (OSTI)

    Conference: Laser Ionized Preformed Plasma at FACET Citation Details In-Document Search Title: Laser Ionized Preformed Plasma at FACET You are accessing a document from the ...

  10. Improvements to Laser Ablation-Inductively Coupled Plasma-Mass...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Improvements to Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry for Quantitative Analysis using Short Pulse UV Laser FWPProject Description: Laser ablation inductively ...

  11. Laser Wakefield Particle Acceleration

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    in new capability for rapid data exploration and analysis. Investigators: Cameron Geddes, Jean-Luc Vay, Carl Schroeder, E. Cormier-Michel, E. Esarey, W.P. Leemans (LBNL); D.L....

  12. Role of the laser pulse-length in producing high-quality electron beams in a homogenous plasma

    SciTech Connect (OSTI)

    Upadhyay, Ajay K.; Arun Samant, Sushil; Krishnagopal, Srinivas

    2012-07-15

    In laser wakefield acceleration, the pulse-length of the laser is an important parameter that affects the laser evolution and electron beam injection and acceleration in the bubble regime. Here, we use three-dimensional simulations to find, for a given plasma density, the optimal pulse-length that gives the best quality electron beam. For three different pulse lengths, we study the evolution dynamics of the laser spot-size and quality of the injected electron beam. We find that a pulse-length that is less than the theoretical optimum, {tau}{sub L} = {lambda}{sub p}/{radical}2{pi}c, derived from linear theory, gives the best beam quality. Conversely, our simulations suggest that for a given laser system, with a fixed pulse-length, there is an optimal value of the plasma density that will give the best quality accelerated beams in experiments. For an rms pulse-length of 10 fs (around 24 fs FWHM), this corresponds to a plasma density of around 3.4 Multiplication-Sign 10{sup 18}/cm{sup 3}. For these parameters, we obtain, in a homogenous plasma and with a single laser, an electron beam with an energy of around 700 MeV, an energy-spread less than 2%, and rms normalized emittance of a few {pi} mm-mrad.

  13. Laser-Plasma Interactions in High-Energy-Density Plasmas

    SciTech Connect (OSTI)

    Baldis, H

    2006-10-17

    High temperature hohlraums (HTH) are designed to reach high radiation temperatures by coupling a maximum amount of laser energy into a small target in a short time. These 400-800 {micro}m diameter gold cylinders rapidly fill with hot plasma during irradiation with multiple beams in 1ns laser pulses. The high-Z plasmas are dense, (electron density, n{sub e}/n{sub c} {approx} 0.1-0.4), hot (electron temperature, T{sub e} {approx} 10keV) and are bathed in a high-temperature radiation field (radiation temperature, T{sub rad} {approx} 300eV). Here n{sub c}, the critical density, equals 9 x 10{sup 21}/cm{sup 3}. The laser beams heating this plasma are intense ({approx} 10{sup 15} - 10{sup 17} W/cm{sup 2}). The coupling of the laser to the plasma is a rich regime for Laser-Plasma Interaction (LPI) physics. The LPI mechanisms in this study include beam deflection and forward scattering. In order to understand the LPI mechanisms, the plasma parameters must be known. An L-band spectrometer is used to measure the and electron temperature. A ride-along experiment is to develop the x-radiation emitted by the thin back wall of the half-hohlraum into a thermal radiation source.

  14. Ultra-low emittance beam generation using two-color ionization injection in a CO2 laser-driven plasma accelerator

    SciTech Connect (OSTI)

    Schroeder, Carl; Benedetti, Carlo; Bulanov, Stepan; Chen, Min; Esarey, Eric; Geddes, Cameron; Vay, J.; Yu, Lule; Leemans, Wim

    2015-05-21

    Ultra-low emittance (tens of nm) beams can be generated in a plasma accelerator using ionization injection of electrons into a wakefield. An all-optical method of beam generation uses two laser pulses of different colors. A long-wavelength drive laser pulse (with a large ponderomotive force and small peak electric field) is used to excite a large wakefield without fully ionizing a gas, and a short-wavelength injection laser pulse (with a small ponderomotive force and large peak electric field), co-propagating and delayed with respect to the pump laser, to ionize a fraction of the remaining bound electrons at a trapped wake phase, generating an electron beam that is accelerated in the wake. The trapping condition, the ionized electron distribution, and the trapped bunch dynamics are discussed. Expressions for the beam transverse emittance, parallel and orthogonal to the ionization laser polarization, are presented. An example is shown using a 10-micron CO2 laser to drive the wake and a frequency-doubled Ti:Al2O3 laser for ionization injection.

  15. Relativistic laser pulse compression in magnetized plasmas

    SciTech Connect (OSTI)

    Liang, Yun; Sang, Hai-Bo Wan, Feng; Lv, Chong; Xie, Bai-Song

    2015-07-15

    The self-compression of a weak relativistic Gaussian laser pulse propagating in a magnetized plasma is investigated. The nonlinear Schrödinger equation, which describes the laser pulse amplitude evolution, is deduced and solved numerically. The pulse compression is observed in the cases of both left- and right-hand circular polarized lasers. It is found that the compressed velocity is increased for the left-hand circular polarized laser fields, while decreased for the right-hand ones, which is reinforced as the enhancement of the external magnetic field. We find a 100 fs left-hand circular polarized laser pulse is compressed in a magnetized (1757 T) plasma medium by more than ten times. The results in this paper indicate the possibility of generating particularly intense and short pulses.

  16. Particle Gas Target for High Density Laser Produced Plasmas Charles...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Particle Gas Target for High Density Laser Produced Plasmas Charles H. Skinner, Nathaniel Fisch, and Ernest Valeo This invention is a novel "particle gas" cell for achieving plasma ...

  17. Laser Ionized Preformed Plasma at FACET (Conference) | SciTech...

    Office of Scientific and Technical Information (OSTI)

    Resource Relation: Journal Name: Plasma Physics and Controlled Fusion; Journal Volume: 56; Journal Issue: 7; Conference: Presented at Laser and Plasma Accelerator Workshop, i Sep ...

  18. Production of plasmas by long-wavelength lasers

    DOE Patents [OSTI]

    Dawson, J.M.

    1973-10-01

    A long-wavelength laser system for heating low-density plasma to high temperatures is described. In one embodiment, means are provided for repeatedly receiving and transmitting long-wavelength laser light in successive stages to form a laser-light beam path that repeatedly intersects with the equilibrium axis of a magnetically confined toroidal plasma column for interacting the laser light with the plasma for providing controlled thermonuclear fusion. Embodiments for heating specific linear plasmas are also provided. (Official Gazette)

  19. Laser propagation in underdense plasmas: Scaling arguments

    SciTech Connect (OSTI)

    Garrison, J.C.

    1993-05-01

    The propagation of an intense laser beam in the underdense plasma is modelled by treating the plasma as a relativistic, zero temperature, charged fluid. For paraxial propagation and a sufficiently underdense plasma ({omega}p/{omega} {much_lt} 1), a multiple-scales technique is used to expand the exact equations in powers of the small parameter {theta} {equivalent_to} {omega}p/{omega}. The zeroth order equations are used in a critical examination of previous work on this problem, and to derive a scaling law for the threshold power required for cavitation.

  20. Laser-driven electron acceleration in an inhomogeneous plasma channel

    SciTech Connect (OSTI)

    Zhang, Rong; Cheng, Li-Hong; Xue, Ju-Kui

    2015-12-15

    We study the laser-driven electron acceleration in a transversely inhomogeneous plasma channel. We find that, in inhomogeneous plasma channel, the developing of instability for electron acceleration and the electron energy gain can be controlled by adjusting the laser polarization angle and inhomogeneity of plasma channel. That is, we can short the accelerating length and enhance the energy gain in inhomogeneous plasma channel by adjusting the laser polarization angle and inhomogeneity of the plasma channel.

  1. PRECISE CHARGE MEASUREMENT FOR LASER PLASMA ACCELERATORS

    SciTech Connect (OSTI)

    Nakamura, Kei; Gonsalves, Anthony; Lin, Chen; Sokollik, Thomas; Shiraishi, Satomi; Tilborg, Jeroen van; Osterhoff, Jens; Donahue, Rich; Rodgers, David; Smith, Alan; Byrne, Warren; Leemans, Wim

    2011-07-19

    Cross-calibrations of charge diagnostics are conducted to verify their validity for measuring electron beams produced by laser plasma accelerators (LPAs). Employed diagnostics are a scintillating screen, activation based measurement, and integrating current transformer. The diagnostics agreed within {+-}8 %, showing that they can provide accurate charge measurements for LPAs provided they are used properly.

  2. Modeling of 10 GeV-1 TeV laser-plasma accelerators using Lorentz booster simulations

    SciTech Connect (OSTI)

    Vay, J.-L.; Geddes, C.G.R.; Esarey, E.; Esarey, E.; Leemans, W.P.; Cormier-Michel, E.; Grote, D.P.

    2011-12-01

    Modeling of laser-plasma wakefield accelerators in an optimal frame of reference [J.-L. Vay, Phys. Rev. Lett. 98 130405 (2007)] allows direct and e#14;fficient full-scale modeling of deeply depleted and beam loaded laser-plasma stages of 10 GeV-1 TeV (parameters not computationally accessible otherwise). This verifies the scaling of plasma accelerators to very high energies and accurately models the laser evolution and the accelerated electron beam transverse dynamics and energy spread. Over 4, 5 and 6 orders of magnitude speedup is achieved for the modeling of 10 GeV, 100 GeV and 1 TeV class stages, respectively. Agreement at the percentage level is demonstrated between simulations using different frames of reference for a 0.1 GeV class stage. Obtaining these speedups and levels of accuracy was permitted by solutions for handling data input (in particular particle and laser beams injection) and output in a relativistically boosted frame of reference, as well as mitigation of a high-frequency instability that otherwise limits effectiveness.

  3. Laser plasma instability experiments with KrF lasers

    SciTech Connect (OSTI)

    Weaver, J. L.; Karasik, M.; Serlin, V.; Obenschain, S.; Chan, L-Y.; Kehne, D.; Schmitt, A. J.; Colombant, D.; Velikovich, A.; Oh, J.; Lehmberg, R. H.; Afeyan, B.; Phillips, L.; Seely, J.; Brown, C.; Feldman, U.; Aglitskiy, Y.; Mostovych, A. N.; Holland, G.

    2007-05-15

    Deleterious effects of laser-plasma instability (LPI) may limit the maximum laser irradiation that can be used for inertial confinement fusion. The short wavelength (248 nm), large bandwidth, and very uniform illumination available with krypton-fluoride (KrF) lasers should increase the maximum usable intensity by suppressing LPI. The concomitant increase in ablation pressure would allow implosion of low-aspect-ratio pellets to ignition with substantial gain (>20) at much reduced laser energy. The proposed KrF-laser-based Fusion Test Facility (FTF) would exploit this strategy to achieve significant fusion power (150 MW) with a rep-rate system that has a per pulse laser energy well below 1 MJ. Measurements of LPI using the Nike KrF laser are presented at and above intensities needed for the FTF (I{approx}2x10{sup 15} W/cm{sup 2}). The results to date indicate that LPI is indeed suppressed. With overlapped beam intensity above the planar, single beam intensity threshold for the two-plasmon decay instability, no evidence of instability was observed via measurements of (3/2){omega}{sub o} and (1/2){omega}{sub o} harmonic emissions.

  4. Control of laser-ablation plasma potential with external electrodes

    SciTech Connect (OSTI)

    Isono, Fumika Nakajima, Mitsuo; Hasegawa, Jun; Kawamura, Tohru; Horioka, Kazuhiko

    2015-08-15

    The potential of a laser-ablation plasma was controlled stably up to +2 kV by using external ring electrodes. A stable electron sheath was formed between the plasma and the external electrodes by placing the ring electrodes away from the boundary of the drifting plasma. The plasma kept the potential for a few μs regardless of the flux change of the ablation plasma. We also found that the plasma potential changed with the expansion angle of the plasma from the target. By changing the distance between the plasma boundary and the external electrodes, we succeeded in controlling the potential of laser-ablation plasma.

  5. Recombination laser by laser-produced xenon plasmas

    SciTech Connect (OSTI)

    Lanying, L.; Zaitong, L.; Dounan, Z.; Zemin, W.

    1982-09-01

    A recombination laser of Xe plasma produced in a gaseous mixture of He and Xe with a CO/sub 2/ laser pulse of 10.6 micron wave is reported. The particle number is the result of electron-ion recombination. The wavelength of the Xe recombination laser obtained in the experiment is 2.03 microns with an output power of more than 80 watts and a pulse width of 2 microsec. The input CO/sub 2/ laser energy is supplied by a CO/sub 2/ laser with cold cathode electron beam controlled discharge. Each pulse has an energy of over 30 joules (pulse width 1 to 2 microsec). After being reflected by a cylindrical reflector of 6 cm focal length in the target chamber, the CO/sub 2/ laser beam is focussed on a metal target 8 cm long 3 mm wide. At the two ends of the chamber are Brewster angle windows at 2.03 microns made by quartz plates.

  6. Compact X-ray Free Electron Laser from a Laser-plasma Accelerator using a

    Office of Scientific and Technical Information (OSTI)

    Transverse Gradient Undulator (Journal Article) | SciTech Connect Compact X-ray Free Electron Laser from a Laser-plasma Accelerator using a Transverse Gradient Undulator Citation Details In-Document Search Title: Compact X-ray Free Electron Laser from a Laser-plasma Accelerator using a Transverse Gradient Undulator Compact laser-plasma accelerators can produce high energy electron beams with low emittance, high peak current but a rather large energy spread. The large energy spread hinders

  7. Light source employing laser-produced plasma

    DOE Patents [OSTI]

    Tao, Yezheng; Tillack, Mark S

    2013-09-17

    A system and a method of generating radiation and/or particle emissions are disclosed. In at least some embodiments, the system includes at least one laser source that generates a first pulse and a second pulse in temporal succession, and a target, where the target (or at least a portion the target) becomes a plasma upon being exposed to the first pulse. The plasma expand after the exposure to the first pulse, the expanded plasma is then exposed to the second pulse, and at least one of a radiation emission and a particle emission occurs after the exposure to the second pulse. In at least some embodiments, the target is a solid piece of material, and/or a time period between the first and second pulses is less than 1 microsecond (e.g., 840 ns).

  8. Collaborative Research: Instability and transport of laser beam in plasma

    SciTech Connect (OSTI)

    Rose, Harvey Arnold; Lushnikov, Pavel

    2014-11-18

    Our goal was to determine the onset of laser light scattering due to plasma wave instabilities. Such scatter is usually regarded as deleterious since laser beam strength is thereby diminished. While this kind of laser-plasma-instability (LPI) has long been understood for the case of coherent laser light, the theory of LPI onset for a laser beam with degraded coherence is recent. Such a laser beam fills plasma with a mottled intensity distribution, which has large fluctuations. The key question is: do the exceptionally large fluctuations control LPI onset or is it controlled by the relatively quiescent background laser intensity? We have answered this question. This is significant because LPI onset power in the former case is typically small compared to that of the latter. In addition, if large laser intensity fluctuations control LPI onset, then nonlinear effects become significant for less powerful laser beams than otherwise estimated.

  9. Effects of laser polarization in the expansion of plasma waveguides

    SciTech Connect (OSTI)

    Lemos, N.; Grismayer, T.; Cardoso, L.; Geada, J.; Figueira, G.; Dias, J. M.

    2013-10-15

    We experimentally demonstrate that a column of hydrogen plasma generated by an ultra-short (sub-picosecond), moderate intensity (∼10{sup 15–16} W.cm{sup –2}) laser, radially expands at a higher velocity when using a circularly polarized laser beam instead of a linearly polarized beam. Interferometry shows that after 1 ns there is a clear shock structure formed, that can be approximated to a cylindrical blast wave. The shock velocity was measured for plasmas created with linearly and circularly polarized laser beams, indicating an approximately 20% higher velocity for plasmas generated with a circularly polarized laser beam, thus implying a higher plasma electron temperature. The heating mechanism was determined to be the Above Threshold Ionization effect. The calculated electrum energy spectrum for a circularly polarized laser beam was broader when compared to the one generated by a linearly polarized laser beam, leading to a higher plasma temperature.

  10. Nonlinear Laser-Plasma Interaction in Magnetized Liner Inertial Fusion

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Geissel, Matthias; Awe, Thomas James; Bliss, David E.; Campbell, Edward Michael; Gomez, Matthew R.; Harding, Eric; Harvey-Thompson, Adam James; Hansen, Stephanie B.; Jennings, Christopher Ashley; Kimmel, Mark W.; et al

    2016-03-04

    Sandia National Laboratories is pursuing a variation of Magneto-Inertial Fusion called Magnetized Liner Inertial Fusion, or MagLIF. The MagLIF approach requires magnetization of the deuterium fuel, which is accomplished by an initial external B-Field and laser-driven pre-heat. Although magnetization is crucial to the concept, it is challenging to couple sufficient energy to the fuel, since laser-plasma instabilities exist, and a compromise between laser spot size, laser entrance window thickness, and fuel density must be found. Ultimately, nonlinear processes in laser plasma interaction, or laser-plasma instabilities (LPI), complicate the deposition of laser energy by enhanced absorption, backscatter, filamentation and beam-spray. Wemore » determine and discuss key LPI processes and mitigation methods. Results with and without improvement measures are presented.« less

  11. The interaction of intense subpicosecond laser pulses with underdense plasmas

    SciTech Connect (OSTI)

    Coverdale, C.A.

    1995-05-11

    Laser-plasma interactions have been of interest for many years not only from a basic physics standpoint, but also for their relevance to numerous applications. Advances in laser technology in recent years have resulted in compact laser systems capable of generating (psec), 10{sup 16} W/cm{sup 2} laser pulses. These lasers have provided a new regime in which to study laser-plasma interactions, a regime characterized by L{sub plasma} {ge} 2L{sub Rayleigh} > c{tau}. The goal of this dissertation is to experimentally characterize the interaction of a short pulse, high intensity laser with an underdense plasma (n{sub o} {le} 0.05n{sub cr}). Specifically, the parametric instability known as stimulated Raman scatter (SRS) is investigated to determine its behavior when driven by a short, intense laser pulse. Both the forward Raman scatter instability and backscattered Raman instability are studied. The coupled partial differential equations which describe the growth of SRS are reviewed and solved for typical experimental laser and plasma parameters. This solution shows the growth of the waves (electron plasma and scattered light) generated via stimulated Raman scatter. The dispersion relation is also derived and solved for experimentally accessible parameters. The solution of the dispersion relation is used to predict where (in k-space) and at what frequency (in {omega}-space) the instability will grow. Both the nonrelativistic and relativistic regimes of the instability are considered.

  12. Argonne Wakefield Accelerator Facility | Argonne National Laboratory

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Facilities 4 Tesla Magnet Facility Argonne Wakefield Accelerator Facility Argonne Wakefield Accelerator Facility Argonne Wakefield Accelerator Facility In order to achieve the high accelerating gradients needed to produce the tremendous energies required by a future particle accelerator, scientists have been looking for new ideas and solutions. Wakefield acceleration offers a potentially bold new path for the construction of the next generation of particle accelerators. The Argonne Wakefield

  13. Intense transient magnetic-field generation by laser plasma

    SciTech Connect (OSTI)

    Benjamin, R.F.

    1981-08-18

    In a laser system, the return current of a laser generated plasma is conducted near a target to subject that target to the magnetic field thereof. In alternate embodiments the target may be either a small non-fusion object for testing under the magnetic field or a laser-fusion pellet. In the laser-fusion embodiment, the laser-fusion pellet is irradiated during the return current flow and the intense transient magnetic field is used to control the hot electrons thereof to hinder them from striking and heating the core of the irradiated laser-fusion pellet.

  14. Laser-induced breakdown spectroscopic study of ammonium nitrate plasma

    SciTech Connect (OSTI)

    Hanif, M.; Salik, M.; Baig, M. A.

    2013-12-15

    We present the optical emission studies of the ammonium nitrate plasma produced by the fundamental (1064 nm) and second (532 nm) harmonics of a Q-switched Nd: YAG laser. The target material was placed in front of the laser beam in an open atmospheric air. The spectrum reveals numerous transitions of neutral nitrogen. We have studied the spatial behavior of the plasma temperature (T{sub e}) and electron number density (N{sub e}) determined using the Boltzmann plot method and Stark broadened line profiles, respectively. Besides, we have studied the variation of the plasma parameters as a function of the laser irradiance.

  15. Laser-driven plasma waves in capillary tubes

    SciTech Connect (OSTI)

    Wojda, F.; Cassou, K.; Cros, B.; Genoud, G.; Burza, M.; Glinec, Y.; Lundh, O.; Persson, A.; Wahlstroem, C.-G.; Vieux, G.; Brunetti, E.; Shanks, R. P.; Jaroszynski, D.; Andreev, N. E.

    2009-12-15

    The excitation of plasma waves over a length of up to 8 cm is demonstrated using laser guiding of intense laser pulses through hydrogen-filled glass capillary tubes. The plasma waves are diagnosed by spectral analysis of the transmitted laser radiation. The dependence of the spectral redshift--measured as a function of filling pressure, capillary tube length, and incident laser energy - is in excellent agreement with simulation results. The longitudinal accelerating field inferred from the simulations is in the range of 1-10 GV/m.

  16. Traveling-wave laser-produced-plasma energy source for photoionization laser pumping and lasers incorporating said

    DOE Patents [OSTI]

    Sher, Mark H.; Macklin, John J.; Harris, Stephen E.

    1989-09-26

    A traveling-wave, laser-produced-plasma, energy source used to obtain single-pass gain saturation of a photoionization pumped laser. A cylindrical lens is used to focus a pump laser beam to a long line on a target. Grooves are cut in the target to present a surface near normal to the incident beam and to reduce the area, and hence increase the intensity and efficiency, of plasma formation.

  17. Interaction of plasmas in laser ion source with double laser system

    SciTech Connect (OSTI)

    Fuwa, Y.; Ikeda, S.; Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Yokohama, Tokyo ; Kumaki, M.; Research Institute for Science and Engineering, Waseda University, Shinjuku, Tokyo ; Sekine, M.; Department of Nuclear Engineering, Tokyo Institute of Technology, Meguro, Tokyo ; Cinquegrani, D.; Romanelli, M.; Kanesue, T.; Okamura, M.; Iwashita, Y.

    2014-02-15

    Multiple laser shots could be used to elongate an ion beam pulse width or to intensify beam current from laser ion sources. In order to confirm the feasibility of the multiple shot scheme, we investigated the properties of plasmas produced by double laser shots. We found that when the interval of the laser shots is shorter than 10 ?s, the ion current profile had a prominent peak, which is not observed in single laser experiments. The height of this peak was up to five times larger than that of single laser experiment.

  18. Plasma Channel Diagnostic Based on Laser Centroid Oscillations

    SciTech Connect (OSTI)

    Gonsalves, A.J.; Nakamura, K.; Lin, C.; Osterhoff, J.; Shiraishi, S.; Schroeder, C.B.; Geddes, C.G.R.; Toth, Cs.; Esarey, E.; Leemans, W.P.

    2010-02-12

    A technique has been developed for measuring the properties of discharge-based plasma channels by monitoring the centroid location of a laser beam exiting the channel as a function of input alignment offset between the laser and the channel. Experiments were performed using low-intensity (< 1014 Wcm-2) laser pulses focused onto the entrance of a hydrogen-filled capillary discharge waveguide. Scanning the laser centroid position at the input of the channel and recording the exit position allows determination of the channel depth with an accuracy of a few percent, measurement of the transverse channel shape, and inference of the matched spot size. In addition, accurate alignment of the laser beam through the plasma channel is provided by minimizing laser centroid motion at the channel exit as the channel depth is scanned either by scanning the plasma density or the discharge timing. The improvement in alignment accuracy provided by this technique will be crucial for minimizing electron beam pointing errors in laser plasma accelerators.

  19. Control of focusing forces and emittances in plasma-based accelerators using near-hollow plasma channels

    SciTech Connect (OSTI)

    Schroeder, C. B.; Esarey, E.; Benedetti, C.; Leemans, W. P.

    2013-08-15

    A near-hollow plasma channel, where the plasma density in the channel is much less than the plasma density in the walls, is proposed to provide independent control over the focusing and accelerating forces in a plasma accelerator. In this geometry the low density in the channel contributes to the focusing forces, while the accelerating fields are determined by the high density in the channel walls. The channel also provides guiding for intense laser pulses used for wakefield excitation. Both electron and positron beams can be accelerated in a nearly symmetric fashion. Near-hollow plasma channels can effectively mitigate emittance growth due to Coulomb scattering for high-energy physics applications.

  20. Intense isolated attosecond pulse generation from relativistic laser plasmas using few-cycle laser pulses

    SciTech Connect (OSTI)

    Ma, Guangjin; Dallari, William; Borot, Antonin; Tsakiris, George D.; Veisz, Laszlo; Krausz, Ferenc; Yu, Wei

    2015-03-15

    We have performed a systematic study through particle-in-cell simulations to investigate the generation of attosecond pulse from relativistic laser plasmas when laser pulse duration approaches the few-cycle regime. A significant enhancement of attosecond pulse energy has been found to depend on laser pulse duration, carrier envelope phase, and plasma scale length. Based on the results obtained in this work, the potential of attaining isolated attosecond pulses with ∼100 μJ energy for photons >16 eV using state-of-the-art laser technology appears to be within reach.

  1. Erosion resistant nozzles for laser plasma extreme ultraviolet (EUV) sources

    DOE Patents [OSTI]

    Kubiak, Glenn D.; Bernardez, II, Luis J.

    2000-01-04

    A gas nozzle having an increased resistance to erosion from energetic plasma particles generated by laser plasma sources. By reducing the area of the plasma-facing portion of the nozzle below a critical dimension and fabricating the nozzle from a material that has a high EUV transmission as well as a low sputtering coefficient such as Be, C, or Si, it has been shown that a significant reduction in reflectance loss of nearby optical components can be achieved even after exposing the nozzle to at least 10.sup.7 Xe plasma pulses.

  2. Laser-electron Compton interaction in plasma channels

    SciTech Connect (OSTI)

    Pogorelsky, I.V.; Ben-Zvi, I.; Hirose, T.

    1998-10-01

    A concept of high intensity femtosecond laser synchrotron source (LSS) is based on Compton backscattering of focused electron and laser beams. The short Rayleigh length of the focused laser beam limits the length of interaction to a few picoseconds. However, the technology of the high repetition rate high-average power picosecond lasers required for high put through LSS applications is not developed yet. Another problem associated with the picosecond laser pulses is undesirable nonlinear effects occurring when the laser photons are concentrated in a short time interval. To avoid the nonlinear Compton scattering, the laser beam has to be split, and the required hard radiation flux is accumulated over a number of consecutive interactions that complicates the LSS design. In order to relieve the technological constraints and achieve a practically feasible high-power laser synchrotron source, the authors propose to confine the laser-electron interaction region in the extended plasma channel. This approach permits to use nanosecond laser pulses instead of the picosecond pulses. That helps to avoid the nonlinear Compton scattering regime and allows to utilize already existing technology of the high-repetition rate TEA CO{sub 2} lasers operating at the atmospheric pressure. They demonstrate the advantages of the channeled LSS approach by the example of the prospective polarized positron source for Japan Linear Collider.

  3. Plasma shape control by pulsed solenoid on laser ion source

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Sekine, M.; Ikeda, S.; Romanelli, M.; Kumaki, M.; Fuwa, Y.; Kanesue, T.; Hayashizaki, N.; Lambiase, R.; Okamura, M.

    2015-05-28

    A Laser ion source (LIS) provides high current heavy ion beams with a very simple mechanical structure. Plasma is produced by a pulsed laser ablation of a solid state target and ions are extracted by an electric field. It was difficult to manipulate the beam parameters of a LIS, since the plasma condition could only be adjusted by the laser irradiation condition. To enhance flexibility of LIS operation, we employed a pulsed solenoid in the plasma drift section and investigated the effect of the solenoid field on singly charged iron beams. The experimentally obtained current profile was satisfactorily controlled bymore » the pulsed magnetic field. Thus, this approach may also be useful to reduce beam emittance of a LIS.« less

  4. Plasma shape control by pulsed solenoid on laser ion source

    SciTech Connect (OSTI)

    Sekine, M.; Ikeda, S.; Romanelli, M.; Kumaki, M.; Fuwa, Y.; Kanesue, T.; Hayashizaki, N.; Lambiase, R.; Okamura, M.

    2015-05-28

    A Laser ion source (LIS) provides high current heavy ion beams with a very simple mechanical structure. Plasma is produced by a pulsed laser ablation of a solid state target and ions are extracted by an electric field. It was difficult to manipulate the beam parameters of a LIS, since the plasma condition could only be adjusted by the laser irradiation condition. To enhance flexibility of LIS operation, we employed a pulsed solenoid in the plasma drift section and investigated the effect of the solenoid field on singly charged iron beams. The experimentally obtained current profile was satisfactorily controlled by the pulsed magnetic field. Thus, this approach may also be useful to reduce beam emittance of a LIS.

  5. Staging of laser-plasma accelerators (Journal Article) | SciTech...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Staging of laser-plasma accelerators Citation Details In-Document Search ... Type: Publisher's Accepted Manuscript Journal Name: Physics of Plasmas Additional ...

  6. Spatial diagnostics of the laser induced lithium fluoride plasma

    SciTech Connect (OSTI)

    Baig, M. A.; Qamar, Aisha; Fareed, M. A.; Anwar-ul-Haq, M.; Ali, Raheel

    2012-06-15

    We present spatial characteristics of the lithium fluoride plasma generated by the fundamental and second harmonic of a Nd:YAG laser. The plume emission has been recorded spatially using five spectrometers covering the spectral region from 200 nm to 720 nm. The electron density is measured from the Stark broadened line profile of the line at 610.37 nm, whereas the plasma temperature has been determined using the Boltzmann plot method including all the observed spectral lines of lithium. Both the plasma parameters; electron density and plasma temperature decrease with the increase of the distance from the target surface. The thermal conduction towards the target, the radiative cooling of the plasma, and the conversion of thermal energy into kinetic energy are the main mechanisms responsible for the spatially decrease of the plasma parameters.

  7. Plasma lenses for ultrashort multi-petawatt laser pulses

    SciTech Connect (OSTI)

    Palastro, J. P.; Gordon, D.; Hafizi, B.; Johnson, L. A.; Peñano, J.; Hubbard, R. F.; Helle, M.; Kaganovich, D.

    2015-12-15

    An ideal plasma lens can provide the focusing power of a small f-number, solid-state focusing optic at a fraction of the diameter. An ideal plasma lens, however, relies on a steady-state, linear laser pulse-plasma interaction. Ultrashort multi-petawatt (MPW) pulses possess broad bandwidths and extreme intensities, and, as a result, their interaction with the plasma lens is neither steady state nor linear. Here, we examine nonlinear and time-dependent modifications to plasma lens focusing, and show that these result in chromatic and phase aberrations and amplitude distortion. We find that a plasma lens can provide enhanced focusing for 30 fs pulses with peak power up to ∼1 PW. The performance degrades through the MPW regime, until finally a focusing penalty is incurred at ∼10 PW.

  8. Petascale Simulations of Laser Plasma Interaction Relevant to IFE | Argonne

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Leadership Computing Facility Petascale Simulations of Laser Plasma Interaction Relevant to IFE PI Name: Frank Tsung PI Email: tsung@physics.ucla.edu Institution: University of California, Los Angeles Allocation Program: INCITE Allocation Hours at ALCF: 90 Million Year: 2015 Research Domain: Physics Inertial (laser-initiated) fusion energy (IFE) holds incredible promise as a source of clean and sustainable energy for powering devices. However, significant obstacles to obtaining and

  9. Persistence of uranium emission in laser-produced plasmas

    SciTech Connect (OSTI)

    LaHaye, N. L.; Harilal, S. S. Diwakar, P. K.; Hassanein, A.

    2014-04-28

    Detection of uranium and other nuclear materials is of the utmost importance for nuclear safeguards and security. Optical emission spectroscopy of laser-ablated U plasmas has been presented as a stand-off, portable analytical method that can yield accurate qualitative and quantitative elemental analysis of a variety of samples. In this study, optimal laser ablation and ambient conditions are explored, as well as the spatio-temporal evolution of the plasma for spectral analysis of excited U species in a glass matrix. Various Ar pressures were explored to investigate the role that plasma collisional effects and confinement have on spectral line emission enhancement and persistence. The plasma-ambient gas interaction was also investigated using spatially resolved spectra and optical time-of-flight measurements. The results indicate that ambient conditions play a very important role in spectral emission intensity as well as the persistence of excited neutral U emission lines, influencing the appropriate spectral acquisition conditions.

  10. Collimation of laser-produced plasmas using axial magnetic field

    SciTech Connect (OSTI)

    Roy, Amitava; Harilal, Sivanandan S.; Hassan, Syed M.; Endo, Akira; Mocek, Tomas; Hassanein, A.

    2015-06-01

    We investigated the expansion dynamics of laser-produced plasmas expanding into an axial magnetic field. Plasmas were generated by focusing 1.064 µm Nd:YAG laser pulses onto a planar tin target in vacuum and allowed to expand into a 0.5 T magnetic-filed where field lines were aligned along the plume expansion direction. Gated images employing intensified CCD showed focusing of the plasma plume, which were also compared with results obtained using particle-in-cell modelling methods. The estimated density and temperature of the plasma plumes employing emission spectroscopy revealed significant changes in the presence and absence of the 0.5T magnetic field. In the presence of the field, the electron temperature is increased with distance from the target, while the density showed opposite effects.

  11. Harmonic generation by circularly polarized laser beams propagating in plasma

    SciTech Connect (OSTI)

    Agrawal, Ekta; Hemlata,; Jha, Pallavi

    2015-04-15

    An analytical theory is developed for studying the phenomenon of generation of harmonics by the propagation of an obliquely incident, circularly polarized laser beam in homogeneous, underdense plasma. The amplitudes of second and third harmonic radiation as well as detuning distance have been obtained and their variation with the angle of incidence is analyzed. The amplitude of harmonic radiation increases with the angle of incidence while the detuning distance decreases, for a given plasma electron density. It is observed that the generated second and third harmonic radiation is linearly and elliptically polarized, respectively. The harmonic radiation vanishes at normal incidence of the circularly polarized laser beam.

  12. Tailoring femtosecond laser pulse filamentation using plasma photonic lattices

    SciTech Connect (OSTI)

    Suntsov, Sergiy; Abdollahpour, Daryoush; Panagiotopoulos, Paris; Papazoglou, Dimitrios G.; Tzortzakis, Stelios; Couairon, Arnaud

    2013-07-08

    We demonstrate experimentally that by using transient plasma photonic lattices, the attributes of intense femtosecond laser filaments, such as peak intensity and length, can be dynamically controlled. The extended plasma lattice structure is generated using two co-propagating non-diffracting intense Bessel beams in water. The use of such transient lattice structures to control the competition between linear and nonlinear effects involved in filamentation opens the way for extensive control of the filamentation process.

  13. Laser produced plasma diagnostics by cavity ringdown spectroscopy and applications

    SciTech Connect (OSTI)

    Milosevic, S.

    2012-05-25

    Laser-produced plasmas have many applications for which detailed characterization of the plume is requested. Cavity ring-down spectroscopy is a versatile absorption method which provides data on the plume and its surroundings, with spatial and temporal resolution. The measured absorption line shapes contain information about angular and velocity distributions within the plume. In various plasmas we have observed molecules or metastable atoms which were not present in the emission spectra.

  14. Laminar shocks in high power laser plasma interactions

    SciTech Connect (OSTI)

    Cairns, R. A.; Bingham, R.; Norreys, P.; Trines, R.

    2014-02-15

    We propose a theory to describe laminar ion sound structures in a collisionless plasma. Reflection of a small fraction of the upstream ions converts the well known ion acoustic soliton into a structure with a steep potential gradient upstream and with downstream oscillations. The theory provides a simple interpretation of results dating back more than forty years but, more importantly, is shown to provide an explanation for recent observations on laser produced plasmas relevant to inertial fusion and to ion acceleration.

  15. Laser diagnostics | Princeton Plasma Physics Lab

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Laser diagnostics Subscribe to RSS - Laser diagnostics The Multi-Point Thomson Scattering (MPTS) diagnostic system has been providing time dependent Te and ne profile measurements on NSTX for ten years. COLLOQUIUM: Controlling the Production and Performance of Materials at the Mesoscale: The Matter-Radiation Interactions in Extremes (MaRIE) Capability The Matter-Radiation Interactions in Extremes (MaRIE) project will provide capability that will address the control of performance and production

  16. Plasma channels during filamentation of a femtosecond laser pulse with wavefront astigmatism in air

    SciTech Connect (OSTI)

    Dergachev, A A; Kandidov, V P; Shlenov, S A; Ionin, A A; Mokrousova, D V; Seleznev, L V; Sinitsyn, D V; Sunchugasheva, E S; Shustikova, A P

    2014-12-31

    We have demonstrated experimentally and numerically the possibility of controlling parameters of plasma channels formed during filamentation of a femtosecond laser pulse by introducing astigmatism in the laser beam wavefront. It is found that weak astigmatism increases the length of the plasma channel in comparison with the case of aberration-free focusing and that strong astigmatism can cause splitting of the plasma channel into two channels located one after another on the filament axis. (interaction of laser radiation with matter. laser plasma)

  17. Xenon plasma sustained by pulse-periodic laser radiation

    SciTech Connect (OSTI)

    Rudoy, I. G.; Solovyov, N. G.; Soroka, A. M.; Shilov, A. O.; Yakimov, M. Yu.

    2015-10-15

    The possibility of sustaining a quasi-stationary pulse-periodic optical discharge (POD) in xenon at a pressure of p = 10–20 bar in a focused 1.07-μm Yb{sup 3+} laser beam with a pulse repetition rate of f{sub rep} ⩾ 2 kHz, pulse duration of τ ⩾ 200 μs, and power of P = 200–300 W has been demonstrated. In the plasma development phase, the POD pulse brightness is generally several times higher than the stationary brightness of a continuous optical discharge at the same laser power, which indicates a higher plasma temperature in the POD regime. Upon termination of the laser pulse, plasma recombines and is then reinitiated in the next pulse. The initial absorption of laser radiation in successive POD pulses is provided by 5p{sup 5}6s excited states of xenon atoms. This kind of discharge can be applied in plasma-based high-brightness broadband light sources.

  18. Saturation of Langmuir waves in laser-produced plasmas

    SciTech Connect (OSTI)

    Baker, K.L.

    1996-04-01

    This dissertation deals with the interaction of an intense laser with a plasma (a quasineutral collection of electrons and ions). During this interaction, the laser drives large-amplitude waves through a class of processes known as parametric instabilities. Several such instabilities drive one type of wave, the Langmuir wave, which involves oscillations of the electrons relative to the nearly-stationary ions. There are a number of mechanisms which limit the amplitude to which Langmuir waves grow. In this dissertation, these mechanisms are examined to identify qualitative features which might be observed in experiments and/or simulations. In addition, a number of experiments are proposed to specifically look for particular saturation mechanisms. In a plasma, a Langmuir wave can decay into an electromagnetic wave and an ion wave. This parametric instability is proposed as a source for electromagnetic emission near half of the incident laser frequency observed from laser-produced plasmas. This interpretation is shown to be consistent with existing experimental data and it is found that one of the previous mechanisms used to explain such emission is not. The scattering version of the electromagnetic decay instability is shown to provide an enhanced noise source of electromagnetic waves near the frequency of the incident laser.

  19. Validating Laser-Induced Birefringence Theory with Plasma Interferometry

    SciTech Connect (OSTI)

    Chen, Cecilia

    2015-09-02

    Intense laser beams crossing paths in plasma is theorized to induce birefringence in the medium, resulting from density and refractive index modulations that affect the polarization of incoming light. The goal of the associated experiment, conducted on Janus at Lawrence Livermore’s Jupiter Laser Facility, was to create a tunable laser-plasma waveplate to verify the relationship between dephasing angle and beam intensity, plasma density, plasma temperature, and interaction length. Interferometry analysis of the plasma channel was performed to obtain a density map and to constrain temperature measured from Thomson scattering. Various analysis techniques, including Fast Fourier transform (FFT) and two variations of fringe-counting, were tried because interferograms captured in this experiment contained unusual features such as fringe discontinuity at channel edges, saddle points, and islands. The chosen method is flexible, semi-automated, and uses a fringe tracking algorithm on a reduced image of pre-traced synthetic fringes. Ultimately, a maximum dephasing angle of 49.6° was achieved using a 1200 μm interaction length, and the experimental results appear to agree with predictions.

  20. Laser separation of uranium chosen for scaleup. [Atomic vapor laser isotope separation, molecular laser isotope separation, and plasma separation process

    SciTech Connect (OSTI)

    Rawls, R.L.

    1982-05-17

    Atomic vapor laser isotope separation (AVLIS) has been selected by the Department of Energy to go into large-scale engineering development and demonstration over two other advanced technologies, molecular laser isotope separation and plasma separation. DOE will continue to support development of another uranium enrichment technology, gas centrifugation. By or around 1990, the most promising gas centrifuge technique will be compared to the further developed AVLIS process, and a selection will be made between the two to replace the current technology, gaseous diffusion. The AVLIS process, plasma separation, and molecular laser isotope separation use the elective absorption of radiation of a particular energy level by the /sup 235/U isotope. The plasma separation process selectively energizes /sup 235/U by ion cyclotron resonance. The AVLIS and molecular laser isotope separation processes both use a carefully tuned laser to excite /sup 235/U isotope selectively. In the AVLIS process, uranium metal feed material is melted and vaporized to form an atomic uranium vapor stream. When this vapor stream passes through the beam of copper vapor lasers, the /sup 235/U atoms absorb the light and become ionized. These ionized atoms are collected by electromagnetic fields while the neutral /sup 238/U atoms pass through the magnetic field and are collected as tailings. The AVLIS process has the potential for significantly reducing the cost of enriching uranium. The status of dvelopment, cost, advantages and drawbacks of the five processes, (gaseous diffusion, gas centrifugation, AVLIS, molecular laser separation, plasma separation) are discussed. (ATT)

  1. Laser separation of uranium chosen for scaleup. [Atomic vapor laser isotope separation, molecular laser isotope separation plasma separation process

    SciTech Connect (OSTI)

    Rawls, R.L.

    1982-05-17

    Atomic vapor laser isotope separation (AVLIS) has been selected by the Department of Energy to go into large-scale engineering development and demonstration over two other advanced technologies, molecular laser isotope separation and plasma separation. DOE will continue to support development of another uranium enrichment technology, gas centrifugation. By or around 1990, the most promising gas centrifuge technique will be compared to the further developed AVLIS process, and a selection will be made between the two to replace the current technology, gaseous diffusion. The AVLIS process, plasma separation, and molecular laser isotope separation use the selective absorption of radiation of a particular energy level by the /sup 235/U isotope. The plasma separation process selectively energizes /sup 235/U by ion cyclotron resonance. The AVLIS and molecular laser isotope separation processes both use a carefully tuned laser to excite /sup 235/U isotope selectively. In the AVLIS process, uranium metal feed material is melted and vaporized to from an atomic uranium vapor stream. When this vapor stream passes through the beam of copper vapor lasers, the /sup 235/U atoms absorb the light and become ionized. These ionized atoms are collected by electromagnetic fields while the neutral /sup 238/U atoms pass through the magnetic field and are collected as tailings. The AVLIS process has the potential for significantly reducing the cost of enriching uranium. The status of development, cost, advantages and drawbacks of the five processes (gaseous diffusion, gas centrifugation, AVLIS, molecular laser separation, plasma separation) are discussed. (ATT)

  2. Aerosol beam-focus laser-induced plasma spectrometer device

    DOE Patents [OSTI]

    Cheng, Meng-Dawn

    2002-01-01

    An apparatus for detecting elements in an aerosol includes an aerosol beam focuser for concentrating aerosol into an aerosol beam; a laser for directing a laser beam into the aerosol beam to form a plasma; a detection device that detects a wavelength of a light emission caused by the formation of the plasma. The detection device can be a spectrometer having at least one grating and a gated intensified charge-coupled device. The apparatus may also include a processor that correlates the wavelength of the light emission caused by the formation of the plasma with an identity of an element that corresponds to the wavelength. Furthermore, the apparatus can also include an aerosol generator for forming an aerosol beam from bulk materials. A method for detecting elements in an aerosol is also disclosed.

  3. Reducing wall plasma expansion with gold foam irradiated by laser

    SciTech Connect (OSTI)

    Zhang, Lu; Ding, Yongkun Jiang, Shaoen Yang, Jiamin; Li, Hang; Kuang, Longyu; Lin, Zhiwei; Jing, Longfei; Li, Liling; Deng, Bo; Yuan, Zheng; Chen, Tao; Yuan, Guanghui; Tan, Xiulan; Li, Ping

    2015-11-15

    The experimental study on the expanding plasma movement of low-density gold foam (∼1% solid density) irradiated by a high power laser is reported in this paper. Experiments were conducted using the SG-III prototype laser. Compared to solid gold with 19.3 g/cc density, the velocities of X-ray emission fronts moving off the wall are much smaller for gold foam with 0.3 g/cc density. Theoretical analysis and MULTI 1D simulation results also show less plasma blow-off, and that the density contour movement velocities of gold foam are smaller than those of solid gold, agreeing with experimental results. These results indicate that foam walls have advantages in symmetry control and lowering plasma fill when used in ignition hohlraum.

  4. Dechirper Wakefields for Short Bunches (Journal Article) | SciTech...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Dechirper Wakefields for Short Bunches Citation Details In-Document Search Title: Dechirper Wakefields for Short Bunches Authors: Bane, Karl ; Stupakov, Gennady ;...

  5. Dechirper Wakefields for Short Bunches (Journal Article) | SciTech...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Dechirper Wakefields for Short Bunches Citation Details In-Document Search Title: Dechirper Wakefields for Short Bunches You are accessing a document from the...

  6. Analytical theory of coherent synchrotron radiation wakefield...

    Office of Scientific and Technical Information (OSTI)

    Analytical theory of coherent synchrotron radiation wakefield of short bunches shielded by ... Word Cloud More Like This Full Text preview image File size NAView Full Text View Full ...

  7. Wakefield Municipal Gas & Light Department - Residential Conservation...

    Broader source: Energy.gov (indexed) [DOE]

    Programmable Thermostats: 25 Water Heater: 100 Summary The Wakefield Municipal Gas & Light Department (WMGLD), in cooperation with the Massachusetts Municipal Wholesale Electric...

  8. Peculiarities of the angular distribution of laser radiation intensity scattered by laser-spark plasma in air

    SciTech Connect (OSTI)

    Malyutin, A A; Podvyaznikov, V A; Chevokin, V K

    2010-02-28

    The spatiotemporal study of the diagram of laser radiation scattering by the laser-spark plasma produced by 3-ns and 50-ns pulses is performed. It is shown that radiation appearing outside the laser beam cone is scattered during the first one - two nanoseconds after the air breakdown, when the spark plasma is located in the vicinity of the laser beam waist and has a shape close to spherical.

  9. Progress in Long Scale Length Laser-Plasma Interactions

    SciTech Connect (OSTI)

    Glenzer, S H; Arnold, P; Bardsley, G; Berger, R L; Bonanno, G; Borger, T; Bower, D E; Bowers, M; Bryant, R; Buckman, S; Burkhart, S C; Campbell, K; Chrisp, M P; Cohen, B I; Constantin, G; Cooper, F; Cox, J; Dewald, E; Divol, L; Dixit, S; Duncan, J; Eder, D; Edwards, J; Erbert, G; Felker, B; Fornes, J; Frieders, G; Froula, D H; Gardner, S D; Gates, C; Gonzalez, M; Grace, S; Gregori, G; Greenwood, A; Griffith, R; Hall, T; Hammel, B A; Haynam, C; Heestand, G; Henesian, M; Hermes, G; Hinkel, D; Holder, J; Holdner, F; Holtmeier, G; Hsing, W; Huber, S; James, T; Johnson, S; Jones, O S; Kalantar, D; Kamperschroer, J H; Kauffman, R; Kelleher, T; Knight, J; Kirkwood, R K; Kruer, W L; Labiak, W; Landen, O L; Langdon, A B; Langer, S; Latray, D; Lee, A; Lee, F D; Lund, D; MacGowan, B; Marshall, S; McBride, J; McCarville, T; McGrew, L; Mackinnon, A J; Mahavandi, S; Manes, K; Marshall, C; Mertens, E; Meezan, N; Miller, G; Montelongo, S; Moody, J D; Moses, E; Munro, D; Murray, J; Neumann, J; Newton, M; Ng, E; Niemann, C; Nikitin, A; Opsahl, P; Padilla, E; Parham, T; Parrish, G; Petty, C; Polk, M; Powell, C; Reinbachs, I; Rekow, V; Rinnert, R; Riordan, B; Rhodes, M

    2003-11-11

    The first experiments on the National Ignition Facility (NIF) have employed the first four beams to measure propagation and laser backscattering losses in large ignition-size plasmas. Gas-filled targets between 2 mm and 7 mm length have been heated from one side by overlapping the focal spots of the four beams from one quad operated at 351 nm (3{omega}) with a total intensity of 2 x 10{sup 15} W cm{sup -2}. The targets were filled with 1 atm of CO{sub 2} producing of up to 7 mm long homogeneously heated plasmas with densities of n{sub e} = 6 x 10{sup 20} cm{sup -3} and temperatures of T{sub e} = 2 keV. The high energy in a NIF quad of beams of 16kJ, illuminating the target from one direction, creates unique conditions for the study of laser plasma interactions at scale lengths not previously accessible. The propagation through the large-scale plasma was measured with a gated x-ray imager that was filtered for 3.5 keV x rays. These data indicate that the beams interact with the full length of this ignition-scale plasma during the last {approx}1 ns of the experiment. During that time, the full aperture measurements of the stimulated Brillouin scattering and stimulated Raman scattering show scattering into the four focusing lenses of 6% for the smallest length ({approx}2 mm). increasing to 12% for {approx}7 mm. These results demonstrate the NIF experimental capabilities and further provide a benchmark for three-dimensional modeling of the laser-plasma interactions at ignition-size scale lengths.

  10. Microwave diagnostics of femtosecond laser-generated plasma filaments

    SciTech Connect (OSTI)

    Papeer, J.; Ehrlich, Y.; Zigler, A.; Mitchell, C.; Penano, J.; Sprangle, P.

    2011-10-03

    We present a simple non-intrusive experimental method allowing a complete single shot temporal measurement of laser produced plasma filament conductivity. The method is based on filament interaction with low intensity microwave radiation in a rectangular waveguide. The suggested diagnostics allow a complete single shot temporal analysis of filament plasma decay with resolution better than 0.3 ns and high spatial resolution along the filament. The experimental results are compared to numerical simulations, and an initial electron density of 7 x 10{sup 16 }cm{sup -3} and decay time of 3 ns are obtained.

  11. Gas laser with dual plasma mixing

    DOE Patents [OSTI]

    Pinnaduwage, Lal A.

    1999-01-01

    A gas laser includes an enclosure forming a first chamber, a second chamber and a lasing chamber which communicates through a first opening to the first chamber and through a second opening to the second chamber. The lasing chamber has a pair of reflectors defining a Fabry-Perot cavity. Separate inlets enable different gases to be introduced into the first and second chambers. A first cathode within the first chamber is provided to produce positive ions which travel into the lasing chamber and a second cathode of a pin-hollow type within the second chamber is provided to produce negative ions which travel into the lasing chamber. A third inlet introduces a molecular gas into the lasing chamber, where the molecular gas becomes excited by the positive and negative ions and emits light which lases in the Fabry-Perot cavity.

