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1

Laser Wakefield Particle Accelerators Project at NERSC  

NLE Websites -- All DOE Office Websites (Extended Search)

Laser Wakefield Particle Acceleration Laser Wakefield Particle Acceleration Vorpal.jpg Key Challenges: Design of multiple-staged, 10-GeV laser-wakefield plasma accelerated...

2

Laser-driven plasma-based accelerators: Wakefield excitation, channel guiding, and laser triggered particle injection*  

E-Print Network (OSTI)

Laser-driven plasma-based accelerators: Wakefield excitation, channel guiding, and laser triggered; accepted 18 February 1998 Plasma-based accelerators are discussed in which high-power short pulse lasers are the power source, suitably tailored plasma structures provide guiding of the laser beam and support large

Wurtele, Jonathan

3

Laser-PlasmaWakefield Acceleration with Higher Order Laser Modes  

E-Print Network (OSTI)

Design considerations for a laser-plasma linear collider,"E.Esarey, and W.P.Leemans, "Free-electron laser driven bythe LBNL laser-plasma accelerator," in Proc. Adv. Acc. Con.

Geddes, C.G.R.

2011-01-01T23:59:59.000Z

4

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

Office of Science (SC) Website

Two GeV Electrons Achieved by Laser Plasma Wakefield Acceleration 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 News & 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: sc.hep@science.doe.gov More Information » July 2013 Two GeV Electrons Achieved by Laser Plasma Wakefield Acceleration Scientists at University of Texas, Austin, accelerate electrons to 2 GeV in table top apparatus. Print Text Size: A A A Subscribe FeedbackShare Page Click to enlarge photo. Enlarge Photo Image courtesy of Neil Fazel The inside of the University of Texas, Austin, vacuum chamber where

5

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

SciTech Connect

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.

Afhami, Saeedeh; Eslami, Esmaeil, E-mail: eeslami@iust.ac.ir [Department of Physics, Iran University of Science and Technology (IUST), Narmak, Tehran 16846-13114 (Iran, Islamic Republic of)

2014-06-15T23:59:59.000Z

6

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

SciTech Connect

he 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 structure in the laser energy density produced by the combined pulses exists 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.

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

2014-05-01T23:59:59.000Z

7

Plasma Wakefield Acceleration  

NLE Websites -- All DOE Office Websites (Extended Search)

rpwa rpwa Sign In Launch the Developer Dashboard SLAC National Accelerator Laboratory DOE | Stanford | SLAC | SSRL | LCLS | AD | PPA | Photon Science | PULSE | SIMES FACET User Facility : FACET An Office of Science User Facility Search this site... Search Help (new window) Top Link Bar FACET User Facility FACET Home About FACET FACET Experimental Facilities FACET Users Research at FACET SAREC Expand SAREC FACET FAQs FACET User Facility Quick Launch FACET Users Home FACET Division ARD Home About FACET FACET News FACET Users FACET Experimental Facilities FACET Research Expand FACET Research FACET Images Expand FACET Images SAREC Expand SAREC FACET Project Site (restricted) FACET FAQs FACET Site TOC All Site Content Department of Energy Page Content Plasma Wakefield Acceleration

8

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

E-Print Network (OSTI)

and W.P. Leemans, Phys. Plasmas 18, 083103 (2011). 34 C.IEEE Transactions on plasma science 36, 1790 (2008). 35 C.Plasma wakefields driven by an incoherent combination of

Benedetti, C

2014-01-01T23:59:59.000Z

9

Unphysical kinetic effects in particle-in-cell modeling of laser wakefield accelerators Estelle Cormier-Michel,1,2  

E-Print Network (OSTI)

Unphysical kinetic effects in particle-in-cell modeling of laser wakefield accelerators Estelle of laser wakefield accelerators using particle-in-cell codes are investigated. A dark current free laser wakefield accelerator stage, in which no trapping of background plasma electrons into the plasma wave should