  12. Gas laser with dual plasma mixing

    DOE Patents [OSTI]

    Pinnaduwage, L.A.

    1999-04-06

    A gas laser includes an enclosure forming a first chamber, a second chamber and a lasing chamber which communicates through a first opening to the first chamber and through a second opening to the second chamber. The lasing chamber has a pair of reflectors defining a Fabry-Perot cavity. Separate inlets enable different gases to be introduced into the first and second chambers. A first cathode within the first chamber is provided to produce positive ions which travel into the lasing chamber and a second cathode of a pin-hollow type within the second chamber is provided to produce negative ions which travel into the lasing chamber. A third inlet introduces a molecular gas into the lasing chamber, where the molecular gas becomes excited by the positive and negative ions and emits light which lases in the Fabry-Perot cavity. 2 figs.

  13. Electron energy spectrum in circularly polarized laser irradiated overdense plasma

    SciTech Connect (OSTI)

    Liu, C. S.; Tripathi, V. K.; Shao, Xi; Kumar, Pawan

    2014-10-15

    A circularly polarized laser normally impinged on an overdense plasma thin foil target is shown to accelerate the electrons in the skin layer towards the rear, converting the quiver energy into streaming energy exactly if one ignores the space charge field. The energy distribution of electrons is close to Maxwellian with an upper cutoff ?{sub max}=mc{sup 2}[(1+a{sub 0}{sup 2}){sup 1/2}?1], where a{sub 0}{sup 2}=(1+(2?{sup 2}/?{sub p}{sup 2})|a{sub in}|{sup 2}){sup 2}?1, |a{sub in}| is the normalized amplitude of the incident laser of frequency ?, and ?{sub p} is the plasma frequency. The energetic electrons create an electrostatic sheath at the rear and cause target normal sheath acceleration of protons. The energy gain by the accelerated ions is of the order of ?{sub max}.

  14. Dielectric Wakefield Accelerator to drive the future FEL Light Source.

    SciTech Connect (OSTI)

    Jing, C.; Power, J.; Zholents, A. )

    2011-04-20

    X-ray free-electron lasers (FELs) are expensive instruments and a large part of the cost of the entire facility is driven by the accelerator. Using a high-energy gain dielectric wake-field accelerator (DWA) instead of the conventional accelerator may provide a significant cost saving and reduction of the facility size. In this article, we investigate using a collinear dielectric wakefield accelerator to provide a high repetition rate, high current, high energy beam to drive a future FEL x-ray light source. As an initial case study, a {approx}100 MV/m loaded gradient, 850 GHz quartz dielectric based 2-stage, wakefield accelerator is proposed to generate a main electron beam of 8 GeV, 50 pC/bunch, {approx}1.2 kA of peak current, 10 x 10 kHz (10 beamlines) in just 100 meters with the fill factor and beam loading considered. This scheme provides 10 parallel main beams with one 100 kHz drive beam. A drive-to-main beam efficiency {approx}38.5% can be achieved with an advanced transformer ratio enhancement technique. rf power dissipation in the structure is only 5 W/cm{sup 2} in the high repetition rate, high gradient operation mode, which is in the range of advanced water cooling capability. Details of study presented in the article include the overall layout, the transform ratio enhancement scheme used to increase the drive to main beam efficiency, main wakefield linac design, cooling of the structure, etc.

  15. The BErkeley Lab Laser Accelerator (BELLA): A 10 GeV Laser Plasma Accelerator

    SciTech Connect (OSTI)

    Leemans, W.P.; Duarte, R.; Esarey, E.; Fournier, S.; Geddes, C.G.R.; Lockhart, D.; Schroeder, C.B.; Toth, C.; Vay, J.-L.; Zimmermann, S.

    2010-06-01

    An overview is presented of the design of a 10 GeV laser plasma accelerator (LPA) that will be driven by a PW-class laser system and of the BELLA Project, which has as its primary goal to build and install the required Ti:sapphire laser system for the acceleration experiments. The basic design of the 10 GeV stage aims at operation in the quasi-linear regime, where the laser excited wakes are largely sinusoidal and offer the possibility of accelerating both electrons and positrons. Simulations show that a 10 GeV electron beam can be generated in a meter scale plasma channel guided LPA operating at a density of about 1017 cm-3 and powered by laser pulses containing 30-40 J of energy in a 50- 200 fs duration pulse, focused to a spotsize of 50-100 micron. The lay-out of the facility and laser system will be presented as well as the progress on building the facility.

  16. Beam loading in a laser-plasma accelerator using a near-hollow plasma channel

    SciTech Connect (OSTI)

    Schroeder, C. B.; Benedetti, C.; Esarey, E.; Leemans, W. P.

    2013-12-15

    Beam loading in laser-plasma accelerators using a near-hollow plasma channel is examined in the linear wake regime. It is shown that, by properly shaping and phasing the witness particle beam, high-gradient acceleration can be achieved with high-efficiency, and without induced energy spread or emittance growth. Both electron and positron beams can be accelerated in this plasma channel geometry. Matched propagation of electron beams can be achieved by the focusing force provided by the channel density. For positron beams, matched propagation can be achieved in a hollow plasma channel with external focusing. The efficiency of energy transfer from the wake to a witness beam is calculated for single ultra-short bunches and bunch trains.

  17. Infrared laser induced plasma diagnostics of silver target

    SciTech Connect (OSTI)

    Ahmat, L. Nadeem, Ali; Ahmed, I.

    2014-09-15

    In the present work, the optical emission spectra of silver (Ag) plasma have been recorded and analyzed using the laser induced breakdown spectroscopy technique. The emission line intensities and plasma parameters were investigated as a function of lens to sample distance, laser irradiance, and distance from the target surface. The electron number density (n{sub e}) and electron temperature (T{sub e}) were determined using the Stark broadened line profile and Boltzmann plot method, respectively. A gradual increase in the spectral line intensities and the plasma parameters, n{sub e} from 2.89 × 10{sup 17} to 3.92 × 10{sup 17 }cm{sup −3} and T{sub e} from 4662 to 8967 K, was observed as the laser irradiance was increased 2.29 × 10{sup 10}–1.06 × 10{sup 11} W cm{sup −2}. The spatial variations in n{sub e} and T{sub e} were investigated from 0 to 5.25 mm from the target surface, yielding the electron number density from 4.78 × 10{sup 17} to 1.72 × 10{sup 17 }cm{sup −3} and electron temperature as 9869–3789 K. In addition, the emission intensities and the plasma parameters of silver were investigated by varying the ambient pressure from 0.36 to 1000 mbars.

  18. Properties of laser radiation scattering by a laser-induced spark plasma revisited after 40 years

    SciTech Connect (OSTI)

    Malyutin, A A

    2008-05-31

    Experimental studies of a laser-induced spark produced in air by 1.05-{mu}m, 100-ns pulses with spatial TEM{sub 00}, TEM{sub 01} and TEM{sub 02} modes are described. It is found that when the spark is observed at an angle of 90{sup 0} to the laser beam axis, the scattered radiation has the maximal intensity outside the beam waist. The intensity ratio of the scattered laser radiation for two orthogonal polarisations is {approx}100, and the spatial structures of their depolarisation considerably differ. These properties are explained by using a model of the Fresnel reflection from the spherical front of the plasma-undisturbed gas interface. (laser radiation scattering)

  19. Xe capillary target for laser-plasma extreme ultraviolet source

    SciTech Connect (OSTI)

    Inoue, Takahiro; Okino, Hideyasu; Nica, Petru Edward; Amano, Sho; Miyamoto, Shuji; Mochizuki, Takayasu

    2007-10-15

    A cryogenic Xe jet system with an annular nozzle has been developed in order to continuously fast supply a Xe capillary target for generating a laser-plasma extreme ultraviolet (EUV) source. The cooling power of the system was evaluated to be 54 W, and the temperature stability was {+-}0.5 K at a cooling temperature of about 180 K. We investigated experimentally the influence of pressure loss inside an annular nozzle on target formation by shortening the nozzle length. Spraying caused by cavitation was mostly suppressed by mitigating the pressure loss, and a focused jet was formed. Around a liquid-solid boundary, a solid-Xe capillary target (100/70 {mu}m {phi}) was formed with a velocity of {<=}0.01 m/s. Laser-plasma EUV generation was tested by focusing a Nd:YAG laser beam on the target. The results suggested that an even thinner-walled capillary target is required to realize the inertial confinement effect.

  20. Relative ion expansion velocity in laser-produced plasmas

    SciTech Connect (OSTI)

    Goldsmith, S.; Moreno, J.C.; Griem, H.R.; Cohen, L.; Richardson, M.C.

    1988-07-15

    The spectra of highly ionized titanium, TiXIII through TiXXI, and CVI Lyman lines were excited in laser-produced plasmas. The plasma was produced by uniformly irradiating spherical glass microballoons coated with thin layers of titanium and parylene. The 24-beam Omega laser system produced short, 0.6 ns, and high intensity, 4 x 10/sup 14/ W/cm,/sup 2/ laser pulses at a wavelength of 351 nm. The measured wavelength for the 2p-3s TiXIII resonance lines had an average shift of +0.023 A relative to the CVI and TiXX spectral lines. No shift was found between the CVI, TiXIX, and TiXX lines. The shift is attributed to a Doppler effect, resulting from a difference of (2.6 +- 0.2) x 10/sup 7/ cm/s in the expansion velocities of TiXIX and TiXX ions compared to TiXIII ions.

  1. Improvements to Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    for Quantitative Analysis using Short Pulse UV Laser | The Ames Laboratory Improvements to Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry for Quantitative Analysis using Short Pulse UV Laser FWP/Project Description: Laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) is a non-destructive method for trace elemental analysis of solids. Trace element composition can be useful in forensic applications for matching or attribution studies, in which a material

  2. Beam Loading by Distributed Injection of Electrons in a Plasma...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Beam Loading by Distributed Injection of Electrons in a Plasma Wakefield ... Visit OSTI to utilize additional information resources in energy science and technology. A ...

  3. Dissipative and non-dissipative solitons in the SRS- backscattering of laser radiation in underdense plasma

    SciTech Connect (OSTI)

    Smetanin, Igor V.

    2012-07-11

    The process of stimulated Raman backscattering of laser pulse in underdense plasma is considered self-consistently in 1D model. Solutions to this problem in the form of backward-propagating bright solitons (the Stokes scattered pulse and the plasma density wave) coupled with the dark soliton in the pump laser pulse are found. These solitary solutions exist both in the non-dissipative (non-collisional plasma) case and in the dissipative (collisional plasma) case.

  4. Laser induced focusing for over-dense plasma beams

    SciTech Connect (OSTI)

    Schmidt, Peter; Boine-Frankenheim, Oliver; Mulser, Peter

    2015-09-15

    The capability of ion acceleration with high power, pulsed lasers has become an active field of research in the past years. In this context, the radiation pressure acceleration (RPA) mechanism has been the topic of numerous theoretical and experimental publications. Within that mechanism, a high power, pulsed laser beam hits a thin film target. In contrast to the target normal sheath acceleration, the entire film target is accelerated as a bulk by the radiation pressure of the laser. Simulations predict heavy ion beams with kinetic energy up to GeV, as well as solid body densities. However, there are several effects which limit the efficiency of the RPA: On the one hand, the Rayleigh-Taylor-instability limits the predicted density. On the other hand, conventional accelerator elements, such as magnetic focusing devices are too bulky to be installed right after the target. Therefore, we present a new beam transport method, suitable for RPA-like/over-dense plasma beams: laser induced focusing.

  5. Picosecond 14.7 nm interferometry of high intensity laser-produced plasmas

    SciTech Connect (OSTI)

    Dunn, J; Filevich, J; Smith, R F; Moon, S J; Rocca, J J; Keenan, R; Nilsen, J; Shlyaptsev, V N; Hunter, J R; Ng, A; Marconi, M C

    2004-10-14

    We have developed a compact, 14.7 nm, sub-5 ps x-ray laser source at LLNL together with a Mach-Zehnder type Diffraction Grating Interferometer built at Colorado State University for probing dense, high intensity laser-produced plasmas. The short wavelength and pulse length of the probe reduces refraction and absorption effects within the plasma and minimizes plasma motion blurring. This unique diagnostic capability gives precise 2-D density profile snapshots and is generating new data for rapidly evolving laser-heated plasmas. A review of the results from dense, mm-scale line focus plasma experiments will be described with detailed comparisons to hydrodynamic simulations.

  6. Accelerating Particles with Plasma

    SciTech Connect (OSTI)

    Litos, Michael; Hogan, Mark

    2014-11-05

    Researchers at SLAC explain how they use plasma wakefields to accelerate bunches of electrons to very high energies over only a short distance. Their experiments offer a possible path for the future of particle accelerators.

  7. Observation of Beam Loading in a Laser-Plasma Accelerator

    SciTech Connect (OSTI)

    Rechatin, C.; Ismail, A. Ben; Lim, J.; Faure, J.; Malka, V.; Davoine, X.; Lefebvre, E.; Lifschitz, A.

    2009-11-06

    Beam loading is the phenomenon which limits the charge and the beam quality in plasma based accelerators. An experimental study conducted with a laser-plasma accelerator is presented. Beam loading manifests itself through the decrease of the beam energy, the reduction of dark current, and the increase of the energy spread for large beam charge. 3D PIC simulations are compared to the experimental results and confirm the effects of beam loading. It is found that, in our experimental conditions, the trapped electron beams generate decelerating fields on the order of 1 (GV/m)/pC and that beam loading effects are optimized for trapped charges of about 20 pC.

  8. Channeling of intense laser beams in underdense plasmas

    SciTech Connect (OSTI)

    Feit, M.D.; Garrison, J.C.; Rubenchik, A.M.

    1997-09-01

    A hydrodynamic simulation is used to show that intense laser pulses propagating in underdense plasmas create stable, long-lived, and completely evacuated channels. At low intensities, I=10{sup 17} W/cm{sup 2}, self focusing seriously distorts the temporal envelope of the pulse, but channeling still occurs. At high intensities, I=10{sup 19} W/cm{sup 2}, channeling can proceed over many diffraction lengths with significant distortion restricted to the leading edge of the pulse. {copyright} {ital 1997} {ital The American Physical Society}

  9. Fast Magnetic Reconnection in Laser-Produced Plasma Bubbles

    SciTech Connect (OSTI)

    Fox, W.; Bhattacharjee, A.; Germaschewski, K.

    2011-05-27

    Recent experiments have observed magnetic reconnection in high-energy-density, laser-produced plasma bubbles, with reconnection rates observed to be much higher than can be explained by classical theory. Based on fully kinetic particle simulations we find that fast reconnection in these strongly driven systems can be explained by magnetic flux pileup at the shoulder of the current sheet and subsequent fast reconnection via two-fluid, collisionless mechanisms. In the strong drive regime with two-fluid effects, we find that the ultimate reconnection time is insensitive to the nominal system Alfven time.

  10. Enhancement of laser plasma extreme ultraviolet emission by shockwave-laser interaction

    SciTech Connect (OSTI)

    Bruijn, Rene de; Koshelev, Konstantin N.; Zakharov, Serguei V.; Novikov, Vladimir G.; Bijkerk, Fred

    2005-04-15

    A double laser pulse heating scheme has been applied to generate plasmas with enhanced emission in the extreme ultraviolet (EUV). The plasmas were produced by focusing two laser beams (prepulse and main pulse) with a small spatial separation between the foci on a xenon gas jet target. Prepulses with ps-duration were applied to obtain high shockwave densities, following indications of earlier published results obtained using ns prepulses. EUV intensities around 13.5 nm and in the range 5-20 nm were recorded, and a maximum increase in intensity exceeding 2 was measured at an optimal delay of 140 ns between prepulse and main pulse. The gain in intensity is explained by the interaction of the shockwave produced by the prepulse with the xenon in the beam waist of the main pulse. Extensive simulation was done using the radiative magnetohydrodynamic code Z{sup *}.

  11. Stable laser–plasma accelerators at low densities

    SciTech Connect (OSTI)

    Li, Song; Hafz, Nasr A. M. Mirzaie, Mohammad; Ge, Xulei; Sokollik, Thomas; Chen, Min; Sheng, Zhengming; Zhang, Jie

    2014-07-28

    We report stable laser wakefield acceleration using 17–50 TW laser pulses interacting with 4 mm-long helium gas jet. The initial laser spot size was relatively large (28 μm) and the plasma densities were 0.48–2.0 × 10{sup 19 }cm{sup −3}. High-quality 100–MeV electron beams were generated at the plasma density of 7.5 × 10{sup 18 }cm{sup −3}, at which the beam parameters (pointing angle, energy spectrum, charge, and divergence angle) were measured and stabilized. At higher densities, filamentation instability of the laser-plasma interaction was observed and it has led to multiple wakefield accelerated electron beams. The experimental results are supported by 2D particle-in-cell simulations. The achievement presented here is an important step toward the use of laser-driven accelerators in real applications.

  12. Upper limit power for self-guided propagation of intense lasers in plasma

    SciTech Connect (OSTI)

    Wang Weimin; Hu Zhidan; Chen Liming; Li Yutong; Sheng Zhengming; Zhang Jie; Zeng Ming; Liu Yue; Kawata, Shigeo; Zheng Chunyang; Mori, Warren B.

    2012-10-29

    It is shown that there is an upper-limit laser power for self-focusing of a laser pulse in plasma in addition to the well-known lower-limit critical power set by the relativistic effect. This upper limit is caused by the transverse ponderomotive force of the laser, which tends to expel plasma electrons from the laser propagating area. Furthermore, there is a lower-limit plasma density for a given laser spot size, below which self-focusing does not occur for any laser power. Both the lower-limit density and the upper-limit power are derived theoretically and verified by two-dimensional and three-dimensional particle-in-cell simulations. It is also found that plasma channels may be unfavorable for stable guiding of lasers above the upper-limit power.

  13. Comment on Stationary self-focusing of Gaussian laser beam in relativistic thermal quantum plasma [Phys. Plasmas 20, 072703 (2013)

    SciTech Connect (OSTI)

    Habibi, M.; Ghamari, F.

    2014-06-15

    Patil and Takale in their recent article [Phys. Plasmas 20, 072703 (2013)], by evaluating the quantum dielectric response in thermal quantum plasma, have modeled the relativistic self-focusing of Gaussian laser beam in a plasma. We have found that there are some important shortcomings and fundamental mistakes in Patil and Takale [Phys. Plasmas 20, 072703 (2013)] that we give a brief description about them and refer readers to important misconception about the use of the Fermi temperature in quantum plasmas, appearing in Patil and Takale [Phys. Plasmas 20, 072703 (2013)].

  14. Plasma expansion into a waveguide created by a linearly polarized femtosecond laser pulse

    SciTech Connect (OSTI)

    Lemos, N.; Grismayer, T.; Cardoso, L.; Figueira, G.; Dias, J. M.

    2013-06-15

    We demonstrate the efficient generation of 4 mm and 8 mm long plasma waveguides in hydrogen and helium. These waveguides have matching spots sizes for 13 to 34 ?m laser beams. The plasma waveguides are created by ultra-short laser pulses (sub-picosecond) of moderate intensities, ?10{sup 15}10{sup 16} W cm{sup ?2}, that heat the plasma to initial temperatures of tens of eV in order to create a hot plasma column that will expand into a plasma waveguide. We have determined that the main heating mechanism when using fs laser pulses and plasma densities ?10{sup 1819} cm{sup ?3} is Above Threshold Ionization. Detailed time and space electron density measurements are presented for the laser produced plasma waveguides.

  15. Ponderomotive self-focusing of Gaussian laser beam in warm collisional plasma

    SciTech Connect (OSTI)

    Jafari Milani, M. R.; Niknam, A. R.; Farahbod, A. H.

    2014-06-15

    The propagation characteristics of a Gaussian laser beam through warm collisional plasma are investigated by considering the ponderomotive force nonlinearity and the complex eikonal function. By introducing the dielectric permittivity of warm unmagnetized plasma and using the WKB and paraxial ray approximations, the coupled differential equations defining the variations of laser beam parameters are obtained and solved numerically. Effects of laser and plasma parameters such as the collision frequency, the initial laser intensity and its spot size on the beam width parameter and the axis laser intensity distribution are analyzed. It is shown that, self-focusing of the laser beam takes place faster by increasing the collision frequency and initial laser spot size and then after some distance propagation the laser beam abruptly loses its initial diameter and vastly diverges. Furthermore, the modified electron density distribution is obtained and the collision frequency effect on this distribution is studied.

  16. XUV laser-plasma source based on solid Ar filament

    SciTech Connect (OSTI)

    Peth, Christian; Kalinin, Anton; Barkusky, Frank; Mann, Klaus; Toennies, J. Peter; Rusin, Lev Yu

    2007-10-15

    We present a laser driven soft x-ray source based on a novel solid argon filament. The continuously flowing micron-sized filament (diameter {approx}56 {mu}m, flow speed {approx}5 mm/s) was used as a laser target in order to generate a plasma source of high brightness in the ''water window'' (2.2-4.4 nm) spectral range. The emission properties of the source were characterized in detail with respect to crucial parameters such as positional and energy stability using an extreme ultraviolet (XUV) sensitive pinhole camera and an XUV spectrometer. The results are compared with an argon plasma based on a gas puff target operated under the same experimental conditions showing an increase of the brilliance by a factor of 84. By changing the capillary geometry from a constant diameter to a convergent shape the flow speed of the filament was significantly increased up to 250 mm/s, facilitating the operation at higher repetition rates.

  17. Optimally enhanced optical emission in laser-induced air plasma by femtosecond double-pulse

    SciTech Connect (OSTI)

    Chen, Anmin; Institute of Theoretical Chemistry, State Key Laboratory of Theoretical and Computational Chemistry, Jilin University, Changchun 130012 ; Li, Suyu; Li, Shuchang; Jiang, Yuanfei; Ding, Dajun; Shao, Junfeng; Wang, Tingfeng; Huang, Xuri; Jin, Mingxing; State Key Laboratory of Laser Interaction with Matter, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033

    2013-10-15

    In laser-induced breakdown spectroscopy, a femtosecond double-pulse laser was used to induce air plasma. The plasma spectroscopy was observed to lead to significant increase of the intensity and reproducibility of the optical emission signal compared to femtosecond single-pulse laser. In particular, the optical emission intensity can be optimized by adjusting the delay time of femtosecond double-pulse. An appropriate pulse-to-pulse delay was selected, that was typically about 50 ps. This effect can be especially advantageous in the context of femtosecond laser-induced breakdown spectroscopy, plasma channel, and so on.

  18. Laser induced plasma on copper target, a non-equilibrium model

    SciTech Connect (OSTI)

    Oumeziane, Amina Ait Liani, Bachir; Parisse, Jean-Denis

    2014-02-15

    The aim of this work is to present a comprehensive numerical model for the UV laser ablation of metal targets, it focuses mainly on the prediction of laser induced plasma thresholds, the effect of the laser-plasma interaction, and the importance of the electronic non-equilibrium in the laser induced plume and its expansion in the background gas. This paper describes a set of numerical models for laser-matter interaction between 193-248 and 355 nm lasers and a copper target. Along with the thermal effects inside the material resulting from the irradiation of the latter with the pulsed laser, the laser-evaporated matter interaction and the plasma formation are thoroughly modelled. In the laser induced plume, the electronic nonequilibrium and the laser beam absorption have been investigated. Our calculations of the plasmas ignition thresholds on copper targets have been validated and compared to experimental as well as theoretical results. Comparison with experiment data indicates that our results are in good agreement with those reported in the literature. Furthermore, the inclusion of electronic non-equilibrium in our work indicated that this important process must be included in models of laser ablation and plasma plume formation.

  19. Particle-in-cell simulations of laser beat-wave magnetization of dense plasmas

    SciTech Connect (OSTI)

    Welch, D. R.; Genoni, T. C.; Thoma, C.; Rose, D. V.; Hsu, S. C.

    2014-03-15

    The interaction of two lasers with a difference frequency near that of the ambient plasma frequency produces beat waves that can resonantly accelerate thermal electrons. These beat waves can be used to drive electron current and thereby embed magnetic fields into the plasma [Welch et al., Phys. Rev. Lett. 109, 225002 (2012)]. In this paper, we present two-dimensional particle-in-cell simulations of the beat-wave current-drive process over a wide range of angles between the injected lasers, laser intensities, and plasma densities. We discuss the application of this technique to the magnetization of dense plasmas, motivated in particular by the problem of forming high-β plasma targets in a standoff manner for magneto-inertial fusion. The feasibility of a near-term experiment embedding magnetic fields using lasers with micron-scale wavelengths into a ∼10{sup 18} cm{sup −3}-density plasma is assessed.

  20. Compact tunable Compton x-ray source from laser-plasma accelerator and plasma mirror

    SciTech Connect (OSTI)

    Tsai, Hai-En; Wang, Xiaoming; Shaw, Joseph M.; Li, Zhengyan; Zgadzaj, Rafal; Henderson, Watson; Downer, M. C.; Arefiev, Alexey V.; Zhang, Xi; Khudik, V.; Shvets, G.

    2015-02-15

    We present an in-depth experimental-computational study of the parameters necessary to optimize a tunable, quasi-monoenergetic, efficient, low-background Compton backscattering (CBS) x-ray source that is based on the self-aligned combination of a laser-plasma accelerator (LPA) and a plasma mirror (PM). The main findings are (1) an LPA driven in the blowout regime by 30 TW, 30 fs laser pulses produce not only a high-quality, tunable, quasi-monoenergetic electron beam, but also a high-quality, relativistically intense (a{sub 0} ∼ 1) spent drive pulse that remains stable in profile and intensity over the LPA tuning range. (2) A thin plastic film near the gas jet exit retro-reflects the spent drive pulse efficiently into oncoming electrons to produce CBS x-rays without detectable bremsstrahlung background. Meanwhile, anomalous far-field divergence of the retro-reflected light demonstrates relativistic “denting” of the PM. Exploiting these optimized LPA and PM conditions, we demonstrate quasi-monoenergetic (50% FWHM energy spread), tunable (75–200 KeV) CBS x-rays, characteristics previously achieved only on more powerful laser systems by CBS of a split-off, counter-propagating pulse. Moreover, laser-to-x-ray photon conversion efficiency (∼6 × 10{sup −12}) exceeds that of any previous LPA-based quasi-monoenergetic Compton source. Particle-in-cell simulations agree well with the measurements.

  1. Holographic Imaging of Evolving Laser-Plasma Structures

    SciTech Connect (OSTI)

    Downer, Michael; Shvets, G.

    2014-07-31

    modifies the probe, imprinting information about its structure. Meanwhile, our reference probe co-propagates ahead of the object, free of its influence. After the interaction, object and reference combine to record a hologram. For technical reasons, our recording device is a spectrometer (a frequency-measuring device), hence the name frequency-domain holography. We read the hologram electronically to obtain a snapshot of the objects average structure as it transits the medium. Our published work shows numerous snapshots of electron density waves (laser wakes) in ionized gas (plasma), analogous to a water wake behind a boat. Such waves are the basis of tabletop particle accelerators, in which charged particles surf on the light-speed wave, gaining energy. Comparing our snapshots to computer simulations deepens understanding of laser wakes. FDH takes snapshots of objects that are quasi-static --- i.e. like Muybridges horse standing still on a treadmill. If the object changes shape, FDH images blur, as when a subject moves while a camera shutter is open. Many laser-generated objects of interest do evolve as they propagate. To overcome this limit of FDH, we developed .... (2) Frequency-Domain Tomography (FDT). In FDT, 5 to 10 probe pulses are fired simultaneously across the objects path at different angles, like a crossfire of bullets. The object imprints a streaked record of its evolution on each probe, which we record as in FDH, then recover a multi-frame movie of the objects evolving structure using algorithms of computerized tomography. When propagation distance exceeds a few millimeters, reconstructed FDT images distort. This is because the lenses that image probes to detector have limited depth of field, like cameras that cannot focus simultaneously on both nearby and distant objects. But some laser-generated objects of interest propagate over meters. For these applications we developed (3) Multi-Object-Plane Phase-Contrast Imaging (MOP-PCI). In MOP

  2. Nonlinear propagation of ultraintense and ultrashort laser pulses in a plasma channel limited by metallic walls

    SciTech Connect (OSTI)

    Sid, A.; Debbache, D.; Bendib, A.

    2006-08-15

    The nonlinear propagation of an ultraintense and ultrashort (UIUS) laser pulse in a metallic capillary is investigated using a classical model which takes into account the inverse bremsstrahlung absorption (IBA) in the formed plasma. The attenuation of the laser pulse due to the IBA in the plasma and to the laser energy dissipation in the metallic walls is shown. The guiding length and the twist of the laser pulse temporal envelope are presented for several values of the parameters of the plasma, the laser pulse and the metal. The numerical treatment shows that the guiding length increases when the pulse duration becomes shorter. This calculus shows also that in the case of moderate electronic densities, n{sub e}<10{sup 17} m{sup -3}, the formed plasma has a negligible effect compared to that of the metallic walls.

  3. Laser scattered images observed from carbon plasma stagnation and following molecular formation

    SciTech Connect (OSTI)

    Nishimura, K.; Shibata, R.; Yabuuchi, T.; Tanaka, K. A.; Sunahara, A.

    2014-06-16

    Two carbon targets were irradiated to create plasma plumes to collide at right angle with two UV laser pulses each other at 10 J/cm{sup 2}/pulse. The collision results in carbon plasma stagnation. Laser scattered imaging indicates that the carbon large molecular formation takes place much later in time after the laser irradiation and stagnation. Compared with the temporal history of electron density (n{sub e}), ion density (n{sub i}), and plasma self-emission dominated by carbon Swan band, it is estimated that the carbon large molecular formation has been initiated with the ion collision followed by the C{sub 2} formation.

  4. Determination of the transient electron temperature in a femtosecond-laser-induced air plasma filament

    SciTech Connect (OSTI)

    Sun Zhanliang; Chen Jinhai; Rudolph, Wolfgang

    2011-04-15

    The transient electron temperature in a weakly ionized femtosecond-laser-produced air plasma filament was determined from optical absorption and diffraction experiments. The electron temperature and plasma density decay on similar time scales of a few hundred picoseconds. Comparison with plasma theory reveals the importance of inelastic collisions that lead to energy transfer to vibrational degrees of freedom of air molecules during the plasma cooling.

  5. Terahertz generation by mixing of two super-Gaussian laser beams in collisional plasma

    SciTech Connect (OSTI)

    Singh, Divya; Malik, Hitendra K. E-mail: hkmalik@physics.iitd.ac.in

    2014-08-15

    Considering a realistic situation, where electron-neutral collisions persist in plasma, analytical calculations are carried out for the Terahertz (THz) radiation generation by beating of two Super-Gaussian (SG) lasers of index p. The competency of these lasers over Gaussian lasers is discussed in detail with respect to the effects of collision and beam width on the THz field amplitude and efficiency of the mechanism. A critical transverse distance of the peak of the THz field is defined that shows a dependence on the index of SG lasers. Although electron-neutral collisions and larger beam width lead to the drastic reduction in the THz field when the SG lasers are used in the plasma, the efficiency of the mechanism remains much larger than the case of Gaussian lasers. Moreover, the higher index SG lasers produce stronger and focused THz radiation.

  6. Strong self-focusing of a cosh-Gaussian laser beam in collisionless magneto-plasma under plasma density ramp

    SciTech Connect (OSTI)

    Nanda, Vikas; Kant, Niti

    2014-07-15

    The effect of plasma density ramp on self-focusing of cosh-Gaussian laser beam considering ponderomotive nonlinearity is analyzed using WKB and paraxial approximation. It is noticed that cosh-Gaussian laser beam focused earlier than Gaussian beam. The focusing and de-focusing nature of the cosh-Gaussian laser beam with decentered parameter, intensity parameter, magnetic field, and relative density parameter has been studied and strong self-focusing is reported. It is investigated that decentered parameter “b” plays a significant role for the self-focusing of the laser beam as for b=2.12, strong self-focusing is seen. Further, it is observed that extraordinary mode is more prominent toward self-focusing rather than ordinary mode of propagation. For b=2.12, with the increase in the value of magnetic field self-focusing effect, in case of extraordinary mode, becomes very strong under plasma density ramp. Present study may be very useful in the applications like the generation of inertial fusion energy driven by lasers, laser driven accelerators, and x-ray lasers. Moreover, plasma density ramp plays a vital role to enhance the self-focusing effect.

  7. PRIMARY TESTS OF LASER / E BEAM INTERACTION IN A PLASMA CHANNEL.

    SciTech Connect (OSTI)

    POGORELSKY,I.V.; BEN ZVI,I.; HIROSE,T.; YAKIMENKO,V.; KUSCHE,K.; SIDDONS,P.; ET AL

    2002-06-23

    A high-energy CO{sub 2} laser is channeled in a capillary discharge. Plasma dynamic simulations confirm occurrence of guiding conditions at the relatively low axial plasma density 1 {divided_by} 4 x 10{sup 17} cm{sup -3}. A relativistic electron beam transmitted through the capillary changes its properties depending upon the plasma density. We observe focusing, defocusing or steering of the e-beam. Counter-propagation of the electron and laser beams in the plasma channel results in generation of intense picosecond x-ray pulses.

  8. Simulation of nanosecond pulsed laser ablation of copper samples: A focus on laser induced plasma radiation

    SciTech Connect (OSTI)

    Aghaei, M.; Mehrabian, S.; Tavassoli, S. H.

    2008-09-01

    A thermal model for nanosecond pulsed laser ablation of Cu in one dimension and in ambient gas, He at 1 atm, is proposed in which equations concerning heat conduction in the target and gas dynamics in the plume are solved. These equations are coupled to each other through the energy and mass balances at interface between the target and the vapor and also Knudsen layer conditions. By assumption of local thermal equilibrium, Saha-Eggert equations are used to investigate plasma formation. The shielding effect of the plasma, due to photoionization and inverse bremsstrahlung processes, is considered. Bremsstrahlung and blackbody radiation and spectral emissions of the plasma are also investigated. Spatial and temporal distribution of the target temperature, number densities of Cu and He, pressure and temperature of the plume, bremsstrahlung and blackbody radiation, and also spectral emissions of Cu at three wavelengths (510, 516, and 521 nm) are obtained. Results show that the spectral power of Cu lines has the same pattern as CuI relative intensities from National Institute of Standard and Technology. Investigation of spatially integrated bremsstrahlung and blackbody radiation, and also Cu spectral emissions indicates that although in early times the bremsstrahlung radiation dominates the two other radiations, the Copper spectral emission is the dominant radiation in later times. It should be mentioned that the blackbody radiation has the least values in both time intervals. The results can be used for prediction of the optimum time and position of the spectral line emission, which is applicable in some time resolved spectroscopic techniques such as laser induced breakdown spectroscopy. Furthermore, the results suggest that for distinguishing between the spectral emission and the bremsstrahlung radiation, a spatially resolved spectroscopy can be used instead of the time resolved one.

  9. The absorption and radiation of a tungsten plasma plume during nanosecond laser ablation

    SciTech Connect (OSTI)

    Moscicki, T. Hoffman, J.; Chrzanowska, J.

    2015-10-15

    In this paper, the effect of absorption of the laser beam and subsequent radiation on the dynamics of a tungsten plasma plume during pulsed laser ablation is analyzed. Different laser wavelengths are taken into consideration. The absorption and emission coefficients of tungsten plasma in a pressure range of 0.1–100 MPa and temperature up to 70 000 K are presented. The shielding effects due to the absorption and radiation of plasma may have an impact on the course of ablation. The numerical model that describes the tungsten target heating and the formation of the plasma and its expansion were made for 355 nm and 1064 nm wavelengths of a Nd:YAG laser. The laser beam with a Gaussian profile was focused to a spot size of 0.055 mm{sup 2} with a power density of 1 × 10{sup 9 }W/cm{sup 2} (10 ns full width half maximum pulse duration). The plasma expands into air at ambient pressure of 1 mPa. The use of the shorter wavelength causes faster heating of the target, thus the higher ablation rate. The consequences of a higher ablation rate are slower expansion and smaller dimensions of the plasma plume. The higher plasma temperature in the case of 1064 nm is due to the lower density and lower plasma radiation. In the initial phase of propagation of the plasma plume, when both the temperature and pressure are very high, the dominant radiation is emission due to photo-recombination. However, for a 1064 nm laser wavelength after 100 ns of plasma expansion, the radiation of the spectral lines is up to 46.5% of the total plasma radiation and should not be neglected.

  10. Characterization Of High Explosives Detonations Via Laser-Induced Plasmas

    SciTech Connect (OSTI)

    Villa-Aleman, E.

    2015-10-08

    One objective of the Department of Energy’s National Security Administration is to develop technologies that can help the United States government to detect foreign nuclear weapons development activities. The realm of high explosive (HE) experiments is one of the key areas to assess the nuclear ambitions of a country. SRNL has participated in the collection of particulates from HE experiments and characterized the material with the purpose to correlate particulate matter with HE. Since these field campaigns are expensive, on-demand simulated laboratory-scale explosion experiments are needed to further our knowledge of the chemistry and particle formation in the process. Our goal is to develop an experimental test bed in the laboratory to test measurement concepts and correlate particle formation processes with the observables from the detonation fireball. The final objective is to use this knowledge to tailor our experimental setups in future field campaigns. The test bed uses pulsed laser-induced plasmas to simulate micro-explosions, with the intent to study the temporal behavior of the fireball observed in field tests. During FY15, a plan was prepared and executed which assembled two laser ablation systems, procured materials for study, and tested a Step-Scan Fourier Transform Infrared Spectrometer (SS-FTIR). Designs for a shadowgraph system for shock wave analysis, design for a micro-particulate collector from ablated pulse were accomplished. A novel spectroscopic system was conceived and a prototype system built for acquisition of spectral/temporal characterization of a high speed event such as from a high explosive detonation. Experiments and analyses will continue into FY16.

  11. Optical emission spectroscopy of metal vapor dominated laser-arc hybrid welding plasma

    SciTech Connect (OSTI)

    Ribic, B.; DebRoy, T.; Burgardt, P.

    2011-04-15

    During laser-arc hybrid welding, plasma properties affect the welding process and the weld quality. However, hybrid welding plasmas have not been systematically studied. Here we examine electron temperatures, species densities, and electrical conductivity for laser, arc, and laser-arc hybrid welding using optical emission spectroscopy. The effects of arc currents and heat source separation distances were examined because these parameters significantly affect weld quality. Time-average plasma electron temperatures, electron and ion densities, electrical conductivity, and arc stability decrease with increasing heat source separation distance during hybrid welding. Heat source separation distance affects these properties more significantly than the arc current within the range of currents considered. Improved arc stability and higher electrical conductivity of the hybrid welding plasma result from increased heat flux, electron temperatures, electron density, and metal vapor concentrations relative to arc or laser welding.

  12. A Versatile High-Resolution X-Ray Imager (HRXI) for Laser-Plasma...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: A Versatile High-Resolution X-Ray Imager (HRXI) for Laser-Plasma Experiments on OMEGA Citation Details In-Document Search Title: A Versatile High-Resolution X-Ray ...

  13. A versatile high-resolution x-ray imager (HRXI) for laser-plasma...

    Office of Scientific and Technical Information (OSTI)

    x-ray imager (HRXI) devoted to laser-plasma experiments combines two state-of-the-art technologies developed in France: a high-resolution x-ray microscope and a high-speed...

  14. I/O Performance of a Large-Scale, Interpreter-Driven Laser-Plasma...

    Office of Scientific and Technical Information (OSTI)

    Conference: IO Performance of a Large-Scale, Interpreter-Driven Laser-Plasma Interaction Code Citation Details In-Document Search Title: IO Performance of a Large-Scale, ...

  15. Electron Beam Charge Diagnostics for Laser Plasma Accelerators

    SciTech Connect (OSTI)

    Nakamura, Kei; Gonsalves, Anthony; Lin, Chen; Smith, Alan; Rodgers, David; Donahue, Rich; Byrne, Warren; Leemans, Wim

    2011-06-27

    A comprehensive study of charge diagnostics is conducted to verify their validity for measuring electron beams produced by laser plasma accelerators (LPAs). First, a scintillating screen (Lanex) was extensively studied using subnanosecond electron beams from the Advanced Light Source booster synchrotron, at the Lawrence Berkeley National Laboratory. The Lanex was cross calibrated with an integrating current transformer (ICT) for up to the electron energy of 1.5 GeV, and the linear response of the screen was confirmed for charge density and intensity up to 160 pC/mm{sup 2} and 0.4 pC/(ps mm{sup 2}), respectively. After the radio-frequency accelerator based cross calibration, a series of measurements was conducted using electron beams from an LPA. Cross calibrations were carried out using an activation-based measurement that is immune to electromagnetic pulse noise, ICT, and Lanex. The diagnostics agreed within {+-}8%, showing that they all can provide accurate charge measurements for LPAs.

  16. Optimizing laser produced plasmas for efficient extreme ultraviolet and soft X-ray light sources

    SciTech Connect (OSTI)

    Sizyuk, Tatyana; Hassanein, Ahmed [Center for Materials under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

    2014-08-15

    Photon sources produced by laser beams with moderate laser intensities, up to 10{sup 14?}W/cm{sup 2}, are being developed for many industrial applications. The performance requirements for high volume manufacture devices necessitate extensive experimental research supported by theoretical plasma analysis and modeling predictions. We simulated laser produced plasma sources currently being developed for several applications such as extreme ultraviolet lithography using 13.5%??1% nm bandwidth, possibly beyond extreme ultraviolet lithography using 6. nm wavelengths, and water-window microscopy utilizing 2.48?nm (La-?) and 2.88?nm (He-?) emission. We comprehensively modeled plasma evolution from solid/liquid tin, gadolinium, and nitrogen targets as three promising materials for the above described sources, respectively. Results of our analysis for plasma characteristics during the entire course of plasma evolution showed the dependence of source conversion efficiency (CE), i.e., laser energy to photons at the desired wavelength, on plasma electron density gradient. Our results showed that utilizing laser intensities which produce hotter plasma than the optimum emission temperatures allows increasing CE for all considered sources that, however, restricted by the reabsorption processes around the main emission region and this restriction is especially actual for the 6.?nm sources.

  17. The splitted laser beam filamentation in interaction of laser and an exponential decay inhomogeneous underdense plasma

    SciTech Connect (OSTI)

    Xia Xiongping; Yi Lin; Xu Bin; Lu Jianduo

    2011-10-15

    The splitted beam filamentation in interaction of laser and an exponential decay inhomogeneous underdense plasma is investigated. Based on Wentzel-Kramers-Brillouin (WKB) approximation and paraxial/nonparaxial ray theory, simulation results show that the steady beam width and single beam filamentation along the propagation distance in paraxial case is due to the influence of ponderomotive nonlinearity. In nonparaxial case, the influence of the off-axial of {alpha}{sub 00} and {alpha}{sub 02} (the departure of the beam from the Gaussian nature) and S{sub 02} (the departure from the spherical nature) results in more complicated ponderomotive nonlinearity and changing of the channel density and refractive index, which led to the formation of two/three splitted beam filamentation and the self-distortion of beam width. In addition, influence of several parameters on two/three splitted beam filamentation is discussed.

  18. 'Erratic' Lasers Pave Way for Tabletop Accelerators

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Lasers Pave Way for Tabletop Accelerators 'Erratic' Lasers Pave Way for Tabletop Accelerators Simulations at NERSC help researchers simplify design of mini particle accelerators June 9, 2014 Kate Green, KGreene@lbl.gov, 510-486-4404 laserplasmaaccelerator 3D map of the longitudinal wakefield generated by the incoherent combination of 208 low-energy laser beamlets. In the region behind the driver, the wakefield is regular. Image: Carlo Benedetti, Berkeley Lab Making a tabletop particle

  19. Numerical studies of third-harmonic generation in laser filament in air perturbed by plasma spot

    SciTech Connect (OSTI)

    Feng Liubin; Lu Xin; Liu Xiaolong; Li Yutong; Chen Liming; Ma Jinglong; Dong Quanli; Wang Weimin; Xi Tingting; Sheng Zhengming; Zhang Jie; He Duanwei

    2012-07-15

    Third-harmonic emission from laser filament intercepted by plasma spot is studied by numerical simulations. Significant enhancement of the third-harmonic generation is obtained due to the disturbance of the additional plasma. The contribution of the pure plasma effect and the possible plasma-enhanced third-order susceptibility on the third-harmonic generation enhancement are compared. It is shown that the plasma induced cancellation of destructive interference [Y. Liu et al., Opt. Commun. 284, 4706 (2011)] of two-colored filament is the dominant mechanism of the enhancement of third-harmonic generation.

  20. Laser beat wave excitation of terahertz radiation in a plasma slab

    SciTech Connect (OSTI)

    Chauhan, Santosh; Parashar, Jetendra

    2014-10-15

    Terahertz (THz) radiation generation by nonlinear mixing of lasers, obliquely incident on a plasma slab is investigated. Two cases are considered: (i) electron density profile is parabolic but density peak is below the critical density corresponding to the beat frequency, (ii) plasma boundaries are sharp and density is uniform. In both cases, nonlinearity arises through the ponderomotive force that gives rise to electron drift at the beat frequency. In the case of inhomogeneous plasma, non zero curl of the nonlinear current density gives rise to electromagnetic THz generation. In case of uniform plasma, the sharp density variation at the plasma boundaries leads to radiation generation. In a slab width of less than a terahertz wavelength, plasma density one fourth of terahertz critical density, laser intensities ∼10{sup 17 }W/cm{sup 2} at 1 μm, one obtains the THz intensity ∼1 GW/cm{sup 2} at 3 THz radiation frequency.

  1. Surface plasma wave assisted second harmonic generation of laser over a metal film

    SciTech Connect (OSTI)

    Chauhan, Santosh; Parashar, J.

    2015-01-15

    Second harmonic generation of laser mode converted surface plasma wave (SPW) over a corrugated metal film is studied. The laser, impinged on the metal film, under attenuated total reflection configuration, excites SPW over the metal–vacuum interface. The excited SPW extends over a much wider surface area than the laser spot cross-section. It exerts a second harmonic ponderomotive force on metal electrons, imparting them velocity that beats with the surface ripple to produce a nonlinear current, driving resonant second harmonic surface plasma wave.

  2. Apparatus and method to enhance X-ray production in laser produced plasmas

    DOE Patents [OSTI]

    Augustoni, Arnold L.; Gerardo, James B.; Raymond, Thomas D.

    1992-01-01

    Method and apparatus for generating x-rays for use in, for instance, x-ray photolithography. The method of generating x-rays includes the steps of providing a target and irradiating the target with a laser system which produces a train of sub-pulses to generate an x-ray producing plasma. The sub-pulses are of both high intensity and short duration. The apparatus for generating x-rays from a plasma includes a vacuum chamber, a target supported within the chamber and a laser system, including a short storage time laser.

  3. Apparatus and method to enhance X-ray production in laser produced plasmas

    DOE Patents [OSTI]

    Augustoni, A.L.; Gerardo, J.B.; Raymond, T.D.

    1992-12-29

    Method and apparatus for generating x-rays for use in, for instance, x-ray photolithography is disclosed. The method of generating x-rays includes the steps of providing a target and irradiating the target with a laser system which produces a train of sub-pulses to generate an x-ray producing plasma. The sub-pulses are of both high intensity and short duration. The apparatus for generating x-rays from a plasma includes a vacuum chamber, a target supported within the chamber and a laser system, including a short storage time laser. 8 figs.

  4. Stationary self-focusing of intense laser beam in cold quantum plasma using ramp density profile

    SciTech Connect (OSTI)

    Habibi, M.; Ghamari, F.

    2012-10-15

    By using a transient density profile, we have demonstrated stationary self-focusing of an electromagnetic Gaussian beam in cold quantum plasma. The paper is devoted to the prospects of using upward increasing ramp density profile of an inhomogeneous nonlinear medium with quantum effects in self-focusing mechanism of high intense laser beam. We have found that the upward ramp density profile in addition to quantum effects causes much higher oscillation and better focusing of laser beam in cold quantum plasma in comparison to that in the classical relativistic case. Our computational results reveal the importance and influence of formation of electron density profiles in enhancing laser self-focusing.

  5. Higher-order paraxial theory of the propagation of ring rippled laser beam in plasma: Relativistic ponderomotive regime

    SciTech Connect (OSTI)

    Purohit, Gunjan Rawat, Priyanka; Chauhan, Prashant; Mahmoud, Saleh T.

    2015-05-15

    This article presents higher-order paraxial theory (non-paraxial theory) for the ring ripple formation on an intense Gaussian laser beam and its propagation in plasma, taking into account the relativistic-ponderomotive nonlinearity. The intensity dependent dielectric constant of the plasma has been determined for the main laser beam and ring ripple superimposed on the main laser beam. The dielectric constant of the plasma is modified due to the contribution of the electric field vector of ring ripple. Nonlinear differential equations have been formulated to examine the growth of ring ripple in plasma, self focusing of main laser beam, and ring rippled laser beam in plasma using higher-order paraxial theory. These equations have been solved numerically for different laser intensities and plasma frequencies. The well established experimental laser and plasma parameters are used in numerical calculation. It is observed that the focusing of the laser beams (main and ring rippled) becomes fast in the nonparaxial region by expanding the eikonal and other relevant quantities up to the fourth power of r. The splitted profile of laser beam in the plasma is observed due to uneven focusing/defocusing of the axial and off-axial rays. The growths of ring ripple increase when the laser beam intensity increases. Furthermore, the intensity profile of ring rippled laser beam gets modified due to the contribution of growth rate.

  6. Isentropic expansion of copper plasma in Mbar pressure range at “Luch” laser facility

    SciTech Connect (OSTI)

    Bel'kov, S. A.; Derkach, V. N.; Garanin, S. G.; Mitrofanov, E. I.; Voronich, I. N.; Fortov, V. E.; Levashov, P. R.; Minakov, D. V.

    2014-01-21

    We present experimental results on thermodynamic properties of dense copper plasma in Mbar pressure range. The laser facility “Luch” with laser intensity 10{sup 14} W/cm{sup 2} is used to compress copper up to ∼8 Mbar by a strong shock wave; subsequent expansion of copper plasma into Al, Ti, Sn allows us to obtain release isentropes of copper by the impedance–matching method. A theoretical analysis and quantum simulations show that in our experiments strongly coupled quantum plasma is generated.

  7. Observation of Magnetized Soliton Remnants in the Wake of Intense Laser Pulse Propagation through Plasmas

    SciTech Connect (OSTI)

    Romagnani, L.; Bigongiari, A.; Kar, S.; Borghesi, M.; Bulanov, S. V.; Esirkepov, T. Zh.; Cecchetti, C. A.; Galimberti, M.; Jung, R.; Osterholz, J.; Willi, O.; Liseykina, T. V.; Macchi, A.; Pegoraro, F.

    2010-10-22

    Slowly evolving, regularly spaced patterns have been observed in proton projection images of plasma channels drilled by intense (> or approx. 10{sup 19} W cm{sup -2}) short ({approx}1 ps) laser pulses propagating in an ionized gas jet. The nature and geometry of the electromagnetic fields generating such patterns have been inferred by simulating the laser-plasma interaction and the following plasma evolution with a two-dimensional particle-in-cell code and the probe proton deflections by particle tracing. The analysis suggests the formation of rows of magnetized soliton remnants, with a quasistatic magnetic field associated with vortexlike electron currents resembling those of magnetic vortices.

  8. Dense strongly coupled plasma in double laser pulse ablation of lithium: Experiment and simulation

    SciTech Connect (OSTI)

    Kumar, Ajai; Sivakumaran, V.; Ganesh, R.; Joshi, H. C. [Institute for Plasma Research, Bhat, Gandhinagar-382428 (India)] [Institute for Plasma Research, Bhat, Gandhinagar-382428 (India); Ashwin, J. [Weizmann Institute of Science, Rehovot - 76100 (Israel)] [Weizmann Institute of Science, Rehovot - 76100 (Israel)

    2013-08-15

    In a simple method of low power nano-second double pulsed laser ablation experiment in collinear geometry, formation of high density strongly coupled plasma is demonstrated. Using time-resolved measurements of the Stark broadened line width and line intensity ratio of the emission lines, the density and temperature of the plasma were estimated respectively. In this experiment, it is shown that ions are strongly coupled (ion-ion coupling parameter comes out to be >4). For comparison, both single and double pulsed laser ablations are presented. For the estimated experimental plasma parameters, first principle Langevin dynamics simulation corroborates the existence of a strongly coupled regime.

  9. Correlated-intensity velocimeter for arbitrary reflector for laser-produced plasma experiments

    SciTech Connect (OSTI)

    Wang Zhehui; Luo Shengnian; Barnes, Cris W.; Briggs, Matthew E.; Paisley, Dennis L.; Paul, Stephen F.

    2006-10-15

    A laser-based technique, called correlated-intensity velocimeter for arbitrary reflector (CIVAR), is described for velocity measurement of reflecting surfaces in real time. Velocity versus time is an important measurement in laser-produced high-energy density plasma experiments because the motion of the surface depends on both the equation of the state of the surface material and laser-produced plasma. The physics and working principle of CIVAR are the same as those of a previous concept that resolves Doppler shift of plasma light emission using a pair of narrow passband interference filters. One unique feature of CIVAR is that a reflected laser beam is used instead of plasma emission. Therefore, CIVAR is applicable to both emitting and nonemitting reflecting surfaces. Other advantages of CIVAR include its simplicity, lower cost, and unambiguous data analysis that can be fully automated. The design of a single-point CIVAR is described in detail with emphasis on laser wavelength selection and signal-to-noise ratio. The single-point CIVAR system can be expanded into a multiple-point system straightforwardly. It is possible to use CIVAR concept to construct a two-dimensional imaging system for a nonuniform velocity field of a large reflecting surface; such a velocity imaging system may have applications beyond laser-produced plasma experiments, for example, in shock compression of condensed matter.

  10. Stainless Steel 18-10 CO2 Laser Welding And Plasma Diagnostics

    SciTech Connect (OSTI)

    Amar, Taibi [Department of Mechanical Engineering, University of M'sila (Algeria); Laboratory of Industrial Physics, Thermal centre of INSA of Lyon, CETHIL (France); Michel, Laurent [Laboratory of Industrial Physics, Thermal centre of INSA of Lyon, CETHIL (France)

    2008-09-23

    The welding of materials by CO2 laser took significant considerations in industry, for the reason of the quality of the carried out weldings, and for other many advantages, but the automation of the welding operation requires a control system in real time. The operation of welding is an operation of interaction between the radiation (laser), and the matter (welded part), which is characterized by the vaporization of the matter, formation of the keyhole in material, and appearance of plasma over the material. This study relates to the relation between the welding (molten material) and the plasma which is formed on material. The light emitted by plasma during laser welding was recorded by an OMA detector (Optical Multichannel Analyzer) over a wavelength width of 450 A ring . The analysis of this light allows to determine the composition of this plasma, its dimensions, and the state of its energy according to the laser parameters. The welded material is the stainless steel 18-10, it was found that the intensity of the light emitted by plasma depends on laser power, the welding speed, the flow rate of assist gas. The relation between the plasma and the state of the bead were analyzed for on-line monitoring welding.

  11. Angular distribution of ions and extreme ultraviolet emission in laser-produced tin droplet plasma

    SciTech Connect (OSTI)

    Chen, Hong; Duan, Lian; Lan, Hui; Wang, Xinbing Chen, Ziqi; Zuo, Duluo; Lu, Peixiang

    2015-05-21

    Angular-resolved ion time-of-flight spectra as well as extreme ultraviolet radiation in laser-produced tin droplet plasma are investigated experimentally and theoretically. Tin droplets with a diameter of 150 μm are irradiated by a pulsed Nd:YAG laser. The ion time-of-flight spectra measured from the plasma formed by laser irradiation of the tin droplets are interpreted in terms of a theoretical elliptical Druyvesteyn distribution to deduce ion density distributions including kinetic temperatures of the plasma. The opacity of the plasma for extreme ultraviolet radiation is calculated based on the deduced ion densities and temperatures, and the angular distribution of extreme ultraviolet radiation is expressed as a function of the opacity using the Beer–Lambert law. Our results show that the calculated angular distribution of extreme ultraviolet radiation is in satisfactory agreement with the experimental data.

  12. Numerical simulation to study the transient self focusing of laser beam in plasma

    SciTech Connect (OSTI)

    Sharma, R. P.; Hussain, Saba Gaur, Nidhi

    2015-02-15

    In this paper, we present the numerical simulation for the coupled system of equations governing the dynamics of laser and Ion Acoustic Wave (IAW) in a collisionless plasma, when the coupling between the waves is through ponderomotive non-linearity. The nonlinear evolution of the laser beam is studied when the pump laser is perturbed by a periodic perturbation. By changing the perturbation wave number, we have studied its effect on the nonlinear evolution pattern of laser beam. In order to have a physical insight into the nonlinear dynamics of laser beam evolution in time and space, we have studied the laser and IAW spectra containing spatial harmonics. The magnitude of these harmonics changes with time and leads to time dependent localization of laser beam in spatial domain. The nonlinear dynamics of this localization is investigated in detail by using simulation and a semi-analytical model.

  13. Near-critical phase explosion promoting breakdown plasma ignition during laser ablation of graphite

    SciTech Connect (OSTI)

    Ionin, A. A.; Kudryashov, S. I.; Seleznev, L. V.

    2010-07-15

    Removal rate, air shock, and ablative recoil pressure parameters were measured as a function of laser intensity I{sub peak} during nanosecond laser ablation of graphite. Surface vaporization of molten graphite at low intensities I{sub peak}<0.15 GW/cm{sup 2} was observed to transform into its near-critical phase explosion (intense homogeneous boiling) at the threshold intensity I{sub PE}approx =0.15 GW/cm{sup 2} in the form of a drastic, correlated rise of removal rate, air shock, and ablative recoil pressure magnitudes. Just above this threshold (I{sub peak}>=0.25 GW/cm{sup 2}), the explosive mass removal ended up with saturation of the removal rate, much slower increase of the air and recoil pressure magnitudes, and appearance of a visible surface plasma spark. In this regime, the measured far-field air shock pressure amplitude exhibits a sublinear dependence on laser intensity (propor toI{sub peak}{sup 4/9}), while the source plasma shock pressure demonstrates a sublinear trend (propor toI{sub peak}{sup 3/4}), both indicating the subcritical character of the plasma. Against expectations, in this regime the plasma recoil pressure increases versus I{sub peak} superlinearly (propor toI{sub peak}{sup 1.1}), rather than sublinearly (propor toI{sub peak}{sup 3/4}), with the mentioned difference related to the intensity-dependent initial spatial plasma dimensions within the laser waist on the graphite surface and to the plasma formation time during the heating laser pulse (overall, the pressure source effect). The strict coincidence of the phase explosion, providing high (kbar) hydrodynamic pressures of ablation products, and the ignition of ablative laser plasma in the carbon plume may indicate the ablative pressure-dependent character of the underlying optical breakdown at the high plume pressures, initiating the plasma formation. The experimental data evidence that the spatiotemporal extension of the plasma in the laser plume and ambient air during the heating laser

  14. Efficient second- and third-harmonic radiation generation from relativistic laser-plasma interactions

    SciTech Connect (OSTI)

    Singh, Mamta; Gupta, D. N.; Suk, H.

    2015-06-15

    We propose an idea to enhance the efficiency of second- and third-harmonic generation by considering the amplitude-modulation of the fundamental laser pulse. A short-pulse laser of finite spot size is modeled as amplitude modulated in time. Amplitude-modulation of fundamental laser contributes in quiver velocity of the plasma electrons and produces the strong plasma-density perturbations, thereby increase in current density at second- and third-harmonic frequency. In a result, the conversion efficiency of harmonic generation increases significantly. Power conversion efficiency of harmonic generation process is the increasing function of the amplitude-modulation parameter of the fundamental laser beam. Harmonic power generated by an amplitude modulated laser is many folds higher than the power obtained in an ordinary case.

  15. In situ mechanical spectroscopy of laser deposited films using plasma plume excited reed

    SciTech Connect (OSTI)

    Scharf, Thorsten; Krebs, Hans-Ulrich

    2006-09-15

    We show a new approach to in situ measure the mechanical properties of pulsed laser deposited thin films by plasma plume excited reed with high accuracy. A vibrating reed, consisting of a Si substrate, is mounted into a pulsed laser deposition chamber. After deposition of the polymer film for investigation, the Si substrate is excited by the energy of the expanding laser plasma coming from a Ag target. The oscillations of the reed and their damping are measured using a diode laser reflected at the back side of the substrate, by observing the reflections with a position sensitive detector. Data collection as well as the coordination with the deposition setup are done computer controlled. Temperature dependent measurements of the damping of the reed oscillations then allow us to perform mechanical spectroscopy investigations of laser deposited polymer films.

  16. Simulation of quasimonoenergetic electron beams produced by colliding pulse wakefield acceleration

    SciTech Connect (OSTI)

    Davoine, X.; Lefebvre, E.; Lifschitz, A.

    2008-11-15

    The collision of two laser pulses can inject electrons into a wakefield accelerator, and has been found to produce stable and tunable quasimonoenergetic electron beams [J. Faure et al., Nature 444, 737 (2006)]. This colliding pulse scheme is studied here with 3D particle-in-cell simulations. The results are successfully compared with experimental data, showing the accuracy of the simulations. The involved mechanisms (laser propagation, wake inhibition, electron heating and trapping, beam loading) are presented in detail. We explain their interplay effects on the beam parameters. The experimental variations of beam charge and energy with collision position are explained.

  17. Spectroscopic characterization and imaging of laser- and unipolar arc-induced plasmas

    SciTech Connect (OSTI)

    Aussems, Damien U. B.; Nishijima, Daisuke; Brandt, Christian; Doerner, Russell P.; Cardozo, Niek J. Lopes

    2014-08-14

    Tungsten plasmas induced by unipolar arcs were investigated using optical emission spectroscopy and imaging, and compared with laser-induced tungsten plasmas. The unipolar arcs were initiated in the linear-plasma simulator PISCES-A at UCSD under fusion relevant conditions. The electron temperature and density of the unipolar arc plasmas were in the range 0.50.7?eV and 0.72.0??10{sup 20?}m{sup ?3}, respectively, and increased with increasing negative bias voltage, but did not correlate with the surface temperature. In comparison, the electron temperature and density of the laser-induced plasmas were in the range 0.61.4?eV and 7??10{sup 19}1??10{sup 22?}m{sup ?3}, respectively.

  18. Wakefield Municipal Gas & Light Department- Residential Conservation Services Program

    Broader source: Energy.gov [DOE]

    The Wakefield Municipal Gas & Light Department (WMGLD), offers the "Incentive Rebate Program" to encourage residential customers to improve the energy efficiency of their homes. After a home...

  19. Resonant- and avalanche-ionization amplification of laser-induced plasma in air

    SciTech Connect (OSTI)

    Wu, Yue; Zhang, Zhili; Jiang, Naibo; Roy, Sukesh; Gord, James R.

    2014-10-14

    Amplification of laser-induced plasma in air is demonstrated utilizing resonant laser ionization and avalanche ionization. Molecular oxygen in air is ionized by a low-energy laser pulse employing (2 + 1) resonance-enhanced multi-photon ionization (REMPI) to generate seed electrons. Subsequent avalanche ionization of molecular oxygen and nitrogen significantly amplifies the laser-induced plasma. In this plasma-amplification effect, three-body attachments to molecular oxygen dominate the electron-generation and -loss processes, while either nitrogen or argon acts as the third body with low electron affinity. Contour maps of the electron density within the plasma obtained in O₂/N₂ and O₂/Ar gas mixtures are provided to show relative degrees of plasma amplification with respect to gas pressure and to verify that the seed electrons generated by O₂ 2 + 1 REMPI are selectively amplified by avalanche ionization of molecular nitrogen in a relatively low-pressure condition (≤100 Torr). Such plasma amplification occurring in air could be useful in aerospace applications at high altitude.

  20. Characteristic x-ray emission from undermines plasmas irradiated by ultra-intense lasers

    SciTech Connect (OSTI)

    Niemann, Christoph

    2012-05-05

    Between FY09 and FY11 we have conducted more than a dozen three-week experimental campaigns at high-power laser facilities around the world to investigate laser-channeling through x-ray and optical imaging and the conversion from laser-energy to xrays. We have performed simultaneous two-wavelength x-ray imaging (K-alpha and He-alpha) to distinguish the hot-plasma region (hot-spot) from the laser-produced electrons (K-alpha). In addition, we have initiated a new collaboration with SNL and have performed first shots on the 100 TW beamlet chamber to commission a fast x-ray streak camera to be used to investigate the temporal evolution of our K-alpha sources. We also collaborated on campaigns at the Rutherford Appleton Laboratory (UK) and the LANL Trident laser to employ laser produced x-ray sources for Thomson scattering off dense matter.

  1. Propagation dynamics of laterally colliding plasma plumes in laser-blow-off of thin film

    SciTech Connect (OSTI)

    Kumar, Bhupesh; Singh, R. K.; Sengupta, Sudip; Kaw, P. K.; Kumar, Ajai, E-mail: ajai@ipr.res.in [Institute for Plasma Research, Bhat, Gandhinagar 382 428 (India)

    2014-08-15

    We report a systematic investigation of two plume interactions at different spatial separation (3-7?mm) in laser-blow-off. The plasmas plumes are created using Laser-blow-off (LBO) scheme of a thin film. The fast imaging technique is used to record the evolution of seed plasmas and the interaction zone which is formed as a result of interaction of the two seed plasmas. Time resolved optical emission spectroscopy is used to study evolution of optical emissions of the species present in the different regions of the plasmas. Neutral Li emissions (Li I 670.8?nm (2s {sup 2}S{sub 1/2} ? 2p {sup 2}P{sub 3/2,1/2}) and Li I 610.3?nm (2p {sup 2}P{sub 3/2,1/2} ? 3d {sup 2}D{sub 3/2,5/2})) are dominant in the plasmas but significant differences are observed in the emission and estimated plasma parameters of the seed and the interaction zone. The transport of plasma species from the seed plasmas to the interaction zone is discussed in the terms of plume divergence, kinetic energy of particles, and ion acoustic speed. An attempt is made to understand the formation and dynamics of the interaction zone in the colliding LBO seed plasmas.

  2. The analytic model of a laser-accelerated plasma target and its stability

    SciTech Connect (OSTI)

    Khudik, V. Yi, S. A.; Siemon, C.; Shvets, G.

    2014-01-15

    A self-consistent kinetic theory of a laser-accelerated plasma target with distributed electron/ion densities is developed. The simplified model assumes that after an initial transition period the bulk of cold ions are uniformly accelerated by the self-consistent electric field generated by hot electrons trapped in combined ponderomotive and electrostatic potentials. Several distinct target regions (non-neutral ion tail, non-neutral electron sheath, and neutral plasma bulk) are identified and analytically described. It is shown analytically that such laser-accelerated finite-thickness target is susceptible to Rayleigh-Taylor (RT) instability. Particle-in-cell simulations of the seeded perturbations of the plasma target reveal that, for ultra-relativistic laser intensities, the growth rate of the RT instability is depressed from the analytic estimates.

  3. Efficient quasi-monoenergetic ion beams from laser-driven relativistic plasmas

    SciTech Connect (OSTI)

    Palaniyappan, Sasi; Huang, Chengkun; Gautier, Donald C.; Hamilton, Christopher E.; Santiago, Miguel A.; Kreuzer, Christian; Sefkow, Adam B.; Shah, Rahul C.; Fernández, Juan C.

    2015-12-11

    Table-top laser–plasma ion accelerators have many exciting applications, many of which require ion beams with simultaneous narrow energy spread and high conversion efficiency. However, achieving these requirements has been elusive. We report the experimental demonstration of laser-driven ion beams with narrow energy spread and energies up to 18 MeV per nucleon and ~5% conversion efficiency (that is 4 J out of 80-J laser). Using computer simulations we identify a self-organizing scheme that reduces the ion energy spread after the laser exits the plasma through persisting self-generated plasma electric (~1012 V m-1) and magnetic (~104 T) fields. Furthermore, these results contribute to the development of next generation compact accelerators suitable for many applications such as isochoric heating for ion-fast ignition and producing warm dense matter for basic science.

  4. Efficient quasi-monoenergetic ion beams from laser-driven relativistic plasmas

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Palaniyappan, Sasi; Huang, Chengkun; Gautier, Donald C.; Hamilton, Christopher E.; Santiago, Miguel A.; Kreuzer, Christian; Sefkow, Adam B.; Shah, Rahul C.; Fernández, Juan C.

    2015-12-11

    Table-top laser–plasma ion accelerators have many exciting applications, many of which require ion beams with simultaneous narrow energy spread and high conversion efficiency. However, achieving these requirements has been elusive. We report the experimental demonstration of laser-driven ion beams with narrow energy spread and energies up to 18 MeV per nucleon and ~5% conversion efficiency (that is 4 J out of 80-J laser). Using computer simulations we identify a self-organizing scheme that reduces the ion energy spread after the laser exits the plasma through persisting self-generated plasma electric (~1012 V m-1) and magnetic (~104 T) fields. Furthermore, these results contributemore » to the development of next generation compact accelerators suitable for many applications such as isochoric heating for ion-fast ignition and producing warm dense matter for basic science.« less

  5. Use of external magnetic fields in hohlraum plasmas to improve laser-coupling

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Montgomery, D. S.; Albright, B. J.; Barnak, D. H.; Chang, P. Y.; Davies, J. R.; Fiksel, G.; Froula, D. H.; Kline, J. L.; MacDonald, M. J.; Sefkow, A. B.; et al

    2015-01-13

    Efficient coupling of laser energy into hohlraum targets is important for indirect drive ignition. Laser-plasma instabilities can reduce coupling, reduce symmetry, and cause preheat. We consider the effects of an external magnetic field on laser-energy coupling in hohlraum targets. Experiments were performed at the Omega Laser Facility using low-Z gas-filled hohlraum targets which were placed in a magnetic coil with Bz ≤ 7.5-T. We found that an external field Bz = 7.5-T aligned along the hohlraum axis results in up to a 50% increase in plasma temperature as measured by Thomson scattering. As a result, the experiments were modeled usingmore » the 2-D magnetohydrodynamics package in HYDRA and were found to be in good agreement.« less

  6. Effects of large laser bandwidth on stimulated Raman scattering instability in underdense plasma

    SciTech Connect (OSTI)

    Zhao, Yao; Yu, Lu-Le; Zheng, Jun; Weng, Su-Ming; Ren, Chuang; Liu, Chuan-Sheng; Sheng, Zheng-Ming E-mail: zhengming.sheng@strath.ac.uk

    2015-05-15

    The effects of laser bandwidth on stimulated Raman scattering (SRS) instability in underdense plasma are studied by particle-in-cell simulations. In the simulations, sinusoidal frequency modulation of the incident laser pulse is used. By changing the size of bandwidth, it is shown that the linear growth of SRS can be suppressed considerably, provided the laser bandwidth is much larger than the SRS linear growth rate. Simulations also show that by choosing the proper frequency modulation parameters or decreasing the linear growth rate of SRS, the inhibitory effects become more obvious. The plasma electron temperature tends to weaken the bandwidth effects especially when it is over a keV level. The laser bandwidth can only increase the time duration for linear growth but cannot diminish the instability completely.

  7. Use of external magnetic fields in hohlraum plasmas to improve laser-coupling

    SciTech Connect (OSTI)

    Montgomery, D. S.; Albright, B. J.; Barnak, D. H.; Chang, P. Y.; Davies, J. R.; Fiksel, G.; Froula, D. H.; Kline, J. L.; MacDonald, M. J.; Sefkow, A. B.; Yin, L.; Betti, R.

    2015-01-13

    Efficient coupling of laser energy into hohlraum targets is important for indirect drive ignition. Laser-plasma instabilities can reduce coupling, reduce symmetry, and cause preheat. We consider the effects of an external magnetic field on laser-energy coupling in hohlraum targets. Experiments were performed at the Omega Laser Facility using low-Z gas-filled hohlraum targets which were placed in a magnetic coil with Bz ≤ 7.5-T. We found that an external field Bz = 7.5-T aligned along the hohlraum axis results in up to a 50% increase in plasma temperature as measured by Thomson scattering. As a result, the experiments were modeled using the 2-D magnetohydrodynamics package in HYDRA and were found to be in good agreement.

  8. Meter Scale Plasma Source for Plasma Wakefield Experiments (Journal...

    Office of Scientific and Technical Information (OSTI)

    Subject: Accelerators,ACCPHY Word Cloud More Like This Full Text Journal Articles Find in Google Scholar Find in Google Scholar Search WorldCat Search WorldCat to find libraries ...

  9. Disassembly time of deuterium-cluster-fusion plasma irradiated by an intense laser pulse

    SciTech Connect (OSTI)

    Bang, W.

    2015-07-02

    Energetic deuterium ions from large deuterium clusters (>10 nm diameter) irradiated by an intense laser pulse (>10? W/cm) produce DD fusion neutrons for a time interval determined by the geometry of the resulting fusion plasma. We show an analytical solution of this time interval, the plasma disassembly time, for deuterium plasmas that are cylindrical in shape. Assuming a symmetrically expanding deuterium plasma, we calculate the expected fusion neutron yield and compare with an independent calculation of the yield using the concept of a finite confinement time at a fixed plasma density. The calculated neutron yields agree quantitatively with the available experimental data. Our one-dimensional simulations indicate that one could expect a tenfold increase in total neutron yield by magnetically confining a 10 - keV deuterium fusion plasma for 10 ns.

  10. Disassembly time of deuterium-cluster-fusion plasma irradiated by an intense laser pulse

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bang, W.

    2015-07-02

    Energetic deuterium ions from large deuterium clusters (>10 nm diameter) irradiated by an intense laser pulse (>10¹⁶ W/cm²) produce DD fusion neutrons for a time interval determined by the geometry of the resulting fusion plasma. We show an analytical solution of this time interval, the plasma disassembly time, for deuterium plasmas that are cylindrical in shape. Assuming a symmetrically expanding deuterium plasma, we calculate the expected fusion neutron yield and compare with an independent calculation of the yield using the concept of a finite confinement time at a fixed plasma density. The calculated neutron yields agree quantitatively with the availablemore » experimental data. Our one-dimensional simulations indicate that one could expect a tenfold increase in total neutron yield by magnetically confining a 10 - keV deuterium fusion plasma for 10 ns.« less

  11. Disassembly time of deuterium-cluster-fusion plasma irradiated by an intense laser pulse

    SciTech Connect (OSTI)

    Bang, W.

    2015-07-02

    Energetic deuterium ions from large deuterium clusters (>10 nm diameter) irradiated by an intense laser pulse (>10¹⁶ W/cm²) produce DD fusion neutrons for a time interval determined by the geometry of the resulting fusion plasma. We show an analytical solution of this time interval, the plasma disassembly time, for deuterium plasmas that are cylindrical in shape. Assuming a symmetrically expanding deuterium plasma, we calculate the expected fusion neutron yield and compare with an independent calculation of the yield using the concept of a finite confinement time at a fixed plasma density. The calculated neutron yields agree quantitatively with the available experimental data. Our one-dimensional simulations indicate that one could expect a tenfold increase in total neutron yield by magnetically confining a 10 - keV deuterium fusion plasma for 10 ns.

  12. Computational model of collisional-radiative nonequilibrium plasma in an air-driven type laser propulsion

    SciTech Connect (OSTI)

    Ogino, Yousuke; Ohnishi, Naofumi

    2010-05-06

    A thrust power of a gas-driven laser-propulsion system is obtained through interaction with a propellant gas heated by a laser energy. Therefore, understanding the nonequilibrium nature of laser-produced plasma is essential for increasing available thrust force and for improving energy conversion efficiency from a laser to a propellant gas. In this work, a time-dependent collisional-radiative model for air plasma has been developed to study the effects of nonequilibrium atomic and molecular processes on population densities for an air-driven type laser propulsion. Many elementary processes are considered in the number density range of 10{sup 12}/cm{sup 3}<=N<=10{sup 19}/cm{sup 3} and the temperature range of 300 K<=T<=40,000 K. We then compute the unsteady nature of pulsively heated air plasma. When the ionization relaxation time is the same order as the time scale of a heating pulse, the effects of unsteady ionization are important for estimating air plasma states. From parametric computations, we determine the appropriate conditions for the collisional-radiative steady state, local thermodynamic equilibrium, and corona equilibrium models in that density and temperature range.

  13. First experiments probing the collision of parallel magnetic fields using laser-produced plasmas

    SciTech Connect (OSTI)

    Rosenberg, M. J.; Li, C. K.; Fox, W.; Igumenshchev, I.; Seguin, F. H.; Town, R. P.; Frenje, J. A.; Stoeckl, C.; Glebov, V.; Petrasso, R. D.

    2015-04-08

    Novel experiments to study the strongly-driven collision of parallel magnetic fields in ?~10, laser-produced plasmas have been conducted using monoenergetic proton radiography. These experiments were designed to probe the process of magnetic flux pileup, which has been identified in prior laser-plasma experiments as a key physical mechanism in the reconnection of anti-parallel magnetic fields when the reconnection inflow is dominated by strong plasma flows. In the present experiments using colliding plasmas carrying parallel magnetic fields, the magnetic flux is found to be conserved and slightly compressed in the collision region. Two-dimensional (2D) particle-in-cell (PIC) simulations predict a stronger flux compression and amplification of the magnetic field strength, and this discrepancy is attributed to the three-dimensional (3D) collision geometry. Future experiments may drive a stronger collision and further explore flux pileup in the context of the strongly-driven interaction of magnetic fields.

  14. First experiments probing the collision of parallel magnetic fields using laser-produced plasmas

    SciTech Connect (OSTI)

    Rosenberg, M. J. Li, C. K.; Séguin, F. H.; Frenje, J. A.; Petrasso, R. D.; Fox, W.; Igumenshchev, I.; Stoeckl, C.; Glebov, V.; Town, R. P. J.

    2015-04-15

    Novel experiments to study the strongly-driven collision of parallel magnetic fields in β ∼ 10, laser-produced plasmas have been conducted using monoenergetic proton radiography. These experiments were designed to probe the process of magnetic flux pileup, which has been identified in prior laser-plasma experiments as a key physical mechanism in the reconnection of anti-parallel magnetic fields when the reconnection inflow is dominated by strong plasma flows. In the present experiments using colliding plasmas carrying parallel magnetic fields, the magnetic flux is found to be conserved and slightly compressed in the collision region. Two-dimensional (2D) particle-in-cell simulations predict a stronger flux compression and amplification of the magnetic field strength, and this discrepancy is attributed to the three-dimensional (3D) collision geometry. Future experiments may drive a stronger collision and further explore flux pileup in the context of the strongly-driven interaction of magnetic fields.

  15. First experiments probing the collision of parallel magnetic fields using laser-produced plasmas

    SciTech Connect (OSTI)

    Rosenberg, M. J.; Li, C. K.; Fox, W.; Igumenshchev, I.; Seguin, F. H.; Town, R. P.; Frenje, J. A.; Stoeckl, C.; Glebov, V.; Petrasso, R. D.

    2015-04-08

    Novel experiments to study the strongly-driven collision of parallel magnetic fields in β~10, laser-produced plasmas have been conducted using monoenergetic proton radiography. These experiments were designed to probe the process of magnetic flux pileup, which has been identified in prior laser-plasma experiments as a key physical mechanism in the reconnection of anti-parallel magnetic fields when the reconnection inflow is dominated by strong plasma flows. In the present experiments using colliding plasmas carrying parallel magnetic fields, the magnetic flux is found to be conserved and slightly compressed in the collision region. Two-dimensional (2D) particle-in-cell (PIC) simulations predict a stronger flux compression and amplification of the magnetic field strength, and this discrepancy is attributed to the three-dimensional (3D) collision geometry. Future experiments may drive a stronger collision and further explore flux pileup in the context of the strongly-driven interaction of magnetic fields.

  16. Spectroscopic study using line ratios of lithiumlike ions in a laser-produced plasma

    SciTech Connect (OSTI)

    Moreno, J.C.; Goldsmith, S.; Griem, H.R.

    1989-02-15

    Spectra of highly ionized titanium and calcium in the extreme ultraviolet region were observed in laser-produced plasmas using the OMEGA 24 beam (351 nm) laser system at the University of Rochester. The plasmas were produced using glass microballoon targets coated with a layer of a medium Z element and a layer of parylene (CH). Time-integrated electron temperatures and densities were obtained by comparing measured line intensity ratios of lithiumlike charge states of Ti and Ca to numerical calculations from a collisional-radiative model. The variation of line intensity ratios with electron density and temperature using the collisional-radiative model is discussed.

  17. Self-compression of intense short laser pulses in relativistic magnetized plasma

    SciTech Connect (OSTI)

    Olumi, M.; Maraghechi, B.

    2014-11-15

    The compression of a relativistic Gaussian laser pulse in a magnetized plasma is investigated. By considering relativistic nonlinearity and using non-linear Schrdinger equation with paraxial approximation, a second-order differential equation is obtained for the pulse width parameter (in time) to demonstrate the longitudinal pulse compression. The compression of laser pulse in a magnetized plasma can be observed by the numerical solution of the equation for the pulse width parameter. The effects of magnetic field and chirping are investigated. It is shown that in the presence of magnetic field and negative initial chirp, compression of pulse is significantly enhanced.

  18. Self-focusing of circularly polarized laser pulse propagating through a magnetized non-Maxwellian plasma

    SciTech Connect (OSTI)

    Sepehri Javan, N.

    2014-10-15

    Self-focusing of an intense circularly polarized laser pulse propagating through a magnetized non-Maxwellian plasma is investigated. Based on a relativistic two-fluid model, nonlinear equation describing dynamics of the slowly varying amplitude is obtained. The evolution of laser spot size is studied and effect of non-Maxwellian distribution of charge density on the spot size is considered. It is shown that the existence of super-thermal particles leads to the enhancement of the self-focusing quality of plasma.

  19. COLLOQUIUM: Exploring Mars With Curiosity and Its Laser | Princeton Plasma

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Physics Lab April 3, 2013, 4:15pm to 5:30pm Colloquia MBG Auditorium COLLOQUIUM: Exploring Mars With Curiosity and Its Laser Dr. Roger C. Wiens Los Alamos National Laboratory Presentation: File WC03APR2013_RCWiens.pptx The ChemCam instrument on board the Curiosity Mars rover employs laser-induced breakdown spectroscopy (LIBS) to determine the chemical composition of rock and soil samples up to 7 m from the rover. Its Nd:KGW laser projects 14 mJ pulses at 1067 nm onto 350-550 µm spots,

  20. Radiation characteristics of femtosecond laser-induced plasma channel Vee antenna

    SciTech Connect (OSTI)

    Choe, Yun-Sik; Hao, Zuoqiang; Lin, Jingquan

    2015-06-15

    A virtual reconfigurable plasma Vee antenna consisting of a set of laser plasma filaments produced by femtosecond laser pulses in air is investigated in this paper. The calculation results show that radiation pattern becomes more complex and gain shows initially rapid rise but gradually saturate as the leg length increases, but the pattern and gain are not seriously affected by the plasma conductivity; particularly, the gain of the Vee antenna with plasma conductivity σ = 100S/m can reach about 80% of that of a copper antenna. Radiation efficiency of the antenna has shown a strong dependence on radius of the antenna leg, and an efficiency of 65%, considered to have a proper performance, can be obtained with the channel radius of about 10 mm. Apex angle variation can lead to significant change of the radiation pattern and influence the gain; the best apex angle corresponding to maximal gain and good directivity for the third resonance antenna leg length is found to be at 74° at 600 MHz and σ = 100 S/m. The calculation has shown that at terawatt laser power level, the plasma channel conductivity is close to that of conventional plasma antenna, and peak gain of the Vee antenna is more than 8 dB with a good directivity. In addition, the radiation pattern of special Vee antennas with apex angle 180°-dipole antennas, for first and third resonance leg lengths, is compared and underneath physics of the difference is given. The laser-induced plasma channel antenna is especially suitable for achieving good directivity and gain, which has advantage over conventional plasma antenna with gas discharge tube or metal antenna.

  1. Simulations of laser-plasma interactions in targets for the National

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ignition Facility and beyond | Argonne Leadership Computing Facility laser-plasma interactions in targets for the National Ignition Facility and beyond PI Name: Denise Hinkel PI Email: hinkel1@llnl.gov Institution: Lawrence Livermore National Laboratory Allocation Program: INCITE Allocation Hours at ALCF: 50,000,000 Year: 2011 Research Domain: Physics In the 2010-2012 time frame, the National Ignition Facility will be creating a burning plasma in the laboratory, and an important aspect of

  2. Simulation of Laser-Plasma Interaction in National Ignition Facility

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Experiments | Argonne Leadership Computing Facility A volume visualization of the laser light that has been backscattered by Stimulated Raman Scattering A volume visualization of the laser light that has been backscattered by Stimulated Raman Scattering in a simulation of a National Ignition Facility inertial fusion experiment. The band of scattered light near the bottom of the simulation extends across all three quads and is an example of "cooperative backscattering." Eric Brugger

  3. Petascale Simulations of Laser Plasma Interaction Relevant to IFE | Argonne

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Leadership Computing Facility Ex-field at two different times showing the evolution of a nonlinear electron plasma wave in an SRS simulation using OSIRIS The Ex-field at two different times showing the evolution of a nonlinear electron plasma wave in an SRS simulation using OSIRIS. The wave breaks up due to modulations in both the longitudinal and transverse directions, the wave-fronts bow due to the nonlinear plasma wave frequency shift, and the wave localizes transversely about its central

  4. Laser acceleration of electrons in two-dimensionally inhomogeneous plasma at the boundary of a metal foil

    SciTech Connect (OSTI)

    Pugachev, L. P. Andreev, N. E. Levashov, P. R.; Malkov, Yu. A. Stepanov, A. N. Yashunin, D. A.

    2015-07-15

    The electron acceleration mechanism associated with the generation of a plasma wave due to self-modulation instability of laser radiation in a subcritical plasma produced by a laser prepulse coming 10 ns before the arrival of the main intense femtosecond pulse is considered. Three-dimensional particle-in-cell simulations of the interaction of laser radiation with two-dimensionally inhomogeneous subcritical plasma have shown that, for a sufficiently strong plasma inhomogeneity and a sharp front of the laser pulse, efficient plasma wave excitation, electron trapping, and generation of collimated electron beams with energies on the order of 0.2–0.5 MeV can occur. The simulation results agree with experiments on the generation of collimated beams of accelerated electrons from metal targets irradiated by intense femtosecond laser pulses.

  5. Theoretical foundations of detection of terahertz radiation in laser-plasma interactions

    SciTech Connect (OSTI)

    Frolov, A. A.

    2013-02-15

    A theory is developed enabling one to calculate the temporal profile and spectrum of a terahertz wave packet from the energy of the second harmonic of optical radiation generated during the nonlinear interaction between terahertz and circularly polarized laser pulses in the skin layer of an overdense plasma. It is shown that the spectral and temporal characteristics of the envelope of the second harmonic of optical radiation coincide with those of the terahertz pulse only at small durations of the detecting laser radiation. For long laser pulses, the temporal profile and spectrum of the second harmonic are mainly determined by the characteristics of optical radiation at the carrier frequency.

  6. Slowing of magnetic reconnection concurrent with weakening plasma inflows and increasing collisionality in strongly-driven laser-plasma experiments

    SciTech Connect (OSTI)

    Rosenberg, M.? J.; Li, C.? K.; Fox, W.; Zylstra, A.? B.; Stoeckl, C.; Sguin, F.? H.; Frenje, J.? A.; Petrasso, R. D.

    2015-05-20

    An evolution of magnetic reconnection behavior, from fast jets to the slowing of reconnection and the establishment of a stable current sheet, has been observed in strongly-driven, ? ? 20 laser-produced plasma experiments. This process has been inferred to occur alongside a slowing of plasma inflows carrying the oppositely-directed magnetic fields as well as the evolution of plasma conditions from collisionless to collisional. High-resolution proton radiography has revealed unprecedented detail of the forced interaction of magnetic fields and super-Alfvnic electron jets (Vjet~ 20VA) ejected from the reconnection region, indicating that two-fluid or collisionless magnetic reconnection occurs early in time. The absence of jets and the persistence of strong, stable magnetic fields at late times indicates that the reconnection process slows down, while plasma flows stagnate and plasma conditions evolve to a cooler, denser, more collisional state. These results demonstrate that powerful initial plasma flows are not sufficient to force a complete reconnection of magnetic fields, even in the strongly-driven regime.

  7. Slowing of magnetic reconnection concurrent with weakening plasma inflows and increasing collisionality in strongly-driven laser-plasma experiments

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Rosenberg, M.  J.; Li, C.  K.; Fox, W.; Zylstra, A.  B.; Stoeckl, C.; Séguin, F.  H.; Frenje, J.  A.; Petrasso, R. D.

    2015-05-20

    An evolution of magnetic reconnection behavior, from fast jets to the slowing of reconnection and the establishment of a stable current sheet, has been observed in strongly-driven, β ≲ 20 laser-produced plasma experiments. This process has been inferred to occur alongside a slowing of plasma inflows carrying the oppositely-directed magnetic fields as well as the evolution of plasma conditions from collisionless to collisional. High-resolution proton radiography has revealed unprecedented detail of the forced interaction of magnetic fields and super-Alfvénic electron jets (Vjet~ 20VA) ejected from the reconnection region, indicating that two-fluid or collisionless magnetic reconnection occurs early in time. Themore » absence of jets and the persistence of strong, stable magnetic fields at late times indicates that the reconnection process slows down, while plasma flows stagnate and plasma conditions evolve to a cooler, denser, more collisional state. These results demonstrate that powerful initial plasma flows are not sufficient to force a complete reconnection of magnetic fields, even in the strongly-driven regime.« less

  8. Slowing of magnetic reconnection concurrent with weakening plasma inflows and increasing collisionality in strongly-driven laser-plasma experiments

    SciTech Connect (OSTI)

    Rosenberg, M.  J.; Li, C.  K.; Fox, W.; Zylstra, A.  B.; Stoeckl, C.; Séguin, F.  H.; Frenje, J.  A.; Petrasso, R. D.

    2015-05-20

    An evolution of magnetic reconnection behavior, from fast jets to the slowing of reconnection and the establishment of a stable current sheet, has been observed in strongly-driven, β ≲ 20 laser-produced plasma experiments. This process has been inferred to occur alongside a slowing of plasma inflows carrying the oppositely-directed magnetic fields as well as the evolution of plasma conditions from collisionless to collisional. High-resolution proton radiography has revealed unprecedented detail of the forced interaction of magnetic fields and super-Alfvénic electron jets (Vjet~ 20VA) ejected from the reconnection region, indicating that two-fluid or collisionless magnetic reconnection occurs early in time. The absence of jets and the persistence of strong, stable magnetic fields at late times indicates that the reconnection process slows down, while plasma flows stagnate and plasma conditions evolve to a cooler, denser, more collisional state. These results demonstrate that powerful initial plasma flows are not sufficient to force a complete reconnection of magnetic fields, even in the strongly-driven regime.

  9. Slowing of magnetic reconnection concurrent with weakening plasma inflows and increasing collisionality in strongly-driven laser-plasma experiments

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Rosenberg, M.? J.; Li, C.? K.; Fox, W.; Zylstra, A.? B.; Stoeckl, C.; Sguin, F.? H.; Frenje, J.? A.; Petrasso, R.? D.

    2015-05-20

    An evolution of magnetic reconnection behavior, from fast jets to the slowing of reconnection and the establishment of a stable current sheet, has been observed in strongly driven, ? ? 20 laser-produced plasma experiments. This process has been inferred to occur alongside a slowing of plasma inflows carrying the oppositely-directed magnetic fields as well as the evolution of plasma conditions from collisionless to collisional. High-resolution proton radiography has revealed unprecedented detail of the forced interaction of magnetic fields and super-Alfvnic electron jets (Vjet ~ 20VA) ejected from the reconnection region, indicating that two-fluid or collisionless magnetic reconnection occurs early inmoretime. The absence of jets and the persistence of strong, stable magnetic fields at late times indicates that the reconnection process slows down, while plasma flows stagnate and plasma conditions evolve to a cooler, denser, more collisional state. These results demonstrate that powerful initial plasma flows are not sufficient to force a complete reconnection of magnetic fields, even in the strongly-driven regime.less

  10. Simulation of Laser-plasma Interaction in National Ignition Facility

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Experiments | Argonne Leadership Computing Facility Figure 1a is a volume visualization of the laser light that has been backscattered by Stimulated Raman Scattering in a simulation of a National Ignition Facility inertial fusion experiment. At this point in time, light is scattering independently from the three laser quads (a quad is a group of 2x2 beams propagating in the same direction). Figure 1b is a volume visualization from the same simulation, but at a different time. The band of

  11. Detailed energy distributions in laser-produced plasmas of solid gold and foam gold planar targets

    SciTech Connect (OSTI)

    Dong, Yunsong; Zhang, Lu; Yang, Jiamin; Shang, Wanli

    2013-12-15

    Foam gold was proposed to increase the laser to x-ray conversion efficiency due to its important applications. To understand the mechanism of x-ray enhancement, the detailed energy distributions and plasma profiles for laser-irradiated solid gold and foam gold targets were studied comparatively by hydrodynamic simulations using the code Multi-1D. It is confirmed that the radiation heat wave is subsonic for the normal solid gold target, while supersonic for the foam gold target. The shock wave, which is behind the supersonic radiation heat wave for the foam gold target, generates a plasma temperature gradient with high temperature near the shock wave front to produce an additional net outward radiation for enhancement of the x-ray emission. Much larger inward plasma velocity is also driven by the shock wave as an initial plasma velocity for the laser deposition and electron thermal conduct zone, which decreases the expanding plasma kinetic energy loss and helps to increase the x-ray radiation.

  12. Third harmonic generation in air ambient and laser ablated carbon plasma

    SciTech Connect (OSTI)

    Singh, Ravi Pratap Gupta, Shyam L.; Thareja, Raj K.

    2015-12-15

    We report the third harmonic generation of a nanosecond laser pulse (1.06 μm) in air ambient and in the presence of nanoparticles from laser ablated carbon plasma. Significant decrease in the threshold of third harmonic generation and multi-fold increment in the intensity of generated third harmonic is observed in presence of carbon plasma. The third harmonic in air is due to the quasi-resonant four photon process involving vibrationally excited states of molecular ion of nitrogen due to electron impact ionization and laser pulse. Following optical emission spectroscopic observations we conclude that the presence of C{sub 2} and CN in the ablated plume play a vital role in the observed third harmonic signals.

  13. Temporal profile measurements of relativistic electron bunch based on wakefield generation

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bettoni, S.; Craievich, P.; Lutman, A. A.; Pedrozzi, M.

    2016-02-25

    A complete characterization of the time-resolved longitudinal beam phase space is important to optimize the final performances of an accelerator, and in particular this is crucial for Free Electron Laser (FEL) facilities. In this study we propose a novel method to characterize the profile of a relativistic electron bunch by passively streaking the beam using its self-interaction with the transverse wakefield excited by the bunch itself passing off-axis through a dielectric-lined or a corrugated waveguide. Results of a proof-of-principle experiment at the SwissFEL Injector Test Facility are discussed.

  14. Sub-structure of laser generated harmonics reveals plasma dynamics of a relativistically oscillating mirror

    SciTech Connect (OSTI)

    Braenzel, J.; Schnürer, M.; Steinke, S.; Priebe, G.; Sandner, W.; Andreev, A.; Vavilov State Optical Institute, Birzhevaya line 4, 199034 St. Petersburg ; Platonov, K.

    2013-08-15

    Theoretical and experimental investigations of the dynamics of a relativistically oscillating plasma slab reveal spectral line splitting in laser driven harmonic spectra, leading to double harmonic series. Both series are well characterized with harmonics arising by two fundamental frequencies. While a relativistic oscillation of the critical density drives the harmonic emission, the splitting is a result of an additional acceleration during the laser pulse duration. In comparison with the oscillatory movement, this acceleration is rather weak and can be described by a plasma shock wave driven by the pressure of light. We introduce particle in cell simulations and an analytical model explaining the harmonic line splitting. The derived analytical formula gives direct access between the splitting in the harmonic spectrum and the acceleration of the plasma surface.

  15. The effect of quantum correction on plasma electron heating in ultraviolet laser interaction

    SciTech Connect (OSTI)

    Zare, S.; Sadighi-Bonabi, R. Anvari, A.; Yazdani, E.; Hora, H.

    2015-04-14

    The interaction of the sub-picosecond UV laser in sub-relativistic intensities with deuterium is investigated. At high plasma temperatures, based on the quantum correction in the collision frequency, the electron heating and the ion block generation in plasma are studied. It is found that due to the quantum correction, the electron heating increases considerably and the electron temperature uniformly reaches up to the maximum value of 4.91 × 10{sup 7 }K. Considering the quantum correction, the electron temperature at the laser initial coupling stage is improved more than 66.55% of the amount achieved in the classical model. As a consequence, by the modified collision frequency, the ion block is accelerated quicker with higher maximum velocity in comparison with the one by the classical collision frequency. This study proves the necessity of considering a quantum mechanical correction in the collision frequency at high plasma temperatures.

  16. Cluster beam targets for laser plasma extreme ultraviolet and soft x-ray sources

    DOE Patents [OSTI]

    Kublak, Glenn D.; Richardson, Martin C. (CREOL

    1996-01-01

    Method and apparatus for producing extreme ultra violet (EUV) and soft x-ray radiation from an ultra-low debris plasma source are disclosed. Targets are produced by the free jet expansion of various gases through a temperature controlled nozzle to form molecular clusters. These target clusters are subsequently irradiated with commercially available lasers of moderate intensity (10.sup.11 -10.sup.12 watts/cm.sup.2) to produce a plasma radiating in the region of 0.5 to 100 nanometers. By appropriate adjustment of the experimental conditions the laser focus can be moved 10-30 mm from the nozzle thereby eliminating debris produced by plasma erosion of the nozzle.

  17. Cluster beam targets for laser plasma extreme ultraviolet and soft x-ray sources

    DOE Patents [OSTI]

    Kublak, G.D.; Richardson, M.C.

    1996-11-19

    Method and apparatus for producing extreme ultraviolet (EUV) and soft x-ray radiation from an ultra-low debris plasma source are disclosed. Targets are produced by the free jet expansion of various gases through a temperature controlled nozzle to form molecular clusters. These target clusters are subsequently irradiated with commercially available lasers of moderate intensity (10{sup 11}--10{sup 12} watts/cm{sup 2}) to produce a plasma radiating in the region of 0.5 to 100 nanometers. By appropriate adjustment of the experimental conditions the laser focus can be moved 10--30 mm from the nozzle thereby eliminating debris produced by plasma erosion of the nozzle. 5 figs.

  18. Effect of nonlinear chirped Gaussian laser pulse on plasma wake field generation

    SciTech Connect (OSTI)

    Afhami, Saeedeh; Eslami, Esmaeil

    2014-08-15

    An ultrashort laser pulse propagating in plasma can excite a nonlinear plasma wake field which can accelerate charged particles up to GeV energies within a compact space compared to the conventional accelerator devices. In this paper, the effect of different kinds of nonlinear chirped Gaussian laser pulse on wake field generation is investigated. The numerical analysis of our results depicts that the excitation of plasma wave with large and highly amplitude can be accomplished by nonlinear chirped pulses. The maximum amplitude of excited wake in nonlinear chirped pulse is approximately three times more than that of linear chirped pulse. In order to achieve high wake field generation, chirp parameters and functions should be set to optimal values.

  19. Extended plasma channels created by UV laser in air and their application to control electric discharges

    SciTech Connect (OSTI)

    Zvorykin, V. D. Ionin, A. A.; Levchenko, A. O.; Seleznev, L. V.; Sinitsyn, D. V.; Smetanin, I. V.; Ustinovskii, N. N.; Shutov, A. V.

    2015-02-15

    Results are presented from a series of experimental and theoretical studies on creating weakly ionized extended plasma channels in atmospheric air by 248-nm UV laser radiation and their application to control long high-voltage discharges. The main mechanisms of air ionization by UV laser pulses with durations from 100 fs to 25 ns and intensities in the ranges of 3×10{sup 11}–1.5×10{sup 13} and 3×10{sup 6}–3×10{sup 11} W/cm{sup 2}, respectively, which are below the threshold for optical gas breakdown, as well as the main relaxation processes in plasma with a density of 10{sup 9}–10{sup 17} cm{sup −3}, are considered. It is shown that plasma channels in air can be efficiently created by amplitude-modulated UV pulses consisting of a train of subpicosecond pulses producing primary photoelectrons and a long UV pulse suppressing electron attachment and sustaining the density of free electrons in plasma. Different modes of the generation and amplification of trains of subterawatt subpicosecond pulses and amplitude-modulated UV pulses with an energy of several tens of joules were implemented on the GARPUN-MTW hybrid Ti:sapphire-KrF laser facility. The filamentation of such UV laser beams during their propagation in air over distances of up to 100 m and the parameters of the corresponding plasma channels were studied experimentally and theoretically. Laser initiation of high-voltage electric discharges and control of their trajectories by means of amplitude-modulated UV pulses, as well as the spatiotemporal structure of breakdowns in air gaps with length of up to 80 cm, were studied.

  20. Spectroscopic study of plasmas produced by a laser equipped with distribution phase plates

    SciTech Connect (OSTI)

    Goldsmith, S.; Moreno, J.C.; Griem, H.R. ); Cohen, L. ); Knauer, J. )

    1993-07-01

    The spectra emitted by Al and Si laser-produced plasmas were recorded in the region of 18--350 A. The bandlike structures observed near the Al XI and Si XII 2[ital p]--3[ital d] transitions at 52 and 44 A, respectively, are identified as Be-like dielectronic satellite transitions in Al and Si. The plasmas were produced with the Omega laser system at the Laboratory for Laser Energetics at the University of Rochester. Typical laser pulse lengths were 650 ps at a laser wavelength of 351 nm, with an intensity of 5--9[times]10[sup 14] W/cm[sup 2]. The spherical targets employed in these experiments consisted of solid-glass spheres coated with a 2 [mu]m layer of Al and an outer layer of parylene 0--8 [mu]m thick, illuminated by 24 laser beams equipped with distributed phase plates (DPP's) to improve the uniformity of illumination. The dielectronic transitions associated with the observed bands belong to the transition arrays 1[ital s][sup 2]2[ital pnl]--1[ital s][sup 2]3[ital dnl], where [ital n] is the principal quantum number (greater than 2) and [ital l] is the azimuthal quantum number of the spectator electron. The observation of Be-like dielectronic transitions suggests that this emission occurs from a lower temperature ([ital T][sub [ital e

  1. Wakefields of Sub-Picosecond Electron Bunches

    SciTech Connect (OSTI)

    Bane, Karl L.F.; /SLAC

    2006-04-19

    We discuss wakefields excited by short bunches in accelerators. In particular, we review some of what has been learned in recent years concerning diffraction wakes, roughness impedance, coherent synchrotron radiation wakes, and the resistive wall wake, focusing on analytical solutions where possible. As examples, we apply formulas for these wakes to various parts of the Linac Coherent Light Source (LCLS) project. The longitudinal accelerator structure wake of the SLAC linac is an important ingredient in the LCLS bunch compression process. Of the wakes in the undulator region, the dominant one is the resistive wall wake of the beam pipe.