Geddes, Cameron Guy Robinson

10

A multi-beam, multi-terawatt Ti:sapphire laser system for laser wake-field acceleration studies  

E-Print Network (OSTI)

­plasma interaction studies, such as development of laser wake-field accelerators [1-4], X-ray lasers, and laserA multi-beam, multi-terawatt Ti:sapphire laser system for laser wake-field acceleration studies 71R0259, 1 Cyclotron Rd., Berkeley, CA 94720, USA, e-mail: ctoth@lbl.gov Abstract. The Lasers

Geddes, Cameron Guy Robinson

11

Modeling Laser Wakefield Accelerators in a Lorentz Boosted Frame  

NLE Websites -- All DOE Office Websites (Extended Search)

Modeling Laser Wakefield Accelerators in a Lorentz Boosted Frame Modeling Laser Wakefield Accelerators in a Lorentz Boosted Frame VayBoost.gif An image showing the "boosted frame,"...

12

Modeling Laser Wakefield Accelerators in a Lorentz Boosted Frame  

NLE Websites -- All DOE Office Websites (Extended Search)

Modeling Laser Modeling Laser Wakefield Accelerators in a Lorentz Boosted Frame Modeling Laser Wakefield Accelerators in a 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 wakefields are colored pale blue and yellow. In this frame, the plasma (yellow box) has contracted and the wavefronts are fewer and farther apart, resulting in far fewer calculations and faster results. Why it Matters: Laser driven plasma waves can produce accelerating gradients orders of magnitude greater than standard accelerating structures. High quality electron beams of energy up to 1 GeV have been produced in just a few centimeters and 10-GeV stages being planned as

13

Ultrafast Diagnostics for Electron Beams from Laser Plasma Accelerators  

E-Print Network (OSTI)

for Laser Plasma Accelerators," in this proceedings, 2010.Based Laser Wakefield Accelerator Electron Beam EnergyMotion in a Laser-Plasma Accelerator," in this proceedings,

Matlis, N. H.

2011-01-01T23:59:59.000Z

14

Frequency chirp and pulse shape effects in self-modulated laser wakefield acceleratorsa...  

E-Print Network (OSTI)

laser-plasma-based harmonic generation,2 x-ray lasers,3 and laser-driven inertial confinement fusionFrequency chirp and pulse shape effects in self-modulated laser wakefield acceleratorsa... C. B Received 7 November 2002; accepted 20 January 2003 The effect of asymmetric laser pulses on plasma wave

Geddes, Cameron Guy Robinson

15

Laser guiding for GeV laserplasma accelerators  

Science Journals Connector (OSTI)

...plasma-beat-wave accelerator. Phys. Rev...Singhal2003Applications for nuclear phenomena generated...laser wakefield accelerators. Phys. Plasmas...crossing a plasma-vacuum boundary. Phys...laser wakefield accelerators. Phys. Plasmas...generated at a plasma-vacuum interface. Phys...

2006-01-01T23:59:59.000Z

16

Development of high gradient laser wakefield accelerators towards nuclear detection applications at LBNL  

E-Print Network (OSTI)

laser wakefield accelerators towards nuclear detectionRecent laser wakefield accelerator experiments at LBNLscaling of laser driven accelerators to GeV energies. Stable

Geddes, Cameron GR

2010-01-01T23:59:59.000Z

17

A compact synchrotron radiation source driven by a laser-plasma wakefield  

E-Print Network (OSTI)

. By demonstrating the wavelength scaling with energy, and narrow-bandwidth spectra, we show the potential-cavity electrical breakdown. In contrast, a plasma, which is already fully broken down, can sustain electric fields proposed harnessing the large ponderomotive forces--arising from the light pressure exerted by intense

Loss, Daniel

18

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

SciTech Connect

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.