  2. CO2 laser and plasma microjet process for improving laser optics

    DOE Patents [OSTI]

    Brusasco, Raymond M.; Penetrante, Bernardino M.; Butler, James A.; Grundler, Walter; Governo, George K.

    2003-09-16

    A optic is produced for operation at the fundamental Nd:YAG laser wavelength of 1.06 micrometers through the tripled Nd:YAG laser wavelength of 355 nanometers by the method of reducing or eliminating the growth of laser damage sites in the optics by processing the optics to stop damage in the optics from growing to a predetermined critical size. A system is provided of mitigating the growth of laser-induced damage in optics by virtue of very localized removal of glass and absorbing material.

  3. Laser plasma x-ray source for ultrafast time-resolved x-ray absorption spectroscopy

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Miaja-Avila, L.; O'Neil, G. C.; Uhlig, J.; Cromer, C. L.; Dowell, M. L.; Jimenez, R.; Hoover, A. S.; Silverman, K. L.; Ullom, J. N.

    2015-03-02

    We describe a laser-driven x-ray plasma source designed for ultrafast x-ray absorption spectroscopy. The source is comprised of a 1 kHz, 20 W, femtosecond pulsed infrared laser and a water target. We present the x-ray spectra as a function of laser energy and pulse duration. Additionally, we investigate the plasma temperature and photon flux as we vary the laser energy. We obtain a 75 μm FWHM x-ray spot size, containing ~106 photons/s, by focusing the produced x-rays with a polycapillary optic. Since the acquisition of x-ray absorption spectra requires the averaging of measurements from >107 laser pulses, we also presentmore » data on the source stability, including single pulse measurements of the x-ray yield and the x-ray spectral shape. In single pulse measurements, the x-ray flux has a measured standard deviation of 8%, where the laser pointing is the main cause of variability. Further, we show that the variability in x-ray spectral shape from single pulses is low, thus justifying the combining of x-rays obtained from different laser pulses into a single spectrum. Finally, we show a static x-ray absorption spectrum of a ferrioxalate solution as detected by a microcalorimeter array. Altogether, our results demonstrate that this water-jet based plasma source is a suitable candidate for laboratory-based time-resolved x-ray absorption spectroscopy experiments.« less

  4. Laser plasma x-ray source for ultrafast time-resolved x-ray absorption spectroscopy

    SciTech Connect (OSTI)

    Miaja-Avila, L.; O'Neil, G. C.; Uhlig, J.; Cromer, C. L.; Dowell, M. L.; Jimenez, R.; Hoover, A. S.; Silverman, K. L.; Ullom, J. N.

    2015-03-02

    We describe a laser-driven x-ray plasma source designed for ultrafast x-ray absorption spectroscopy. The source is comprised of a 1 kHz, 20 W, femtosecond pulsed infrared laser and a water target. We present the x-ray spectra as a function of laser energy and pulse duration. Additionally, we investigate the plasma temperature and photon flux as we vary the laser energy. We obtain a 75 μm FWHM x-ray spot size, containing ~106 photons/s, by focusing the produced x-rays with a polycapillary optic. Since the acquisition of x-ray absorption spectra requires the averaging of measurements from >107 laser pulses, we also present data on the source stability, including single pulse measurements of the x-ray yield and the x-ray spectral shape. In single pulse measurements, the x-ray flux has a measured standard deviation of 8%, where the laser pointing is the main cause of variability. Further, we show that the variability in x-ray spectral shape from single pulses is low, thus justifying the combining of x-rays obtained from different laser pulses into a single spectrum. Finally, we show a static x-ray absorption spectrum of a ferrioxalate solution as detected by a microcalorimeter array. Altogether, our results demonstrate that this water-jet based plasma source is a suitable candidate for laboratory-based time-resolved x-ray absorption spectroscopy experiments.

  5. 0.351 micron Laser Beam propagation in High-temperature Plasmas

    SciTech Connect (OSTI)

    Froula, D; Divol, L; Meezan, N; Ross, J; Berger, R L; Michel, P; Dixit, S; Rekow, V; Sorce, C; Moody, J D; Neumayer, P; Pollock, B; Wallace, R; Suter, L; Glenzer, S H

    2007-12-10

    A study of the laser-plasma interaction processes have been performed in plasmas that are created to emulate the plasma conditions in indirect drive inertial confinement fusion targets. The plasma emulator is produced in a gas-filled hohlraum; a blue 351-nm laser beam propagates along the axis of the hohlraum interacting with a high-temperature (T{sub e} = 3.5 keV), dense (n{sub e} = 5 x 10{sup 20}cm{sup -3}), long-scale length (L {approx} 2 mm) plasma. Experiments at these conditions have demonstrated that the interaction beam produces less than 1% total backscatter resulting in transmission greater than 90% for laser intensities less than I < 2 x 10{sup 15} W-cm{sup -2}. The bulk plasma conditions have been independently characterized using Thomson scattering where the peak electron temperatures are shown to scale with the hohlraum heater beam energy in the range from 2 keV to 3.5 keV. This feature has allowed us to determine the thresholds for both backscattering and filamentation instabilities; the former measured with absolutely calibrated full aperture backscatter and near backscatter diagnostics and the latter with a transmitted beam diagnostics. A plasma length scaling is also investigated extending our measurements to 4-mm long high-temperature plasmas. At intensities I < 5 x 10{sup 14} W-cm{sup -2}, greater than 80% of the energy in the laser is transmitted through a 5-mm long, high-temperature (T{sub e} > 2.5 keV) high-density (n{sub e} = 5 x 10{sup 20} w-cm{sup -3}) plasma. Comparing the experimental results with detailed gain calculations for the onset of significant laser scattering processes shows a stimulated Brillouin scattering threshold (R=10%) for a linear gain of 15; these high temperature, low density experiments produce plasma conditions comparable to those along the outer beams in ignition hohlraum designs. By increasing the gas fill density (n{sub e} = 10{sup 21} cm{sup -3}) in these targets, the inner beam ignition hohlraum conditions are

  6. Microwave modeling of laser plasma interactions. Final report

    SciTech Connect (OSTI)

    Not Available

    1983-08-01

    For a large laser fusion targets and nanosecond pulse lengths, stimulated Brillouin scattering (SBS) and self-focusing are expected to be significant problems. The goal of the contractual effort was to examine certain aspects of these physical phenomena in a wavelength regime (lambda approx.5 cm) more amenable to detailed diagnostics than that characteristic of laser fusion (lambda approx.1 micron). The effort was to include the design, fabrication and operation of a suitable experimental apparatus. In addition, collaboration with Dr. Neville Luhmann and his associates at UCLA and with Dr. Curt Randall of LLNL, on analysis and modelling of the UCLA experiments was continued. Design and fabrication of the TRW experiment is described under ''Experiment Design'' and ''Experimental Apparatus''. The design goals for the key elements of the experimental apparatus were met, but final integration and operation of the experiment was not accomplished. Some theoretical considerations on the interaction between Stimulated Brillouin Scattering and Self-Focusing are also presented.

  7. Pulsed laser stereophotography of plasmas and dynamically moving surfaces

    SciTech Connect (OSTI)

    Paisley, D.L.

    1987-01-01

    A pulsed laser is used as a light source for illuminating the surface of a dynamic event of less than or equal to1 mm/sup 2/ moving at >3 mm/..mu..s. At a predetermined time during the dynamic action, a stereo camera is used to record a pair of images of the dynamically moving surface. The stereoimage pair can be quantified for surface contour. 3 refs., 8 figs.

  8. Electrons trajectories around a bubble regime in intense laser plasma interaction

    SciTech Connect (OSTI)

    Lu, Ding; Xie, Bai-Song; Ali Bake, Muhammad; Sang, Hai-Bo; Zhao, Xue-Yan; Wu, Hai-Cheng

    2013-06-15

    Some typical electrons trajectories around a bubble regime in intense laser plasma interaction are investigated theoretically. By considering a modification of the fields and ellipsoid bubble shape due to the presence of residual electrons in the bubble regime, we study in detail the electrons nonlinear dynamics with or without laser pulse. To examine the electron dynamical behaviors, a set of typical electrons, which locate initially at the front of the bubble, on the transverse edge and at the bottom of the bubble respectively, are chosen for study. It is found that the range of trapped electrons in the case with laser pulse is a little narrower than that without laser pulse. The partial phase portraits for electrons around the bubble are presented numerically and their characteristic behaviors are discussed theoretically. Implication of our results on the high quality electron beam generation is also discussed briefly.

  9. Response to Comment on Stationary self-focusing of Gaussian laser beam in relativistic thermal quantum plasma [Phys. Plasmas 21, 064701 (2014)

    SciTech Connect (OSTI)

    Patil, S. D.; Takale, M. V.

    2014-06-15

    Habibi and Ghamari have presented a Comment on our paper [Phys. Plasmas 20, 072703 (2013)] by examining quantum dielectric response in thermal quantum plasma. They have modeled the relativistic self-focusing of Gaussian laser beam in cold and warm quantum plasmas and reported that self-focusing length does not change in both situations. In this response, we have reached the following important conclusions about the comment itself.

  10. Excitation wavelength dependence of water-window line emissions from boron-nitride laser-produced plasmas

    SciTech Connect (OSTI)

    Crank, M.; Harilal, S. S.; Hassan, S. M.; Hassanein, A.

    2012-02-01

    We investigated the effects of laser excitation wavelength on water-window emission lines of laser-produced boron-nitride plasmas. Plasmas are produced by focusing 1064 nm and harmonically generated 532 and 266 nm radiation from a Nd:YAG laser on BN target in vacuum. Soft x-ray emission lines in the water-window region are recorded using a grazing-incidence spectrograph. Filtered photodiodes are used to obtain complementary data for water-window emission intensity and angular dependence. Spectral emission intensity changes in nitrogen Ly-{alpha} and He-{alpha} are used to show how laser wavelength affects emission. Our results show that the relative intensity of spectral lines is laser wavelength dependent, with the ratio of Ly-{alpha} to He-{alpha} emission intensity decreasing as laser wavelength is shortened. Filtered photodiode measurements of angular dependence showed that 266 and 532 nm laser wavelengths produce uniform emission.

  11. Test particle simulation of direct laser acceleration in a density-modulated plasma waveguide

    SciTech Connect (OSTI)

    Lin, M.-W.; Jovanovic, I.

    2012-11-15

    Direct laser acceleration (DLA) of electrons by the use of the intense axial electric field of an ultrafast radially polarized laser pulse is a promising technique for future compact accelerators. Density-modulated plasma waveguides can be implemented for guiding the propagation of the laser pulse to extend the acceleration distance and for the quasi-phase-matching between the accelerated electrons and the laser pulse. A test particle model is developed to study the optimal axial density modulation structure of plasma waveguides for laser pulses to efficiently accelerate co-propagating electrons. A simple analytical approach is also presented, which can be used to estimate the energy gain in DLA. The analytical model is validated by the test particle simulation. The effect of injection phase and acceleration of electrons injected at various radial positions are studied. The results indicate that a positively chirped density modulation of the waveguide structure is required to accelerate electron with low initial energies, and can be effectively optimized. A wider tolerance on the injection phase and radial distance from the waveguide axis exists for electrons injected with a higher initial energy.

  12. Electronic excitation as a mode of heat dissipation in laser-driven cluster plasmas

    SciTech Connect (OSTI)

    Rajeev, R.; Rishad, K. P. M.; Madhu Trivikram, T.; Krishnamurthy, M.

    2013-12-15

    Electrons streaming out of laser plasma are known for non-local heat transport and energy deposition by the ionization wave. At 100 eV electron temperature, since the electronic excitation cross section is comparable to that of ionization for Ar and CO{sub 2}, a non-local excitation wave akin to the ionization wave is envisaged where energy deposition in excitations forms a excited cluster sheath beyond the laser focus. Here, we show that nano-cluster systems have the right parameters to form such an exciton sheath and experimentally demonstrate this via charge transfer reactions.

  13. Multiple-beam laserplasma interactions in inertial confinement fusion

    SciTech Connect (OSTI)

    Myatt, J. F. Zhang, J.; Maximov, A. V.; Short, R. W.; Seka, W.; Edgell, D. H.; Michel, D. T.; Igumenshchev, I. V.; Froula, D. H.; Hinkel, D. E.; Michel, P.; Moody, J. D.

    2014-05-15

    The experimental evidence for multiple-beam laser-plasma instabilities of relevance to laser driven inertial confinement fusion at the ignition scale is reviewed, in both the indirect and direct-drive approaches. The instabilities described are cross-beam energy transfer (in both indirectly driven targets on the NIF and in direct-drive targets), multiple-beam stimulated Raman scattering (for indirect-drive), and multiple-beam two-plasmon decay instability (in direct drive). Advances in theoretical understanding and in the numerical modeling of these multiple beam instabilities are presented.

  14. The development of laser-plasma interaction program LAP3D on thousands of processors

    SciTech Connect (OSTI)

    Hu, Xiaoyan Hao, Liang; Liu, Zhanjun; Zheng, Chunyang; Li, Bin Guo, Hong

    2015-08-15

    Modeling laser-plasma interaction (LPI) processes in real-size experiments scale is recognized as a challenging task. For explorering the influence of various instabilities in LPI processes, a three-dimensional laser and plasma code (LAP3D) has been developed, which includes filamentation, stimulated Brillouin backscattering (SBS), stimulated Raman backscattering (SRS), non-local heat transport and plasmas flow computation modules. In this program, a second-order upwind scheme is applied to solve the plasma equations which are represented by an Euler fluid model. Operator splitting method is used for solving the equations of the light wave propagation, where the Fast Fourier translation (FFT) is applied to compute the diffraction operator and the coordinate translations is used to solve the acoustic wave equation. The coupled terms of the different physics processes are computed by the second-order interpolations algorithm. In order to simulate the LPI processes in massively parallel computers well, several parallel techniques are used, such as the coupled parallel algorithm of FFT and fluid numerical computation, the load balance algorithm, and the data transfer algorithm. Now the phenomena of filamentation, SBS and SRS have been studied in low-density plasma successfully with LAP3D. Scalability of the program is demonstrated with a parallel efficiency above 50% on about ten thousand of processors.

  15. Modeling of laser induced plasma expansion in the presence of non-Maxwellian electrons

    SciTech Connect (OSTI)

    Bennaceur-Doumaz, D.; Djebli, M.

    2010-07-15

    The one-dimensional expansion into vacuum of ion-electron plasma produced by laser ablation is investigated. The ions considered as an ideal fluid are governed by a fluid model where charge quasineutrality is assumed to prevail, while electron density follows a non-Maxwellian distribution. Showing that the expansion can be described by a self-similar solution, the resulting nonlinear Euler equations are solved numerically. It is found that the deviation of the electrons from Maxwellian distribution gives rise to new asymptotic solutions of physical interest affecting the density and velocity of plasma expansion.

  16. Spectral characteristics of ultra-short laser pulses in plasma amplifiers

    SciTech Connect (OSTI)

    Riconda, C.; Weber, S.; Institute of Physics of the ASCR, ELI-Beamlines, 18221 Prague ; Lancia, L.; INFNSez. RomaSAPIENZA, University of Rome, 00185 Rome ; Marqus, J.-R.; Fuchs, J.; Mourou, G. A.

    2013-08-15

    Amplification of laser pulses based on the backscattering process in plasmas can be performed using either the response of an electron plasma wave or an ion-acoustic wave. However, if the pulse durations become very short and the natural spread in frequency a substantial amount of the frequency itself, the Raman and Brillouin processes start to mix. Kinetic simulations show the transition from a pure amplification regime, in this case strong-coupling Brillouin, to a regime where a considerable downshift of the frequency of the amplified pulse takes place. It is conjectured that in the case of very short pulses, multi-modes are excited which contribute to the amplification process.

  17. Third harmonic stimulated Raman backscattering of laser in a magnetized plasma

    SciTech Connect (OSTI)

    Paknezhad, Alireza; Dorranian, Davoud

    2013-09-15

    This article studies the nonlinear Raman shifted third harmonic backscattering of an intense extraordinary laser wave through a homogenous transversely magnetized cold plasma. Due to the relativistic nonlinearity, the plasma dynamic is modified in the presence of transversely magnetic field, and this can generate the third harmonic scattered wave and an electrostatic upper hybrid wave via the Raman scattering process. Using the nonlinear wave equation, the mechanism of nonlinear third harmonic Raman scattering is discussed in detail to obtain the maximum growth rate of instability in the mildly relativistic regime. The growth rate decreases as the static magnetic field increases. It also increases with the pump wave amplitude.

  18. Observation of plasma density dependence of electromagnetic soliton excitation by an intense laser pulse

    SciTech Connect (OSTI)

    Sarri, G.; Kar, S.; Kourakis, I.; Borghesi, M.; Romagnani, L.; Bulanov, S. V.; Cecchetti, C. A.; Gizzi, L. A.; Galimberti, M.; Heathcote, R.; Jung, R.; Osterholz, J.; Willi, O.; Schiavi, A.

    2011-08-15

    The experimental evidence of the correlation between the initial electron density of the plasma and electromagnetic soliton excitation at the wake of an intense (10{sup 19} W/cm{sup 2}) and short (1 ps) laser pulse is presented. The spatial distribution of the solitons, together with their late time evolution into post-solitons, is found to be dependent upon the background plasma parameters, in agreement with published analytical and numerical findings. The measured temporal evolution and electrostatic field distribution of the structures are consistent with their late time evolution and the occurrence of multiple merging of neighboring post-solitons.

  19. Induction-linac based free-electron laser amplifiers for plasma heating

    SciTech Connect (OSTI)

    Jong, R.A.

    1988-08-22

    We describe an induction-linac based free-electron laser amplifier that is presently under construction at the Lawrence Livermore National Laboratory. It is designed to produce up to 2 MW of average power at a frequency of 250 GHz for plasma heating experiments in the Microwave Tokamak Experiment. In addition, we shall describe a FEL amplifier design for plasma heating of advanced tokamak fusion devices. This system is designed to produce average power levels of about 10 MW at frequencies ranging form 280 to 560 GHz. 7 refs., 1 tab.

  20. Temporal evolution of femtosecond laser induced plasma filament in air and N{sub 2}

    SciTech Connect (OSTI)

    Papeer, J.; Botton, M.; Zigler, A.; Gordon, D.; Sprangle, P.

    2013-12-09

    We present single shot, high resolution, time-resolved measurements of the relaxation of laser induced plasma filaments in air and in N{sub 2} gas. Based on the measurements of the time dependent electromagnetic signal in a waveguide, an accurate and simple derivation of the electron density in the filament is demonstrated. This experimental method does not require prior knowledge of filament dimensions or control over its exact spatial location. The experimental results are compared to numerical simulations of air plasma chemistry. Results reveal the role of various decay mechanisms including the importance of O{sub 4}{sup +} molecular levels.

  1. A unified model to determine the energy partitioning between target and plasma in nanosecond laser ablation of silicon

    SciTech Connect (OSTI)

    Galasso, G.; Kaltenbacher, M.; Tomaselli, A.; Scarpa, D.

    2015-03-28

    In semiconductor industry, pulsed nanosecond lasers are widely applied for the separation of silicon wafers. Here, the high intensities employed activate a cascade of complex multi-physical and multi-phase mechanisms, which finally result in the formation of a laser induced plasma, shielding the target from the incoming laser beam. Such induced plasma plume, by preventing the laser to effectively reach the target, reduces the overall efficiency and controllability of the ablation process. Modelling can be a useful tool in the optimization of industrial laser applications, allowing a deeper understanding of the way the laser energy distributes between target and induced plasma. Nevertheless, the highly multi-physical character of laser ablation poses serious challenges on the implementation of the various mechanisms underlying the process within a common modelling framework. A novel strategy is here proposed in order to simulate in a simplified, yet physically consistent way, a typical industrial application as laser ablation of silicon wafers. Reasonable agreement with experimental findings is obtained. Three fundamental mechanisms have been identified as the main factors influencing the accuracy of the numerical predictions: the transition from evaporative to volumetric mass removal occurring at critical temperature, the collisional and radiative processes underlying the initial plasma formation stage and the increased impact of the liquid ejection mechanism when a sub-millimeter laser footprint is used.

  2. Test of models for electron transport in laser produced plasmas

    SciTech Connect (OSTI)

    Colombant, D.G.; Manheimer, W.M.; Busquet, M.

    2005-07-15

    This paper examines five different models of electron thermal transport in laser produced spherical implosions. These are classical, classical with a flux limit f, delocalization, beam deposition model, and Fokker-Planck solutions. In small targets, the results are strongly dependent on f for flux limit models, with small f's generating very steep temperature gradients. Delocalization models are characterized by large preheat in the center of the target. The beam deposition model agrees reasonably well with the Fokker-Planck simulation results. For large, high gain fusion targets, the delocalization model shows the gain substantially reduced by the preheat. However, flux limitation models show gain largely independent of f, with the beam deposition model also showing the same high gain.

  3. Diagnosing laser-preheated magnetized plasmas relevant to magnetized liner inertial fusion

    SciTech Connect (OSTI)

    Harvey-Thompson, Adam James; Sefkow, Adam B.; Nagayama, Taisuke N.; Wei, Mingsheng; Campbell, Edward Michael; Fiksel, Gennady; Chang, Po -Yu; Davies, Jonathan R.; Barnak, Daniel H.; Glebov, Vladimir Y.; Fitzsimmons, Paul; Fooks, Julie; Blue, Brent E.

    2015-12-22

    In this paper, we present a platform on the OMEGA EP Laser Facility that creates and diagnoses the conditions present during the preheat stage of the MAGnetized Liner Inertial Fusion (MagLIF) concept. Experiments were conducted using 9 kJ of 3ω (355 nm) light to heat an underdense deuterium gas (electron density: 2.5 × 1020 cm-3 = 0.025 of critical density) magnetized with a 10 T axial field. Results show that the deuterium plasma reached a peak electron temperature of 670 ± 140 eV, diagnosed using streaked spectroscopy of an argon dopant. The results demonstrate that plasmas relevant to the preheat stage of MagLIF can be produced at multiple laser facilities, thereby enabling more rapid progress in understanding magnetized preheat. Results are compared with magneto-radiation-hydrodynamics simulations, and plans for future experiments are described.

  4. Diagnosing laser-preheated magnetized plasmas relevant to magnetized liner inertial fusion

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Harvey-Thompson, Adam James; Sefkow, Adam B.; Nagayama, Taisuke N.; Wei, Mingsheng; Campbell, Edward Michael; Fiksel, Gennady; Chang, Po -Yu; Davies, Jonathan R.; Barnak, Daniel H.; Glebov, Vladimir Y.; et al

    2015-12-22

    In this paper, we present a platform on the OMEGA EP Laser Facility that creates and diagnoses the conditions present during the preheat stage of the MAGnetized Liner Inertial Fusion (MagLIF) concept. Experiments were conducted using 9 kJ of 3ω (355 nm) light to heat an underdense deuterium gas (electron density: 2.5 × 1020 cm-3 = 0.025 of critical density) magnetized with a 10 T axial field. Results show that the deuterium plasma reached a peak electron temperature of 670 ± 140 eV, diagnosed using streaked spectroscopy of an argon dopant. The results demonstrate that plasmas relevant to the preheatmore » stage of MagLIF can be produced at multiple laser facilities, thereby enabling more rapid progress in understanding magnetized preheat. Results are compared with magneto-radiation-hydrodynamics simulations, and plans for future experiments are described.« less

  5. Shock wave acceleration of protons in inhomogeneous plasma interacting with ultrashort intense laser pulses

    SciTech Connect (OSTI)

    Lecz, Zs.; Andreev, A.

    2015-04-15

    The acceleration of protons, triggered by solitary waves in expanded solid targets is investigated using particle-in-cell simulations. The near-critical density plasma is irradiated by ultrashort high power laser pulses, which generate the solitary wave. The transformation of this soliton into a shock wave during propagation in plasma with exponentially decreasing density profile is described analytically, which allows to obtain a scaling law for the proton energy. The high quality proton bunch with small energy spread is produced by reflection from the shock-front. According to the 2D simulations, the mechanism is stable only if the laser pulse duration is shorter than the characteristic development time of the parasitic Weibel instability.

  6. Time-resolved extreme-ultraviolet spectroscopy of laser-produced plasmas originating at the parylene layer of microballon targets

    SciTech Connect (OSTI)

    Griem, H.R.; Moreno, J.

    1991-03-01

    In experiments this past year at the University of Rochester's Laboratory for Laser Energetics we obtained time-integrated and time-resolved spectra from the ultraviolet to the x-ray region. We have investigated various phenomena in laser-produced plasmas including spectral line broadening, plasma expansion velocities, ionization and recombination of low-Z materials in spherical targets, and the formation of satellites near some resonance lines. In addition we have improved our spectroscopic instrumentation.

  7. Simulations of Laser-Plasma Interactions in Targets for the National

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ignition Facility and Beyond | Argonne Leadership Computing Facility Laser-Plasma Interactions in Targets for the National Ignition Facility and Beyond PI Name: Denise Hinkel PI Email: hinkel1@llnl.gov Institution: Lawrence Livermore National Laboratory Allocation Program: INCITE Allocation Hours at ALCF: 63,000,000 Year: 2012 Research Domain: Physics In the 2010-2012 timeframe, Lawrence Livermore National Laboratory is tasked with achieving ignition at the National Ignition Facility (NIF).

  8. Electron Generation and Transport in Intense Relativistic Laser-Plasma Interactions Relevant to Fast Ignition ICF

    SciTech Connect (OSTI)

    Ma, Tammy Yee Wing

    2010-01-01

    The reentrant cone approach to Fast Ignition, an advanced Inertial Confinement Fusion scheme, remains one of the most attractive because of the potential to efficiently collect and guide the laser light into the cone tip and direct energetic electrons into the high density core of the fuel. However, in the presence of a preformed plasma, the laser energy is largely absorbed before it can reach the cone tip. Full scale fast ignition laser systems are envisioned to have prepulses ranging between 100 mJ to 1 J. A few of the imperative issues facing fast ignition, then, are the conversion efficiency with which the laser light is converted to hot electrons, the subsequent transport characteristics of those electrons, and requirements for maximum allowable prepulse this may put on the laser system. This dissertation examines the laser-to-fast electron conversion efficiency scaling with prepulse for cone-guided fast ignition. Work in developing an extreme ultraviolet imager diagnostic for the temperature measurements of electron-heated targets, as well as the validation of the use of a thin wire for simultaneous determination of electron number density and electron temperature will be discussed.

  9. Parabolic lithium mirror for a laser-driven hot plasma producing device

    DOE Patents [OSTI]

    Baird, James K.

    1979-06-19

    A hot plasma producing device is provided, wherein pellets, singly injected, of frozen fuel are each ignited with a plurality of pulsed laser beams. Ignition takes place within a void area in liquid lithium contained within a pressure vessel. The void in the liquid lithium is created by rotating the pressure vessel such that the free liquid surface of molten lithium therein forms a paraboloid of revolution. The paraboloid functions as a laser mirror with a reflectivity greater than 90%. A hot plasma is produced when each of the frozen deuterium-tritium pellets sequentially arrive at the paraboloid focus, at which time each pellet is illuminated by the plurality of pulsed lasers whose rays pass through circular annuli across the top of the paraboloid. The beams from the lasers are respectively directed by associated mirrors, or by means of a single conical mirror in another embodiment, and by the mirror-like paraboloid formed by the rotating liquid lithium onto the fuel pellet such that the optical flux reaching the pellet can be made to be uniform over 96% of the pellet surface area. The very hot plasma produced by the action of the lasers on the respective singly injected fuel pellets in turn produces a copious quantity of neutrons and X-rays such that the device has utility as a neutron source or as an x-ray source. In addition, the neutrons produced in the device may be utilized to produce tritium in a lithium blanket and is thus a mechanism for producing tritium.

  10. Specular Reflectivity and Hot-Electron Generation in High-Contrast Relativistic Laser-Plasma Interactions

    SciTech Connect (OSTI)

    Kemp, Gregory Elijah

    2013-01-01

    Ultra-intense laser (> 1018 W/cm2) interactions with matter are capable of producing relativistic electrons which have a variety of applications in state-of-the-art scientific and medical research conducted at universities and national laboratories across the world. Control of various aspects of these hot-electron distributions is highly desired to optimize a particular outcome. Hot-electron generation in low-contrast interactions, where significant amounts of under-dense pre-plasma are present, can be plagued by highly non-linear relativistic laser-plasma instabilities and quasi-static magnetic field generation, often resulting in less than desirable and predictable electron source characteristics. High-contrast interactions offer more controlled interactions but often at the cost of overall lower coupling and increased sensitivity to initial target conditions. An experiment studying the differences in hot-electron generation between high and low-contrast pulse interactions with solid density targets was performed on the Titan laser platform at the Jupiter Laser Facility at Lawrence Livermore National Laboratory in Livermore, CA. To date, these hot-electrons generated in the laboratory are not directly observable at the source of the interaction. Instead, indirect studies are performed using state-of-the-art simulations, constrained by the various experimental measurements. These measurements, more-often-than-not, rely on secondary processes generated by the transport of these electrons through the solid density materials which can susceptible to a variety instabilities and target material/geometry effects. Although often neglected in these types of studies, the specularly reflected light can provide invaluable insight as it is directly influenced by the interaction. In this thesis, I address the use of (personally obtained) experimental specular reflectivity measurements to indirectly study hot-electron generation in the context of high-contrast, relativistic

  11. Optical control of electron phase space in plasma accelerators with incoherently stacked laser pulses

    SciTech Connect (OSTI)

    Kalmykov, S. Y. Shadwick, B. A.; Davoine, X.; Lehe, R.; Lifschitz, A. F.

    2015-05-15

    It is demonstrated that synthesizing an ultrahigh-bandwidth, negatively chirped laser pulse by incoherently stacking pulses of different wavelengths makes it possible to optimize the process of electron self-injection in a dense, highly dispersive plasma (n{sub 0}∼10{sup 19} cm{sup −3}). Avoiding transformation of the driving pulse into a relativistic optical shock maintains a quasi-monoenergetic electron spectrum through electron dephasing and boosts electron energy far beyond the limits suggested by existing scaling laws. In addition, evolution of the accelerating bucket in a plasma channel is shown to produce a background-free, tunable train of femtosecond-duration, 35–100 kA, time-synchronized quasi-monoenergetic electron bunches. The combination of the negative chirp and the channel permits acceleration of electrons beyond 1 GeV in a 3 mm plasma with 1.4 J of laser pulse energy, thus offering the opportunity of high-repetition-rate operation at manageable average laser power.

  12. Refluxed electrons direct laser acceleration in ultrahigh laser and relativistic critical density plasma interaction

    SciTech Connect (OSTI)

    Wang, J.; Zhao, Z. Q.; Zhu, B.; Zhang, Z. M.; Zhou, W. M.; Gu, Y. Q.; Cao, L. H.

    2015-01-15

    Refluxed electrons direct laser acceleration is proposed so as to generate a high-charge energetic electron beam. When a laser pulse is incident on a relativistic critical density target, the rising edge of the pulse heats the target and the sheath fields on the both sides of the target reflux some electrons inside the expanding target. These electrons can be trapped and accelerated due to the self-transparency and the negative longitudinal electrostatic field in the expanding target. Some of the electrons can be accelerated to energies exceeding the ponderomotive limit 1/2a{sub 0}{sup 2}mc{sup 2}. Effective temperature significantly above the ponderomotive scaling is observed. Furthermore, due to the limited expanding length, the laser propagating instabilities are suppressed in the interaction. Thus, high collimated beams with tens of μC charge can be generated.

  13. High harmonic generation in underdense plasmas by intense laser pulses with orbital angular momentum

    SciTech Connect (OSTI)

    Mendonça, J. T.; Vieira, J.

    2015-12-15

    We study high harmonic generation produced by twisted laser pulses, with orbital angular momentum in the relativistic regime, for pulse propagation in underdense plasma. We consider fast time scale processes associated with an ultra-short pulse, where the ion motion can be neglected. We use both analytical models and numerical simulations using a relativistic particle-in-cell code. The present description is valid for relativistic laser intensities, when the normalized field amplitude is much larger than one, a ≫ 1. We also discuss two distinct processes associated with linear and circular polarization. Using both analytical solutions and particle-in-cell simulations, we are able to show that, for laser pulses in a well defined Laguerre-Gauss mode, angular momentum conservation is observed during the process of harmonic generation. Intensity modulation of the harmonic spectrum is also verified, as imposed by the nonlinear time-scale for energy transfer between different harmonics.

  14. Resonant stimulated Brillouin interaction of opposed laser beams in a drifting plasma

    SciTech Connect (OSTI)

    Cohen, B.I.; Lasinski, B.F.; Langdon, A.B.; Williams, E.A.; Wharton, K.B.; Kirkwood, R.K.; Estabrook, K.G.

    1998-09-01

    Particle simulations and solutions of coupled mode equations are used to analyze the energy transfer between two equal-frequency, opposed laser beams resonantly interacting with ion acoustic waves in a plasma drifting at the sound speed. The simulations and analysis illustrate the dependence of the energy transfer and the ion wave dynamics on laser intensities and detuning, and the time dependence of the phenomena. The simulation results are in qualitative agreement with experimental observations in the NOVA laser facility [E. M. Campbell {ital et al.}, Rev. Sci. Instrum. {bold 57}, 2101 (1986)] at the Lawrence Livermore National Laboratory. This work is part of a continuing examination of possible resonant crossed-beam interactions in flowing plasmas and their potential effects on the fusion performance of current and future laser-fusion experiments with multiple crossing beams, e.g., proposed experiments in the National Ignition Facility [National Tech. Info. Service Document Nos. DE95017671-DE95017673 and DE95017676-DE95017700 (J. A. Paisner, E. M. Campbell, and W. J. Hogan, The Natl. Ignition Facility Project, UCRL-JC-117397 and UCRL-PROP-117093, May, 1994)]. {copyright} {ital 1998 American Institute of Physics.}

  15. First experiments probing the collision of parallel magnetic fields using laser-produced plasmas

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Rosenberg, M. J.; Li, C. K.; Fox, W.; Igumenshchev, I.; S??guin, F. H.; Town, R. P.; Frenje, J. A.; Stoeckl, C.; Glebov, V.; Petrasso, R. D.

    2015-04-01

    Novel experiments to study the strongly-driven collision of parallel magnetic fields in ß~10, laser-produced plasmas have been conducted using monoenergetic proton radiography. These experiments were designed to probe the process of magnetic flux pileup, which has been identified in prior laser-plasma experiments as a key physical mechanism in the reconnection of anti-parallel magnetic fields when the reconnection inflow is dominated by strong plasma flows. In the present experiments using colliding plasmas carrying parallel magnetic fields, the magnetic flux is found to be conserved and slightly compressed in the collision region. Two-dimensional (2D) particle-in-cell (PIC) simulations predict a stronger flux compressionmore » and amplification of the magnetic field strength, and this discrepancy is attributed to the three-dimensional (3D) collision geometry. Future experiments may drive a stronger collision and further explore flux pileup in the context of the strongly-driven interaction of magnetic fields.« less

  16. First experiments probing the collision of parallel magnetic fields using laser-produced plasmas

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Rosenberg, M. J.; Li, C. K.; Fox, W.; Igumenshchev, I.; Seguin, F. H.; Town, R. P.; Frenje, J. A.; Stoeckl, C.; Glebov, V.; Petrasso, R. D.

    2015-04-08

    Novel experiments to study the strongly-driven collision of parallel magnetic fields in β~10, laser-produced plasmas have been conducted using monoenergetic proton radiography. These experiments were designed to probe the process of magnetic flux pileup, which has been identified in prior laser-plasma experiments as a key physical mechanism in the reconnection of anti-parallel magnetic fields when the reconnection inflow is dominated by strong plasma flows. In the present experiments using colliding plasmas carrying parallel magnetic fields, the magnetic flux is found to be conserved and slightly compressed in the collision region. Two-dimensional (2D) particle-in-cell (PIC) simulations predict a stronger flux compressionmore » and amplification of the magnetic field strength, and this discrepancy is attributed to the three-dimensional (3D) collision geometry. Future experiments may drive a stronger collision and further explore flux pileup in the context of the strongly-driven interaction of magnetic fields.« less

  17. Evolution of laser induced electromagnetic postsolitons in multi-species plasma

    SciTech Connect (OSTI)

    Liu, Yue Gu, Yanjun; Weber, Stefan; Korn, Georg; Klimo, Ondřej; Esirkepov, Timur Zh.; Bulanov, Sergei V.

    2015-11-15

    The evolution of an s-polarized relativistic electromagnetic soliton created in multi-species plasma by an intense short laser pulse is investigated using two-dimensional particle-in-cell simulations. The multi-component plasma consists of electrons and high-Z ions with a small addition of protons. By comparison, the evolution of postsoliton is very different from that in hydrogen plasma. A halo-like structure is found in spatial patterns of both electromagnetic fields and electron densities. The process of energy depletion is much slower due to the smaller charge-to-mass ratio of ions, which implies a better way of detecting postsolitons in simulations and experiments. In addition, it is found that the Coulomb explosion of high-Z ions in the postsoliton stage facilitates low-Z ion acceleration, and the maximum energy of low-Z ions increases with the component ratio of high-Z to low-Z ions.

  18. Optical probe investigation of laser ablated carbon plasma plume in nitrogen ambient

    SciTech Connect (OSTI)

    Singh, Ravi Pratap; Gupta, Shyam L.; Thareja, Raj K.

    2013-12-15

    We report the study of carbon plasma produced using 1064 nm laser in nitrogen ambient at atmospheric pressure using 2-dimensional fast imaging of ablated plume, optical emission spectroscopy, and optical probe at 532 nm for interferometry and shadowgraphy. The dominance of C{sub 2} and CN molecules over ionic species at later stages of expanding carbon plasma plume is reported. The observed ring structure in shadowgrams and change in the direction of fringe shift from positive to negative in recorded interferograms are correlated with the relative abundance of different species in the plasma plume as function of time delay with respect to ablating pulse. An agreement in observed onset time of formation of clusters/atomic species or low ionic species using different diagnostic techniques has been reported.

  19. Simultaneous observation of nascent plasma and bubble induced by laser ablation in water with various pulse durations

    SciTech Connect (OSTI)

    Tamura, Ayaka Matsumoto, Ayumu; Nishi, Naoya; Sakka, Tetsuo; Fukami, Kazuhiro

    2015-05-07

    We investigate the effects of pulse duration on the dynamics of the nascent plasma and bubble induced by laser ablation in water. To examine the relationship between the nascent plasma and the bubble without disturbed by shot-to-shot fluctuation, we observe the images of the plasma and the bubble simultaneously by using two intensified charge coupled device detectors. We successfully observe the images of the plasma and bubble during the pulsed-irradiation, when the bubble size is as small as 20??m. The light-emitting region of the plasma during the laser irradiation seems to exceed the bubble boundary in the case of the short-pulse (30-ns pulse) irradiation, while the size of the plasma is significantly smaller than that of the bubble in the case of the long-pulse (100-ns pulse) irradiation. The results suggest that the extent of the plasma quenching in the initial stage significantly depends on the pulse duration. Also, we investigate how the plasma-bubble relationship in the very early stage affects the shape of the atomic spectral lines observed at the later delay time of 600?ns. The present work gives important information to obtain high quality spectra in the application of underwater laser-induced breakdown spectroscopy, as well as to clarify the mechanism of liquid-phase laser ablation.

  20. Laser acceleration of protons using multi-ion plasma gaseous targets

    SciTech Connect (OSTI)

    Liu, Tung -Chang; Shao, Xi; Liu, Chuan -Sheng; Eliasson, Bengt; W. T. Hill, III; Wang, Jyhpyng; Chen, Shih -Hung

    2015-02-01

    We present a theoretical and numerical study of a novel acceleration scheme by applying a combination of laser radiation pressure and shielded Coulomb repulsion in laser acceleration of protons in multi-species gaseous targets. By using a circularly polarized CO₂ laser pulse with a wavelength of 10 μm—much greater than that of a Ti: Sapphire laser—the critical density is significantly reduced, and a high-pressure gaseous target can be used to achieve an overdense plasma. This gives us a larger degree of freedom in selecting the target compounds or mixtures, as well as their density and thickness profiles. By impinging such a laser beam on a carbon–hydrogen target, the gaseous target is first compressed and accelerated by radiation pressure until the electron layer disrupts, after which the protons are further accelerated by the electron-shielded carbon ion layer. An 80 MeV quasi-monoenergetic proton beam can be generated using a half-sine shaped laser beam with a peak power of 70 TW and a pulse duration of 150 wave periods.

  1. Method and apparatus for fast laser pulse detection using gaseous plasmas

    DOE Patents [OSTI]

    McLellan, Edward J.; Webb, John A.

    1984-01-01

    The method and device of the instant invention is a detector of pulsed laser radiation which utilizes the electromotive force generated by the plasma formed when such radiation is focused onto a surface (1). Measurements are made with a 10.6 .mu.m CO.sub.2 laser capable of producing peak intensities of 10.sup.13 W/cm.sup.2 when directed through a converging lens (2). Evacuated detector response to such laser intensity is 1 kV signal peak amplitude and subnanosecond risetimes into a 50.OMEGA. load (3). Detector performance is found to be greatly altered with the introduction of a background gas (4). For example, with one atmosphere of air, the detector produces prompt signals of the order of 1 V with subnanosecond response for pulse trains lasting 100 ns. With argon, krypton, or zenon at pressures of the order of 10 torr, the detector generates "trigger pulses" of about 250 V amplitude and 0.2 ns risetimes. Such detectors are quite robust when irradiated with high intensity laser radiation and are useful for qualitative laser beam monitoring.

  2. Method and apparatus for fast laser-pulse detection using gaseous plasmas

    DOE Patents [OSTI]

    McLellan, E.J.; Webb, J.A.

    1981-06-18

    The method and device of the instant invention is a detector of pulsed laser radiation which utilizes the electromotive force generated by the plasma formed when such radiation is focused onto a surface. Measurements are made with a 10.6 ..mu..m CO/sub 2/ laser capable of producing peak intensities of 10/sup 13/ W/cm/sup 2/ when directed through a converging lens. Evacuated detector response to such laser intensity if 1 kV signal peak amplitude and subnanosecond risetimes into a 50 ..cap omega.. load. Detector performance is found to be greatly altered with the introduction of a background gas. For example, with one atmosphere of air, the detector produces prompt signals of the order of 1 V with subnanosecond response for pulse trains lasting 100 ns. With argon, krypton, or zenon at pressures of the order of 10 torr, the detector generates trigger pulses of about 250 V amplitude and 0.2 ns risetimes. Such detectors are quite robust when irradiated with high intensity laser radiation and are useful for qualitative laser beam monitoring.

  3. Laser acceleration of protons using multi-ion plasma gaseous targets

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Liu, Tung -Chang; Shao, Xi; Liu, Chuan -Sheng; Eliasson, Bengt; W. T. Hill, III; Wang, Jyhpyng; Chen, Shih -Hung

    2015-02-01

    We present a theoretical and numerical study of a novel acceleration scheme by applying a combination of laser radiation pressure and shielded Coulomb repulsion in laser acceleration of protons in multi-species gaseous targets. By using a circularly polarized CO₂ laser pulse with a wavelength of 10 μm—much greater than that of a Ti: Sapphire laser—the critical density is significantly reduced, and a high-pressure gaseous target can be used to achieve an overdense plasma. This gives us a larger degree of freedom in selecting the target compounds or mixtures, as well as their density and thickness profiles. By impinging such amore » laser beam on a carbon–hydrogen target, the gaseous target is first compressed and accelerated by radiation pressure until the electron layer disrupts, after which the protons are further accelerated by the electron-shielded carbon ion layer. An 80 MeV quasi-monoenergetic proton beam can be generated using a half-sine shaped laser beam with a peak power of 70 TW and a pulse duration of 150 wave periods.« less

  4. Compact disposal of high-energy electron beams using passive or laser-driven plasma decelerating stage

    SciTech Connect (OSTI)

    Bonatto, A.; Schroeder, C.B.; Vay, J.-L.; Geddes, C.R.; Benedetti, C.; Esarey and, E.; Leemans, W.P.

    2014-07-13

    A plasma decelerating stage is investigated as a compact alternative for the disposal of high-energy beams (beam dumps). This could benefit the design of laser-driven plasma accelerator (LPA) applications that require transportability and or high-repetition-rate operation regimes. Passive and laser-driven (active) plasma-based beam dumps are studied analytically and with particle-in-cell (PIC) simulations in a 1D geometry. Analytical estimates for the beam energy loss are compared to and extended by the PIC simulations, showing that with the proposed schemes a beam can be efficiently decelerated in a centimeter-scale distance.

  5. Weakly relativistic and ponderomotive effects on self-focusing and self-compression of laser pulses in near critical plasmas

    SciTech Connect (OSTI)

    Bokaei, B.; Niknam, A. R., E-mail: a-niknam@sbu.ac.ir [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Tehran (Iran, Islamic Republic of)

    2014-10-15

    The spatiotemporal dynamics of high power laser pulses in near critical plasmas are studied taking in to account the effects of relativistic and ponderomotive nonlinearities. First, within one-dimensional analysis, the effects of initial parameters such as laser intensity, plasma density, and plasma electron temperature on the self-compression mechanism are discussed. The results illustrate that the ponderomotive nonlinearity obstructs the relativistic self-compression above a certain intensity value. Moreover, the results indicate the existence of the turning point temperature in which the compression process has its strongest strength. Next, the three-dimensional analysis of laser pulse propagation is investigated by coupling the self-focusing equation with the self-compression one. It is shown that in contrast to the case in which the only relativistic nonlinearity is considered, in the presence of ponderomotive nonlinearity, the self-compression mechanism obstructs the self-focusing and leads to an increase of the laser spot size.

  6. The impact of laser plasma interactions on three-dimensional drive symmetry in inertial confinement fusion implosions

    SciTech Connect (OSTI)

    Peterson, J. L. Michel, P.; Thomas, C. A.; Town, R. P. J.

    2014-07-15

    Achieving symmetric hohlraum radiation drive is an important aspect of indirectly driven inertial confinement fusion experiments. However, when experimentally delivered laser powers deviate from ideal conditions, the resultant radiation field can become asymmetric. Two situations in which this may arise are random uncorrelated fluctuations, in as-delivered laser power and laser beams that do not participate in the implosion (either intentionally or unintentionally). Furthermore, laser plasma interactions in the hohlraum obfuscate the connection between laser powers and radiation drive. To study the effect of these situations on drive symmetry, we develop a simplified model for crossed-beam energy transfer, laser backscatter, and plasma absorption that can be used in conjunction with view factor calculations to expediently translate laser powers into three-dimensional capsule flux symmetries. We find that crossed-beam energy transfer can alter both the statistical properties of uncorrelated laser fluctuations and the impact of missing laser beams on radiation symmetry. A method is proposed to mitigate the effects of missing laser beams.

  7. Emerging trends in X-ray spectroscopic studies of plasma produced by intense laser beams

    SciTech Connect (OSTI)

    Arora, V.; Chakera, J. A.; Naik, P. A.; Gupta, P. D.

    2015-07-31

    X-ray line emission from hot dense plasmas, produced by ultra-short high intensity laser systems, has been studied experimentally in recent years for applications in materials science as well as for back-lighter applications. By virtue of the CPA technology, several laser facilities delivering pulses with peak powers in excess of one petawatt (focused intensities > 10{sup 20} W-cm{sup −2}) have either been commissioned across the globe during the last few years or are presently under construction. On the other hand, hard x-ray sources on table top, generating ultra-short duration x-rays at a repetition rate up to 10 kHz, are routinely available for time resolved x-ray diffraction studies. In this paper, the recent experiments on x-ray spectroscopic studies of plasma produced by 45 fs, Ti:sapphire laser pulses (focused iintensity > 10{sup 18} W-cm{sup −2}) at RRCAT Indore will be presented.

  8. Optical time of flight studies of lithium plasma in double pulse laser ablation: Evidence of inverse Bremsstrahlung absorption

    SciTech Connect (OSTI)

    Sivakumaran, V.; Joshi, H. C.; Singh, R. K.; Kumar, Ajai, E-mail: ajai@ipr.res.in [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India)

    2014-06-15

    The early stage of formation of lithium plasma in a collineardouble pulse laser ablation mode has been studied using optical time of flight (OTOF) spectroscopy as a function of inter-pulse delay time, the distance from the target surface and the fluence of the ablation lasers. The experimental TOF measurements were carried out for lithium neutral (670.8?nm and 610.3?nm), and ionic (548.4?nm and 478.8?nm) lines. These experimental observations have been compared with that for single pulse laser ablation mode. It is found that depending on the fluence and laser pulse shape of the first pre-ablation laser and the second main ablation laser, the plasma plume formation and its characteristic features can be described in terms of plume-plume or laser-plume interaction processes. Moreover, the enhancement in the intensity of Li neutral and ionic lines is observed when the laser-plume interaction is the dominant process. Here, we see the evidence of the role of inverse Bremsstrahlung absorption process in the initial stage of formation of lithium plasma in this case.

  9. Simulation of direct plasma injection for laser ion beam acceleration with a radio frequency quadrupole

    SciTech Connect (OSTI)

    Jin, Q. Y.; Li, Zh. M.; Liu, W.; Zhao, H. Y. Zhang, J. J.; Sha, Sh.; Zhang, Zh. L.; Zhang, X. Zh.; Sun, L. T.; Zhao, H. W.

    2014-07-15

    The direct plasma injection scheme (DPIS) has been being studied at Institute of Modern Physics since several years ago. A C{sup 6+} beam with peak current of 13 mA, energy of 593 keV/u has been successfully achieved after acceleration with DPIS method. To understand the process of DPIS, some simulations have been done as follows. First, with the total current intensity and the relative yields of different charge states for carbon ions measured at the different distance from the target, the absolute current intensities and time-dependences for different charge states are scaled to the exit of the laser ion source in the DPIS. Then with these derived values as the input parameters, the extraction of carbon beam from the laser ion source to the radio frequency quadrupole with DPIS is simulated, which is well agreed with the experiment results.

  10. Systems and methods for imaging using radiation from laser produced plasmas

    DOE Patents [OSTI]

    Renard-Le Galloudec, Nathalie; Cowan, Thomas E.; Sentoku, Yasuhiko; Rassuchine, Jennifer

    2009-06-30

    In particular embodiments, the present disclosure provides systems and methods for imaging a subject using radiation emitted from a laser produced plasma generating by irradiating a target with a laser. In particular examples, the target includes at least one radiation enhancing component, such as a fluor, cap, or wire. In further examples, the target has a metal layer and an internal surface defining an internal apex, the internal apex of less than about 15 .mu.m, such as less than about 1 .mu.m. The targets may take a variety of shapes, including cones, pyramids, and hemispheres. Certain aspects of the present disclosure provide improved imaging of a subject, such as improved medical images of a radiation dose than typical conventional methods and systems.

  11. On the structure of quasi-stationary laser ablation fronts in strongly radiating plasmas

    SciTech Connect (OSTI)

    Basko, M. M. Novikov, V. G.; Grushin, A. S.

    2015-05-15

    The effect of strong thermal radiation on the structure of quasi-stationary laser ablation fronts is investigated under the assumption that all the laser flux is absorbed at the critical surface. Special attention is paid to adequate formulation of the boundary-value problem for a steady-state planar ablation flow. The dependence of the laser-to-x-ray conversion efficiency ϕ{sub r} on the laser intensity I{sub L} and wavelength λ{sub L} is analyzed within the non-equilibrium diffusion approximation for radiation transfer. The scaling of the main ablation parameters with I{sub L} and λ{sub L} in the strongly radiative regime 1−ϕ{sub r}≪1 is derived. It is demonstrated that strongly radiating ablation fronts develop a characteristic extended cushion of “radiation-soaked” plasma between the condensed ablated material and the critical surface, which can efficiently suppress perturbations from the instabilities at the critical surface.

  12. Analysis of plasma density profiles and thermal transport in laser-irradiated spherical targets

    SciTech Connect (OSTI)

    Fechner, W.B.; Shepard, C.L.; Busch, G.E.; Schroeder, R.J.; Tarvin, J.A.

    1984-06-01

    Measurements are presented for plasma density profiles, critical surface trajectories, and mass-ablation rates, as obtained from experiments in which layered spherical targets were irradiated with 1.05-..mu..m laser light at intensities between 1 x 10/sup 14/ and 1 x 10/sup 15/ W/cm/sup 2/. The targets were designed to allow study of thermal transport in overdense plasmas. They were from 70 to 110 ..mu..m in diameter, with a variable thickness parylene ablator and an aluminum substrate. Simulated results are consistent with all three sets of data if transport of both thermal and suprathermal electrons is severely inhibited, with a flux limiter of 0.03< or =f< or =0.06 being appropriate.

  13. Filamentation of magnetosonic wave and generation of magnetic turbulence in laser plasma interaction

    SciTech Connect (OSTI)

    Modi, K. V.; Tiwary, Prem Pyari; Singh, Ram Kishor Sharma, R. P.; Satsangi, V. R.

    2014-10-15

    This paper presents a theoretical model for the magnetic turbulence in laser plasma interaction due to the nonlinear coupling of magnetosonic wave with ion acoustic wave in overdense plasma. For this study, dynamical equations of magnetosonic waves and the ion acoustic waves have been developed in the presence of ponderomotive force due to the pump magnetosonic wave. Slowly converging and diverging behavior has been studied semi-analytically, this results in the formation of filaments of the magnetosonic wave. Numerical simulation has also been carried out to study nonlinear stage. From the results, it has been found that the localized structures become quite complex in nature. Further, power spectrum has been studied. Results show that the spectral index follows (∼k{sup −2.0}) scaling at smaller scale. Relevance of the present investigation has been shown with the experimental observation.

  14. Analytical description of generation of the residual current density in the plasma produced by a few-cycle laser pulse

    SciTech Connect (OSTI)

    Silaev, A. A. Vvedenskii, N. V.

    2015-05-15

    When a gas is ionized by a few-cycle laser pulse, some residual current density (RCD) of free electrons remains in the produced plasma after the passage of the laser pulse. This quasi-dc RCD is an initial impetus to plasma polarization and excitation of the plasma oscillations which can radiate terahertz (THz) waves. In this work, the analytical model for calculation of RCD excited by a few-cycle laser pulse is developed for the first time. The dependences of the RCD on the carrier-envelope phase (CEP), wavelength, duration, and intensity of the laser pulse are derived. It is shown that maximum RCD corresponding to optimal CEP increases with the laser pulse wavelength, which indicates the prospects of using mid-infrared few-cycle laser pulses in the schemes of generation of high-power THz pulses. Analytical formulas for optimal pulse intensity and maximum efficiency of excitation of the RCD are obtained. Basing on numerical solution of the 3D time-dependent Schrödinger equation for hydrogen atoms, RCD dependence on CEP is calculated in a wide range of wavelengths. High accuracy of analytical formulas is demonstrated at the laser pulse parameters which correspond to the tunneling regime of ionization.

  15. Effects of the dynamics of droplet-based laser-produced plasma on angular extreme ultraviolet emission profile

    SciTech Connect (OSTI)

    Giovannini, Andrea Z.; Abhari, Reza S.

    2014-05-12

    The emission distribution of extreme ultraviolet (EUV) radiation from droplet targets is dependent on the dynamics of the laser-produced plasma. The EUV emission is measured on a 2% bandwidth centered at 13.5 nm (in-band). The targets of the laser are small (sub-50 μm) tin droplets, and the in-band emission distribution is measured for different laser irradiances and droplet sizes at various angular positions. Larger droplets lead to a faster decay of EUV emission at larger angles with respect to the laser axis. A decrease in laser irradiance has the opposite effect. The measurements are used together with an analytical model to estimate plume dynamics. Additionally, the model is used to estimate EUV emission distribution for a desired droplet diameter and laser irradiance.

  16. Preliminary design of laser-induced breakdown spectroscopy for proto-Material Plasma Exposure eXperiment

    SciTech Connect (OSTI)

    Shaw, G.; Martin, M. Z.; Martin, R.; Biewer, T. M.

    2014-11-15

    Laser-induced breakdown spectroscopy (LIBS) is a technique for measuring surface matter composition. LIBS is performed by focusing laser radiation onto a target surface, ablating the surface, forming a plasma, and analyzing the light produced. LIBS surface analysis is a possible diagnostic for characterizing plasma-facing materials in ITER. Oak Ridge National Laboratory has enabled the initial installation of a laser-induced breakdown spectroscopy diagnostic on the prototype Material-Plasma Exposure eXperiment (Proto-MPEX), which strives to mimic the conditions found at the surface of the ITER divertor. This paper will discuss the LIBS implementation on Proto-MPEX, preliminary design of the fiber optic LIBS collection probe, and the expected results.

  17. Production of large volume, strongly magnetized laser-produced plasmas by use of pulsed external magnetic fields

    SciTech Connect (OSTI)

    Albertazzi, B.; Beard, J.; Billette, J.; Portugall, O.; Ciardi, A.; Vinci, T.; Albrecht, J.; Chen, S. N.; Da Silva, D.; Hirardin, B.; Nakatsutsumi, M.; Romagnagni, L.; Simond, S.; Veuillot, E.; Fuchs, J.; Burris-Mog, T.; Dittrich, S.; Herrmannsdoerfer, T.; Kroll, F.; Nitsche, S.; and others

    2013-04-15

    The production of strongly magnetized laser plasmas, of interest for laboratory astrophysics and inertial confinement fusion studies, is presented. This is achieved by coupling a 16 kV pulse-power system. This is achieved by coupling a 16 kV pulse-power system, which generates a magnetic field by means of a split coil, with the ELFIE laser facility at Ecole Polytechnique. In order to influence the plasma dynamics in a significant manner, the system can generate, repetitively and without debris, high amplitude magnetic fields (40 T) in a manner compatible with a high-energy laser environment. A description of the system and preliminary results demonstrating the possibility to magnetically collimate plasma jets are given.

  18. Plasma Interactions in Laser Irradiated Semi-Cylindrical Cavities Studied with Soft X-Ray Interferometry Using a Capillary Discharge Laser

    SciTech Connect (OSTI)

    Purvis, M A; Grava, J; Filevich, J; Marconi, M; Rocca, J J; Moon, S J; Dunn, J; Nilsen, J; Shlyaptsev, V N; Jankowska, E

    2007-09-19

    Soft x-ray interferometry was used to measure the evolution of dense converging plasmas created by laser irradiation of 500 {micro}m diameter semi-cylindrical carbon targets. Optical laser pulses with an intensity of {approx} 1 x 10{sup 12} W cm{sup -2} and 120 ps duration were used to heat the surface of the cavities. The dense plasma formed expands from the walls converging slightly off the semi-cylinder's axis, giving rise to a bright localized high density plasma region. A sequence of electron density maps were measured using a 46.9 nm wavelength tabletop capillary discharge soft x-ray laser probe and a amplitude division interferometer based on diffraction gratings. The measured density profiles are compared with simulations conducted using the multi-dimensional hydrodynamic code HYDRA. The benchmarked model was then used to simulate particle trajectories which reveal that the increase in electron density near the axis is mainly the result of the convergence of plasma that originated at the bottom of the groove during laser irradiation.

  19. Second harmonic generation by relativistic self-focusing of q-Gaussian laser beam in preformed parabolic plasma channel

    SciTech Connect (OSTI)

    Singh, Arvinder E-mail: naveens222@rediffmail.com; Gupta, Naveen E-mail: naveens222@rediffmail.com

    2015-01-15

    This paper presents an investigation of relativistic self-focusing effect of a q-Gaussian laser beam on second harmonic generation in a preformed parabolic plasma channel. An expression has been derived for density perturbation associated with the plasma wave excited by the laser beam. This in turn acts as a source of second harmonic generation. The moment theory approach has been used to derive a differential equation that governs the evolution of spot size of the laser beam with the distance of propagation. The detailed effects of intensity distribution deviation from Gaussian distribution, intensity of laser beam, density, and depth of the channel have been studied on self-focusing as well as on second harmonic generation.

  20. Kinetics of ion and prompt electron emission from laser-produced plasma

    SciTech Connect (OSTI)

    Farid, N. [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States) [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, School of Physics and Optical Engineering, Dalian University of Technology, Dalian (China); Harilal, S. S.; Hassanein, A. [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)] [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Ding, H. [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, School of Physics and Optical Engineering, Dalian University of Technology, Dalian (China)] [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, School of Physics and Optical Engineering, Dalian University of Technology, Dalian (China)

    2013-07-15

    We investigated ion emission dynamics of laser-produced plasma from several elements, comprised of metals and non-metals (C, Al, Si, Cu, Mo, Ta, W), under vacuum conditions using a Faraday cup. The estimated ion flux for various targets studied showed a decreasing tendency with increasing atomic mass. For metals, the ion flux is found to be a function of sublimation energy. A comparison of temporal ion profiles of various materials showed only high-Z elements exhibited multiple structures in the ion time of flight profile indicated by the observation of higher peak kinetic energies, which were absent for low-Z element targets. The slower ions were seen regardless of the atomic number of target material propagated with a kinetic energy of 15 keV, while the fast ions observed in high-Z materials possessed significantly higher energies. A systematic study of plasma properties employing fast photography, time, and space resolved optical emission spectroscopy, and electron analysis showed that there existed different mechanisms for generating ions in laser ablation plumes. The origin of high kinetic energy ions is related to prompt electron emission from high-Z targets.

  1. Confinement effects of shock waves on laser-induced plasma from a graphite target

    SciTech Connect (OSTI)

    Huang, Feiling; Liang, Peipei; Yang, Xu; Cai, Hua; Wu, Jiada; Xu, Ning; Ying, Zhifeng; Sun, Jian

    2015-06-15

    The spatial confinement effects of shock waves on the laser-induced plasma (LIP) from a graphite target in air were studied by probe beam deflection (PBD) measurements and optical emission spectroscopy (OES). A clear relationship between the confinement of the LIP by the shock wave and the effects on the LIP emission was observed, and the underlying mechanisms are discussed. PBD monitoring revealed that the laser-ablation induced shock wave could be well analogized to the shock wave generated by a point explosion and would be reflected by a block. OES measurements indicated that the optical emission of the LIP exhibited significant variations with the block placement. A first enhancement and then a fast decay of CN molecular emission as well as a suppression of carbon atomic emission were observed in the presence of the block. The results revealed that the reflected shock wave spatially confined the expansion of the LIP and compressed the LIP after encountering it, pushing back the species of the LIP and changing the density of the LIP species including luminous carbon atoms and CN molecules. It is suggested that the change of the LIP emission is attributed to the density variation of the LIP species due to the compression of the LIP and the reactions occurring in the plasma.

  2. Magnetic reconnection in high-energy-density laser-produced plasmas

    SciTech Connect (OSTI)

    Fox, W.; Bhattacharjee, A.; Germaschewski, K.

    2012-05-15

    Recently, novel experiments on magnetic reconnection have been conducted in laser-produced plasmas in a high-energy-density regime. Individual plasma bubbles self-generate toroidal, mega-gauss-scale magnetic fields through the Biermann battery effect. When multiple bubbles are created at small separation, they expand into one another, driving reconnection of this field. Reconnection in the experiments was reported to be much faster than allowed by both Sweet-Parker, and even Hall-MHD theories, when normalized to the nominal magnetic fields self-generated by single bubbles. Through particle-in-cell simulations (both with and without a binary collision operator), we model the bubble interaction at parameters and geometry relevant to the experiments. This paper discusses in detail the reconnection regime of the laser-driven experiments and reports the qualitative features of simulations. We find substantial flux-pileup effects, which boost the relevant magnetic field for reconnection in the current sheet. When this is accounted for, the normalized reconnection rates are much more in line with standard two-fluid theory of reconnection. At the largest system sizes, we additionally find that the current sheet is prone to breakup into plasmoids.

  3. Second harmonic generation by propagation of a p-polarized obliquely incident laser beam in underdense plasma

    SciTech Connect (OSTI)

    Jha, Pallavi; Agrawal, Ekta

    2014-05-15

    An analytical study of second harmonic generation due to interaction an intense, p-polarized laser beam propagating obliquely in homogeneous underdense plasma, in the mildly relativistic regime, has been presented. The efficiency of the second harmonic radiation as well as its detuning length has been obtained and their variation with the angle of incidence is analyzed. It is shown that, for a given plasma electron density, the second harmonic efficiency increases with the angle of incidence while the detuning length decreases. The second harmonic amplitude vanishes at normal incidence of the laser beam.

  4. Plasma channel produced by femtosecond laser pulses as a medium for amplifying electromagnetic radiation of the subterahertz frequency range

    SciTech Connect (OSTI)

    Bogatskaya, A V; Volkova, E A; Popov, A M

    2013-12-31

    The electron energy distribution function in the plasma channel produced by a femtosecond laser pulse with a wavelength of 248 nm in atmospheric-pressure gases was considered. Conditions were determined whereby this channel may be employed for amplifying electromagnetic waves up to the terahertz frequency range over the energy spectrum relaxation time ∼10{sup -7} s. Gains were calculated as functions of time and radiation frequency. The effect of electron – electron collisions on the rate of relaxation processes in the plasma and on its ability to amplify the electromagnetic radiation was investigated. (interaction of laser radiation with matter)

  5. Critical Fluences And Modeling Of CO{sub 2} Laser Ablation Of Polyoxymethylene From Vaporization To The Plasma Regime

    SciTech Connect (OSTI)

    Sinko, John E.; Phipps, Claude R.; Tsukiyama, Yosuke; Ogita, Naoya; Sasoh, Akihiro; Umehara, Noritsugu; Gregory, Don A.

    2010-05-06

    A CO{sub 2} laser was operated at pulse energies up to 10 J to ablate polyoxymethylene targets in air and vacuum conditions. Critical effects predicted by ablation models are discussed in relation to the experimental data, including specifically the threshold fluences for vaporization and critical plasma formation, and the fluence at which the optimal momentum coupling coefficient is found. Finally, we discuss a new approach for modeling polymers at long wavelengths, including a connection formula that links the vaporization and plasma regimes for laser ablation propulsion.

  6. Channeling of microwave radiation in a double line containing a plasma filament produced by intense femtosecond laser pulses in air

    SciTech Connect (OSTI)

    Bogatov, N A; Kuznetsov, A I; Smirnov, A I; Stepanov, A N

    2009-10-31

    The channeling of microwave radiation is demonstrated experimentally in a double line in which a plasma filament produced in air by intense femtosecond laser pulses serves as one of the conductors. It is shown that during the propagation of microwave radiation in this line, ultrashort pulses are formed, their duration monotonically decreasing with increasing the propagation length (down to the value comparable with the microwave field period). These effects can be used for diagnostics of plasma in a filament. (laser applications and other topics in quantum electronics)

  7. Laser schlieren deflectometry for temperature analysis of filamentary non-thermal atmospheric pressure plasma

    SciTech Connect (OSTI)

    Schaefer, J.; Foest, R.; Reuter, S.; Weltmann, K.-D.; Kewitz, T.; Sperka, J.

    2012-10-15

    The heat convection generated by micro filaments of a self-organized non-thermal atmospheric pressure plasma jet in Ar is characterized by employing laser schlieren deflectometry (LSD). It is demonstrated as a proof of principle, that the spatial and temporal changes of the refractive index n in the optical beam path related to the neutral gas temperature of the plasma jet can be monitored and evaluated simultaneously. The refraction of a laser beam in a high gradient field of n(r) with cylindrical symmetry is given for a general real refraction index profile. However, the usually applied Abel approach represents an ill-posed problem and in particular for this plasma configuration. A simple analytical model is proposed in order to minimize the statistical error. Based on that, the temperature profile, specifically the absolute temperature in the filament core, the FWHM, and the frequencies of the collective filament dynamics are obtained for non-stationary conditions. For a gas temperature of 700 K inside the filament, the presented model predicts maximum deflection angles of the laser beam of 0.3 mrad which is in accordance to the experimental results obtained with LSD. Furthermore, the experimentally obtained FWHM of the temperature profile produced by the filament at the end of capillary is (1.5 {+-} 0.2) mm, which is about 10 times wider than the visual radius of the filament. The obtained maximum temperature in the effluent is (450 {+-} 30) K and is in consistence with results of other techniques. The study demonstrates that LSD represents a useful low-cost method for monitoring the spatiotemporal behaviour of microdischarges and allows to uncover their dynamic characteristics, e.g., the temperature profile even for challenging diagnostic conditions such as moving thin discharge filaments. The method is not restricted to the miniaturized and self-organized plasma studied here. Instead, it can be readily applied to other configurations that produce measurable

  8. Ion Acceleration by Laser Plasma Interaction from Cryogenic Micro Jets - Oral Presentation

    SciTech Connect (OSTI)

    Propp, Adrienne

    2015-08-25

    Processes that occur in extreme conditions, such as in the center of stars and large planets, can be simulated in the laboratory using facilities such as SLAC National Accelerator Laboratory and the Jupiter Laser Facility (JLF) at Lawrence Livermore National Laboratory (LLNL). These facilities allow scientists to investigate the properties of matter by observing their interactions with high power lasers. Ion acceleration from laser plasma interaction is gaining greater attention today due to its widespread potential applications, including proton beam cancer therapy and fast ignition for energy production. Typically, ion acceleration is achieved by focusing a high power laser on thin foil targets through a mechanism called Target Normal Sheath Acceleration. Based on research and recent experiments, we hypothesized that a pure liquid cryogenic jet would be an ideal target for this type of interaction, capable of producing the highest proton energies possible with today’s laser technologies. Furthermore, it would provide a continuous, pure target, unlike metal foils which are consumed in the interaction and easily contaminated. In an effort to test this hypothesis and investigate new, potentially more efficient mechanisms of ion acceleration, we used the 527 nm split beam, frequency-doubled TITAN laser at JLF. Data from the cryogenic jets was limited due to the flow of current up the jet into the nozzle during the interaction, heating the jet and damaging the orifice. However, we acheived a pure proton beam with an indiciation of a monoenergetic feature. Furthermore, data from gold and carbon wires showed surprising and interesting results. Preliminary analysis of data from two ion emission diagnostics, Thomson parabola spectrometers (TPs) and radio chromic films (RCFs), suggests that shockwave acceleration occurred rather than target normal sheath acceleration, the standard mechanism of ion acceleration. Upon completion of the experiment at TITAN, I researched the

  9. Collisional absorption of laser light in under-dense plasma: The role of Coulomb logarithm

    SciTech Connect (OSTI)

    Kundu, M. [Institute for Plasma Research, Bhat, Gandhinagar 382 428, Gujarat (India)] [Institute for Plasma Research, Bhat, Gandhinagar 382 428, Gujarat (India)

    2014-01-15

    In this work, we re-examine collisional absorption of 800?nm wavelength laser pulses in under-dense plasma. For a given temperature and density of the plasma, most of the conventional models of the electron-ion collision frequency ?{sub ei}, with a Coulomb logarithm independent of the electron-ponderomotive velocity, show that ?{sub ei} and the corresponding fractional laser absorption ? remain almost constant (or decrease slowly) up to a value I{sub c} of the peak intensity I{sub 0} of the laser pulse, and then ?{sub ei} and ? decrease as ?I{sub 0}{sup ?3/2} when I{sub 0} is increased beyond I{sub c}. On the contrary, below some temperature (?10?eV) and density, with a total-velocity (thermal velocity plus the ponderomotive velocity) dependent Coulomb logarithm, we find that ?{sub ei} and ? grow hand in hand up to a maximum value around I{sub c} followed by the conventional I{sub 0}{sup ?3/2} decrease when I{sub 0}>I{sub c}. Such a non-conventional anomalous variation of ? with I{sub 0} was observed in some earlier experiments, but no explanation has been given so far. The modified Coulomb logarithm considered in this work may be responsible for those experimental observations. With increasing temperature and density, the anomalous behavior is found to disappear even with the modified Coulomb logarithm, and the variation of ?{sub ei} and ? with I{sub 0} approach to the conventional scenario.

  10. Characterization of gas targets for laser produced extreme ultraviolet plasmas with a Hartmann-Shack sensor

    SciTech Connect (OSTI)

    Peth, Christian; Kranzusch, Sebastian; Mann, Klaus; Vioel, Wolfgang

    2004-10-01

    A table top extreme ultraviolet (EUV)-source was developed at Laser-Laboratorium Goettingen for the characterization of optical components and sensoric devices in the wavelength region from 11 to 13 nm. EUV radiation is generated by focusing the beam of a Q-switched Nd:YAG laser into a pulsed xenon gas jet. Since a directed gas jet with a high number density is needed for an optimal performance of the source, conical nozzles with different cone angles were drilled with an excimer laser to produce a supersonic gas jet. The influence of the nozzle geometry on the gas jet was characterized with a Hartmann-Shack wave front sensor. The deformation of a planar wave front after passing the gas jet was analyzed with this sensor, allowing a reconstruction of the gas density distribution. Thus, the gas jet was optimized resulting in an increase of EUV emission by a factor of two and a decrease of the plasma size at the same time.

  11. Results From Plasma Wakefield Acceleration Experiments at FACET...

    Office of Scientific and Technical Information (OSTI)

    Resource Relation: Journal Name: Conf.Proc.C110904:2814-2816,2011; Conference: Presented at the 2nd International Particle Accelerator Conference (IPAC-2011), San Sebastian, Spain, ...

  12. Mesurement of the Decelerating Wake in a Plasma Wakefield Accelerator...

    Office of Scientific and Technical Information (OSTI)

    Sponsoring Org: USDOE Country of Publication: United States Language: English Subject: 43 PARTICLE ACCELERATORS; ACCELERATION; ACCELERATORS; ELECTRON BEAMS; ELECTRONS; METERS; ...

  13. Emittance and Current of Electrons Trapped in a Plasma Wakefield...

    Office of Scientific and Technical Information (OSTI)

    Research Org: Stanford Linear Accelerator Center (SLAC) Sponsoring Org: USDOE Country of Publication: United States Language: English Subject: 43 PARTICLE ACCELERATORS; ...

  14. Emittance and Current of Electrons Trapped in a Plasma Wakefield...

    Office of Scientific and Technical Information (OSTI)

    Publication Date: 2008-09-24 OSTI Identifier: 938639 Report Number(s): SLAC-PUB-13389 TRN: ... Concepts Workshop (AAC08), Santa Cruz, California, 27 Jul - 2 Aug 2008 Research ...

  15. Mesurement of the Decelerating Wake in a Plasma Wakefield Accelerator...

    Office of Scientific and Technical Information (OSTI)

    Publication Date: 2008-09-24 OSTI Identifier: 938638 Report Number(s): SLAC-PUB-13390 TRN: ... Concepts Workshop (AAC08), Santa Cruz, California, 27 Jul - 2 Aug 2008 Research ...

  16. Latest Plasma Wakefield Acceleration Results from the FACET Project...

    Office of Scientific and Technical Information (OSTI)

    Resource Relation: Conference: Invited paper at the North American Particle Accelerator Conference (PAC 2013), 29 Sep - 4 Oct 2013, Pasadena, CA, USA Research Org: SLAC National ...

  17. Results From Plasma Wakefield Acceleration Experiments at FACET...

    Office of Scientific and Technical Information (OSTI)

    International Particle Accelerator Conference (IPAC-2011), San Sebastian, Spain, 4-9 Sep 2011 Research Org: SLAC National Accelerator Laboratory (SLAC) Sponsoring Org: US DOE ...

  18. Model-independent determination of the astrophysical S factor in laser-induced fusion plasmas

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lattuada, D.; Barbarino, M.; Bonasera, A.; Bang, W.; Quevedo, H. J.; Warren, M.; Consoli, F.; De Angelis, R.; Andreoli, P.; Kimura, S.; et al

    2016-04-01

    In this paper, we present a new and general method for measuring the astrophysical S factor of nuclear reactions in laser-induced plasmas and we apply it to 2H(d,n)3He. The experiment was performed with the Texas Petawatt Laser, which delivered 150–270 fs pulses of energy ranging from 90 to 180 J to D2 or CD4 molecular clusters (where D denotes 2H). After removing the background noise, we used the measured time-of-flight data of energetic deuterium ions to obtain their energy distribution. We derive the S factor using the measured energy distribution of the ions, the measured volume of the fusion plasma,more » and the measured fusion yields. This method is model independent in the sense that no assumption on the state of the system is required, but it requires an accurate measurement of the ion energy distribution, especially at high energies, and of the relevant fusion yields. In the 2H(d,n)3He and 3He(d,p)4He cases discussed here, it is very important to apply the background subtraction for the energetic ions and to measure the fusion yields with high precision. While the available data on both ion distribution and fusion yields allow us to determine with good precision the S factor in the d+d case (lower Gamow energies), for the d+3He case the data are not precise enough to obtain the S factor using this method. Our results agree with other experiments within the experimental error, even though smaller values of the S factor were obtained. This might be due to the plasma environment differing from the beam target conditions in a conventional accelerator experiment.« less

  19. Improvement of bonding properties of laser transmission welded, dissimilar thermoplastics by plasma surface treatment

    SciTech Connect (OSTI)

    Hopmann, Ch.; Weber, M.; Schöngart, M.; Sooriyapiragasam, S.; Behm, H.; Dahlmann, R.

    2015-05-22

    Compared to different welding methods such as ultrasonic welding, laser transmission welding is a relatively new technology to join thermoplastic parts. The most significant advantages over other methods are the contactless energy input which can be controlled very precisely and the low mechanical loads on the welded parts. Therefore, laser transmission welding is used in various areas of application, for example in medical technology or for assembling headlights in the automotive sector. However, there are several challenges in welding dissimilar thermoplastics. This may be due to different melting points on the one hand and different polarities on the other hand. So far these problems are faced with the intermediate layer technique. In this process a layer bonding together the two components is placed between the components. This means that an additional step in the production is needed to apply the extra layer. To avoid this additional step, different ways of joining dissimilar thermoplastics are investigated. In this regard, the improvement in the weldability of the dissimilar thermoplastics polyamide 6 (PA 6) and polypropylene (PP) by means of plasma surface modification and contour welding is examined. To evaluate the influence of the plasma surface modification process on the subsequent welding process of the two dissimilar materials, the treatment time as well as the storage time between treatment and welding are varied. The treatment time in pulsed micro wave excited oxygen plasmas with an electron density of about 1x10{sup 17} m{sup −3} is varied from 0.5 s to 120 s and the time between treatment and welding is varied from a few minutes up to a week. As reference, parts being made of the same polymer (PP and PA 6) are welded and tested. For the evaluation of the results of the welding experiments, short-time tensile tests are used to determine the bond strength. Without plasma treatment the described combination of PA 6/PP cannot be welded with

  20. Developing the model of laser ablation by considering the interplay between emission and expansion of aluminum plasma

    SciTech Connect (OSTI)

    Rezaei, F.; Tavassoli, S. H.

    2013-01-15

    In the present study, the ablation behavior of aluminum target and its plasma radiation in noble ambient gases by a laser pulse with wavelength of 266 nm and pulse duration of 10 ns are numerically studied. A thermal model of laser ablation considering heat conduction, Euler equations, Saha-Eggert equations, Knudsen layer, mass and energy balance relations and optical shielding effects are used for calculation of plasma parameters. Effects of excitation energy on plasma expansion and its emissivity are investigated. Time and spatial-resolved plasma emission including bremsstrahlung, recombination and spectral emission at early delay times after laser irradiation is obtained. Effects of two ambient gases (He and Ar) as well as different gas pressures of 100, 300, 500, and 760 Torr on plasma expansion and its spectrum are studied. Results illustrate that at initial delay times, especially at high noble gas pressures, ionic lines have the maximum intensities, while at later times neutral lines dominate. When the pressure of ambient gas increases, a confinement of the plasma plume is predicted and the intensity of neutral lines decreases. Continuous emission increases with wavelength in both ambient gases. Spatially resolved analysis shows that an intense continuous emission is predicted next to the sample surface decreasing with distance from the latter.

  1. Generation and pointing stabilization of multi-GeV electron beams from a laser plasma accelerator driven in a pre-formed plasma waveguide

    SciTech Connect (OSTI)

    Gonsalves, A. J.; Nakamura, K.; Daniels, J.; Mao, H.-S.; Benedetti, C.; Schroeder, C. B.; Tóth, Cs.; Tilborg, J. van; Vay, J.-L.; Geddes, C. G. R.; Esarey, E.; Mittelberger, D. E.; Bulanov, S. S.; Leemans, W. P.

    2015-05-15

    Laser pulses with peak power 0.3 PW were used to generate electron beams with energy >4 GeV within a 9 cm-long capillary discharge waveguide operated with a plasma density of ≈7×10{sup 17} cm{sup −3}. Simulations showed that the super-Gaussian near-field laser profile that is typical of high-power femtosecond laser systems reduces the efficacy of guiding in parabolic plasma channels compared with the Gaussian laser pulses that are typically simulated. In the experiments, this was mitigated by increasing the plasma density and hence the contribution of self-guiding. This allowed for the generation of multi-GeV electron beams, but these had angular fluctuation ≳2 mrad rms. Mitigation of capillary damage and more accurate alignment allowed for stable beams to be produced with energy 2.7±0.1 GeV. The pointing fluctuation was 0.6 mrad rms, which was less than the beam divergence of ≲1 mrad full-width-half-maximum.

  2. Numerical simulation of microwave amplification in a plasma channel produced in a gas via multiphoton ionisation by a femtosecond laser pulse

    SciTech Connect (OSTI)

    Bogatskaya, A V; Popov, A M; Volkova, E A

    2014-12-31

    This paper examines the evolution of a nonequilibrium plasma channel produced in xenon by a femtosecond KrF laser pulse. We demonstrate that such a channel can be used to amplify microwave pulses over times of the order of the relaxation time of the photoelectron energy spectrum in xenon. Using the slowly varying amplitude approximation, we analyse the propagation and amplification of an rf pulse in a plasma channel, in particular when the rf field influences the electron energy distribution function in the plasma. (interaction of laser radiation with matter. laser plasma)

  3. Increasing the upper-limit intensity and temperature range for thermal self-focusing of a laser beam by using plasma density ramp-up

    SciTech Connect (OSTI)

    Bokaei, B.; Niknam, A. R.

    2014-03-15

    This work is devoted to improving relativistic and ponderomotive thermal self-focusing of the intense laser beam in an underdense plasma. It is shown that the ponderomotive nonlinearity induces a saturation mechanism for thermal self-focusing. Therefore, in addition to the well-known lower-limit critical intensity, there is an upper-limit intensity for thermal self-focusing above which the laser beam starts to experience ponderomotive defocusing. It is indicated that the upper-limit intensity value is dependent on plasma and laser parameters such as the plasma electron temperature, plasma density, and laser spot size. Furthermore, the effect of the upward plasma density ramp profile on the thermal self-focusing is studied. Results show that by using the plasma density ramp-up, the upper-limit intensity increases and the self-focusing temperature range expands.

  4. Application of Plasma Waveguides to High Energy Accelerators

    SciTech Connect (OSTI)

    Milchberg, Howard M

    2013-03-30

    will continue our development of advanced simulation tools by modifying the QuickPIC algorithm to allow for the simulation of plasma particle pick-up by the wake fields. We have also performed extensive simulations of plasma slow wave structures for efficient THz generation by guided laser beams or accelerated electron beams. We will pursue experimental studies of direct laser acceleration, and THz generation by two methods, ponderomotive-induced THz polarization, and THz radiation by laser accelerated electron beams. We also plan to study both conventional and corrugated plasma channels using our new 30 TW in our new lab facilities. We will investigate production of very long hydrogen plasma waveguides (5 cm). We will study guiding at increasing power levels through the onset of laser-induced cavitation (bubble regime) to assess the role played by the preformed channel. Experiments in direct acceleration will be performed, using laser plasma wakefields as the electron injector. Finally, we will use 2-colour ionization of gases as a high frequency THz source (<60 THz) in order for femtosecond measurements of low plasma densities in waveguides and beams.

  5. Multiple self-injection in the acceleration of monoenergetic electrons by a laser wake field

    SciTech Connect (OSTI)

    Oguchi, A.; Takano, K.; Hotta, E.; Zhidkov, A.; Nemoto, K.; Nakajima, K.

    2008-04-15

    Multiple electron self-injection in laser wake-field acceleration is studied via fully relativistic two- and three-dimensional particle-in-cell simulation. The electron density modulation in the laser wake originating from oscillations of the laser pulse waist and relativistic effects can provoke the parametric resonance in the electron fluid momentum. This may result in repetitive trapping of plasma electrons in the acceleration phase of the laser wake: multiple electron self-injection. The maximal energy of the accelerated electrons depends strongly on the total charge of the injected electrons. A low energy spread, less than 1%, for an almost 1 GeV energy electron beam with charge about 10 pC is found numerically in the plasma channel irradiated by a 25 TW laser pulse, while a 200 TW laser pulse produces a few nC beam with only 150 MeV energy. Essentially thermalization of accelerated electrons is also a result of charge loading.

  6. Effects of Landau quantization on the equations of state in intense laser plasma interactions with strong magnetic fields

    SciTech Connect (OSTI)

    Eliezer, Shalom; Norreys, Peter; Mendonca, Jose T.; Lancaster, Kate

    2005-05-15

    Recently, magnetic fields of 0.7({+-}0.1) gigaGauss (GG) have been observed in the laboratory in laser plasma interactions. From scaling arguments, it appears that a few gigaGauss magnetic fields may be within reach of existing petawatt lasers. In this paper, the equations of state (EOS) are calculated in the presence of these very large magnetic fields. The appropriate domain for electron degeneracy and for Landau quantization is calculated for the density-temperature domain relevant to laser plasma interactions. The conditions for a strong Landau quantization, for a magnetic field in the domain of 1-10 GG, are obtained. The role of this paper is to formulate the EOS in terms of those that can potentially be realized in laboratory plasmas. By doing so, it is intended to alert the experimental laser-plasma physics community to the potential of realizing Landau quantization in the laboratory for the first time since the theory was first formulated.

  7. Integrated Kinetic Simulation of Laser-Plasma Interactions, Fast-Electron Generation and Transport in Fast Ignition

    SciTech Connect (OSTI)

    Kemp, A; Cohen, B; Divol, L

    2009-11-16

    We present new results on the physics of short-pulse laser-matter interaction of kilojoule-picosecond pulses at full spatial and temporal scale, using a new approach that combines a 3D collisional electromagnetic Particle-in-Cell code with an MHD-hybrid model of high-density plasma. In the latter, collisions damp out plasma waves, and an Ohm's law with electron inertia effects neglected determines the electric field. In addition to yielding orders of magnitude in speed-up while avoiding numerical instabilities, this allows us to model the whole problem in a single unified framework: the laser-plasma interaction at sub-critical densities, energy deposition at relativistic critical densities, and fast-electron transport in solid densities. Key questions such as the multi-picosecond temporal evolution of the laser energy conversion into hot electrons, the impact of return currents on the laser-plasma interaction, and the effect of self-generated electric and magnetic fields on electron transport will be addressed. We will report applications to current experiments.

  8. Observation of Wakefield Suppression in a Photonic-Band-Gap Accelerator Structure

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Simakov, Evgenya I.; Arsenyev, Sergey A.; Buechler, Cynthia E.; Edwards, Randall L.; Romero, William P.; Conde, Manoel; Ha, Gwanghui; Power, John G.; Wisniewski, Eric E.; Jing, Chunguang

    2016-02-10

    We report experimental observation of higher order mode (HOM) wakefield suppression in a room-temperature traveling-wave photonic band gap (PBG) accelerating structure at 11.700 GHz. It has been long recognized that PBG structures have potential for reducing long-range wakefields in accelerators. The first ever demonstration of acceleration in a room-temperature PBG structure was conducted in 2005. Since then, the importance of PBG accelerator research has been recognized by many institutions. However, the full experimental characterization of the wakefield spectrum and demonstration of wakefield suppression when the accelerating structure is excited by an electron beam has not been performed to date. Wemore » conducted an experiment at the Argonne Wakefield Accelerator (AWA) test facility and observed wakefields excited by a single high charge electron bunch when it passes through a PBG accelerator structure. Lastly, excellent HOM suppression properties of the PBG accelerator were demonstrated in the beam test.« less

  9. High-resolution x-ray spectrometer based on spherically bent crystals for investigations of femtosecond laser plasmas

    SciTech Connect (OSTI)

    Young, B.K.; Osterheld, A.L.; Price, D.F.; Shepherd, R.; Stewart, R.E.; Faenov, A.Y.; Magunov, A.I.; Pikuz, T.A.; Skobelev, I.Y.; Flora, F.; Bollanti, S.; Di Lazzaro, P.; Letardi, T.; Grilli, A.; Palladino, L.; Reale, A.; Scafati, A.; Reale, L.

    1998-12-01

    Ultrashort-pulse, laser-produced plasmas have become very interesting laboratory sources to study spectroscopically due to their very high densities and temperatures, and the high laser-induced electromagnetic fields present. Typically, these plasmas are of very small volume and very low emissivity. Thus, studying these near point source plasmas requires advanced experimental techniques. We present a new spectrometer design called the focusing spectrometer with spatial resolution (FSSR-2D) based on a spherically bent crystal which provides simultaneous high spectral ({lambda}/{Delta}{lambda}{approx}10{sup 4}) and spatial resolution ({approx}10thinsp{mu}m) as well as high luminosity (high collection efficiency). We described in detail the FSSR-2D case in which a small, near point source plasma is investigated. An estimate for the spectral and spatial resolution for the spectrometer is outlined based on geometric considerations. Using the FSSR-2D instrument, experimental data measured from both a 100 fs and a nanosecond pulse laser-produced plasma are presented. {copyright} {ital 1998 American Institute of Physics.}

  10. Development of a Laser-Produced Plasma X-ray source for Phase-Contrast Radiography of DT Ice layers

    SciTech Connect (OSTI)

    Izumi, N; Dewald, E; Kozioziemski, B; Landen, O L; Koch, J A

    2008-07-21

    Refraction enhanced x-ray phase contrast imaging is crucial for characterization of deuterium-tritium (DT) ice layer roughness in optically opaque inertial confinement fusion capsules. To observe the time development of DT ice roughness over {approx} second timescales, we need a bright x-ray source that can produce an image faster than the evolution of the ice surface roughness. A laser produced plasma x-ray source is one of the candidates that can meet this requirement. We performed experiments at the Janus laser facility at Lawrence Livermore National Laboratory and assessed the characteristics of the laser produced plasma x-ray source as a potential backlight for in situ target characterization.

  11. Full aperture backscatter station imager diagnostics system for far-field imaging of laser plasma instabilities on Nova

    SciTech Connect (OSTI)

    Wilke, M.D.; Fernandez, J.C.; Berggren, R.R.; Horton, R.F.; Montgomery, D.S.; Faulkner, J.A.; Looney, L.D.; Jimerson, J.R.

    1997-01-01

    In ICF, the understanding of laser plasma scattering processes is essential for laser target coupling and for controlling the symmetry of indirect drive implosions. The existing Nova full aperture backscatter station has been useful in understanding laser plasma instabilities occurring in hohlraums by measuring the quantity, spectral distribution, and near-field spatial distributions of Brillouin and more recently Raman backscatter. Equally important is an understanding of the far-field spatial intensity distribution which could help in understanding filamentation, threshold and saturation processes. This article describes a broadband, color-corrected far-field imager and associated diagnostics capable of imaging the source of scattered light to better than 25 {mu}m resolution. Brillouin and Raman backscatter can be imaged through the Nova beam-7 focusing lens or the imager can be used like a microscope to image side scatter from other beams. {copyright} {ital 1997 American Institute of Physics.}

  12. Resonance laser-plasma excitation of coherent terahertz phonons in the bulk of fluorine-bearing crystals under high-intensity femtosecond laser irradiation

    SciTech Connect (OSTI)

    Potemkin, F V; Mareev, E I; Khodakovskii, N G; Mikheev, P M

    2013-08-31

    The dynamics of coherent phonons in fluorine-containing crystals was investigated by pump-probe technique in the plasma production regime. Several phonon modes, whose frequencies are overtones of the 0.38-THz fundamental frequency, were simultaneously observed in a lithium fluoride crystal. Phonons with frequencies of 1 and 0.1 THz were discovered in a calcium fluoride crystal and coherent phonons with frequencies of 1 THz and 67 GHz were observed in a barium fluoride crystal. Furthermore, in the latter case the amplitudes of phonon mode oscillations were found to significantly increase 15 ps after laser irradiation. (interaction of laser radiation with matter)

  13. Direct analysis of samples by mass spectrometry: From elements to bio-molecules using laser ablation inductively couple plasma mass spectrometry and laser desorption/ionization mass spectrometry

    SciTech Connect (OSTI)

    Perdian, David C.

    2009-08-19

    Mass spectrometric methods that are able to analyze solid samples or biological materials with little or no sample preparation are invaluable to science as well as society. Fundamental research that has discovered experimental and instrumental parameters that inhibit fractionation effects that occur during the quantification of elemental species in solid samples by laser ablation inductively coupled plasma mass spectrometry is described. Research that determines the effectiveness of novel laser desorption/ionization mass spectrometric methods for the molecular analysis of biological tissues at atmospheric pressure and at high spatial resolution is also described. A spatial resolution is achieved that is able to analyze samples at the single cell level.

  14. Comparison of plasma temperature and electron density on nanosecond laser ablation of Cu and nano-Cu

    SciTech Connect (OSTI)

    Chen, Anmin; Jiang, Yuanfei; Wang, Tingfeng; Shao, Junfeng; Jin, Mingxing

    2015-03-15

    Laser-induced breakdown spectroscopy is performed through the collection of spectra by spectral detection equipment at different delay times and distances from targets composed of Cu and nano-Cu, which are ablated using a Nd:YAG laser (532 nm, 10 ns, 10 Hz) in our experiments. The measured wavelength range is from 475 nm to 525 nm. Using the local thermodynamic equilibrium model, we analyze the characteristics of the plasma temperature and the electron number density for different distances between the target surface and the lens. The results show that when compared with the nano-Cu plasma case, the temperature of the Cu plasma is higher, while its electron number density is lower.

  15. Numerical simulations used for a validity check on the laser induced photo-detachment diagnostic method in electronegative plasmas

    SciTech Connect (OSTI)

    Oudini, N.; Taccogna, F.; Aanesland, A.

    2014-06-15

    Laser photo-detachment is used as a method to measure or determine the negative ion density and temperature in electronegative plasmas. In essence, the method consists of producing an electropositive channel (negative ion free region) via pulsed laser photo-detachment within an electronegative plasma bulk. Electrostatic probes placed in this channel measure the change in the electron density. A second pulse might be used to track the negative ion recovery. From this, the negative ion density and temperature can be determined. We study the formation and relaxation of the electropositive channel via a two-dimensional Particle-In-Cell/Mote Carlo collision model. The simulation is mainly carried out in a Hydrogen plasma with an electronegativity of α = 1, with a parametric study for α up to 20. The temporal and spatial evolution of the plasma potential and the electron densities shows the formation of a double layer (DL) confining the photo-detached electrons within the electropositive channel. This DL evolves into two fronts that move in the opposite directions inside and outside of the laser spot region. As a consequence, within the laser spot region, the background and photo-detached electron energy distribution function relaxes/thermalizes via collisionless effects such as Fermi acceleration and Landau damping. Moreover, the simulations show that collisional effects and the DL electric field strength might play a non-negligible role in the negative ion recovery within the laser spot region, leading to a two-temperature negative ion distribution. The latter result might have important effects in the determination of the negative ion density and temperature from laser photo detachment diagnostic.

  16. Experimental Plans to Explore Dielectric Wakefield Acceleration in the THZ Regime

    SciTech Connect (OSTI)

    Lemery, F.; Mihalcea, D.; Piot, P.; Behrens, C.; Elsen, E.; Flottmann, K.; Gerth, C.; Kube, G.; Schmidt, B.; Osterhoff, J.; Stoltz, P.

    2011-09-07

    Dielectric wakefield accelerators have shown great promise toward high-gradient acceleration. We investigate the performances of a possible experiment under consideration at the FLASH facility in DESY to explore wakefield acceleration with an enhanced transformer ratio. The experiment capitalizes on a unique pulse shaping capability recently demonstrated at this facility. In addition, the facility incorporates a superconducting linear accelerator that could generate bunch trains with closely spaced bunches thereby opening the exploration of potential dynamical effects in dielectric wakefield accelerators.

  17. Laser-ablation sampling for inductively coupled plasma distance-of-flight mass spectrometry

    SciTech Connect (OSTI)

    Gundlach-Graham, Alexander W.; Dennis, Elise; Ray, Steven J.; Enke, Christie G.; Barinaga, Charles J.; Koppenaal, David W.; Hieftje, Gary M.

    2015-01-01

    An inductively coupled plasma distance-of-flight mass spectrometer (ICP-DOFMS) has been coupled with laser-ablation (LA) sample introduction for the elemental analysis of solids. ICP-DOFMS is well suited for the analysis of laser-generated aerosols because it offers both high-speed mass analysis and simultaneous multi-elemental detection. Here, we evaluate the analytical performance of the LA-ICP-DOFMS instrument, equipped with a microchannel plate-based imaging detector, for the measurement of steady-state LA signals, as well as transient signals produced from single LA events. Steady-state detection limits are 1 mg g1, and absolute single-pulse LA detection limits are 200 fg for uranium; the system is shown capable of performing time-resolved single-pulse LA analysis. By leveraging the benefits of simultaneous multi-elemental detection, we also attain a good shot-to-shot reproducibility of 6% relative standard deviation (RSD) and isotope-ratio precision of 0.3% RSD with a 10 s integration time.

  18. Spatio-temporal evolution of magnetosonic wave in the laser plasma interaction

    SciTech Connect (OSTI)

    Sharma, R. P. Singh, Ram Kishor Sharma, Swati; Tiwary, Prem Pyari; Modi, K. V.; Satsangi, V. R.

    2015-05-15

    This paper presents a theoretical model for the transient response of nonlinear coupling between magnetosonic wave and ion acoustic wave in the overdense plasma. Filamentation of magnetosonic wave has been considered to be responsible for magnetic turbulence during the laser plasma interaction. The ion acoustic wave gets excited due to the ponderomotive force exerted by magnetosonic wave and this ion acoustic wave in turn generates perturbation in the background density in the form of spatial density harmonics. Numerical simulation has been carried out for dimensionless coupled equations of magnetosonic wave and ion acoustic wave; and the results show quite complex localized structures that grow with time. The power spectrum has also been studied which shows that the spectral index follows an approximate scaling of the order of ∼k{sup −2.4} at smaller scales. The data obtained from numerical simulation are used in semi analytical model to better understand the mechanism of nonlinear evolution of magnetosonic wave. The results indicate considerable randomness in the spatial structure of the magnetic field profile which gives sufficient indication of turbulence.

  19. Preliminary Results of Mono-energetic Electron Beams from a Laser-plasma Accelerator Driven by 200 TW Femto Second Pulses

    SciTech Connect (OSTI)

    Taki, R.; Kameshima, T.; An, W. M.; Hua, J. F.; Huang, W. H.; Tang, C. X.; Gu, Y. Q.; Guo, Y.; Hong, W.; Jiao, C. Y.; Lin, Y. Z.; Liu, H. J.; Peng, H. S.; Sun, L.; Tang, C. M.; Wang, X. D.; Wen, T. S.; Wen, X. L.; Wu, Y. C.; Zhang, B. H.

    2006-11-27

    Relativistic mono-energetic electron beams have been demonstrated by worldwide laser-plasma accelerator experiments in the range of a few tens TW. Laser-plasma accelerator experiment has been carried out with 200TW, 30fs Ti:Sapphire laser pulses focused on helium gas-jets with F/8.7 optics. Intense mono-energetic electron beams have been produced in the energy range of 30 to 150 MeV by controlling plasma length and density precisely. Images of Thomson scattering and fluorescence side scattering from plasma indicate highly relativistic effects such as a long self-channeling and filamentation as well as energetic electron deflection and intense backward Raman scattering. Preliminary results of the first laser-plasma accelerator experiment in the range of 200TW femto second pulses are presented.

  20. Low- and high-order harmonic generation in the extended plasmas produced by laser ablation of zinc and manganese targets

    SciTech Connect (OSTI)

    Ganeev, R. A.; Baba, M.; Suzuki, M.; Yoneya, S.; Kuroda, H.

    2014-12-28

    The systematic studies of the harmonic generation of ultrashort laser pulses in the 5-mm-long Zn and Mn plasmas (i.e., application of nanosecond, picosecond, and femtosecond pulses for ablation, comparison of harmonic generation from atomic, ionic, and cluster-contained species of plasma, variation of plasma length, two-color pump of plasmas, etc.) are presented. The conversion efficiency of the 11th–19th harmonics generated in the Zn plasma was ∼5 × 10{sup −5}. The role of the ionic resonances of Zn near the 9th and 10th harmonics on the enhancement of harmonics is discussed. The enhancement of harmonics was also analyzed using the two-color pump of extended plasmas, which showed similar intensities of the odd and even harmonics along the whole range of generation. The harmonics up to the 107th order were demonstrated in the case of manganese plasma. The comparison of harmonic generation in the 5-mm-long and commonly used short (≤0.5 mm) plasma plumes showed the advanced properties of extended media.

  1. Specific features of microheterogeneous plasma produced by irradiation of a polymer aerogel target with an intense 500-ps-long laser pulse

    SciTech Connect (OSTI)

    Borisenko, N. G.; Merkul’ev, Yu. A.; Orekhov, A. S.; Chaurasia, S.; Tripathi, S.; Munda, D. S.; Dhareshwar, L. J.; Pimenov, V. G.; Sheveleva, E. E.

    2013-08-15

    The properties of microheterogeneous plasma produced by irradiation of a polymer aerogel target with an intense (10{sup 14} W/cm{sup 3}) short (0.5 ps) 1.064-μm laser pulse were studied. It is found that, even at plasma densities exceeding the critical density, a small fraction of the incident laser radiation penetrates through the plasma in which the processes of density and temperature equalization still take place. The intensification (as compared to plasmas produced from denser foams and solid films) of transport processes in such plasma along and across the laser beam can be caused by the initial microheterogeneity of the solid target. The replacement of a small (10% by mass) part of the polymer with copper nanoparticles leads to a nearly twofold increase in the intensity of the plasma X-ray emission.