Ju, J.; Dpp, A.; Cros, B. [Laboratoire de Physique des Gaz et des Plasmas, CNRS-Universit Paris-Sud, 91405 Orsay (France)] [Laboratoire de Physique des Gaz et des Plasmas, CNRS-Universit Paris-Sud, 91405 Orsay (France); Svensson, K.; Genoud, G.; Wojda, F.; Burza, M.; Persson, A.; Lundh, O.; Wahlstrm, C.-G. [Department of Physics, Lund University, P.O. Box 118, S-22100 Lund (Sweden)] [Department of Physics, Lund University, P.O. Box 118, S-22100 Lund (Sweden); Ferrari, H. [Consejo Nacional de Investigaciones Cientficas y Tcnicas (CONICET) and CNEA-CAB (Argentina)] [Consejo Nacional de Investigaciones Cientficas y Tcnicas (CONICET) and CNEA-CAB (Argentina)

2013-08-15T23:59:59.000Z

19

Results from Plasma Wakefield Experiments at FACET  

SciTech Connect

We report initial results of the Plasma Wakefield Acceleration (PWFA) Experiments performed at FACET - Facility for Advanced aCcelertor Experimental Tests at SLAC National Accelerator Laboratory. At FACET a 23 GeV electron beam with 1.8 x 10{sup 10} electrons is compressed to 20 {mu}m longitudinally and focused down to 10 {mu}m x 10 {mu}m transverse spot size for user driven experiments. Construction of the FACET facility completed in May 2011 with a first run of user assisted commissioning throughout the summer. The first PWFA experiments will use single electron bunches combined with a high density lithium plasma to produce accelerating gradients > 10 GeV/m benchmarking the FACET beam and the newly installed experimental hardware. Future plans for further study of plasma wakefield acceleration will be reviewed. The experimental hardware and operation of the plasma heat-pipe oven have been successfully commissioned. Plasma wakefield acceleration was not observed because the electron bunch density was insufficient to ionize the lithium vapor. The remaining commissioning time in summer 2011 will be dedicated to delivering the FACET design parameters for the experimental programs which will begin in early 2012. PWFA experiments require the shorter bunches and smaller transverse sizes to create the plasma and drive large amplitude wakefields. Low emittance and high energy will minimize head erosion which was found to be a limiting factor in acceleration distance and energy gain. We will run the PWFA experiments with the design single bunch conditions in early 2012. Future PWFA experiments at FACET are discussed in [5][6] and include drive and witness bunch production for high energy beam manipulation, ramped bunch to optimize tranformer ratio, field-ionized cesium plasma, preionized plasmas, positron acceleration, etc.. We will install a notch collimator for two-bunch operation as well as new beam diagnostics such as the X-band TCAV [7] to resolve the two bunches. With these new instruments and desired beam parameters in place next year, we will be able to complete the studies of plasma wakefield acceleration in the next few years.

Li, S.Z.; Clarke, C.I.; England, R.J.; Frederico, J.; Gessner, S.J.; Hogan, M.J.; Jobe, R.K.; Litos, M.D.; Walz, D.R.; /SLAC; Muggli, P.; /Munich, Max Planck Inst.; An, W.; Clayton, C.E.; Joshi, C.; Lu, W.; Marsh, K.A.; Mori, W.; Tochitsky, S.; /UCLA; Adli, E.; /U. Oslo

2011-12-13T23:59:59.000Z

20

Multimode Analysis of the Hollow Plasma Channel Wakefield Accelerator C. B. Schroeder,1  

E-Print Network (OSTI)

this breakdown constraint. Two schemes of plasma excitation have been the focus of much of the work: the laserMultimode Analysis of the Hollow Plasma Channel Wakefield Accelerator C. B. Schroeder,1 D. H April 1998) The hollow plasma channel is analyzed as an accelerating structure. The excitation

Geddes, Cameron Guy Robinson

Note: This page contains sample records for the topic "laser plasma wakefield" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Plasma Focusing & Dielectric Wakefield Acceleration  