  2. An experimental investigation of stimulated Brillouin scattering in laser-produced plasmas relevant to inertial confinement fusion

    SciTech Connect (OSTI)

    Bradley, K.S.

    1993-02-11

    Despite the apparent simplicity of controlled fusion, there are many phenomena which have prevented its achievement. One phenomenon is laser-plasma instabilities. An investigation of one such instability, stimulated Brillouin scattering (SBS), is reported here. SBS is a parametric process whereby an electromagnetic wave (the parent wave) decays into another electromagnetic wave and an ion acoustic wave (the daughter waves). SBS impedes controlled fusion since it can scatter much or all of the incident laser light, resulting in poor drive symmetry and inefficient laser-plasma coupling. It is widely believed that SBS becomes convectively unstable--that is, it grows as it traverses the plasma. Though it has yet to be definitively tested, convective theory is often invoked to explain experimental observations, even when one or more of the theory`s assumptions are violated. In contrast, the experiments reported here not only obeyed the assumptions of the theory, but were also conducted in plasmas with peak densities well below quarter-critical density. This prevented other competing or coexisting phenomena from occurring, thereby providing clearly interpretable results. These are the first SBS experiments that were designed to be both a clear test of linear convective theory and pertinent to controlled fusion research. A crucial part of this series of experiments was the development of a new instrument, the Multiple Angle Time Resolving Spectrometer (MATRS). MATRS has the unique capability of both spectrally and temporally resolving absolute levels of scattered light at many angles simultaneously, and is the first of its kind used in laser-plasma experiments. A detailed comparison of the theoretical predictions and the experimental observations is made.

  3. Dynamics of plasma expansion and shockwave formation in femtosecond laser-ablated aluminum plumes in argon gas at atmospheric pressures

    SciTech Connect (OSTI)

    Miloshevsky, Alexander; Harilal, Sivanandan S.; Miloshevsky, Gennady Hassanein, Ahmed

    2014-04-15

    Plasma expansion with shockwave formation during laser ablation of materials in a background gasses is a complex process. The spatial and temporal evolution of pressure, temperature, density, and velocity fields is needed for its complete understanding. We have studied the expansion of femtosecond (fs) laser-ablated aluminum (Al) plumes in Argon (Ar) gas at 0.5 and 1 atmosphere (atm). The expansion of the plume is investigated experimentally using shadowgraphy and fast-gated imaging. The computational fluid dynamics (CFD) modeling is also carried out. The position of the shock front measured by shadowgraphy and fast-gated imaging is then compared to that obtained from the CFD modeling. The results from the three methods are found to be in good agreement, especially during the initial stage of plasma expansion. The computed time- and space-resolved fields of gas-dynamic parameters have provided valuable insights into the dynamics of plasma expansion and shockwave formation in fs-pulse ablated Al plumes in Ar gas at 0.5 and 1 atm. These results are compared to our previous data on nanosecond (ns) laser ablation of Al [S. S. Harilal et al., Phys. Plasmas 19, 083504 (2012)]. It is observed that both fs and ns plumes acquire a nearly spherical shape at the end of expansion in Ar gas at 1 atm. However, due to significantly lower pulse energy of the fs laser (5 mJ) compared to pulse energy of the ns laser (100 mJ) used in our studies, the values of pressure, temperature, mass density, and velocity are found to be smaller in the fs laser plume, and their time evolution occurs much faster on the same time scale. The oscillatory shock waves clearly visible in the ns plume are not observed in the internal region of the fs plume. These experimental and computational results provide a quantitative understanding of plasma expansion and shockwave formation in fs-pulse and ns-pulse laser ablated Al plumes in an ambient gas at atmospheric pressures.

  4. Characterization of Heat-Wave Propagation through Laser-Driven...

    Office of Scientific and Technical Information (OSTI)

    74 ATOMIC AND MOLECULAR PHYSICS; 70 PLASMA PHYSICS AND FUSION; ABSORPTION; ELECTRON TEMPERATURE; HYDRODYNAMICS; K SHELL; LASER-PRODUCED PLASMA; LASERS; PLASMA; PLASMA ...

  5. Enhancement of a laminar premixed methane/oxygen/nitrogen flame speed using femtosecond-laser-induced plasma

    SciTech Connect (OSTI)

    Yu Xin; Peng Jiangbo; Yi Yachao; Zhao Yongpeng; Chen Deying; Yu Junhua [National Key Laboratory of Science and Technology on Tunable Laser, Harbin Institute of Technology, Harbin 150080 (China); Institute of Opto-electronics, Harbin Institute of Technology, Harbin 150080 (China); Yang Peng; Sun Rui [Institute of Combustion Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2010-07-05

    We first investigate the effects of femtosecond-laser-induced plasma on the flame speed of a laminar premixed methane/oxygen/nitrogen flame with a wide range of the equivalence ratios (0.8-1.05) at atmospheric pressure. It is experimentally found that the flame speed increases 20.5% at equivalence ratios 1.05. The self-emission spectra from the flame and the plasma are studied and an efficient production of active radicals under the action of femtosecond (fs)-laser pulses has been observed. Based on the experimental data obtained, the presence of oxygen atom and hydrocarbon radicals is suggested to be a key factor enhancing flame speed.

  6. Talbot-Lau X-ray Deflectometer electron density diagnostic for laser and pulsed power high energy density plasma experiments

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Valdivia, M. P.; Stutman, D.; Stoeckl, C.; Mileham, C.; Begishev, I.; Theobald, W.; Bromage, J.; Regan, S. P.; Klein, S. R.; Munoz-Cordoves, G.; et al

    2016-04-21

    Talbot-Lau X-ray Deflectometry has been developed as an electron density diagnostic for High Energy Density plasmas. The technique can deliver x-ray refraction, attenuation, elemental composition, and scatter information from a single Moiré image. An 8 keV Talbot-Lau interferometer was deployed using laser and x-pinch backlighters. Grating survival and electron density mapping was demonstrated for 25-29 J, 8-30 ps laser pulses using copper foil targets. Moire pattern formation and grating survival was also observed using a copper x-pinch driven at 400 kA, ~1 kA/ns. Lastly, these results demonstrate the potential of TXD as an electron density diagnostic for HED plasmas.

  7. Properties of CO/sub 2/ laser produced long-life plasmas observed by x-ray spectroscopic methods

    SciTech Connect (OSTI)

    Daido, H.; Nishihara, K.; Mima, K.; Kitagawa, Y.; Nakai, S.; Yamanaka, C.; Hasegawa, A.

    1988-03-01

    We present the properties of shell confinement long-life plasmas produced by a CO/sub 2/ laser. The temperature measurement for parylene shell targets based on the x-ray spectroscopic method gives the electron temperature of more than 500 eV at the center of a 1-mm-diam target. An enchanced confinement time is obtained in a thick gold shell (100 ..mu..m thick) target coated internally with parylene. The duration of the x ray emitted from the hot core in a 3-mm-diam target of this type is 34 ns, while the laser pulse duration is 1 ns. The long duration of the x-ray manifests the hot core plasma lifetime; the observed duration presents a strong evidence of thermal insulation by the self-generated magnetic field.

  8. One-dimensional time resolved soft x-ray imaging of colliding plasmas in a laser heated cavity

    SciTech Connect (OSTI)

    Eagleton, R.T.; Foster, J.M.; Rosen, P.A.; Graham, P.

    1997-01-01

    We describe x-ray streak camera measurements of wall motion and plasma filling in hohlraum targets heated by the AWE HELEN laser. An x-ray streak camera using a transmission mode photocathode on a thin plastic substrate (1000 {Angstrom} Parylene-N) was coupled to a 15{degree} incidence gold mirror to define a spectral channel response of width 45 eV full width at half-maximum centered around 120 eV. A 20 {mu}m diam pinhole was used to image the hohlraum interior onto the photocathode slit of the streak camera, via the gold reflector. Plasma expansion from the laser hot spots, and the indirectly heated wall, was recorded. The experimental data are compared with simulations using the AWE Lagrangian hydrocode NYM. {copyright} {ital 1997 American Institute of Physics.}

  9. On the origin of super-hot electrons from intense laser interactions with solid targets having moderate scale length preformed plasmas

    SciTech Connect (OSTI)

    Krygier, A. G.; Schumacher, D. W.; Freeman, R. R.

    2014-02-15

    We use particle-in-cell modeling to identify the acceleration mechanism responsible for the observed generation of super-hot electrons in ultra-intense laser-plasma interactions with solid targets with pre-formed plasma. We identify several features of direct laser acceleration that drive the generation of super-hot electrons. We find that, in this regime, electrons that become super-hot are primarily injected by a looping mechanism that we call loop-injected direct acceleration.

  10. High resolution soft x-ray spectroscopy of low Z K-shell emission from laser-produced plasmas

    SciTech Connect (OSTI)

    Dunn, J; Magee, E W; Shepherd, R; Chen, H; Hansen, S B; Moon, S J; Brown, G V; Gu, M; Beiersdorfer, P; Purvis, M A

    2008-05-21

    A large radius, R = 44.3 m, High Resolution Grating Spectrometer (HRGS) with 2400 line/mm variable line spacing has been designed for laser-produced plasma experiments conducted at the Lawrence Livermore National Laboratory Jupiter Laser Facility. The instrument has been run with a low-noise, charge-coupled device detector to record high signal-to-noise spectra in the 10-50 {angstrom} wavelength range. The instrument can be run with a 10-20 {micro}m wide slit to achieve the best spectral resolving power, approaching 1000 and similar to crystal spectrometers at 12-20 {angstrom}, or in slitless operation with a small symmetrical emission source. We describe preliminary spectra emitted from various H-like and He-like low Z ion plasmas heated by 100-500 ps (FWHM), 527 nm wavelength laser pulses. This instrument can be developed as a useful spectroscopy platform relevant to laboratory-based astrophysics as well as high energy density plasma studies.

  11. Self similar solution of superradiant amplification of ultrashort laser pulses in plasma

    SciTech Connect (OSTI)

    Moghadasin, H.; Niknam, A. R. Shokri, B.

    2015-05-15

    Based on the self-similar method, superradiant amplification of ultrashort laser pulses by the counterpropagating pump in a plasma is investigated. Here, we present a governing system of partial differential equations for the signal pulse and the motion of the electrons. These equations are transformed to ordinary differential equations by the self-similar method and numerically solved. It is found that the increase of the signal intensity is proportional to the square of the propagation distance and the signal frequency has a red shift. Also, depending on the pulse width, the signal breaks up into a train of short pulses or its duration decreases with the inverse square root of the distance. Moreover, we identified two distinct categories of the electrons by the phase space analysis. In the beginning, one of them is trapped in the ponderomotive potential well and oscillates while the other is untrapped. Over time, electrons of the second kind also join to the trapped electrons. In the potential well, the electrons are bunched to form an electron density grating which reflects the pump pulse into the signal pulse. It is shown that the backscattered intensity is enhanced with the increase of the electron bunching parameter which leads to the enhanced efficiency of superradiant amplification.

  12. Highly collimated monoenergetic target-surface electron acceleration in near-critical-density plasmas

    SciTech Connect (OSTI)

    Mao, J. Y.; Chen, L. M.; Huang, K.; Ma, Y.; Zhao, J. R.; Yan, W. C.; Ma, J. L.; Wei, Z. Y.; Li, D. Z.; Aeschlimann, M.; Zhang, J.

    2015-03-30

    Optimized-quality monoenergetic target surface electron beams at MeV level with low normalized emittance (0.03π mm mrad) and high charge (30 pC) per shot have been obtained from 3 TW laser-solid interactions at a grazing incidence. The 2-Dimension particle-in-cell simulations suggest that electrons are wake-field accelerated in a large-scale, near-critical-density preplasma. It reveals that a bubble-like structure as an accelerating cavity appears in the near-critical-density plasma region and travels along the target surface. A bunch of electrons are pinched transversely and accelerated longitudinally by the wake field in the bubble. The outstanding normalized emittance and monochromaticity of such highly collimated surface electron beams could make it an ideal beam for fast ignition or may serve as an injector in traditional accelerators.

  13. Hydrodynamic study of plasma amplifiers for soft-x-ray lasers: A transition in hydrodynamic behavior for plasma columns with widths ranging from 20 {mu}m to 2 mm

    SciTech Connect (OSTI)

    Oliva, Eduardo; Zeitoun, Philippe; Sebban, Stephan; Velarde, Pedro; Portillo, David; Fajardo, Marta; Cassou, Kevin; Ros, David; Le Pape, Sebastien

    2010-11-15

    Plasma-based seeded soft-x-ray lasers have the potential to generate high energy and highly coherent short pulse beams. Due to their high density, plasmas created by the interaction of an intense laser with a solid target should store the highest amount of energy density among all plasma amplifiers. Our previous numerical work with a two-dimensional (2D) adaptive mesh refinement hydrodynamic code demonstrated that careful tailoring of plasma shapes leads to a dramatic enhancement of both soft-x-ray laser output energy and pumping efficiency. Benchmarking of our 2D hydrodynamic code in previous experiments demonstrated a high level of confidence, allowing us to perform a full study with the aim of the way for 10-100 {mu}J seeded soft-x-ray lasers. In this paper, we describe in detail the mechanisms that drive the hydrodynamics of plasma columns. We observed transitions between narrow plasmas, where very strong bidimensional flow prevents them from storing energy, to large plasmas that store a high amount of energy. Millimeter-sized plasmas are outstanding amplifiers, but they have the limitation of transverse lasing. In this paper, we provide a preliminary solution to this problem.

  14. Tunable and efficient terahertz radiation generation by photomixing of two super Gaussian laser pulses in a corrugated magnetized plasma

    SciTech Connect (OSTI)

    Varshney, Prateek; Sajal, Vivek Kumar, Ravindra; Sharma, Navneet K.; Singh, Kunwar Pal

    2015-05-21

    A scheme of terahertz (THz) radiation generation is investigated by photo-mixing of two super Gaussian laser beams having different frequencies (ω{sub 1}, ω{sub 2}) and wave numbers (k{sup →}{sub 1}, k{sup →}{sub 2}) in a performed corrugated plasma embedded with transverse dc magnetic field. Lasers exert a nonlinear ponderomotive force, imparting an oscillatory velocity to plasma electrons that couples with the density corrugations (n{sup ′}=n{sub α0}e{sup iαz}) to generate a strong transient nonlinear current, that resonantly derives THz radiation of frequency ∼ω{sub h} (upper hybrid frequency). The periodicity of density corrugations is suitably chosen to transfer maximum momentum from lasers to THz radiation at phase matching conditions ω=ω{sub 1}−ω{sub 2} and k{sup →}=k{sup →}{sub 1}−k{sup →}{sub 2}+α{sup →}. The efficiency, power, beam quality, and tunability of the present scheme exhibit high dependency upon the applied transverse dc magnetic field along with q-indices and beam width parameters (a{sub 0}) of super Gaussian lasers. In the present scheme, efficiency ∼10{sup −2} is achieved with the optimization of all these parameters.

  15. Two decades of progress in understanding and control of laser plasma instabilities in indirect drive inertial fusion

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Montgomery, David S.

    2016-05-01

    Here, our understanding of laser-plasma instability (LPI) physics has improved dramatically over the past two decades through advancements in experimental techniques, diagnostics, and theoretical and modeling approaches. We have progressed from single-beam experiments—ns pulses with ~kJ energy incident on hundred-micron-scale target plasmas with ~keV electron temperatures—to ones involving nearly 2 MJ energy in 192 beams onto multi-mm-scale plasmas with temperatures ~4 keV. At the same time, we have also been able to use smaller-scale laser facilities to substantially improve our understanding of LPI physics and evaluate novel approaches to their control. These efforts have led to a change in paradigmmore » for LPI research, ushering in an era of engineering LPI to accomplish specific objectives, from tuning capsule implosion symmetry to fixing nonlinear saturation of LPI processes at acceptable levels to enable the exploration of high energy density physics in novel plasma regimes. A tutorial is provided that reviews the progress in the field from the vantage of the foundational LPI experimental results. The pedagogical framework of the simplest models of LPI will be employed, but attention will also be paid to settings where more sophisticated models are needed to understand the observations. Prospects for the application of our improved understanding for inertial fusion (both indirect- and direct-drive) and other applications will also be discussed.« less

  16. Influence of magnetic field on laser-produced barium plasmas: Spectral and dynamic behaviour of neutral and ionic species

    SciTech Connect (OSTI)

    Raju, Makaraju Srinivasa; Gopinath, Pramod, E-mail: pramod@iist.ac.in [Department of Physics, Indian Institute of Space Science and Technology, Thiruvananthapuram 695547 (India); Singh, R. K.; Kumar, Ajai [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)

    2014-10-21

    The expansion dynamics and spectral behaviour of plasma produced by a Nd:YAG laser (?=1.064 ?m, pulse width: 8 ns) from barium target and expanding in 0.45 T transverse magnetic field in vacuum (10??Torr pressure) are investigated using time-of-flight optical emission spectroscopy. The experiments are carried out at various laser fluences from 12 to 31 J/cm. The temporal profiles of neutral (Ba I 553.5 and 577.7 nm) lines are temporally broadened, while that of ionic (Ba II 413.0 and 455.4 nm) lines show strong confinement in the presence of a magnetic field. In the absence of magnetic field, the temporal profile of Ba I 553.5 nm is exactly reproduced by fitting with two Shifted Maxwell Boltzmann (SMB) Distribution components, while in the presence of a magnetic field the profile could only be fitted with three components. The field enhanced and field induced SMB components of neutral profile are correlated with populations of ground state, metastable states, and long-lived Rydberg states present in the barium plasma, while SMB components of ionic lines are explained on the basis of the presence of super-elastic collisions among the excited species in the plasma. The spatial variation of electron temperature and temporal variation of electron density are deduced and correlated to the different collisional processes in the barium plasma. The ionic profiles show efficient confinement in the presence of a magnetic field at higher fluences.

  17. Refraction-Enhanced X-ray Radiography for Inertial Confinement Fusion and Laser-Produced Plasma Applications

    SciTech Connect (OSTI)

    Koch, J A; Landen, O L; Kozioziemski, B J; Izumi, N; Dewald, E L; Salmonson, J D; Hammel, B A

    2008-08-26

    We explore various laser-produced plasma and inertial-confinement fusion (ICF) applications of phase-contrast x-ray radiography, and we show how the main features of these enhancements can be considered from a geometrical optics perspective as refraction enhancements. This perspective simplifies the analysis, and often permits simple analytical formulae to be derived that predict the enhancements. We explore a raytrace approach to various material interface applications, and we explore a more general example of refractive bending of x-rays by an implosion plasma. We find that refraction-enhanced x-ray radiography of implosions may provide a means to quantify density differences across shock fronts as well as density variations caused by local heating due to high-Z dopants. We also point out that refractive bending by implosions plasmas can blur fine radiograph features, and can also provide misleading contrast information in area-backlit pinhole imaging experiments unless its effects are taken into consideration.

  18. Enhanced relativistic self-focusing of Hermite-cosh-Gaussian laser beam in plasma under density transition

    SciTech Connect (OSTI)

    Nanda, Vikas; Kant, Niti

    2014-04-15

    Enhanced and early relativistic self-focusing of Hermite-cosh-Gaussian (HChG) beam in the plasmas under density transition has been investigated theoretically using Wentzel-Kramers-Brillouin and paraxial ray approximation for mode indices m=0, 1, and 2. The variation of beam width parameter with normalized propagation distance for m=0, 1, and 2 is reported, and it is observed that strong self-focusing occurs as the HChG beam propagates deeper inside the nonlinear medium as spot size shrinks due to highly dense plasmas and the results are presented graphically. A comparative study between self-focusing of HChG beam in the presence and absence of plasmas density transition is reported. The dependency of beam width parameter on the normalized propagation distance for different values of decentered parameter “b” has also been presented graphically. For m=0 and 1, strong self-focusing is reported for b=1.8, and for m=2 and b=1.8, beam gets diffracted. The results obtained indicate the dependency of the self-focusing of the HChG beam on the selected values of decentered parameter. Moreover, proper selection of decentered parameter results strong self-focusing of HChG beam. Stronger self-focusing of laser beam is observed due to the presence of plasma density transition which might be very useful in the applications like the generation of inertial fusion energy driven by lasers, laser driven accelerators, etc.

  19. Kinetic (particle-in-cell) simulation of nonlinear laser absorption in a finite-size plasma with a background inhomogeneous magnetic field

    SciTech Connect (OSTI)

    Mehdian, H. Kargarian, A.; Hajisharifi, K.

    2015-06-15

    In this paper, the effect of an external inhomogeneous magnetic field on the high intensity laser absorption rate in a sub-critical plasma has been investigated by employing a relativistic electromagnetic 1.5 dimensional particle-in-cell code. Relying on the effective nonlinear phenomena such as phase-mixing and scattering, this study shows that in a finite-size plasma the laser absorption increases with inhomogeneity of the magnetic field (i.e., reduction of characteristic length of inhomogeneous magnetic field, λ{sub p}) before exiting a considerable amount of laser energy from the plasma due to scattering process. On the other hand, the presence of the external inhomogeneous magnetic field causes the maximum absorption of laser to occur at a shorter time. Moreover, study of the kinetic results associated with the distribution function of plasma particles shows that, in a special range of the plasma density and the characteristic length of inhomogeneous magnetic field, a considerable amount of laser energy is transferred to the particles producing a population of electrons with kinetic energy along the laser direction.

  20. The effect of external magnetic field on the bremsstrahlung nonlinear absorption mechanism in the interaction of high intensity short laser pulse with collisional underdense plasma

    SciTech Connect (OSTI)

    Sedaghat, M.; Ettehadi-Abari, M.; Shokri, B. Ghorbanalilu, M.

    2015-03-15

    Laser absorption in the interaction between ultra-intense femtosecond laser and solid density plasma is studied theoretically here in the intensity range I?{sup 2}?10{sup 14}?10{sup 16}Wcm{sup ?2}?m{sup 2}. The collisional effect is found to be significant when the incident laser intensity is less than 10{sup 16}Wcm{sup ?2}?m{sup 2}. In the current work, the propagation of a high frequency electromagnetic wave, for underdense collisional plasma in the presence of an external magnetic field is investigated. It is shown that, by considering the effect of the ponderomotive force in collisional magnetized plasmas, the increase of laser pulse intensity leads to steepening of the electron density profile and the electron bunches of plasma makes narrower. Moreover, it is found that the wavelength of electric and magnetic fields oscillations increases by increasing the external magnetic field and the density distribution of electrons also grows in comparison with the unmagnetized collisional plasma. Furthermore, the spatial damping rate of laser energy and the nonlinear bremsstrahlung absorption coefficient are obtained in the collisional regime of magnetized plasma. The other remarkable result is that by increasing the external magnetic field in this case, the absorption coefficient increases strongly.

  1. Investigation of thermodynamic equilibrium in laser-induced aluminum plasma using the H{sub α} line profiles and Thomson scattering spectra

    SciTech Connect (OSTI)

    Cvejić, M. E-mail: krzysztof.dzierzega@uj.edu.pl; Dzierżęga, K. E-mail: krzysztof.dzierzega@uj.edu.pl; Pięta, T.

    2015-07-13

    We have studied isothermal equilibrium in the laser-induced plasma from aluminum pellets in argon at pressure of 200 mbar by using a method which combines the standard laser Thomson scattering and analysis of the H{sub α}, Stark-broadened, line profiles. Plasma was created using 4.5 ns, 4 mJ pulses from a Nd:YAG laser at 1064 nm. While electron density and temperature were determined from the electron feature of Thomson scattering spectra, the heavy particle temperature was obtained from the H{sub α} full profile applying computer simulation including ion-dynamical effects. We have found strong imbalance between these two temperatures during entire plasma evolution which indicates its non-isothermal character. At the same time, according to the McWhirter criterion, the electron density was high enough to establish plasma in local thermodynamic equilibrium.

  2. A hemispherical Langmuir probe array detector for angular resolved measurements on droplet-based laser-produced plasmas

    SciTech Connect (OSTI)

    Gambino, Nadia Brandsttter, Markus; Rollinger, Bob; Abhari, Reza

    2014-09-15

    In this work, a new diagnostic tool for laser-produced plasmas (LPPs) is presented. The detector is based on a multiple array of six motorized Langmuir probes. It allows to measure the dynamics of a LPP in terms of charged particles detection with particular attention to droplet-based LPP sources for EUV lithography. The system design permits to temporally resolve the angular and radial plasma charge distribution and to obtain a hemispherical mapping of the ions and electrons around the droplet plasma. The understanding of these dynamics is fundamental to improve the debris mitigation techniques for droplet-based LPP sources. The device has been developed, built, and employed at the Laboratory for Energy Conversion, ETH Zrich. The experimental results have been obtained on the droplet-based LPP source ALPS II. For the first time, 2D mappings of the ion kinetic energy distribution around the droplet plasma have been obtained with an array of multiple Langmuir probes. These measurements show an anisotropic expansion of the ions in terms of kinetic energy and amount of ion charge around the droplet target. First estimations of the plasma density and electron temperature were also obtained from the analysis of the probe current signals.

  3. Self-focusing and defocusing of Gaussian laser beams in collisional underdense magnetized plasmas with considering the nonlinear ohmic heating and ponderomotive force effects

    SciTech Connect (OSTI)

    Ettehadi Abari, Mehdi; Sedaghat, Mahsa; Shokri, Babak

    2015-10-15

    The propagation characteristics of a Gaussian laser beam in collisional magnetized plasma are investigated by considering the ponderomotive and ohmic heating nonlinearities. Here, by taking into account the effect of the external magnetic field, the second order differential equation of the dimensionless beam width parameter is solved numerically. Furthermore, the nonlinear dielectric permittivity of the mentioned plasma medium in the paraxial approximation and its dependence on the propagation characteristics of the Gaussian laser pulse is obtained, and its variation in terms of the dimensionless plasma length is analyzed at different initial normalized plasma and cyclotron frequencies. The results show that the dimensionless beam width parameter is strongly affected by the initial plasma frequency, magnetic strength, and laser pulse intensity. Furthermore, it is found that there exists a certain intensity value below which the laser pulse tends to self focus, while the beam diverges above of this value. In addition, the results confirm that, by increasing the plasma and cyclotron frequencies (plasma density and magnetic strength), the self-focusing effect can occur intensively.

  4. Full aperture backscatter station imager (FABSI) diagnostics system for far-field imaging of laser plasma instabilities on Nova

    SciTech Connect (OSTI)

    Wilke, M.D.; Fernandez, J.C.; Berggren, R.R.; Montgomery, D.; Faulkner, J.; Looney, L.; Jimerson, J.; Horton, R.F.

    1996-06-01

    In ICF, the understanding of laser plasma scattering processes is essential for laser target coupling and in controlling the symmetry of indirect drive implosions. The existing Nova Full Aperture Backscatter Station (FABS) has been useful in understanding laser plasma instabilities occurring in hohlraums by measuring the quantity, spectral distribution and near-field spatial distributions of Brillouin and more recently Raman backscatter. Equally important is an understanding of the farfield spatial intensity distribution which provides information on density, temperature and velocity gradient distributions, and which affect capsule implosion symmetry in hohlraums. Such information could potentially help in understanding processes such as filamentation and saturation mechanism. This paper describes a broad-band, color-corrected far-field imager and associated diagnostics capable of imaging the source of scattered light to better than 25 {micro}m resolution. The imager can either image Brillouin or Raman backscatter through the Nova beam 7 focusing lens or be used like a microscope to image side scatter from other beams.

  5. Stimulated Raman scattering of beat wave of two counter-propagating X-mode lasers in a magnetized plasma

    SciTech Connect (OSTI)

    Verma, Kanika; Sajal, Vivek Varshney, Prateek; Kumar, Ravindra; Sharma, Navneet K.

    2014-02-15

    Effects of transverse static magnetic field on stimulated Raman scattering (SRS) of the beat wave excited by two counter-propagating lasers are studied. Two counter-propagating lasers with frequency difference, ?{sub 1}??{sub 2}?2?{sub p}, drive a non resonant space charge beat mode at wave number k{sup ?}{sub 0}?k{sup ?}{sub 1}+k{sup ?}{sub 2} in a plasma, where k{sup ?}{sub 1} and k{sup ?}{sub 2} are wave vectors of lasers having frequencies ?{sub 1} and ?{sub 2}, respectively. The driven beat wave acts as a pump for SRS and excites parametrically a pair of plasma wave (?,k{sup ?}) and side band electromagnetic wave (?{sub 3},k{sup ?}{sub 3}) propagating in the sideward direction in such a way that momentum remains conserved. The growth rate of Raman process is maximum for side scattering at ?{sub s}=?/2 for lower values of applied magnetic field (?1?kG), which can be three fold by applying magnetic field ?5.0?kG. Thus, optimum value of magnetic field can be utilized to achieve maximum electron acceleration in counter propagating geometry of beat wave acceleration by reducing the growth rate of Raman process.

  6. Time-resolved soft x-ray spectra from laser-produced Cu plasma...

    Office of Scientific and Technical Information (OSTI)

    Cu plasma The volumetric heating of a thin copper target has been studied with time resolved x-ray spectroscopy. The copper target was heated from a plasma produced using ...

  7. Positron jitter and wakefield effects in the SLC injector linac

    SciTech Connect (OSTI)

    Tian, F.; McCormick, D.; Ross, M.

    1994-06-01

    The positron beam in the SLC injector linac is a high current (7*10{sup 10} particles/bunch), large universe emittance ({gamma}{var_epsilon} = .01 m-rad) and long bunch length ({approximately}4 mm) beam. A large 5% positron intensity jitter was observed and correlated with the accelerating phase of the RF cavities in the positron source linac. For high transmission, the positron jitter must be reduced and strong wakefield effects cannot be ignored. A code was written to study causes of the positron jitter and wakefields in the SLC injector linac. The tracking results show that when the bunch lengths are 1.5, 2.1, 3.0, 4.0 mm, the injection apertures (leading to 30% loss) are 1.8, 1,6, 1.2, 1.0 sigma of transverse size at the beginning of the sector respectively. For the long bunches, the nominal 20% of beam size transverse pulse to pulse jitter causes an additional 3% loss. Also the bunch energy spread is more sensitive to the accelerating phase of the RF cavities.

  8. Turning point temperature and competition between relativistic and ponderomotive effects in self-focusing of laser beam in plasma

    SciTech Connect (OSTI)

    Bokaei, B.; Niknam, A. R.; Jafari Milani, M. R.

    2013-10-15

    The propagation characters of Gaussian laser beam in collisionless plasma are investigated by considering the ponderomotive and relativistic nonlinearities. The second-order differential equation of dimensionless beam width parameter is solved numerically, taking into account the effect of electron temperature. The results show that the ponderomotive force does not facilitate the relativistic self-focusing in all intensity ranges. In fact, there exists a certain intensity value that, if below this value, the ponderomotive nonlinearity can contribute to the relativistic self-focusing, or obstruct it, if above. It is also indicated that there is a temperature interval in which self-focusing can occur, while the beam diverges outside of this region. In addition, the results represent the existence of a “turning point temperature” in the mentioned interval that the self-focusing has the strongest power. The value of the turning point is dependent on laser intensity in which higher intensities result in higher turning point.

  9. Density and x-ray emission profile relationships in highly ionized high-Z laser-produced plasmas

    SciTech Connect (OSTI)

    Yoshida, Kensuke; Fujioka, Shinsuke Ugomori, Teruyuki; Tanaka, Nozomi; Azechi, Hiroshi; Nishimura, Hiroaki; Higashiguchi, Takeshi Kawasaki, Masato; Suzuki, Yuhei; Suzuki, Chihiro; Tomita, Kentaro; Hirose, Ryoichi; Ejima, Takeo; Ohashi, Hayato; Nishikino, Masaharu; Sunahara, Atsushi; Li, Bowen; Dunne, Padraig; O'Sullivan, Gerry; Yanagida, Tatsuya

    2015-03-23

    We present a benchmark measurement of the electron density profile in the region where the electron density is 10{sup 19?}cm{sup 3} and where the bulk of extreme ultraviolet (EUV) emission occurs from isotropically expanding spherical high-Z gadolinium plasmas. It was found that, due to opacity effects, the observed EUV emission is mostly produced from an underdense region. We have analyzed time-resolved emission spectra with the aid of atomic structure calculations and find the multiple ion charge states around 18+ during the laser pulse irradiation.

  10. Effects of higher-order Kerr nonlinearity and plasma diffraction on multiple filamentation of ultrashort laser pulses in air

    SciTech Connect (OSTI)

    Huang, T. W.; Zhou, C. T.; Institute of Applied Physics and Computational Mathematics, Beijing 100094; Science College, National University of Defense Technology, Changsha 410073 ; Zhang, H.; He, X. T.; Institute of Applied Physics and Computational Mathematics, Beijing 100094

    2013-07-15

    The effect of higher-order Kerr nonlinearity on channel formation by, and filamentation of, ultrashort laser pulses propagating in air is considered. Filament patterns originating from multiphoton ionization of the air molecules with and without the higher-order Kerr and molecular-rotation effects are investigated. It is found that diverging multiple filaments are formed if only the plasma-induced defocusing effect is included. In the presence of the higher-order Kerr effects, the light channel can exist for a long distance. The effect of noise on the filament patterns is also discussed.

  11. High-energy x-ray microscopy of laser-fusion plasmas at the National Ignition Facility

    SciTech Connect (OSTI)

    Koch, J.A.; Landen, O.L.; Hammel, B.A.

    1997-08-26

    Multi-keV x-ray microscopy will be an important laser-produced plasma diagnostic at future megajoule facilities such as the National Ignition Facility (NIF).In preparation for the construction of this facility, we have investigated several instrumentation options in detail, and we conclude that near normal incidence single spherical or toroidal crystals may offer the best general solution for high-energy x-raymicroscopy at NIF and at similar large facilities. Kirkpatrick-Baez microscopes using multi-layer mirrors may also be good secondary options, particularly if apertures are used to increase the band-width limited field of view.

  12. Toward a self-consistent model of the interaction between an ultra-intense, normally incident laser pulse with an overdense plasma

    SciTech Connect (OSTI)

    Debayle, A.; ETSI Aeronáuticos. Universidad Politécnica de Madrid, Madrid 28040 ; Sanz, J.; Gremillet, L.; Mima, K.

    2013-05-15

    Following a recent work by Sanz et al. [Phys. Rev. E 85, 046411 (2012)], we elaborate upon a one-dimensional model describing the interaction between an ultra-intense, normally incident laser pulse and an overdense plasma. The analytical solutions of the reflected laser field, the electrostatic field, and the plasma surface oscillation are obtained within the cold-fluid approximation. The high-order harmonic spectrum is calculated from the exact solution of the plasma surface oscillations. In agreement with particle-in-cell simulations, two regimes of harmonic generation are predicted: for moderately relativistic laser intensities, or high plasma densities, the harmonic spectrum is determined by the discontinuity in the derivative of the reflected field when the electron plasma boundary oscillates across the fixed ion boundary. For higher intensities, the electron plasma boundary is confined inside the ion region and oscillates at relativistic velocities, giving rise to a train of reflected attosecond pulses. In both cases, the harmonic spectrum obeys an asymptotic ω{sup −4} scaling. The acceleration of electrons and the related laser absorption efficiency are computed by a test particle method. The model self-consistently reproduces the transition between the “anomalous skin effect” and the “J × B” heating predicted by particle-in-cell simulations. Analytical estimates of the different scalings are presented.

  13. Plasma

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    confinement by circularly polarized electromagnetic field in toroidal geometry Vladimir A. Svidzinski University of Wisconsin-Madison, Madison, Wisconsin 53706, USA and Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA ͑Received 21 May 2007; accepted 2 July 2007; published online 31 October 2007͒ A novel plasma confinement concept based on plasma confinement by electromagnetic pressure of circularly polarized electromagnetic fields is proposed. Practical implementation of this

  14. Collimator Wakefield Calculations for ILC-TRC Report(LCC-0101)

    SciTech Connect (OSTI)

    Tenenbaum, P

    2003-10-07

    We summarize the formalism of collimator wakefields and their effect on beams that are near the center of the collimator gap, and apply the formalism to the TESLA, NLC, and CLIC collimation systems.

  15. Novel high-energy physics studies using intense lasers and plasmas

    SciTech Connect (OSTI)

    Leemans, Wim P.; Bulanov, Stepan; Esarey, Eric; Schroeder, Carl

    2015-06-29

    In the framework of the project “Novel high-energy physics studies using intense lasers and plasmas” we conducted the study of ion acceleration and “flying mirrors” with high intensity lasers in order to develop sources of ion beams and high frequency radiation for different applications. Since some schemes of laser ion acceleration are also considered a good source of “flying mirrors”, we proposed to investigate the mechanisms of “mirror” formation. As a result we were able to study the laser ion acceleration from thin foils and near critical density targets. We identified several fundamental factors limiting the acceleration in the RPA regime and proposed the target design to compensate these limitations. In the case of near critical density targets, we developed a concept for the laser driven ion source for the hadron therapy. Also we studied the mechanism of “flying mirror” generation during the intense laser interaction with thin solid density targets. As for the laser-based positron creation and capture we initially proposed to study different regimes of positron beam generation and positron beam cooling. Since the for some of these schemes a good quality electron beam is required, we studied the generation of ultra-low emittance electron beams. In order to understand the fundamental physics of high energy electron beam interaction with high intensity laser pulses, which may affect the efficient generation of positron beams, we studied the radiation reaction effects.

  16. Structural Study of SiC Nanoparticles Grown by Inductively Coupled Plasma and Laser Pyrolysis for Nano-structured Ceramics Elaboration

    SciTech Connect (OSTI)

    Leconte, Yann; Portier, Xavier; Herlin-Boime, Nathalie; Reynaud, Cecile

    2008-07-01

    Refractory carbide nano-structured ceramics as SiC constitute interesting materials for high temperature applications and particularly for fourth generation nuclear plants. To elaborate such nano-materials, weighable amounts of SiC nano-powders have to be synthesized first with an accurate control of the grain size and stoichiometry. The inductively coupled plasma and the laser pyrolysis techniques, respectively developed at EMPA Thun and CEA Saclay, allow meeting these requirements. Both techniques are able to produce dozens of grams per hour of silicon carbide nano-powders. The particle size can be adjusted down to around 20 nm for the plasma synthesis and even down to 5-10 nm for the laser pyrolysis. The stoichiometry Si/C can be tuned by the addition of methane into the plasma and acetylene for the laser process. (authors)

  17. Calibration of laser ablation inductively coupled plasma mass spectrometry using dried solution aerosols for the quantitative analysis of solid samples

    SciTech Connect (OSTI)

    Leach, J.

    1999-02-12

    Inductively coupled plasma mass spectrometry (ICP-MS) has become the method of choice for elemental and isotopic analysis. Several factors contribute to its success. Modern instruments are capable of routine analysis at part per trillion levels with relative detection limits in part per quadrillion levels. Sensitivities in these instruments can be as high as 200 million counts per second per part per million with linear dynamic ranges up to eight orders of magnitude. With standards for only a few elements, rapid semiquantitative analysis of over 70 elements in an individual sample can be performed. Less than 20 years after its inception ICP-MS has shown to be applicable to several areas of science. These include geochemistry, the nuclear industry, environmental chemistry, clinical chemistry, the semiconductor industry, and forensic chemistry. In this introduction, the general attributes of ICP-MS will be discussed in terms of instrumentation and sample introduction. The advantages and disadvantages of current systems are presented. A detailed description of one method of sample introduction, laser ablation, is given. The paper also gives conclusions and suggestions for future work. Chapter 2, Quantitative analysis of solids by laser ablation inductively coupled plasma mass spectrometry using dried solution aerosols for calibration, has been removed for separate processing.

  18. Spectroscopic study of carbon plasma produced by the first (1064 nm) and second (532 nm) harmonics of Nd:YAG laser

    SciTech Connect (OSTI)

    Hanif, M.; Salik, M.; Arif, F.

    2015-03-15

    In this research work, spectroscopic studies of carbon (C) plasma by using laser-induced breakdown spectroscopy (LIBS) are presented. The plasma was produced by the first (1064 nm) and second (532 nm) harmonics of a Q-switched Nd:YAG (Quantel Brilliant) pulsed laser having a pulse duration of 5 ns and 10-Hz repetition rate, which is capable of delivering 400 mJ at 1064 nm and 200 mJ at 532 nm. The laser beam was focused on the target material (100% carbon) by placing it in air at atmospheric pressure. The experimentally observed line profiles of five neutral carbon (C I) lines at 247.85, 394.22, 396.14, 588.95, and 591.25 nm were used to extract the electron temperature T{sub e} by using the Boltzmann plot method and determine its value, 9880 and 9400 K, respectively, for the fundamental and second harmonics of the laser, whereas the electron density N{sub e} was determined from the Stark broadening profile of neutral carbon line at 247.85 nm. The values of N{sub e} at a distance of 0.05 mm from the target surface for the fundamental-harmonic laser with a pulse energy of 130 mJ and the second-harmonic laser with a pulse energy of 72 mJ are 4.68 × 10{sup 17} and 5.98 × 10{sup 17} cm{sup −3}, respectively. This extracted information on T{sub e} and N{sub e} is useful for the deposition of carbon thin films by using the pulsed laser deposition technique. Moreover, both plasma parameters (T{sub e} and N{sub e}) were also calculated by varying the distance from the target surface along the line of propagation of the plasma plume and also by varying the laser irradiance.

  19. Photoionized plasmas induced in neon with extreme ultraviolet and soft X-ray pulses produced using low and high energy laser systems

    SciTech Connect (OSTI)

    Bartnik, A.; Wachulak, P.; Fok, T.; Węgrzyński, Ł.; Fiedorowicz, H.; Pisarczyk, T.; Chodukowski, T.; Kalinowska, Z.; Dudzak, R.; Dostal, J.; Krousky, E.; Skala, J.; Ullschmied, J.; Hrebicek, J.; Medrik, T.

    2015-04-15

    A comparative study of photoionized plasmas created by two soft X-ray and extreme ultraviolet (SXR/EUV) laser plasma sources with different parameters is presented. The two sources are based on double-stream Xe/He gas-puff targets irradiated with high (500 J/0.3 ns) and low energy (10 J/1 ns) laser pulses. In both cases, the SXR/EUV beam irradiated the gas stream, injected into a vacuum chamber synchronously with the radiation pulse. Irradiation of gases resulted in formation of photoionized plasmas emitting radiation in the SXR/EUV range. The measured Ne plasma radiation spectra are dominated by emission lines corresponding to radiative transitions in singly charged ions. A significant difference concerns origin of the lines: K-shell or L-shell emissions occur in case of the high and low energy irradiating system, respectively. In high energy system, the electron density measurements were also performed by laser interferometry, employing a femtosecond laser system. A maximum electron density for Ne plasma reached the value of 2·10{sup 18 }cm{sup −3}. For the low energy system, a detection limit was too high for the interferometric measurements, thus only an upper estimation for electron density could be made.

  20. Guiding and collimation of laser-accelerated proton beams using thin foils followed with a hollow plasma channel

    SciTech Connect (OSTI)

    Xiao, K. D.; Zhou, C. T.; Qiao, B.; He, X. T.

    2015-09-15

    It is proposed that guided and collimated proton acceleration by intense lasers can be achieved using an advanced target—a thin foil followed by a hollow plasma channel. For the advanced target, the laser-accelerated hot electrons can be confined in the hollow channel at the foil rear side, which leads to the formation of transversely localized, Gaussian-distributed sheath electric field and resultantly guiding of proton acceleration. Further, due to the hot electron flow along the channel wall, a strong focusing transverse electric field is induced, taking the place of the original defocusing one driven by hot electron pressure in the case of a purely thin foil target, which results in collimation of proton beams. Two-dimensional particle-in-cell simulations show that collimated proton beams with energy about 20 MeV and nearly half-reduced divergence of 26° are produced at laser intensities 10{sup 20 }W/cm{sup 2} by using the advanced target.

  1. X-ray Spectral Measurements and Collisional Radiative Modeling of Hot, Gold Plasmas at the Omega Laser

    SciTech Connect (OSTI)

    May, M J; Schneider, M B; Hansen, S B; Chung, H; Hinkel, D E; Baldis, H A; Constantin, C

    2008-07-02

    M-Band and L-Band Gold spectra between 3 to 5 keV and 8 to 13 keV, respectively, have been recorded by a photometrically calibrated crystal spectrometer. The spectra were emitted from the plasma in the laser deposition region of a 'hot hohlraum'. This is a reduced-scale hohlraum heated with {approx} 9 kJ of 351 nm light in a 1 ns square pulse at the OMEGA laser. The space- and time-integrated spectra included L-Band line emission from Co-like to Ne-like gold. The three L-Band line features were identified to be the 3s {yields} 2p, 3d{sub 5/2} {yields} 2p{sub 3/2} and 3d{sub 3/2} {yields} 2p{sub 1/2} transitions at {approx}9 keV, {approx}10 keV and {approx}13 keV, respectively. M-Band 5f {yields} 3d, 4d {yields} 3p, and 4p {yields} 3s transition features from Fe-like to P-like gold were also recorded between 3 to 5 keV. Modeling from the radiation-hydrodynamics code LASNEX, the collisional-radiative codes FLYCHK and SCRAM, and the atomic structure code FAC were used to model the plasma and generate simulated spectra for comparison with the recorded spectra. Through these comparisons, we have determined the average electron temperature of the emitting plasma to be between 6.0 and 6.5 keV. The electron temperatures predicted by LASNEX appear to be too large by a factor of about 1.5.

  2. Design studies and commissioning plans for plasma acceleration research station experimental program

    SciTech Connect (OSTI)

    Mete, O.; Xia, G.; Hanahoe, K.; Dover, M.; Wigram, M.; Wright, J.; Zhang, J.; Smith, J.

    2015-10-15

    Plasma acceleration research station is an electron beam driven plasma wakefield acceleration test stand proposed for CLARA facility in Daresbury Laboratory. In this paper, the interaction between the electron beam and the plasma is numerically characterised via 2D numerical studies by using VSIM code. The wakefields induced by a single bunch travelling through the plasma were found to vary from 200 MV/m to 3 GV/m for a range of bunch length, bunch radius, and plasma densities. Energy gain for the particles populating the bunch tail through the wakefields driven by the head of the bunch was demonstrated. After determining the achievable field for various beams and plasma configurations, a reference setting was determined for further studies. Considering this reference setting, the beam quality studies were performed for a two-bunch acceleration case. The maximum energy gain as well as the energy spread mitigation by benefiting from the beam loading was investigated by positioning the witness and driver bunches with respect to each other. Emittance growth mechanisms were studied considering the beam-plasma and beam-wakefield interactions. Eventually, regarding the findings, the initial commissioning plans and the aims for the later stages were summarised.

  3. Mathematical simulation of the amplification of 1790-nm laser radiation in a nuclear-excited He Ar plasma containing nanoclusters of uranium compounds

    SciTech Connect (OSTI)

    Kosarev, V A; Kuznetsova, E E

    2014-02-28

    The possibility of applying dusty active media in nuclearpumped lasers has been considered. The amplification of 1790-nm radiation in a nuclear-excited dusty He Ar plasma is studied by mathematical simulation. The influence of nanoclusters on the component composition of the medium and the kinetics of the processes occurring in it is analysed using a specially developed kinetic model, including 72 components and more than 400 reactions. An analysis of the results indicates that amplification can in principle be implemented in an active laser He Ar medium containing 10-nm nanoclusters of metallic uranium and uranium dioxide. (lasers)

  4. Comparison of natural and forced amplification regimes in plasma-based soft-x-ray lasers seeded by high-order harmonics

    SciTech Connect (OSTI)

    Oliva, Eduardo; Zeitoun, Philippe; Lambert, Guillaume; Sebban, Stephane; Fajardo, Marta; Ros, David; Velarde, Pedro

    2011-07-15

    The amplification of high-order harmonics (HOH) in a plasma-based amplifier is a multiscale, temporal phenomenon that couples plasma hydrodynamics, atomic processes, and HOH electromagnetic fields. We use a one-dimensional, time-dependent Maxwell-Bloch code to compare the natural amplification regime and another regime where plasma polarization is constantly forced by the HOH. In this regime, a 10-MW (i.e., 100 times higher than current seeded soft x-ray laser power), 1.5-{mu}J, 140-fs pulse free from the parasitic temporal structures appearing on the natural amplification regime can be obtained.

  5. Study of nonlinear ohmic heating and ponderomotive force effects on the self-focusing and defocusing of Gaussian laser beams in collisional underdense plasmas

    SciTech Connect (OSTI)

    Etehadi Abari, M.; Shokri, B. [Physics Department and Laser-Plasma Research Institute of Shahid Beheshti University, G.C., Evin, Tehran (Iran, Islamic Republic of)

    2012-11-15

    In the present paper, the propagation characteristics of a linearly polarized gaussian laser beam in a non-isothermal underdense collisional plasma is studied. By considering the effects of the ponderomotive force and ohmic heating of plasma electrons as the nonlinear mechanisms, the second order differential equation of the dimensionless beam width parameter has been obtained and solved at several initial ion temperatures. Furthermore, by using the nonlinear dielectric permittivity of the mentioned plasma medium in the paraxial approximation and its dependence on the propagation characteristics of the gaussian laser pulse, the perturbed electron density n{sub e}/n{sub 0e} is obtained and its variation in terms of the dimensionless plasma length is analyzed at different initial ion temperatures. Our results show that the dimensionless beam width parameter is strongly influenced by the initial plasma ion temperature. It is found that, for the self-focusing regime, the plasma electron density perturbation continuously oscillates between the initial density distribution and a minimum, and for the defocusing regime, the plasma electron density perturbation continuously oscillates between the initial density distribution and a maximum.

  6. Enhancing the energy of terahertz radiation from plasma produced by intense femtosecond laser pulses

    SciTech Connect (OSTI)

    Jahangiri, Fazel; Laser and Plasma Research Institute, Shahid Beheshti University, Tehran ; Hashida, Masaki; Tokita, Shigeki; Sakabe, Shuji; Department of Physics, GSS, Kyoto University, Kyoto ; Nagashima, Takeshi; Hangyo, Masanori; Institute of Laser Engineering, Osaka University, Osaka

    2013-05-13

    Terahertz (THz) radiation from atomic clusters illuminated by intense femtosecond laser pulses is investigated. By studying the angular distribution, polarization properties and energy dependence of THz waves, we aim to obtain a proper understanding of the mechanism of THz generation. The properties of THz waves measured in this study differ from those predicted by previously proposed mechanisms. To interpret these properties qualitatively, we propose that the radiation is generated by time-varying quadrupoles, which are produced by the ponderomotive force of the laser pulse.

  7. Influence of a strong laser field on Coulomb explosion and stopping power of energetic H{sub 3}{sup +} clusters in plasmas

    SciTech Connect (OSTI)

    Wang Guiqiu; Gao Hong; Wang Yaochuan; Yao Li; Zhong Haiyang; Cheng Lihong; Yang Kun; Liu Wei [Department of Physics, Dalian Maritime University, Dalian 116026 (China); E Peng; Xu Dianguo [Department of Electrical Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wang Younian; Hu Zhanghu [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023 (China)

    2012-09-15

    The influence of a high-intensity laser field on the Coulomb explosion and stopping power for a swift H{sub 3}{sup +} cluster ion in a plasma target is studied by means of the molecular dynamic (MD) method based on the linearized Vlasov-Poisson theory. Excitations of the plasma are described by the classical plasma dielectric function. In the presence of the laser field, the general expressions for the induced potential in the target and the interaction force among the ions within the cluster are derived. Based on the numerical solution of the equations of motion for the constituent ions, the Coulomb explosion patterns and the cluster's stopping power are discussed for a range of laser parameters. Numerical results show that the laser field affects the correlation between the ions and contributes to weaken the wake effect and the stopping power as compared to the laser-free case. On the other hand, the stopping power ratio of H{sub 3}{sup +} cluster is higher than the situation of dicluster of H{sub 2}{sup +} due to the vicinage effect in the cluster.

  8. Effects of high energy photon emissions in laser generated ultra-relativistic plasmas: Real-time synchrotron simulations

    SciTech Connect (OSTI)

    Wallin, Erik; Gonoskov, Arkady; Marklund, Mattias

    2015-03-15

    We model the emission of high energy photons due to relativistic charged particle motion in intense laser-plasma interactions. This is done within a particle-in-cell code, for which high frequency radiation normally cannot be resolved due to finite time steps and grid size. A simple expression for the synchrotron radiation spectra is used together with a Monte-Carlo method for the emittance. We extend previous work by allowing for arbitrary fields, considering the particles to be in instantaneous circular motion due to an effective magnetic field. Furthermore, we implement noise reduction techniques and present validity estimates of the method. Finally, we perform a rigorous comparison to the mechanism of radiation reaction, and find the emitted energy to be in excellent agreement with the losses calculated using radiation reaction.

  9. Angular ion species distribution in droplet-based laser-produced plasmas

    SciTech Connect (OSTI)

    Giovannini, Andrea Z.; Gambino, Nadia; Rollinger, Bob; Abhari, Reza S.

    2015-01-21

    The angular distribution of the ion species generated from a laser irradiated droplet target is measured. The employed instrument was an electrostatic energy analyzer with differential pumping. Singly and doubly charged ions were detected at an argon ambient gas pressure of 2 × 10{sup −2} mbar. The amount of Sn{sup +} and Sn{sup 2+} and their kinetic energy is measured from 45° to 120° from the laser axis. Sn{sup +} expands approximately isotropically, and Sn{sup 2+} expansion is peaked towards the incoming laser radiation. The singly charged ion kinetic energy is close to constant over the measurement range, while it decreases by around 30% for Sn{sup 2+}. A calibrated model of the ion expansion that includes recombinations correctly predicts the mean ion charge distribution. The model is able to qualitatively estimate the influence of the laser wavelength on the mean ion charge distribution. The results show a more pronounced isotropic distribution for shorter wavelengths, and a more forward-peaked distribution for longer wavelengths. The ion charge distribution expected without the ambient gas is estimated through the measured ion kinetic energy. The presence of the ambient gas results in a decrease of the mean ion charge state and a decrease in angular anisotropy.

  10. Plasma

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    heating in reversed field pinches at the fundamental ion cyclotron frequency V. A. Svidzinski and S. C. Prager University of Wisconsin-Madison, Madison, Wisconsin 53706 ͑Received 14 November 2001; accepted 29 January 2002͒ The possibility of plasma heating in reversed field pinches ͑RFP͒ by radio-frequency ͑rf͒ waves at ␻Ϸ␻ ci is studied. A simple cylindrical RFP equilibrium which is symmetric in poloidal and axial directions is considered. RF fields are excited with given poloidal

  11. Plasma channels in a filament of a femtosecond laser pulse focused by an axicon

    SciTech Connect (OSTI)

    Chekalin, S V; Kompanets, V O; Dokukina, A E; Smetanina, E O; Kandidov, V P

    2014-06-30

    We report the results of experimental and numerical investigation of the influence of the wavefront curvature of femtosecond light focused by an axicon on the length and position of plasma channels in the filament under conditions of normal and anomalous group velocity dispersion in fused silica. It is shown that a change in the wavefront curvature by a value much greater than the longitudinal dimensions of the filament noticeably changes the geometry of the plasma channel position. The role of axicon focusing for ordering multiple filamentation is studied experimentally. (extreme light fields and their applications)

  12. The interaction of polarized microwaves with planar arrays of femtosecond laser-produced plasma filaments in air

    SciTech Connect (OSTI)

    Marian, Anca; El Morsli, Mbark; Vidal, Francois; Payeur, Stephane; Kieffer, Jean-Claude; Chateauneuf, Marc; Theberge, Francis; Dubois, Jacques

    2013-02-15

    The interaction of polarized microwaves with subwavelength arrays of parallel plasma filaments, such as those produced by the propagation of high-power femtosecond laser pulses in ambient air, was investigated by calculating the reflection and transmission coefficients as a function of the incidence angles using the finite-difference time-domain (FDTD) method. The time evolution of these coefficients was calculated and compared with experiments. It is found that the plasma filaments array becomes transparent when the polarization of the microwave radiation is perpendicular to the filaments axis, regardless the incidence angle of the microwave with respect to the filaments, except near grazing incidence. Increasing the filaments electron density or diameter, or decreasing the electron collision frequency or filaments spacing, decreases the transmission and increases the reflection. Transmission decreases when increasing the number of filament layers while reflection remains unchanged as the number of filament layers exceeds a given number ({approx}3 in our case). Transmission slightly increases when disorder is introduced in the filament arrays. The detailed calculation results are compared with those obtained from the simple birefringent slab model, which provides a convenient framework to calculate approximately the properties of filament arrays.

  13. A comparison of ion beam measurements by retarding field energy analyzer and laser induced fluorescence in helicon plasma devices

    SciTech Connect (OSTI)

    Gulbrandsen, N. Fredriksen, Å.; Carr, J.; Scime, E.

    2015-03-15

    Both Laser-Induced Fluorescence (LIF) and Retarding Field Energy Analyzers (RFEA) have been applied to the investigation of beams formed in inductively coupled helicon plasmas. While the LIF technique provides a direct measurement of the velocity distribution in the plasma, the RFEA measures ion flux as a function of a retarding potential. In this paper, we present a method to compare the two techniques, by converting the LIF velocity distribution to an equivalent of a RFEA measurement. We applied this method to compare new LIF and RFEA measurements in two different experiments; the Hot Helicon Experiment (HELIX) - Large Experiment on Instabilities and Anisotropies (LEIA) at West Virginia University and Njord at University of Tromsø. We find good agreement between beam energies of the two methods. In agreement with earlier observations, the RFEA is found to measure ion beams with densities too low for the LIF to resolve. In addition, we present measurements of the axial development of the ion beam in both experiments. Beam densities drop exponentially with distance from the source, both in LIF and RFEA measurements. The effective quenching cross section from LIF in LEIA is found to be σ{sub b,*}=4×10{sup −19} m{sup 2}, and the effective beam collisional cross sections by RFEA in Njord to be σ{sub b}=1.7×10{sup −18} m{sup 2}.

  14. Nonlinear Raman forward scattering driven by a short laser pulse in a collisional transversely magnetized plasma with nonextensive distribution

    SciTech Connect (OSTI)

    Qiu, Hui-Bin; Song, Hai-Ying; Liu, Shi-Bing

    2015-09-15

    Nonlinear Raman forward scattering of an intense short laser pulse with a duration shorter than the plasma period propagating through a homogenous collisional nonextensive distributed plasma in the presence of a uniform magnetic field perpendicular to both the direction of propagation and electric vector of the radiation field is investigated theoretically when ponderomotive, relativistic, and collisional nonlinearities are taken into account. The governing equations for nonlinear wave in the context of nonextensive statistics are given, the nonextensive coupled equations describing the nonlinear Raman forward scattering instability are solved by the Fourier transformation method, and the growth rate of the nonlinear Raman forward scattering instability is obtained. The results in the case q → 1 are consistent with those in the framework of the Maxwellian distribution. It is found that the instability growth rate first decreases on increasing electron thermal velocity, minimizes at a critical thermal velocity, and then increases steeply; the critical temperature dependents on the nonextensive parameter, and the greater nonextensive parameter, correspond to the greater critical temperature; when the thermal velocity of electron is less than the critical speed, the instability growth rate is found to be enhanced as the nonextensive parameter increases; but when the thermal velocity is greater than the critical speed, the instability growth rate decreases on increasing the nonextensive parameter.

  15. Simulations of laser-plasma interactions in targets for the National

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ignition Facility and beyond | Argonne Leadership Computing Facility NIF Hohlraum. This artist's rendering shows a NIF target pellet inside a hohlraum capsule with laser beams entering through openings on either end. The beams compress and heat the target to the necessary conditions for nuclear fusion to occur. Ignition experiments on NIF will be the culmination of more than 30 years of inertial confinement fusion research and development, opening the door to exploration of previously

  16. High-energy resolution Thomson Parabola spectrometer for laser plasma diagnostics

    SciTech Connect (OSTI)

    Cirrone, G. A. P.; Schillaci, F.; Carpinelli, M.; Maggiore, M.; Ter-Avetisyan, S.; Tramontana, A.; Velyhan, A.

    2013-07-26

    Thomson Parabola (TP) spectrometers are widely used devices for laser-driven beam diagnostics as they provide a complete set of information on the accelerated particles. A novel TP has been developed at LNS with a design able to detect protons up to 20 MeV. The layout design and some results obtained during the experimental campaign at PALS laboratory will be reported in the following.

  17. Generation of ultra-high-pressure shocks by collision of a fast plasma projectile driven in the laser-induced cavity pressure acceleration scheme with a solid target

    SciTech Connect (OSTI)

    Badziak, J.; Rosiński, M.; Krousky, E.; Kucharik, M.; Liska, R.; Ullschmied, J.

    2015-03-15

    A novel, efficient method of generating ultra-high-pressure shocks is proposed and investigated. In this method, the shock is generated by collision of a fast plasma projectile (a macro-particle) driven by laser-induced cavity pressure acceleration (LICPA) with a solid target placed at the LICPA accelerator channel exit. Using the measurements performed at the kilojoule PALS laser facility and two-dimensional hydrodynamic simulations, it is shown that the shock pressure ∼ Gbar can be produced with this method at the laser driver energy of only a few hundred joules, by an order of magnitude lower than the energy needed for production of such pressure with other laser-based methods known so far.

  18. Final report for the NSF/DOE partnership in basic plasma science grant DE-FG02-06ER54906 'Laser-driven collisionless shocks in the Large Plasma Device'

    SciTech Connect (OSTI)

    Niemann, Christoph; Gekelman, W.; Winske, D.; Larsen, D.

    2012-12-14

    We have performed several thousand high-energy laser shots in the LAPD to investigate the dynamics of an exploding laser-produced plasma in a large ambient magneto-plasma. Debris-ions expanding at super-Alfvenic velocity (up to MA=1.5) expel the ambient magnetic field, creating a large (> 20 cm) diamagnetic cavity. We observed field compressions of up to B/B{sub 0} = 1.5 at the edge of the bubble, consistent with the MHD jump conditions, as well as localized electron heating at the edge of the bubble. Two-dimensional hybrid simulations reproduce these measurements well and show that the majority of the ambient ions are energized by the magnetic piston to super-Alfvenic speeds and swept outside the bubble volume. Nonlinear shear-Alfven waves ({delta}B/B{sub 0} > 25%) are radiated from the cavity with a coupling efficiency of 70% from magnetic energy in the bubble to the wave. While the data is consistent with a weak magneto-sonic shock, the experiments were severely limited by the low ambient plasma densities (10{sup 12} cm{sup -3}). 2D hybrid simulations indicate that future experiments with the new LAPD plasma source and densities in excess of 10{sup 13} cm{sup -3} will drive full-blown collisionless shocks with MA>10 over several c/wpi and shocked Larmor radii. In a separate experiment at the LANL Trident laser facility we have performed a proof-of-principle experiment at higher densities to demonstrate key elements of collisionless shocks in laser-produced magnetized plasmas with important implications to NIF. Simultaneously we have upgraded the UCLA glass-laser system by adding two large amplitude disk amplifiers from the NOVA laser and boost the on-target energy from 30 J to up to 1 kJ, making this one of the world’s largest university-scale laser systems. We now have the infrastructure in place to perform novel and unique high-impact experiments on collision-less shocks at the LAPD.

  19. Relativistic self-focusing of ultra-high intensity X-ray laser beams in warm quantum plasma with upward density profile

    SciTech Connect (OSTI)

    Habibi, M.; Ghamari, F.

    2014-05-15

    The results of a numerical study of high-intensity X-ray laser beam interaction with warm quantum plasma (WQP) are presented. By means of an upward ramp density profile combined with quantum factors specially the Fermi velocity, we have demonstrated significant relativistic self-focusing (RSF) of a Gaussian electromagnetic beam in the WQP where the Fermi temperature term in the dielectric function is important. For this purpose, we have considered the quantum hydrodynamics model that modifies refractive index of inhomogeneous WQPs with the inclusion of quantum correction through the quantum statistical and diffraction effects in the relativistic regime. Also, to better illustration of the physical difference between warm and cold quantum plasmas and their effect on the RSF, we have derived the envelope equation governing the spot size of X-ray laser beam in Q-plasmas. In addition to the upward ramp density profile, we have found that the quantum effects would be caused much higher oscillation and better focusing of X-ray laser beam in the WQP compared to that of cold quantum case. Our computational results reveal the importance of the use of electrons density profile and Fermi speed in enhancing self-focusing of laser beam.

  20. Solutions and reductions for radiative energy transport in laser-heated plasma

    SciTech Connect (OSTI)

    Broadbridge, P.; Ivanova, N. M.

    2015-01-15

    A full symmetry classification is given for models of energy transport in radiant plasma when the mass density is spatially variable and the diffusivity is nonlinear. A systematic search for conservation laws also leads to some potential symmetries and to an integrable nonlinear model. Classical point symmetries, potential symmetries, and nonclassical symmetries are used to effect variable reductions and exact solutions. The simplest time-dependent solution is shown to be stable and relevant to a closed system.

  1. Investigation Of Plasma Produced By High-Energy Low-Intensity Laser Pulses For Implantation Of Ge Ions Into Si And Sio2 Substrates

    SciTech Connect (OSTI)

    Rosinski, M.; Wolowski, J.; Badziak, J.; Parys, P.; Boody, F. P.; Gammino, S.; Krasa, J.; Laska, L.; Pfeifer, M.; Rohlena, K.; Ullschmied, J.; Mezzasalma, A.; Torrisi, L.

    2006-01-15

    The development of implantation techniques requires investigation of laser plasma as a potential source of multiply charged ions. The laser ion source delivers ions with kinetic energy and a charge state dependent on the irradiated target material and the parameters of the laser radiation used. By the focusing the laser beam on the solid target the higher current densities of ions than by using other currently available ion sources can be produced. The crucial issue for efficiency of the ion implantation technology is selection of proper laser beam characteristics. Implantation of different kinds of laser-produced ions into metals and organic materials were performed recently at the PALS Research Center in Prague, in cooperative experiments using 0.4-ns iodine laser pulses having energies up to 750 J at wavelength of 1315 nm or up to 250 J at wavelength of 438 nm. In this contribution we describe the characterization and optimization of laser-produced Ge ion streams as well as analysis of the direct implantation of these ions into Si and SiO2 substrates. The Ge target was irradiated with the use of laser pulses of energy up to 50 J at radiation intensities of {approx}1011 W/cm2 and {approx}2'1013 W/cm2. The implanted samples were placed along the target normal at distances of 17, 31 and 83 cm from the target surface. The ion stream parameters were measured using the time-of-fight method. The depth of ion implantation was determined by the Rutherford backscattering method (RBS). The maximum depth of implantation of Ge ions was {approx}450 nm. These investigations were carried out for optimization of low and medium energy laser-generated Ge ion streams, suitable for specific implantation technique, namely for fabrication of semiconductor nanostructures within the SRAP 'SEMINANO' project.

  2. Plasma Physics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    4 Plasma Physics By leveraging plasma under extreme conditions, we concentrate on solving critical scientific challenges such as detecting smuggled nuclear materials, advancing weapons physics and generating fusion energy. Contact Us Group Leader Ray Leeper Email Deputy Group Leader Julie Canepa Email Group Office (505) 665-9145 Laser-generated neutrons Researchers at Los Alamos have successfully demonstrated for the first time that laser-generated neutrons can be enlisted as a useful tool in

  3. Lasers

    SciTech Connect (OSTI)

    1995-01-01

    The scope of our research in laser and related technologies has grown over the years and has attracted a broad user base for applications within DOE, DOD, and private industry. Within the next few years, we expect to begin constructing the National Ignition Facility, to make substantial progress in deploying AVLIS technology for uranium and gadolinium enrichment, and to develop new radar sensing techniques to detect underwater objects. Further, we expect to translate LLNL patent ideas in microlithography into useful industrial products and to successfully apply high-power, diode-based laser technology to industrial and government applications.

  4. A novel femtosecond-gated, high-resolution, frequency-shifted shearing interferometry technique for probing pre-plasma expansion in ultra-intense laser experiments

    SciTech Connect (OSTI)

    Feister, S. Orban, C.; Nees, J. A.; Morrison, J. T.; Frische, K. D.; Chowdhury, E. A.; Roquemore, W. M.

    2014-11-15

    Ultra-intense laser-matter interaction experiments (>10{sup 18} W/cm{sup 2}) with dense targets are highly sensitive to the effect of laser “noise” (in the form of pre-pulses) preceding the main ultra-intense pulse. These system-dependent pre-pulses in the nanosecond and/or picosecond regimes are often intense enough to modify the target significantly by ionizing and forming a plasma layer in front of the target before the arrival of the main pulse. Time resolved interferometry offers a robust way to characterize the expanding plasma during this period. We have developed a novel pump-probe interferometry system for an ultra-intense laser experiment that uses two short-pulse amplifiers synchronized by one ultra-fast seed oscillator to achieve 40-fs time resolution over hundreds of nanoseconds, using a variable delay line and other techniques. The first of these amplifiers acts as the pump and delivers maximal energy to the interaction region. The second amplifier is frequency shifted and then frequency doubled to generate the femtosecond probe pulse. After passing through the laser-target interaction region, the probe pulse is split and recombined in a laterally sheared Michelson interferometer. Importantly, the frequency shift in the probe allows strong plasma self-emission at the second harmonic of the pump to be filtered out, allowing plasma expansion near the critical surface and elsewhere to be clearly visible in the interferograms. To aid in the reconstruction of phase dependent imagery from fringe shifts, three separate 120° phase-shifted (temporally sheared) interferograms are acquired for each probe delay. Three-phase reconstructions of the electron densities are then inferred by Abel inversion. This interferometric system delivers precise measurements of pre-plasma expansion that can identify the condition of the target at the moment that the ultra-intense pulse arrives. Such measurements are indispensable for correlating laser pre-pulse measurements

  5. Damage threshold and focusability of mid-infrared free-electron laser pulses gated by a plasma mirror with nanosecond switching pulses

    SciTech Connect (OSTI)

    Wang, Xiaolong; Nakajima, Takashi; Zen, Heishun; Kii, Toshiteru; Ohgaki, Hideaki

    2013-11-04

    The presence of a pulse train structure of an oscillator-type free-electron laser (FEL) results in the immediate damage of a solid target upon focusing. We demonstrate that the laser-induced damage threshold can be significantly improved by gating the mid-infrared FEL pulses with a plasma mirror. Although the switching pulses we employ have a nanosecond duration which does not guarantee the clean wavefront of the gated FEL pulses, the high focusability is experimentally confirmed through the observation of spectral broadening by a factor of 2.1 when we tightly focus the gated FEL pulses onto the Ge plate.

  6. Comment on 'Stimulated Raman scattering of laser from periodically spaced nanoparticles' [Phys. Plasmas 16, 093106 (2009)

    SciTech Connect (OSTI)

    Maraghechi, B.; Chakhmachi, A.

    2010-08-15

    Parashar [Phys. Plasmas 16, 093106 (2009)] studied the Raman backscattering of electromagnetic waves from nanoparticle lattice. We have demonstrated that the uncoupled dispersion curves have incorrect cutoff frequencies and the electromagnetic dispersion curves do not have correct asymptotic behavior at large frequencies. It has been shown that Parashar obtained an incorrect diagram of the growth rate for which the pump wave frequency goes below the cutoff frequency of the electromagnetic wave. Correct diagrams for the Raman backscattering as well as forward scattering are presented. It has been shown that backscattering has a larger maximum growth rate. We also found no instability if scattered radiation belongs to the lower branch of the dispersion curves.

  7. Dense electron-positron plasmas and gamma-ray bursts generation by counter-propagating quantum electrodynamics-strong laser interaction with solid targets

    SciTech Connect (OSTI)

    Luo, Wen; Zhu, Yi-Bo; Song, Ying-Ming; Zhu, Zhi-Chao; Wang, Xiao-Dong; Zhuo, Hong-Bin; Ma, Yan-Yun; Li, Xing-Huo; Turcu, I. C. E.; Chen, Min

    2015-06-15

    We use quantum electrodynamics (QED) particle-in-cell simulations to investigate and compare the generation of dense electron-positron plasmas and intense γ-ray bursts in the case of counter-propagating laser solid interaction (two-side irradiation) and single laser solid interaction (one-side irradiation). In the case of counter-propagating linearly polarized laser pulses irradiating a thin aluminum foil with each pulse peak power of 12.5 PW (I = 4 × 10{sup 23 }W/cm{sup 2}), we calculate that about 20% of the laser energy is converted into a burst of γ-rays with flux exceeding 10{sup 14 }s.{sup −1} This would be one of the most intense γ-ray sources among those currently available in laboratories. The γ-ray conversion efficiency in the case of two-side irradiation is three times higher than in the case of one-side irradiation using a single 12.5 PW laser. Dense electron-positron plasma with a maximum density of 6 × 10{sup 27 }m{sup −3} are generated simultaneously during the two-side irradiation which is eightfold denser compared to the one-side irradiation. The enhancement of the effects in the case of counter-propagating lasers are the results of the symmetrical compression of the foil target and the formation of electric potential and standing wave around the target. Realizing experimentally the proposed counter-propagating QED-strong laser-solid interaction to produce dense electron-positron pairs and prolific γ-rays will be made possible by the Extreme Light Infrastructure-Nuclear Physics facility under construction.

  8. Tunable THz Generation by the Interaction of a Super-luminous Laser Pulse with Biased Semiconductor Plasma

    SciTech Connect (OSTI)

    Papadopoulos, K.; Zigler, A.

    2006-01-03

    Terahertz (THz) radiation is electromagnetic radiation in the range between several hundred and a few thousand GHz. It covers the gap between fast-wave electronics (millimeter waves) and optics (infrared). This spectral region offers enormous potential for detection of explosives and chemical/biological agents, non-destructive testing of non-metallic structural materials and coatings of aircraft structures, medical imaging, bio-sensing of DNA stretching modes and high-altitude secure communications. The development of these applications has been hindered by the lack of powerful, tunable THz sources with controlled waveform. The need for such sources is accentuated by the strong, but selective absorption of THz radiation during transmission through air with high vapor content. The majority of the current experimental work relies on time-domain spectroscopy using fast electrically biased photoconductive sources in conjunction with femto-second mode-locked Ti:Sapphire lasers. These sources known as Large Aperture Photoconductive Antennas (LAPA) have very limited tunability, relatively low upper bound of power and no bandwidth control. The paper presents a novel source of THz radiation known as Miniature Photoconductive Capacitor Array (MPCA). Experiments demonstrated tunability between .1 - 2 THz, control of the relative bandwidth {delta}f/f between .5-.01, and controlled pulse length and pulse waveform (temporal shape, chirp, pulse-to-pulse modulation etc.). Direct scaling from the current device indicates efficiency in excess of 30% at 1 THz with 1/f2 scaling at higher frequencies, peak power of 100 kW and average power between .1-1 W. The physics underlying the MPCA is the interaction of a super-luminous ionization front generated by the oblique incidence of a Ti:Sapphire laser pulse on a semiconductor crystal (ZnSe) biased with an alternating electrostatic field, similar to that of a frozen wave generator. It is shown theoretically and experimentally that the

  9. Effects of initially energetic electrons on relativistic laser-driven electron plasma waves

    SciTech Connect (OSTI)

    Yazdanpanah, J., E-mail: jamal.yazdan@gmail.com; Anvari, A. [Department of Physics, Sharif University of Technology, P.O. Box 1155-4161, Tehran (Iran, Islamic Republic of)] [Department of Physics, Sharif University of Technology, P.O. Box 1155-4161, Tehran (Iran, Islamic Republic of)

    2014-02-15

    In this paper, using kinetic calculations and accurate 1D2V particle-in-cell simulations, we point out the important role of initially energetic electrons of the distribution tail in the behavior of high amplitude electron plasma waves (EPWs). In the presence of these electrons, the conventional warm fluid theory (WFT) breaks at very high wave amplitudes that are still noticeably lower than the wave breaking amplitude (WBA). The fluid breakdown results in electron super-heating with respect to the adiabatic laws. Indeed, a new kinetic regime of the relativistic EPWs appears below the WBA. It is argued that the mentioned super-heating results in WBA values lower than the corresponding WFT prediction.

  10. Note: Experimental platform for magnetized high-energy-density plasma studies at the omega laser facility

    SciTech Connect (OSTI)

    Fiksel, G.; Agliata, A.; Barnak, D.; Brent, G.; Chang, P. -Y.; Folnsbee, L.; Gates, G.; Hasset, D.; Lonobile, D.; Magoon, J.; Mastrosimone, D.; Shoup, III, M. J.; Betti, R.

    2015-01-12

    Here, an upgrade of the pulsed magnetic field generator magneto-inertial fusion electrical discharge system [O. Gotchev et al., Rev. Sci. Instrum. 80, 043504 (2009)] is described. The device is used to study magnetized high-energy-density plasma and is capable of producing a pulsed magnetic field of tens of tesla in a volume of a few cubic centimeters. The magnetic field is created by discharging a high-voltage capacitor through a small wire-wound coil. The coil current pulse has a duration of about 1 μs and a peak value of 40 kA. Compared to the original, the updated version has a larger energy storage and improved switching system. In addition, magnetic coils are fabricated using 3-D printing technology which allows for a greater variety of the magnetic field topology.

  11. Note: Experimental platform for magnetized high-energy-density plasma studies at the omega laser facility

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Fiksel, G.; Agliata, A.; Barnak, D.; Brent, G.; Chang, P. -Y.; Folnsbee, L.; Gates, G.; Hasset, D.; Lonobile, D.; Magoon, J.; et al

    2015-01-12

    Here, an upgrade of the pulsed magnetic field generator magneto-inertial fusion electrical discharge system [O. Gotchev et al., Rev. Sci. Instrum. 80, 043504 (2009)] is described. The device is used to study magnetized high-energy-density plasma and is capable of producing a pulsed magnetic field of tens of tesla in a volume of a few cubic centimeters. The magnetic field is created by discharging a high-voltage capacitor through a small wire-wound coil. The coil current pulse has a duration of about 1 μs and a peak value of 40 kA. Compared to the original, the updated version has a larger energymore » storage and improved switching system. In addition, magnetic coils are fabricated using 3-D printing technology which allows for a greater variety of the magnetic field topology.« less

  12. Generation of very low energy-spread electron beams using low-intensity laser pulses in a low-density plasma

    SciTech Connect (OSTI)

    Upadhyay, Ajay K.; Samant, Sushil Arun; Sarkar, Deepangkar; Krishnagopal, Srinivas; Jha, Pallavi

    2011-03-15

    The possibility of obtaining high-energy electron beams of high quality by using a low-density homogeneous plasma and a low-intensity laser (just above the self-injection threshold in the bubble regime) has been explored. Three-dimensional simulations are used to demonstrate, for the first time, an energy-spread of less than 1%, from self-trapping. More specifically, for a plasma density of 2x10{sup 18} cm{sup -3} and a laser intensity of a{sub 0}=2, a high-energy (0.55 GeV), ultrashort (1.4 fs) electron beam with very low energy-spread (0.55%) and high current (3 kA) is obtained. These parameters satisfy the requirements for drivers of short-wavelength free-electron lasers. It is also found that the quality of the electron beam depends strongly on the plasma length, which therefore needs to be optimized carefully to get the best performance in the experiments.

  13. Single-pulse picking at kHz repetition rates using a Ge plasma switch at the free-electron laser FELBE

    SciTech Connect (OSTI)

    Schmidt, J. Helm, M.; Winnerl, S.; Seidel, W.; Schneider, H.; Bauer, C.; Gensch, M.

    2015-06-15

    We demonstrate a system for picking of mid-infrared and terahertz (THz) radiation pulses from the free-electron laser (FEL) FELBE operating at a repetition rate of 13 MHz. Single pulses are reflected by a dense electron-hole plasma in a Ge slab that is photoexcited by amplified near-infrared (NIR) laser systems operating at repetition rates of 1 kHz and 100 kHz, respectively. The peak intensity of picked pulses is up to 400 times larger than the peak intensity of residual pulses. The required NIR fluence for picking pulses at wavelengths in the range from 5 μm to 30 μm is discussed. In addition, we show that the reflectivity of the plasma decays on a time scale from 100 ps to 1 ns dependent on the wavelengths of the FEL and the NIR laser. The plasma switch enables experiments with the FEL that require high peak power but lower average power. Furthermore, the system is well suited to investigate processes with decay times in the μs to ms regime, i.e., much longer than the 77 ns long pulse repetition period of FELBE.

  14. Wakefield computations for a corrugated pipe as a beam dechirper for FEL applications

    SciTech Connect (OSTI)

    Ng, C. K.; Bane, K. L.F.

    2015-06-09

    A beam “dechirper” based on a corrugated, metallic vacuum chamber has been proposed recently to cancel residual energy chirp in a beam before it enters the undulator in a linac-based X-ray FEL. Rather than the round geometry that was originally proposed, we consider a pipe composed of two parallel plates with corrugations. The advantage is that the strength of the wake effect can be tuned by adjusting the separation of the plates. The separation of the plates is on the order of millimeters, and the corrugations are fractions of a millimeter in size. The dechirper needs to be meters long in order to provide sufficient longitudinal wakefield to cancel the beam chirp. Considerable computation resources are required to determine accurately the wakefield for such a long structure with small corrugation gaps. Combining the moving window technique and parallel computing using multiple processors, the time domain module in the parallel finite-element electromagnetic suite ACE3P allows efficient determination of the wakefield through convergence studies. In this paper, we will calculate the longitudinal, dipole and quadrupole wakefields for the dechirper and compare the results with those of analytical and field matching approaches.

  15. Hybrid interferometric/dispersive atomic spectroscopy of laser-induced uranium plasma

    SciTech Connect (OSTI)

    Morgan, Phyllis K.; Scott, Jill R.; Jovanovic, Igor

    2015-12-19

    An established optical emission spectroscopy technique, laser-induced breakdown spectroscopy (LIBS), holds promise for detection and rapid analysis of elements relevant for nuclear safeguards, nonproliferation, and nuclear power, including the measurement of isotope ratios. One such important application of LIBS is the measurement of uranium enrichment (235U/238U), which requires high spectral resolution (e.g., 25 pm for the 424.4 nm U II line). High-resolution dispersive spectrometers necessary for such measurements are typically bulky and expensive. We demonstrate the use of an alternative measurement approach, which is based on an inexpensive and compact Fabry–Perot etalon integrated with a low to moderate resolution Czerny–Turner spectrometer, to achieve the resolution needed for isotope selectivity of LIBS of uranium in ambient air. Furthermore, spectral line widths of ~ 10 pm have been measured at a center wavelength 424.437 nm, clearly discriminating the natural from the highly enriched uranium.

  16. Hybrid interferometric/dispersive atomic spectroscopy of laser-induced uranium plasma

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Morgan, Phyllis K.; Scott, Jill R.; Jovanovic, Igor

    2015-12-19

    An established optical emission spectroscopy technique, laser-induced breakdown spectroscopy (LIBS), holds promise for detection and rapid analysis of elements relevant for nuclear safeguards, nonproliferation, and nuclear power, including the measurement of isotope ratios. One such important application of LIBS is the measurement of uranium enrichment (235U/238U), which requires high spectral resolution (e.g., 25 pm for the 424.4 nm U II line). High-resolution dispersive spectrometers necessary for such measurements are typically bulky and expensive. We demonstrate the use of an alternative measurement approach, which is based on an inexpensive and compact Fabry–Perot etalon integrated with a low to moderate resolution Czerny–Turnermore » spectrometer, to achieve the resolution needed for isotope selectivity of LIBS of uranium in ambient air. Furthermore, spectral line widths of ~ 10 pm have been measured at a center wavelength 424.437 nm, clearly discriminating the natural from the highly enriched uranium.« less

  17. Betatron radiation based measurement of the electron-beam size in a wakefield accelerator

    SciTech Connect (OSTI)

    Schnell, Michael; Saevert, Alexander; Reuter, Maria; and others

    2012-07-09

    We present a spatial and spectral characterization of a laser-plasma based betatron source which allows us to determine the betatron oscillation amplitude of the electrons which decreases with increasing electron energies. Due to the observed oscillation amplitude and the independently measured x-ray source size of (1.8{+-}0.3){mu}m we are able to estimate the electron bunch diameter to be (1.6{+-}0.3){mu}m.

  18. OMEGA Laser - Laboratory for Laser Energetics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    - Laboratory for Laser Energetics Laboratory for Laser Energetics Logo Search Home Around the Lab Past Issues Past Quick Shots About Office of the Director Map to LLE LLE Tours LLE Building Map Partnerships Careers Education Undergraduate Program Graduate Program High School Program Faculty Contacts Computational Astrophysics H-E-D Physics Inertial Confinement Fusion Laser-Plasma Interaction Radiative Hydrodynamics Plasma Astrophysics Organization Director's Office Laser Development and

  19. Wakefield Simulation of CLIC PETS Structure Using Parallel 3D Finite Element Time-Domain Solver T3P

    SciTech Connect (OSTI)

    Candel, A.; Kabel, A.; Lee, L.; Li, Z.; Ng, C.; Schussman, G.; Ko, K.; Syratchev, I.; /CERN

    2009-06-19

    In recent years, SLAC's Advanced Computations Department (ACD) has developed the parallel 3D Finite Element electromagnetic time-domain code T3P. Higher-order Finite Element methods on conformal unstructured meshes and massively parallel processing allow unprecedented simulation accuracy for wakefield computations and simulations of transient effects in realistic accelerator structures. Applications include simulation of wakefield damping in the Compact Linear Collider (CLIC) power extraction and transfer structure (PETS).

  20. Nonlinear plasma wave in magnetized plasmas

    SciTech Connect (OSTI)

    Bulanov, Sergei V.; Prokhorov Institute of General Physics, Russian Academy of Sciences, Moscow 119991; Moscow Institute of Physics and Technology, Dolgoprudny, Moscow region 141700 ; Esirkepov, Timur Zh.; Kando, Masaki; Koga, James K.; Hosokai, Tomonao; Zhidkov, Alexei G.; Japan Science and Technology Agency, CREST, 2-1, Yamadaoka, Suita, Osaka 565-0871 ; Kodama, Ryosuke; Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871

    2013-08-15

    Nonlinear axisymmetric cylindrical plasma oscillations in magnetized collisionless plasmas are a model for the electron fluid collapse on the axis behind an ultrashort relativisically intense laser pulse exciting a plasma wake wave. We present an analytical description of the strongly nonlinear oscillations showing that the magnetic field prevents closing of the cavity formed behind the laser pulse. This effect is demonstrated with 3D PIC simulations of the laser-plasma interaction. An analysis of the betatron oscillations of fast electrons in the presence of the magnetic field reveals a characteristic Four-Ray Star pattern.

  1. Laser-produced plasma sensor-probe system for in situ molten metal analysis. Final technical report

    SciTech Connect (OSTI)

    Kim, Y.W.

    1997-01-28

    The radically new methodology of in-situ laser-produced plasma (LPP) analysis of molten metals, as developed at Lehigh University, has been implemented into an LPP sensor-probe system, ready for deployment at steelmaking facilities. The system consists of an LPP sensor-probe head, which is immersed into the molten metal bath for the short duration of measurement, a control console, an umbilical cord connecting the above two units, and a support console providing coolants and pneumatic supports to the control console. The Department of Energy funding has supported Phase III-A and -B of the project in a joint sponsorship with AISI, CTU 5-2 Consortium, and Lehigh University. The objectives have been to: (1) implement the molten metal calibration protocol for the LPP analysis methodology; (2) implement the methodology in the form of a second-generation LPP sensor-probe system, which facilitates real-time process control by in-situ determination of elemental composition of molten steel alloys; (3) deploy such developmental systems in steelmaking facilities; (4) upgrade the systems to a third-generation design; and (5) effect technology transfer by selecting a manufacturer of commercial LPP sensor-probe systems. Four of the five objectives have been fully met. The deployment objective has been partially realized at present. The full LPP sensor-probe system has been put through trial immersion runs at a foundry, but its deployment at steelmaking facilities has progressed to a stage where various issues of financial and legal nature are being codified into a formal agreement between a host site and Lehigh University.

  2. Highly focused and efficient terahertz radiation generation by photo-mixing of lasers in plasma in the presence of magnetic field

    SciTech Connect (OSTI)

    Malik, Anil K.; Singh, Kunwar Pal; Sajal, V.

    2014-07-15

    A mechanism of efficient and highly focused terahertz (THz) radiation generation by photo-mixing of top-hat like lasers with frequencies ?{sub 1}, ?{sub 2} and wave numbers k{sub 1}, k{sub 2} in pre-formed rippled density (corrugated) plasma is proposed. In this mechanism, intensity variation of lasers offers nonlinear ponderomotive force at frequency ?{sup ?}=?{sub 1}??{sub 2} and wave number k{sup ?}=k{sub 1}?k{sub 2} which couples with density ripples in the plasma and leads to a strong nonlinear oscillatory current that resonantly excites highly focused and intense THz radiation at frequency ?{sub UH}=?((?{sub p}{sup 2}+?{sub c}{sup 2})) (where ?{sub c} is electron cyclotron frequency). The efficiency of emitted THz radiation of the order of 15% is obtained under optimum conditions. It is observed that focus and intensity of emitted radiation can be controlled by selecting a proper profile index of the lasers, ripple parameters, and tuning of external magnetic field.

  3. Numerical Verification of the Power Transfer and Wakefield Coupling in the Clic Two-Beam Accelerator

    SciTech Connect (OSTI)

    Candel, Arno; Li, Z.; Ng, C.; Rawat, V.; Schussman, G.; Ko, K.; Syratchev, I.; Grudiev, A.; Wuensch, W.; /CERN

    2011-08-19

    The Compact Linear Collider (CLIC) provides a path to a multi-TeV accelerator to explore the energy frontier of High Energy Physics. Its two-beam accelerator (TBA) concept envisions complex 3D structures, which must be modeled to high accuracy so that simulation results can be directly used to prepare CAD drawings for machining. The required simulations include not only the fundamental mode properties of the accelerating structures but also the Power Extraction and Transfer Structure (PETS), as well as the coupling between the two systems. Time-domain simulations will be performed to understand pulse formation, wakefield damping, fundamental power transfer and wakefield coupling in these structures. Applying SLAC's parallel finite element code suite, these large-scale problems will be solved on some of the largest supercomputers available. The results will help to identify potential issues and provide new insights on the design, leading to further improvements on the novel two-beam accelerator scheme.

  4. High spatial resolution mapping of deposition layers on plasma facing materials by laser ablation microprobe time-of-flight mass spectroscopy

    SciTech Connect (OSTI)

    Xiao, Qingmei; Li, Cong; Hai, Ran; Zhang, Lei; Feng, Chunlei; Ding, Hongbin, E-mail: hding@dlut.edu.cn [School of Physics and Optical Electronic Technology, Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Chinese Ministry of Education, Dalian University of Technology, Dalian 116024 (China); Zhou, Yan; Yan, Longwen; Duan, Xuru [Southwestern Institute of Physics, P.O. Box 432, No. 3 South Section 3, Circle Road 2, Chengdu 610041, Sichuan (China)

    2014-05-15

    A laser ablation microprobe time-of-flight mass spectroscopy (LAM-TOF-MS) system with high spatial resolution, ?20 nm in depth and ?500 ?m or better on the surface, is developed to analyze the composition distributions of deposition layers on the first wall materials or first mirrors in tokamak. The LAM-TOF-MS system consists of a laser ablation microprobe combined with a TOF-MS and a data acquisition system based on a LabVIEW program software package. Laser induced ablation combined with TOF-MS is an attractive method to analyze the depth profile of deposited layer with successive laser shots, therefore, it can provide information for composition reconstruction of the plasma wall interaction process. In this work, we demonstrate that the LAM-TOF-MS system is capable of characterizing the depth profile as well as mapping 2D composition of deposited film on the molybdenum first mirror retrieved from HL-2A tokamak, with particular emphasis on some of the species produced during the ablation process. The presented LAM-TOF-MS system provides not only the 3D characterization of deposition but also the removal efficiency of species of concern.

  5. Self-focusing and stimulated Brillouin back-scattering of a long intense laser pulse in a finite temperature relativistic plasma

    SciTech Connect (OSTI)

    Niknam, A. R.; Barzegar, S.; Hashemzadeh, M.

    2013-12-15

    The nonlinear dynamics of electromagnetic waves propagating through a plasma considering the effects of relativistic mass and ponderomotive nonlinearities is investigated. The modified electron density distribution, the dispersion relation, and the spatial profiles of electromagnetic wave amplitude in the plasma are obtained. It is shown that the cut-off frequency decreases, and there is an intensity range in which the ponderomotive self-focusing takes place. In the upper limit of this range, the laser beam is defocused due to the relativistic ponderomotive force. In addition, the stability of electromagnetic waves to stimulated Brillouin scattering is studied, and the backscattered wave resulting from decay of high power electromagnetic beam is resolved in relativistic regime. The study of effects of electron density and temperature on the growth rate of backscattered wave has been shown that by increasing these effects, the growth rate of instability increases.

  6. LASER ABLATION-INDUCTIVELY COUPLED PLASMA-ATOMIC EMISSION SPECTROSCOPY STUDY AT THE 222-S LABORATORY USING HOT-CELL GLOVE BOX PROTOTYPE SYSTEM

    SciTech Connect (OSTI)

    LOCKREM LL; OWENS JW; SEIDEL CM

    2009-03-26

    This report describes the installation, testing and acceptance of the Waste Treatment and Immobilization Plant procured laser ablation-inductively coupled plasma-atomic emission spectroscopy (LA-ICP-AES) system for remotely analyzing high-level waste samples in a hot cell environment. The 2005-003; ATS MP 1027, Management Plan for Waste Treatment Plant Project Work Performed by Analytical Technical Services. The APD group at the 222-S laboratory demonstrated acceptable turnaround time (TAT) and provide sufficient data to assess sensitivity, accuracy, and precision of the LA-ICP-AES method.

  7. LASER ABLATION-INDUCTIVELY COUPLED PLASMA-ATOMIC EMISSION SPECTROSCOPY STUDY AT THE 222-S LABORATORY USING HOT-CELL GLOVE BOX PROTOTYPE SYSTEM

    SciTech Connect (OSTI)

    SEIDEL CM; JAIN J; OWENS JW

    2009-02-23

    This report describes the installation, testing, and acceptance of the Waste Treatment and Immobilization Plant (WTP) procured laser ablation-inductively coupled plasma-atomic emission spectroscopy (LA-ICP-AES) system for remotely analyzing high-level waste (HLW) samples in a hot cell environment. The work was completed by the Analytical Process Development (APD) group in accordance with Task Order 2005-003; ATS MP 1027, Management Plan for Waste Treatment Plant Project Work Performed by Analytical Technical Services. The APD group at the 222-S Laboratory demonstrated acceptable turnaround time (TAT) and provide sufficient data to assess sensitivity, accuracy, and precision of the LA-ICP-AES method.

  8. Direct photo-etching of poly(methyl methacrylate) using focused extreme ultraviolet radiation from a table-top laser-induced plasma source

    SciTech Connect (OSTI)

    Barkusky, Frank; Peth, Christian; Bayer, Armin; Mann, Klaus

    2007-06-15

    In order to perform material interaction studies with intense extreme ultraviolet (EUV) radiation, a Schwarzschild mirror objective coated with Mo/Si multilayers was adapted to a compact laser-based EUV plasma source (pulse energy 3 mJ at {lambda}=13.5 nm, plasma diameter {approx}300 {mu}m). By 10x demagnified imaging of the plasma a pulse energy density of {approx}75 mJ/cm{sup 2} at a pulse length of 6 ns can be achieved in the image plane of the objective. As demonstrated for poly(methyl methacrylate) (PMMA), photoetching of polymer surfaces is possible at this EUV fluence level. This paper presents first results, including a systematic determination of PMMA etching rates under EUV irradiation. Furthermore, the contribution of out-of-band radiation to the surface etching of PMMA was investigated by conducting a diffraction experiment for spectral discrimination from higher wavelength radiation. Imaging of a pinhole positioned behind the plasma accomplished the generation of an EUV spot of 1 {mu}m diameter, which was employed for direct writing of surface structures in PMMA.

  9. Energy Spread Reduction of Electron Beams Produced via Laser Wake

    SciTech Connect (OSTI)

    Pollock, Bradley Bolt

    2012-01-01

    Laser wakefield acceleration of electrons holds great promise for producing ultra-compact stages of GeV scale, high quality electron beams for applications such as x-ray free electron lasers and high energy colliders. Ultra-high intensity laser pulses can be self-guided by relativistic plasma waves over tens of vacuum diffraction lengths, to give >1 GeV energy in cm-scale low density plasma using ionization-induced injection to inject charge into the wake at low densities. This thesis describes a series of experiments which investigates the physics of LWFA in the self-guided blowout regime. Beginning with high density gas jet experiments the scaling of the LWFA-produced electron beam energy with plasma electron density is found to be in excellent agreement with both phenomenological theory and with 3-D PIC simulations. It is also determined that self-trapping of background electrons into the wake exhibits a threshold as a function of the electron density, and at the densities required to produce electron beams with energies exceeding 1 GeV a different mechanism is required to trap charge into low density wakes. By introducing small concentrations of high-Z gas to the nominal He background the ionization-induced injection mechanism is enabled. Electron trapping is observed at densities as low as 1.3 x 1018 cm-3 in a gas cell target, and 1.45 GeV electrons are demonstrated for the first time from LWFA. This is currently the highest electron energy ever produced from LWFA. The ionization-induced trapping mechanism is also shown to generate quasi-continuous electron beam energies, which is undesirable for accelerator applications. By limiting the region over which ionization-induced trapping occurs, the energy spread of the electron beams can be controlled. The development of a novel two-stage gas cell target provides the capability to tailor the gas composition in the longitudinal direction, and confine the trapping process to occur only in a

  10. A Beam Driven Plasma-Wakefield Linear Collider: From Higgs Factory...

    Office of Scientific and Technical Information (OSTI)

    Research Org: SLAC National Accelerator Laboratory (SLAC) Sponsoring Org: US DOE Office of Science (DOE SC);High Energy Physics (HEP) Country of Publication: United States ...

  11. The Facility for 500 MeV Plasma Wake-Field Acceleration Experiments at Budker INP

    SciTech Connect (OSTI)

    Petrenko, A. V.; Lotov, K. V.; Logatchov, P. V.; Burdakov, A. V.

    2010-11-04

    The experimental PWFA facility currently under construction at the Budker INP is described. The objective is to use electron and positron beams extracted from the VEPP-5 damping ring in PWFA experiments. Due to longitudinal beam compression many PWFA schemes including the efficient blowout regime as well as multibunch regime can be studied. The simulations of beam dynamics in the facility are presented. Also we propose a simple technique for longitudinal beam slicing using dipole kickers and collimator in the damping ring.

  12. 9 GeV energy gain in a beam-driven plasma wakefield accelerator

    Office of Scientific and Technical Information (OSTI)

    ... The mechanism can be described as a compact beam energy transformer, increasing the voltage of the trailing beam at the expense of that of the drive beam. Energy is first ...

  13. Time dependent Doppler shifts in high-order harmonic generation in intense laser interactions with solid density plasma and frequency chirped pulses

    SciTech Connect (OSTI)

    Welch, E. C.; Zhang, P.; He, Z.-H.; Dollar, F.; Krushelnick, K.; Thomas, A. G. R.

    2015-05-15

    High order harmonic generation from solid targets is a compelling route to generating intense attosecond or even zeptosecond pulses. However, the effects of ion motion on the generation of harmonics have only recently started to be considered. Here, we study the effects of ion motion in harmonics production at ultrahigh laser intensities interacting with solid density plasma. Using particle-in-cell simulations, we find that there is an optimum density for harmonic production that depends on laser intensity, which scales linearly with a{sub 0} with no ion motion but with a reduced scaling if ion motion is included. We derive a scaling for this optimum density with ion motion and also find that the background ion motion induces Doppler red-shifts in the harmonic structures of the reflected pulse. The temporal structure of the Doppler shifts is correlated to the envelope of the incident laser pulse. We demonstrate that by introducing a frequency chirp in the incident pulse we are able to eliminate these Doppler shifts almost completely.

  14. INTERACTION OF MUON BEAM WITH PLASMA DEVELOPED DURING IONIZATION COOLING

    SciTech Connect (OSTI)

    S. Ahmed, D. Kaplan, T. Roberts, L. Spentzouris, K. Beard

    2012-07-01

    Particle-in-cell simulations involving the interaction of muon beam (peak density 10{sup 18} m{sup 3}) with Li plasma (ionized medium) of density 10{sup 16}-10{sup 22} m{sup -3} have been performed. This study aimed to understand the effects of plasma on an incoming beam in order to explore scenario developed during the process of ionization cooling. The computer code takes into account the self-consistent electromagnetic effects of beam interacting with plasma. This study shows that the beam can pass through the plasma of densities four order of magnitude higher than its peak density. The low density plasmas are wiped out by the beam, however, the resonance is observed for densities of similar order. Study reveals the signature of plasma wakefield acceleration.

  15. Space and time resolved spectroscopy of laser-produced plasmas: A study of density-sensitive x-ray transitions in helium-like and neon-like ions

    SciTech Connect (OSTI)

    Young, Bruce Kai Fong

    1988-09-01

    The determination of level populations and detailed population mechanisms in dense plasmas has become an increasingly important problem in atomic physics. In this work, the density variation of line intensities and level populations in aluminum K-shell and molybdenum and silver L-shell emission spectra have been measured from high-powered, laser-produced plasmas. For each case, the density dependence of the observed line emission is due to the effect of high frequency electron-ion collisions on metastable levels. The density dependent line intensities vary greatly in laser-produced plasmas and can be used to extract detailed information concerning the population kinetics and level populations of the ions. The laser-plasmas had to be fully characterized in order to clearly compare the observed density dependence with atomic theory predictions. This has been achieved through the combined use of new diagnostic instruments and microdot targets which provided simultaneously space, time, and spectrally resolved data. The plasma temperatures were determined from the slope of the hydrogen-like recombination continuum. The time resolved electron density profiles were measured using multiple frame holographic interferometry. Thus, the density dependence of K-shell spectral lines could be clearly examined, independent of assumptions concerning the dynamics of the plasma. In aluminum, the electron density dependence of various helium-like line intensity ratios were measured. Standard collisional radiative equilibrium models fail to account for the observed density dependence measured for the ''He/sub ..cap alpha..//IC'' ratio. Instead, a quasi-steady state atomic model based on a purely recombining plasma is shown to accurately predict the measured density dependence. This same recombining plasma calculation successfully models the density dependence of the high-n ''He/sub ..gamma..//He/sub ..beta../'' and ''He/sub delta//He/sub ..beta../'' helium-like resonance line intensity

  16. Soft X-ray microscopy in the spectral region of 'carbon window' with the use of multilayer optics and a laser-plasma source

    SciTech Connect (OSTI)

    Artyukov, I. A. Vinogradov, A. V.; Bugayev, Ye. A.; Devizenko, A. Yu.; Kondratenko, V. V.; Kasyanov, Yu. S.

    2009-11-15

    This paper reports on the fabrication and testing of multilayer mirrors for X-ray optical systems operating in the 'carbon window' region (at wavelengths from 4.5 to 5.0 nm) and the results of their application in soft X-ray imaging of the internal structure of organic objects. The developed approaches to the fabrication and control of graded Co/C multilayer coatings have made it possible to create an X-ray multimirror system with a maximum known entrance aperture and throughput. The use of the developed high-spatial-resolution X-ray optics can significantly extend the field of practical application of soft X-ray absorption microscopy based on compact laser-plasma sources.

  17. Laser ablation-inductively coupled plasma-mass spectrometry: Examinations of the origins of polyatomic ions and advances in the sampling of particulates

    SciTech Connect (OSTI)

    Witte, Travis

    2011-01-01

    This dissertation provides a general introduction to Inductively coupled plasma-mass spectrometry (ICP-MS) and laser ablation (LA) sampling, with an examination of analytical challenges in the employment of this technique. It discusses the origin of metal oxide ions (MO+) in LA-ICP-MS, as well as the effect of introducing helium and nitrogen to the aerosol gas flow on the formation of these polyatomic interferences. It extends the study of polyatomic ions in LA-ICP-MS to metal argide (MAr+) species, an additional source of possible significant interferences in the spectrum. It describes the application of fs-LA-ICP-MS to the determination of uranium isotope ratios in particulate samples.

  18. Demonstration of femtosecond laser ablation inductively coupled plasma mass spectrometry for uranium isotopic measurements in U-10Mo nuclear fuel foils

    SciTech Connect (OSTI)

    Havrilla, George Joseph; Gonzalez, Jhanis

    2015-06-10

    The use of femtosecond laser ablation inductively coupled plasma mass spectrometry was used to demonstrate the feasibility of measuring the isotopic ratio of uranium directly in U-10Mo fuel foils. The measurements were done on both the flat surface and cross sections of bare and Zr clad U-10Mo fuel foil samples. The results for the depleted uranium content measurements were less than 10% of the accepted U235/238 ratio of 0.0020. Sampling was demonstrated for line scans and elemental mapping over large areas. In addition to the U isotopic ratio measurement, the Zr thickness could be measured as well as trace elemental composition if required. A number of interesting features were observed during the feasibility measurements which could provide the basis for further investigation using this methodology. The results demonstrate the feasibility of using fs-LA-ICP-MS for measuring the U isotopic ratio in U-10Mo fuel foils.

  19. Hot Electron Diagnostic in a Solid Laser Target by Buried K-Shell Fluorer Technique from Ultra-Intense (3x1020W/cm2,< 500 J) Laser-Plasma Interactions on the Petawatt Laser at LLNL

    SciTech Connect (OSTI)

    Yasuike, K.; Key, M.H.; Hatchett, S.P.; Snavely, R.A.

    2000-06-29

    Characterization of hot electron production (a conversion efficiency from laser energy into electrons) in ultra intense laser-solid target interaction, using 1.06 {micro}m laser light with an intensity of up to 3 x 10{sup 20}W cm{sup -2} and an on target laser energy of {le}500 J, has been done by observing K{sub {beta}} as well as K{sub {alpha}} emissions from a buried Mo layer in the targets, which are same structure as in the previous 100 TW experiments but done under less laser intensity and energy conditions ({le} 4 x 10{sup 19} Wcm{sup -2} and {le} 30 J). The conversion efficiency from the laser energy into the energy, carried by hot electrons, has been estimated to be {approx}50%, which are little bit higher than the previous less laser energy ({approx} 20 J) experiments, yet the x-ray emission spectra from the target has change drastically, i.e., gamma flash.

  20. Three regimes of relativistic beam - plasma interaction

    SciTech Connect (OSTI)

    Muggli, P.; Allen, B.; Fang, Y.; Yakimenko, V.; Babzien, M.; Kusche, K.; Fedurin, M.; Vieira, J.; Martins, J.; Silva, L.

    2012-12-21

    Three regimes of relativistic beam - plasma interaction can in principle be reached at the ATF depending on the relative transverse and longitudinal size of the electron bunch when compared to the cold plasma collisionless skin depth c?{omega}{sub pe}: the plasma wakefield accelerator (PWFA), the self-modulation instability (SMI), and the current filamentation instability (CFI) regime. In addition, by choosing the bunch density, the linear, quasi-nonlinear and non linear regime of the PWFA can be reached. In the case of the two instabilities, the bunch density determines the growth rate and therefore the occurrence or not of the instability. We briefly describe these three regimes and outline results demonstrating that all these regime have or will be reached experimentally. We also outline planned and possible follow-on experiments.

  1. Absolute radiant power measurement for the Au M lines of laser-plasma using a calibrated broadband soft X-ray spectrometer with flat-spectral response

    SciTech Connect (OSTI)

    Troussel, Ph.; Villette, B.; Oudot, G.; Tassin, V.; Bridou, F.; Delmotte, F.; Krumrey, M.

    2014-01-15

    CEA implemented an absolutely calibrated broadband soft X-ray spectrometer called DMX on the Omega laser facility at the Laboratory for Laser Energetics (LLE) in 1999 to measure radiant power and spectral distribution of the radiation of the Au plasma. The DMX spectrometer is composed of 20 channels covering the spectral range from 50 eV to 20 keV. The channels for energies below 1.5 keV combine a mirror and a filter with a coaxial photo-emissive detector. For the channels above 5 keV the photoemissive detector is replaced by a conductive detector. The intermediate energy channels (1.5 keV < photon energy < 5 keV) use only a filter and a coaxial detector. A further improvement of DMX consists in flat-response X-ray channels for a precise absolute measurement of the photon flux in the photon energy range from 0.1 keV to 6 keV. Such channels are equipped with a filter, a Multilayer Mirror (MLM), and a coaxial detector. We present as an example the development of channel for the gold M emission lines in the photon energy range from 2 keV to 4 keV which has been successfully used on the OMEGA laser facility. The results of the radiant power measurements with the new MLM channel and with the usual channel composed of a thin titanium filter and a coaxial detector (without mirror) are compared. All elements of the channel have been calibrated in the laboratory of the Physikalisch-Technische Bundesanstalt, Germany's National Metrology Institute, at the synchrotron radiation facility BESSY II in Berlin using dedicated well established and validated methods.

  2. Formation and direct writing of color centers in LiF using a laser-induced extreme ultraviolet plasma in combination with a Schwarzschild objective

    SciTech Connect (OSTI)

    Barkusky, Frank; Peth, Christian; Mann, Klaus; Feigl, Torsten; Kaiser, Norbert

    2005-10-15

    In order to generate high-energy densities of 13.5 nm radiation, an extreme ultraviolet (EUV) Schwarzschild mirror objective with a numerical aperture of 0.44 and a demagnification of 10 was developed and adapted to a compact laser-based EUV source. The annular spherical mirror substrates were coated with Mo/Si multilayer systems. With a single mirror reflectance of more than 65% the total transmittance of the Schwarzschild objective exceeds 40% at 13.5 nm. From the properties of the EUV source (pulse energy 3 mJ at 13.5 nm and plasma diameter approximately 300 {mu}m), energy densities of 73 mJ/cm{sup 2} at a pulse length of 6 ns can be estimated in the image plane of the objective. As a first application, the formation of color centers in lithium fluoride crystals by EUV radiation was investigated. F{sub 2}, F{sub 3}, and F{sub 3}{sup +} color centers could be identified by absorption spectroscopy. The formation dynamics was studied as a function of the EUV dose. By imaging of a pinhole positioned behind the plasma, an EUV spot of 5 {mu}m diameter was generated, which accomplishes direct writing of color centers with micrometer resolution.

  3. High Frequency, High Gradient Dielectric Wakefield Acceleration Experiments at SLAC and BNL

    SciTech Connect (OSTI)

    Rosenzweig, James; Travish, Gil; Hogan, Mark; Muggli, Patric; /Southern California U.

    2012-07-05

    Given the recent success of >GV/m dielectric wakefield accelerator (DWA) breakdown experiments at SLAC, and follow-on coherent Cerenkov radiation production at the UCLA Neptune, a UCLA-USC-SLAC collaboration is now implementing a new set of experiments that explore various DWA scenarios. These experiments are motivated by the opportunities presented by the approval of FACET facility at SLAC, as well as unique pulse-train wakefield drivers at BNL. The SLAC experiments permit further exploration of the multi-GeV/m envelope in DWAs, and will entail investigations of novel materials (e.g. CVD diamond) and geometries (Bragg cylindrical structures, slab-symmetric DWAs), and have an over-riding goal of demonstrating >GeV acceleration in {approx}33 cm DWA tubes. In the nearer term before FACET's commissioning, we are planning measurements at the BNL ATF, in which we drive {approx}50-200 MV/m fields with single pulses or pulse trains. These experiments are of high relevance to enhancing linear collider DWA designs, as they will demonstrate potential for efficient operation with pulse trains.

  4. High Frequency, High Gradient Dielectric Wakefield Acceleration Experiments at SLAC and BNL

    SciTech Connect (OSTI)

    Rosenzweig, J. B.; Andonian, G.; Niknejadi, P.; Travish, G.; Williams, O.; Xuan, K.; Muggli, P.; Yakimenko, V.

    2010-11-04

    Given the recent success of >GV/m dielectric wakefield accelerator (DWA) breakdown experiments at SLAC, and follow-on coherent Cerenkov radiation (CCR) production at the UCLA Neptune, a UCLA-USC-SLAC collaboration is now implementing a new set of experiments that explore various DWA scenarios. These experiments are motivated by the opportunities presented by the approval of the FACET facility at SLAC, as well as unique pulse-train wakefield drivers at BNL. The SLAC experiments permit further exploration of the multi-GeV/m envelope in DWAs, and will entail investigations of novel materials (e.g. CVD diamond) and geometries (Bragg cylindrical structures, slab-symmetric DWAs), and have an over-riding goal of demonstrating >GeV acceleration in {approx}33 cm DWA tubes. In the nearer term before FACET's commissioning, we are performing measurements at the BNL ATF, in which we drive {approx}50-200 MV/m fields with single pulses or pulse trains, and observe resonantly driven CCR as well as deflection modes. These experiments are of high relevance to enhancing linear collider DWA designs, as they will demonstrate potential for high efficiency operation with pulse trains, and explore transverse modes for the first time.

  5. High-power radio frequency pulse generation and extration based on wakefield excited by an intense charged particle beam in dielectric-loaded waveguides.

    SciTech Connect (OSTI)

    Gao, F.; High Energy Physics; Illinois Inst. of Tech

    2009-07-24

    Power extraction using a dielectric-loaded (DL) waveguide is a way to generate high-power radio frequency (RF) waves for future particle accelerators, especially for two-beam-acceleration. In a two-beam-acceleration scheme, a low-energy, high-current particle beam is passed through a deceleration section of waveguide (decelerator), where the power from the beam is partially transferred to trailing electromagnetic waves (wakefields); then with a properly designed RF output coupler, the power generated in the decelerator is extracted to an output waveguide, where finally the power can be transmitted and used to accelerate another usually high-energy low-current beam. The decelerator, together with the RF output coupler, is called a power extractor. At Argonne Wakefield Accelerator (AWA), we designed a 7.8GHz power extractor with a circular DL waveguide and tested it with single electron bunches and bunch trains. The output RF frequency (7.8GHz) is the sixth harmonic of the operational frequency (1.3GHz) of the electron gun and the linac at AWA. In single bunch excitation, a 1.7ns RF pulse with 30MW of power was generated by a single 66nC electron bunch passing through the decelerator. In subsequent experiments, by employing different splitting-recombining optics for the photoinjector laser, electron bunch trains were generated and thus longer RF pulses could be successfully generated and extracted. In 16-bunch experiments, 10ns and 22ns RF pulses have been generated and extracted; and in 4-bunch experiments, the maximum power generated was 44MW with 40MW extracted. A 26GHz DL power extractor has also been designed to test this technique in the millimeter-wave range. A power level of 148MW is expected to be generated by a bunch train with a bunch spacing of 769ps and bunch charges of 20nC each. The arrangement for the experiment is illustrated in a diagram. Higher-order-mode (HOM) power extraction has also been explored in a dual-frequency design. By using a bunch

  6. Beam-driven acceleration in ultra-dense plasma media

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Shin, Young-Min

    2014-09-15

    Accelerating parameters of beam-driven wakefield acceleration in an extremely dense plasma column has been analyzed with the dynamic framed particle-in-cell plasma simulator, and compared with analytic calculations. In the model, a witness beam undergoes a TeV/m scale alternating potential gradient excited by a micro-bunched drive beam in a 1025 m-3 and 1.6 x 1028 m-3 plasma column. The acceleration gradient, energy gain, and transformer ratio have been extensively studied in quasi-linear, linear-, and blowout-regimes. The simulation analysis indicated that in the beam-driven acceleration system a hollow plasma channel offers 20 % higher acceleration gradient by enlarging the channel radius (r)morefrom 0.2 ?p to 0.6 ?p in a blowout regime. This paper suggests a feasibility of TeV/m scale acceleration with a hollow crystalline structure (e.g. nanotubes) of high electron plasma density.less

  7. A new spectrometer design for the x-ray spectroscopy of laser-produced plasmas with high (sub-ns) time resolution

    SciTech Connect (OSTI)

    Bitter, M. Hill, K. W.; Efthimion, P. C.; Delgado-Aparicio, L.; Pablant, N.; Lu, Jian; Beiersdorfer, P.; Chen, Hui

    2014-11-15

    This paper describes a new type of x-ray crystal spectrometer, which can be used in combination with gated x-ray detectors to obtain spectra from laser-produced plasmas with a high (sub-ns) time resolution. The spectrometer consists of a convex, spherically bent crystal, which images individual spectral lines as perfectly straight lines across multiple, sequentially gated, strip detectors. Since the Bragg-reflected rays are divergent, the distance between detector and crystal is arbitrary, so that this distance can be appropriately chosen to optimize the experimental arrangement with respect to the detector parameters. The spectrometer concept was verified in proof-of-principle experiments by imaging the L?{sub 1}- and L?{sub 2}-lines of tungsten, at 9.6735 and 9.96150 keV, from a micro-focus x-ray tube with a tungsten target onto a two-dimensional pixilated Pilatus detector, using a convex, spherically bent Si-422 crystal with a radius of curvature of 500 mm.

  8. Method for characterization of a spherically bent crystal for K.alpha. X-ray imaging of laser plasmas using a focusing monochromator geometry

    DOE Patents [OSTI]

    Kugland, Nathan; Doeppner, Tilo; Glenzer, Siegfried; Constantin, Carmen; Niemann, Chris; Neumayer, Paul

    2015-04-07

    A method is provided for characterizing spectrometric properties (e.g., peak reflectivity, reflection curve width, and Bragg angle offset) of the K.alpha. emission line reflected narrowly off angle of the direct reflection of a bent crystal and in particular of a spherically bent quartz 200 crystal by analyzing the off-angle x-ray emission from a stronger emission line reflected at angles far from normal incidence. The bent quartz crystal can therefore accurately image argon K.alpha. x-rays at near-normal incidence (Bragg angle of approximately 81 degrees). The method is useful for in-situ calibration of instruments employing the crystal as a grating by first operating the crystal as a high throughput focusing monochromator on the Rowland circle at angles far from normal incidence (Bragg angle approximately 68 degrees) to make a reflection curve with the He-like x-rays such as the He-.alpha. emission line observed from a laser-excited plasma.

  9. Stimulated forward Raman scattering in large scale-length laser...

    Office of Scientific and Technical Information (OSTI)

    in large scale-length laser-produced plasmas Citation Details In-Document Search Title: Stimulated forward Raman scattering in large scale-length laser-produced plasmas You ...

  10. Trident Laser Facility

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Trident Laser Facility Trident Laser Facility Enabling world-class science in high-energy density physics and fundamental laser-matter interactions April 12, 2012 Invisible infrared light from the 200-trillion watt Trident Laser enters from the bottom to interact with a one-micrometer thick foil target in the center of the photo. The laser pulse produces a plasma - an ionized gas - many times hotter than the center of the sun, which lasts for a trillionth of a second. During this time some

  11. Weakly relativistic plasma expansion

    SciTech Connect (OSTI)

    Fermous, Rachid Djebli, Mourad

    2015-04-15

    Plasma expansion is an important physical process that takes place in laser interactions with solid targets. Within a self-similar model for the hydrodynamical multi-fluid equations, we investigated the expansion of both dense and under-dense plasmas. The weakly relativistic electrons are produced by ultra-intense laser pulses, while ions are supposed to be in a non-relativistic regime. Numerical investigations have shown that relativistic effects are important for under-dense plasma and are characterized by a finite ion front velocity. Dense plasma expansion is found to be governed mainly by quantum contributions in the fluid equations that originate from the degenerate pressure in addition to the nonlinear contributions from exchange and correlation potentials. The quantum degeneracy parameter profile provides clues to set the limit between under-dense and dense relativistic plasma expansions at a given density and temperature.

  12. Press Releases Archive | Princeton Plasma Physics Lab

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Runaway electrons, a searing, laser-like beam of electric current released by plasma ... Read more... August 19, 2016 How to keep the superhot plasma inside tokamaks from chirping ...

  13. Press Releases | Princeton Plasma Physics Lab

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    By John Greenwald, Greenwald Physicist Dylan Brennan Runaway electrons, a searing, laser-like beam of electric current released by plasma disruptions, could damage the interior ...

  14. Princeton Plasma Physics Laboratory

    SciTech Connect (OSTI)

    Not Available

    1990-01-01

    This report discusses the following topics: principal parameters achieved in experimental devices fiscal year 1990; tokamak fusion test reactor; compact ignition tokamak; Princeton beta experiment- modification; current drive experiment-upgrade; international collaboration; x-ray laser studies; spacecraft glow experiment; plasma processing: deposition and etching of thin films; theoretical studies; tokamak modeling; international thermonuclear experimental reactor; engineering department; project planning and safety office; quality assurance and reliability; technology transfer; administrative operations; PPPL patent invention disclosures for fiscal year 1990; graduate education; plasma physics; graduate education: plasma science and technology; science education program; and Princeton Plasma Physics Laboratory reports fiscal year 1990.

  15. Current developments in laser ablation-inductively coupled plasma-mass spectrometry for use in geology, forensics, and nuclear nonproliferation research

    SciTech Connect (OSTI)

    Messerly, Joshua D.

    2008-08-26

    This dissertation focused on new applications of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The diverse fields that were investigated show the versatility of the technique. In Chapter 2, LA-ICP-MS was used to investigate the rare earth element (REE) profiles of garnets from the Broken Hill Deposit in New South Wales, Australia. The normalized REE profiles helped to shed new light on the formation of deposits of sulfide ores. This information may be helpful in identifying the location of sulfide ore deposits in other locations. New sources of metals such as Pg, Zn, and Ag, produced from these ores, are needed to sustain our current technological society. The application of LA-ICP-MS presented in Chapter 3 is the forensics analysis of automotive putty and caulking. The elemental analysis of these materials was combined with the use of Principal Components Analysis (PCA). The PCA comparison was able to differentiate the automotive putty samples by manufacturer and lot number. The analysis of caulk was able to show a differentiation based on manufacturer, but no clear differentiation was shown by lot number. This differentiation may allow matching of evidence in the future. This will require many more analyses and the construction of a database made up of many different samples. The 4th chapter was a study of the capabilities of LA-ICP-MS for fast and precise analysis of particle ensembles for nuclear nonproliferation applications. Laser ablation has the ability to spatially resolve particle ensembles which may contain uranium or other actinides from other particles present in a sample. This is of importance in samples obtained from air on filter media. The particle ensembles of interest may be mixed in amongst dust and other particulates. A problem arises when ablating these particle ensembles directly from the filter media. Dust particles other than ones of interest may be accidentally entrained in the aerosol of the ablated particle

  16. Parallel Higher-order Finite Element Method for Accurate Field Computations in Wakefield and PIC Simulations

    SciTech Connect (OSTI)

    Candel, A.; Kabel, A.; Lee, L.; Li, Z.; Limborg, C.; Ng, C.; Prudencio, E.; Schussman, G.; Uplenchwar, R.; Ko, K.; /SLAC

    2009-06-19

    Over the past years, SLAC's Advanced Computations Department (ACD), under SciDAC sponsorship, has developed a suite of 3D (2D) parallel higher-order finite element (FE) codes, T3P (T2P) and Pic3P (Pic2P), aimed at accurate, large-scale simulation of wakefields and particle-field interactions in radio-frequency (RF) cavities of complex shape. The codes are built on the FE infrastructure that supports SLAC's frequency domain codes, Omega3P and S3P, to utilize conformal tetrahedral (triangular)meshes, higher-order basis functions and quadratic geometry approximation. For time integration, they adopt an unconditionally stable implicit scheme. Pic3P (Pic2P) extends T3P (T2P) to treat charged-particle dynamics self-consistently using the PIC (particle-in-cell) approach, the first such implementation on a conformal, unstructured grid using Whitney basis functions. Examples from applications to the International Linear Collider (ILC), Positron Electron Project-II (PEP-II), Linac Coherent Light Source (LCLS) and other accelerators will be presented to compare the accuracy and computational efficiency of these codes versus their counterparts using structured grids.

  17. ACE3P Computations of Wakefield Coupling in the CLIC Two-Beam Accelerator

    SciTech Connect (OSTI)

    Candel, Arno; Li, Z.; Ng, C.; Rawat, V.; Schussman, G.; Ko, K.; Syratchev, I.; Grudiev, A.; Wuensch, W.

    2010-10-27

    The Compact Linear Collider (CLIC) provides a path to a multi-TeV accelerator to explore the energy frontier of High Energy Physics. Its novel two-beam accelerator concept envisions rf power transfer to the accelerating structures from a separate high-current decelerator beam line consisting of power extraction and transfer structures (PETS). It is critical to numerically verify the fundamental and higher-order mode properties in and between the two beam lines with high accuracy and confidence. To solve these large-scale problems, SLAC's parallel finite element electromagnetic code suite ACE3P is employed. Using curvilinear conformal meshes and higher-order finite element vector basis functions, unprecedented accuracy and computational efficiency are achieved, enabling high-fidelity modeling of complex detuned structures such as the CLIC TD24 accelerating structure. In this paper, time-domain simulations of wakefield coupling effects in the combined system of PETS and the TD24 structures are presented. The results will help to identify potential issues and provide new insights on the design, leading to further improvements on the novel CLIC two-beam accelerator scheme.

  18. Wakefield and RF Kicks Due to Coupler Asymmetry in TESLA-Type Accelerating Cavities

    SciTech Connect (OSTI)

    Bane, K.L.F.; Adolphsen, C.; Li, Z.; Dohlus, M.; Zagorodnov, I.; Gonin, I.; Lunin, A.; Solyak, N.; Yakovlev, V.; Gjonaj, E.; Weiland, T.; /Darmstadt, Tech. Hochsch.

    2008-07-07

    In a future linear collider, such as the International Linear Collider (ILC), trains of high current, low emittance bunches will be accelerated in a linac before colliding at the interaction point. Asymmetries in the accelerating cavities of the linac will generate fields that will kick the beam transversely and degrade the beam emittance and thus the collider performance. In the main linac of the ILC, which is filled with TESLA-type superconducting cavities, it is the fundamental (FM) and higher mode (HM) couplers that are asymmetric and thus the source of such kicks. The kicks are of two types: one, due to (the asymmetry in) the fundamental RF fields and the other, due to transverse wakefields that are generated by the beam even when it is on axis. In this report we calculate the strength of these kicks and estimate their effect on the ILC beam. The TESLA cavity comprises nine cells, one HM coupler in the upstream end, and one (identical, though rotated) HM coupler and one FM coupler in the downstream end (for their shapes and location see Figs. 1, 2) [1]. The cavity is 1.1 m long, the iris radius 35 mm, and the coupler beam pipe radius 39 mm. Note that the couplers reach closer to the axis than the irises, down to a distance of 30 mm.

  19. OMEGA EP Construction - Laboratory for Laser Energetics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Construction - Laboratory for Laser Energetics Laboratory for Laser Energetics Logo Search Home Around the Lab Past Issues Past Quick Shots About Office of the Director Map to LLE LLE Tours LLE Building Map Partnerships Careers Education Undergraduate Program Graduate Program High School Program Faculty Contacts Computational Astrophysics H-E-D Physics Inertial Confinement Fusion Laser-Plasma Interaction Radiative Hydrodynamics Plasma Astrophysics Organization Director's Office Laser Development

  20. OMEGA Experimental Systems - Laboratory for Laser Energetics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Experimental Systems - Laboratory for Laser Energetics Laboratory for Laser Energetics Logo Search Home Around the Lab Past Issues Past Quick Shots About Office of the Director Map to LLE LLE Tours LLE Building Map Partnerships Careers Education Undergraduate Program Graduate Program High School Program Faculty Contacts Computational Astrophysics H-E-D Physics Inertial Confinement Fusion Laser-Plasma Interaction Radiative Hydrodynamics Plasma Astrophysics Organization Director's Office Laser

  1. Joint Operations - Laboratory for Laser Energetics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Operations - Laboratory for Laser Energetics Laboratory for Laser Energetics Logo Search Home Around the Lab Past Issues Past Quick Shots About Office of the Director Map to LLE LLE Tours LLE Building Map Partnerships Careers Education Undergraduate Program Graduate Program High School Program Faculty Contacts Computational Astrophysics H-E-D Physics Inertial Confinement Fusion Laser-Plasma Interaction Radiative Hydrodynamics Plasma Astrophysics Organization Director's Office Laser Development

  2. Wakefield Computations for the CLIC PETS using the Parallel Finite Element Time-Domain Code T3P

    SciTech Connect (OSTI)

    Candel, A; Kabel, A.; Lee, L.; Li, Z.; Ng, C.; Schussman, G.; Ko, K.; Syratchev, I.; /CERN

    2009-06-19

    In recent years, SLAC's Advanced Computations Department (ACD) has developed the high-performance parallel 3D electromagnetic time-domain code, T3P, for simulations of wakefields and transients in complex accelerator structures. T3P is based on advanced higher-order Finite Element methods on unstructured grids with quadratic surface approximation. Optimized for large-scale parallel processing on leadership supercomputing facilities, T3P allows simulations of realistic 3D structures with unprecedented accuracy, aiding the design of the next generation of accelerator facilities. Applications to the Compact Linear Collider (CLIC) Power Extraction and Transfer Structure (PETS) are presented.

  3. Internal electron conversion of the isomeric {sup 57}Fe nucleus state with an energy of 14.4 keV excited by the radiation of the plasma of a high-power femtosecond laser pulse

    SciTech Connect (OSTI)

    Golovin, G V; Savel'ev-Trofimov, Andrei B; Uryupina, D S; Volkov, Roman V

    2011-03-31

    We recorded the spectrum of delayed secondary electrons ejected from the target, which was coated with a layer of iron enriched with the {sup 57}Fe isotope to 98%, under its irradiation by fluxes of broadband X-ray radiation and fast electrons from the plasma produced by a femtosecond laser pulse at an intensity of 10{sup 17} W cm{sup -2}. Maxima were identified at energies of 5.6, 7.2, and 13.6 keV in the spectrum obtained for a delay of 90 - 120 ns. The two last-listed maxima owe their origin to the internal electron conversion of the isomeric level with an energy of 14.4 keV and a lifetime of 98 ns to the K and L shells of atomic iron, respectively; the first-named level arises from a cascade K - L{sub 2}L{sub 3} Auger process. Photoexcitaion by the X-ray plasma radiation is shown to be the principal channel of the isomeric level excitation. (interaction of laser radiation with matter)

  4. plasma | National Nuclear Security Administration

    National Nuclear Security Administration (NNSA)

    plasma Los Alamos plasma research shows promise for future compact accelerators The team in front of Los Alamos' Trident Laser Target Chamber. Back, from left: Tom Shimada, Sha-Marie Reid, Adam Sefkow, Miguel Santiago, and Chris Hamilton. Front, from left: Russ Mortensen, Chengkun Huang, Sasi Palaniyappan, Juan Fernandez, Cort Gautier and Randy Johnson. A

  5. Analysis of radiofrequency discharges in plasma

    DOE Patents [OSTI]

    Kumar, D.; McGlynn, S.P.

    1992-08-04

    Separation of laser optogalvanic signals in plasma into two components: (1) an ionization rate change component, and (2) a photoacoustic mediated component. This separation of components may be performed even when the two components overlap in time, by measuring time-resolved laser optogalvanic signals in an rf discharge plasma as the rf frequency is varied near the electrical resonance peak of the plasma and associated driving/detecting circuits. A novel spectrometer may be constructed to make these measurements. Such a spectrometer would be useful in better understanding and controlling such processes as plasma etching and plasma deposition. 15 figs.

  6. Analysis of radiofrequency discharges in plasma

    DOE Patents [OSTI]

    Kumar, Devendra; McGlynn, Sean P.

    1992-01-01

    Separation of laser optogalvanic signals in plasma into two components: (1) an ionization rate change component, and (2) a photoacoustic mediated component. This separation of components may be performed even when the two components overlap in time, by measuring time-resolved laser optogalvanic signals in an rf discharge plasma as the rf frequency is varied near the electrical resonance peak of the plasma and associated driving/detecting circuits. A novel spectrometer may be constructed to make these measurements. Such a spectrometer would be useful in better understanding and controlling such processes as plasma etching and plasma deposition.

  7. Expert Topics | Princeton Plasma Physics Lab

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AC power Carbon-free Climate change Education Emergency planning Engineering Fusion energy Fusion reactor design Fusion roadmapping ITER Inertial confinement fusion International collaborations Laser diagnostics Lithium Magnetic reconnection NSTX-U Nanotechnology Nuclear energy Nuclear safety Particle beam dynamics Plasma astrophysics Plasma diagnostics Plasma physics Power system design Power systems Quality assurance STEM Science literacy Stellarators Surface science Sustainability Tokamaks

  8. Mobile inductively coupled plasma system

    DOE Patents [OSTI]

    D'Silva, Arthur P. (Ames, IA); Jaselskis, Edward J. (Ames, IA)

    1999-03-30

    A system for sampling and analyzing a material located at a hazardous site. A laser located remote from the hazardous site is connected to an optical fiber, which directs laser radiation proximate the material at the hazardous site. The laser radiation abates a sample of the material. An inductively coupled plasma is located remotely from the material. An aerosol transport system carries the ablated particles to a plasma, where they are dissociated, atomized and excited to provide characteristic optical reduction of the elemental constituents of the sample. An optical spectrometer is located remotely from the site. A second optical fiber is connected to the optical spectrometer at one end and the plasma source at the other end to carry the optical radiation from the plasma source to the spectrometer.

  9. Mobile inductively coupled plasma system

    DOE Patents [OSTI]

    D`Silva, A.P.; Jaselskis, E.J.

    1999-03-30

    A system is described for sampling and analyzing a material located at a hazardous site. A laser located remotely from the hazardous site is connected to an optical fiber, which directs laser radiation proximate the material at the hazardous site. The laser radiation abates a sample of the material. An inductively coupled plasma is located remotely from the material. An aerosol transport system carries the ablated particles to a plasma, where they are dissociated, atomized and excited to provide characteristic optical reduction of the elemental constituents of the sample. An optical spectrometer is located remotely from the site. A second optical fiber is connected to the optical spectrometer at one end and the plasma source at the other end to carry the optical radiation from the plasma source to the spectrometer. 10 figs.

  10. Mars mission laser tool heads to JPL

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Mars mission laser tool Mars mission laser tool heads to JPL Curiosity will carry the newly delivered laser instrument to reveal which elements are present in Mars' rocks and soils. September 21, 2010 A bright ball of plasma is produced by ChemCam's invisible laser beam striking a rock within the Mars sample chamber. A bright ball of plasma is produced by ChemCam's invisible laser beam striking a rock within the Mars sample chamber. Contact Nancy Ambrosiano Communications Office (505) 667-0471

  11. Laser controlled flame stabilization

    DOE Patents [OSTI]

    Early, James W.; Thomas, Matthew E.

    2001-01-01

    A method and apparatus is provided for initiating and stabilizing fuel combustion in applications such as gas turbine electrical power generating engines and jet turbine engines where it is desired to burn lean fuel/air mixtures which produce lower amounts of NO.sub.x. A laser induced spark is propagated at a distance from the fuel nozzle with the laser ignitor being remotely located from the high temperature environment of the combustion chamber. A laser initiating spark generated by focusing high peak power laser light to a sufficiently tight laser spot within the fuel to cause the ionization of air and fuel into a plasma is unobtrusive to the flow dynamics of the combustion chamber of a fuel injector, thereby facilitating whatever advantage can be taken of flow dynamics in the design of the fuel injector.

  12. Spectroscopic study of carbon plasma produced by the first (1064...

    Office of Scientific and Technical Information (OSTI)

    carbon plasma produced by the first (1064 nm) and second (532 nm) harmonics of Nd:YAG laser Citation Details In-Document Search Title: Spectroscopic study of carbon plasma produced ...

  13. High Energy Density Laboratory Plasmas Program | National Nuclear...

    National Nuclear Security Administration (NNSA)

    selected embody the breadth of research in HEDLP science, ranging from the study of magnetized astrophysical jets to large-scale simulation of kinetic laser plasma interactions.

  14. Simultaneous observation of nascent plasma and bubble induced...

    Office of Scientific and Technical Information (OSTI)

    in water with various pulse durations Citation Details In-Document Search Title: Simultaneous observation of nascent plasma and bubble induced by laser ablation in water with ...

  15. Plasma channel optical pumping device and method

    DOE Patents [OSTI]

    Judd, O.P.

    1983-06-28

    A device and method are disclosed for optically pumping a gaseous laser using blackbody radiation produced by a plasma channel which is formed from an electrical discharge between two electrodes spaced at opposite longitudinal ends of the laser. A preionization device which can comprise a laser or electron beam accelerator produces a preionization beam which is sufficient to cause an electrical discharge between the electrodes to initiate the plasma channel along the preionization path. The optical pumping energy is supplied by a high voltage power supply rather than by the preionization beam. High output optical intensities are produced by the laser due to the high temperature blackbody radiation produced by the plasma channel, in the same manner as an exploding wire type laser. However, unlike the exploding wire type laser, the disclosed invention can be operated in a repetitive manner by utilizing a repetitive pulsed preionization device. 5 figs.

  16. Plasma channel optical pumping device and method

    DOE Patents [OSTI]

    Judd, O'Dean P.

    1983-06-28

    A device and method for optically pumping a gaseous laser using blackbody radiation produced by a plasma channel which is formed from an electrical discharge between two electrodes spaced at opposite longitudinal ends of the laser. A preionization device which can comprise a laser or electron beam accelerator produces a preionization beam which is sufficient to cause an electrical discharge between the electrodes to initiate the plasma channel along the preionization path. The optical pumping energy is supplied by a high voltage power supply rather than by the preionization beam. High output optical intensities are produced by the laser due to the high temperature blackbody radiation produced by the plasma channel, in the same manner as an exploding wire type laser. However, unlike the exploding wire type laser, the disclosed invention can be operated in a repetitive manner by utilizing a repetitive pulsed preionization device.

  17. Plasma isotope separation methods

    SciTech Connect (OSTI)

    Grossman, M.W. ); Shepp, T.A. )

    1991-12-01

    Isotope separation has many important industrial, medical, and research applications. Large-scale processes have typically utilized complex cascade systems; for example, the gas centrifuge. Alternatively, high single-stage enrichment processes (as in the case of the calutron) are very energy intensive. Plasma-based methods being developed for the past 15 to 20 years have attempted to overcome these two drawbacks. In this review, six major types of isotope separation methods which involve plasma phenomena are discussed. These methods are: plasma centrifuge, AVLIS (atomic vapor laser isotope separation), ion wave, ICR (ion-cyclotron resonance), calutron, and gas discharge. The emphasis of this paper is to describe the plasma phenomena in these major categories. An attempt was made to include enough references so that more detailed study or evaluation of a particular method could readily be pursued. A brief discussion of isotope separation using mass balance concepts is also carried out.

  18. Controllable high-quality electron beam generation by phase slippage effect in layered targets

    SciTech Connect (OSTI)

    Yu, Q.; Li, X. F.; Huang, S.; Zhang, F.; Kong, Q.; Gu, Y. J.; Ma, Y. Y.; Kawata, S.

    2014-11-15

    The bubble structure generated by laser-plasma interactions changes in size depending on the local plasma density. The self-injection electrons' position with respect to wakefield can be controlled by tailoring the longitudinal plasma density. A regime to enhance the energy of the wakefield accelerated electrons and to improve the beam quality is proposed and achieved using layered plasmas with increasing densities. Both the wakefield size and the electron bunch duration are significantly contracted in this regime. The electrons remain in the strong acceleration phase of the wakefield, while their energy spread decreases because of their tight spatial distribution. An electron beam of 0.5?GeV with less than 1% energy spread is obtained through 2.5D particle-in-cell simulations.

  19. Summary report of working group 3: High gradient and laser-structure based acceleration

    SciTech Connect (OSTI)

    Solyak, N.; Cowan, B.M.; /Tech-X, Boulder

    2010-01-01

    The charge for the working group on high gradient and laser-structure based acceleration was to assess the current challenges involved in developing an advanced accelerator based on electromagnetic structures, and survey state-of-the-art methods to address those challenges. The topics of more than 50 presentations in the working group covered a very broad range of issues, from ideas, theoretical models and simulations, to design and manufacturing of accelerating structures and, finally, experimental results on obtaining extremely high accelerating gradients in structures from conventional microwave frequency range up to THz and laser frequencies. Workshop discussion topics included advances in the understanding of the physics of breakdown and other phenomena, limiting high gradient performance of accelerating structures. New results presented in this workshop demonstrated significant progress in the fields of conventional vacuum structure-based acceleration, dielectric wakefield acceleration, and laser-structure acceleration.

  20. Formation and propagation of laser-driven plasma jets in an ambient medium studied with X-ray radiography and optical diagnostics

    SciTech Connect (OSTI)

    Dizière, A.; Pelka, A.; Ravasio, A.; Yurchak, R.; Loupias, B.; Falize, E.; Kuramitsu, Y.; Sakawa, Y.; Morita, T.; Pikuz, S.; Koenig, M.

    2015-01-15

    In this paper, we present experimental results obtained on the LULI2000 laser facility regarding structure and dynamics of astrophysical jets propagating in interstellar medium. The jets, generated by using a cone-shaped target, propagate in a nitrogen gas that mimics the interstellar medium. X-ray radiography as well as optical diagnostics were used to probe both high and low density regions. In this paper, we show how collimation of the jets evolves with the gas density.

  1. Laser research shows promise for cancer treatment

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Cancer treatment Laser research shows promise for cancer treatment Scientists have observed for the first time how a laser penetrates dense, electron-rich plasma to generate ions. August 20, 2012 Sasi Palaniyappan, right, and Rahul Shah inside a target chamber where the TRIDENT short pulse laser is aimed at a very thin foil target. Sasi Palaniyappan, right, and Rahul Shah inside a target chamber where the TRIDENT short pulse laser is aimed at a very thin foil target. Contact Nancy Ambrosiano

  2. OMEGA EP Experimental Systems - Laboratory for Laser Energetics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Experimental Systems - Laboratory for Laser Energetics Laboratory for Laser Energetics Logo Search Home Around the Lab Past Issues Past Quick Shots About Office of the Director Map to LLE LLE Tours LLE Building Map Partnerships Careers Education Undergraduate Program Graduate Program High School Program Faculty Contacts Computational Astrophysics H-E-D Physics Inertial Confinement Fusion Laser-Plasma Interaction Radiative Hydrodynamics Plasma Astrophysics Organization Director's Office Laser

  3. Beam-driven acceleration in ultra-dense plasma media

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Shin, Young-Min

    2014-09-15

    Accelerating parameters of beam-driven wakefield acceleration in an extremely dense plasma column has been analyzed with the dynamic framed particle-in-cell plasma simulator, and compared with analytic calculations. In the model, a witness beam undergoes a TeV/m scale alternating potential gradient excited by a micro-bunched drive beam in a 1025 m-3 and 1.6 x 1028 m-3 plasma column. The acceleration gradient, energy gain, and transformer ratio have been extensively studied in quasi-linear, linear-, and blowout-regimes. The simulation analysis indicated that in the beam-driven acceleration system a hollow plasma channel offers 20 % higher acceleration gradient by enlarging the channel radius (r)more » from 0.2 Ap to 0.6 .Ap in a blowout regime. This paper suggests a feasibility of TeV/m scale acceleration with a hollow crystalline structure (e.g. nanotubes) of high electron plasma density.« less

  4. Stimulated forward Raman scattering in large scale-length laser...

    Office of Scientific and Technical Information (OSTI)

    Stimulated forward Raman scattering in large scale-length laser-produced plasmas Citation Details In-Document Search Title: Stimulated forward Raman scattering in large ...

  5. Characterization of Heat-Wave Propagation through Laser-Driven...

    Office of Scientific and Technical Information (OSTI)

    Characterization of Heat-Wave Propagation through Laser-Driven Ti-Doped Underdense Plasma Citation Details In-Document Search Title: Characterization of Heat-Wave Propagation...

  6. Supersonic Heat Wave Propagation in Laser-Produced Underdense...

    Office of Scientific and Technical Information (OSTI)

    Conference: Supersonic Heat Wave Propagation in Laser-Produced Underdense Plasma for Efficient X-Ray Generation Citation Details In-Document Search Title: Supersonic Heat Wave...

  7. Supersonic Heat Wave Propagation in Laser-Produced Underdense...

    Office of Scientific and Technical Information (OSTI)

    Supersonic Heat Wave Propagation in Laser-Produced Underdense Plasma for Efficient X-Ray Generation Citation Details In-Document Search Title: Supersonic Heat Wave Propagation in...

  8. Metal vapor laser including hot electrodes and integral wick

    DOE Patents [OSTI]

    Ault, E.R.; Alger, T.W.

    1995-03-07

    A metal vapor laser, specifically one utilizing copper vapor, is disclosed herein. This laser utilizes a plasma tube assembly including a thermally insulated plasma tube containing a specific metal, e.g., copper, and a buffer gas therein. The laser also utilizes means including hot electrodes located at opposite ends of the plasma tube for electrically exciting the metal vapor and heating its interior to a sufficiently high temperature to cause the metal contained therein to vaporize and for subjecting the vapor to an electrical discharge excitation in order to lase. The laser also utilizes external wicking arrangements, that is, wicking arrangements located outside the plasma tube. 5 figs.

  9. Metal vapor laser including hot electrodes and integral wick

    DOE Patents [OSTI]

    Ault, Earl R.; Alger, Terry W.

    1995-01-01

    A metal vapor laser, specifically one utilizing copper vapor, is disclosed herein. This laser utilizes a plasma tube assembly including a thermally insulated plasma tube containing a specific metal, e.g., copper, and a buffer gas therein. The laser also utilizes means including hot electrodes located at opposite ends of the plasma tube for electrically exciting the metal vapor and heating its interior to a sufficiently high temperature to cause the metal contained therein to vaporize and for subjecting the vapor to an electrical discharge excitation in order to lase. The laser also utilizes external wicking arrangements, that is, wicking arrangements located outside the plasma tube.

  10. PLASMA GENERATOR

    DOE Patents [OSTI]

    Foster, J.S. Jr.

    1958-03-11

    This patent describes apparatus for producing an electricity neutral ionized gas discharge, termed a plasma, substantially free from contamination with neutral gas particles. The plasma generator of the present invention comprises a plasma chamber wherein gas introduced into the chamber is ionized by a radiofrequency source. A magnetic field is used to focus the plasma in line with an exit. This magnetic field cooperates with a differential pressure created across the exit to draw a uniform and uncontaminated plasma from the plasma chamber.

  11. The behavior of the electron plasma boundary in ultraintense laser–highly overdense plasma interaction

    SciTech Connect (OSTI)

    Sánchez-Arriaga, G.; Sanz, J.; Debayle, A.; Lehmann, G.

    2014-12-15

    The structural stability of the laser/plasma interaction is discussed, for the case of a linearly polarized laser beam interacting with a solid at normal incidence. Using a semi-analytical cold fluid model, the dynamics of the electron plasma boundary (EPB), usually related to the high-order harmonic generation and laser absorption, are presented. While the well-known J × B plasma oscillations at two times the laser frequency are recovered by the model, several other periodic in time stable solutions exist for exactly the same value of the physical parameters. This novel behavior highlights the importance of the laser pulse history among other factors. Some important features, such as the synchronization between the incident laser and the EPB oscillation, depend on the solution under consideration. A description of the possible types of stable oscillations in a parametric plane involving plasma density and laser amplitude is presented. The semi-analytical model is compared with particle-in-cell and semi-Lagrangian Vlasov simulations. They show that, among all the stable solutions, the plasma preferentially evolves to a state with the EPB oscillating twice faster than the laser. The effect of the plasma temperature and the existence of a ramp in the ion density profile are also discussed.

  12. Princeton Plasma Physics Laboratory:

    SciTech Connect (OSTI)

    Phillips, C.A.

    1986-01-01

    This paper discusses progress on experiments at the Princeton Plasma Physics Laboratory. The projects and areas discussed are: Principal Parameters Achieved in Experimental Devices, Tokamak Fusion Test Reactor, Princeton Large Torus, Princeton Beta Experiment, S-1 Spheromak, Current-Drive Experiment, X-ray Laser Studies, Theoretical Division, Tokamak Modeling, Spacecraft Glow Experiment, Compact Ignition Tokamak, Engineering Department, Project Planning and Safety Office, Quality Assurance and Reliability, and Administrative Operations.

  13. Laser Roadshow

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    outreach / laser roadshow Laser Roadshow The NIF Laser Roadshow includes a number of interactive laser demonstrations (Laser Light Fountain, Laser DJ, and NIF "3D ride") that have traveled across the country to museums and science fairs to bring awareness and education to students and the general public about lasers and how they function. These demonstrations have been presented at the Lawrence Hall of Science, the National Boy Scout Jamboree, meetings of the American Association for

  14. Fiber optic mounted laser driven flyer plates

    SciTech Connect (OSTI)

    Paisley, D.L.

    1990-12-31

    This invention is comprised of a laser driven flyer plate where the flyer plate is deposited directly onto the squared end of an optical fiber. The plasma generated by a laser pulse drives the flyer plate toward a target. In another embodiment, a first metal layer is deposited onto the squared end of an optical fiber, followed by a layer of a dielectric material and a second metal layer. The laser pulse generates a plasma in the first metal layer, but the plasma is kept away from the second metal layer by the dielectric layer until the pressure reaches the point where shearing occurs. 2 figs.

  15. Fiber optic mounted laser driven flyer plates

    SciTech Connect (OSTI)

    Paisley, D.L.

    1991-07-09

    A laser driven flyer plate is described where the flyer plate is deposited directly onto the squared end of an optical fiber. The plasma generated by a laser pulse drives the flyer plate toward a target. In another embodiment, a first metal layer is deposited onto the squared end of an optical fiber, followed by a layer of a dielectric material and a second metal layer. The laser pulse generates a plasma in the first metal layer, but the plasma is kept away from the second metal layer by the dielectric layer until the pressure reaches the point where shearing occurs.

  16. Fiber optic mounted laser driven flyer plates

    SciTech Connect (OSTI)

    Paisley, D.L.

    1990-01-01

    This invention is comprised of a laser driven flyer plate where the flyer plate is deposited directly onto the squared end of an optical fiber. The plasma generated by a laser pulse drives the flyer plate toward a target. In another embodiment, a first metal layer is deposited onto the squared end of an optical fiber, followed by a layer of a dielectric material and a second metal layer. The laser pulse generates a plasma in the first metal layer, but the plasma is kept away from the second metal layer by the dielectric layer until the pressure reaches the point where shearing occurs. 2 figs.

  17. Fiber optic mounted laser driven flyer plates

    DOE Patents [OSTI]

    Paisley, Dennis L. (Santa Fe, NM)

    1991-01-01

    A laser driven flyer plate where the flyer plate is deposited directly onto the squared end of an optical fiber. The plasma generated by a laser pulse drives the flyer plate toward a target. In another embodiment, a first metal layer is deposited onto the squared end of an optical fiber, followed by a layer of a dielectric material and a second metal layer. The laser pulse generates a plasma in the first metal layer, but the plasma is kept away from the second metal layer by the dielectric layer until the pressure reaches the point where shearing occurs.

  18. Fabrication of nanoscale patterns in lithium fluoride crystal using a 13.5 nm Schwarzschild objective and a laser produced plasma source

    SciTech Connect (OSTI)

    Wang Xin; Mu Baozhong; Jiang Li; Zhu Jingtao; Yi Shengzhen; Wang Zhanshan; He Pengfei

    2011-12-15

    Lithium fluoride (LiF) crystal is a radiation sensitive material widely used as EUV and soft x-ray detector. The LiF-based detector has high resolution, in principle limited by the point defect size, large field of view, and wide dynamic range. Using LiF crystal as an imaging detector, a resolution of 900 nm was achieved by a projection imaging of test meshes with a Schwarzschild objective operating at 13.5 nm. In addition, by imaging of a pinhole illuminated by the plasma, an EUV spot of 1.5 {mu}m diameter in the image plane of the objective was generated, which accomplished direct writing of color centers with resolution of 800 nm. In order to avoid sample damage and contamination due to the influence of huge debris flux produced by the plasma source, a spherical normal-incidence condenser was used to collect EUV radiation. Together with a description of experimental results, the development of the Schwarzschild objective, the influence of condenser on energy density and the alignment of the imaging system are also reported.

  19. Plasma Physics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    plasma physics Plasma Physics Almost all of the observable matter in the universe is in the plasma state. Formed at high temperatures, plasmas consist of freely moving ions and free electrons. They are often called the "fourth state of matter" because their unique physical properties distinguish them from solids, liquids and gases. Plasma densities and temperatures vary widely, from the cold gases of interstellar space to the extraordinarily hot, dense cores of stars and inside a

  20. Spatiotemporal focusing dynamics in plasmas at X-ray wavelength

    SciTech Connect (OSTI)

    Sharma, A., E-mail: a-physics2001@yahoo.com; Tibai, Z. [Institute of Physics, University of Pecs, Pecs7624 (Hungary)] [Institute of Physics, University of Pecs, Pecs7624 (Hungary); Hebling, J. [Institute of Physics, University of Pecs, Pecs7624 (Hungary) [Institute of Physics, University of Pecs, Pecs7624 (Hungary); Szentagothai Research Centre, University of Pecs, Pecs-7624 (Hungary); Mishra, S. K. [Institute for Plasma Research, Gandhinagar (India)] [Institute for Plasma Research, Gandhinagar (India)

    2014-03-15

    Using a finite curvature beam, we investigate here the spatiotemporal focusing dynamics of a laser pulse in plasmas at X-ray wavelength. We trace the dependence of curvature parameter on the focusing of laser pulse and recognize that the self-focusing in plasma is more intense for the X-ray laser pulse with curved wavefront than with flat wavefront. The simulation results demonstrate that spatiotemporal focusing dynamics in plasmas can be controlled with the appropriate choice of beam-plasma parameters to explore the high intensity effects in X-ray regime.