NLE Websites -- All DOE Office Websites (Extended Search)

pf pf Sign In Launch the Developer Dashboard SLAC National Accelerator Laboratory DOE | Stanford | SLAC | SSRL | LCLS | AD | PPA | Photon Science | PULSE | SIMES FACET User Facility : FACET An Office of Science User Facility Search this site... Search Help (new window) Top Link Bar FACET User Facility FACET Home About FACET FACET Experimental Facilities FACET Users Research at FACET SAREC Expand SAREC FACET FAQs FACET User Facility Quick Launch FACET Users Home FACET Division ARD Home About FACET FACET News FACET Users FACET Experimental Facilities FACET Research Expand FACET Research FACET Images Expand FACET Images SAREC Expand SAREC FACET Project Site (restricted) FACET FAQs FACET Site TOC All Site Content Department of Energy Page Content Plasma Focusing & Dielectric Wakefield Acceleration

22

Proton-driven plasma wakefield acceleration: a path to the future of high-energy particle physics  

E-Print Network (OSTI)

New acceleration technology is mandatory for the future elucidation of fundamental particles and their interactions. A promising approach is to exploit the properties of plasmas. Past research has focused on creating large-amplitude plasma waves by injecting an intense laser pulse or an electron bunch into the plasma. However, the maximum energy gain of electrons accelerated in a single plasma stage is limited by the energy of the driver. Proton bunches are the most promising drivers of wakefields to accelerate electrons to the TeV energy scale in a single stage. An experimental program at CERN -- the AWAKE experiment -- has been launched to study in detail the important physical processes and to demonstrate the power of proton-driven plasma wakefield acceleration. Here we review the physical principles and some experimental considerations for a future proton-driven plasma wakefield accelerator.

Assmann, R; Bohl, T; Bracco, C; Buttenschon, B; Butterworth, A; Caldwell, A; Chattopadhyay, S; Cipiccia, S; Feldbaumer, E; Fonseca, R A; Goddard, B; Gross, M; Grulke, O; Gschwendtner, E; Holloway, J; Huang, C; Jaroszynski, D; Jolly, S; Kempkes, P; Lopes, N; Lotov, K; Machacek, J; Mandry, S R; McKenzie, J W; Meddahi, M; Militsyn, B L; Moschuering, N; Muggli, P; Najmudin, Z; Noakes, T C Q; Norreys, P A; Oz, E; Pardons, A; Petrenko, A; Pukhov, A; Rieger, K; Reimann, O; Ruhl, H; Shaposhnikova, E; Silva, L O; Sosedkin, A; Tarkeshian, R; Trines, R M G N; Tuckmantel, T; Vieira, J; Vincke, H; Wing, M; Xia, G

2014-01-01T23:59:59.000Z

23

Two-Screen Method for Determining Electron Beam Energy and Deflection from Laser Wakefield Acceleration  

SciTech Connect

Laser Wakefield Acceleration (LWFA) experiments have been performed at the Jupiter Laser Facility, Lawrence Livermore National Laboratory. In order to unambiguously determine the output electron beam energy and deflection angle at the plasma exit, we have implemented a two-screen electron spectrometer. This system is comprised of a dipole magnet followed by two image plates. By measuring the electron beam deviation from the laser axis on each plate, both the energy and deflection angle at the plasma exit are determined through the relativistic equation of motion.

Pollock, B B; Ross, J S; Tynan, G R; Divol, L; Glenzer, S H; Leurent, V; Palastro, J P; Ralph, J E; Froula, D H; Clayton, C E; Marsh, K A; Pak, A E; Wang, T L; Joshi, C

2009-04-24T23:59:59.000Z

24

VOLUME 82, NUMBER 6 P H Y S I C A L R E V I E W L E T T E R S 8 FEBRUARY 1999 Multimode Analysis of the Hollow Plasma Channel Wakefield Accelerator  

E-Print Network (OSTI)

. Two schemes of plasma excitation have been the focus of much of the work: the laser wakefield of the Hollow Plasma Channel Wakefield Accelerator C. B. Schroeder,1 D. H. Whittum,2 and J. S. Wurtele1,3 1 Berkeley National Laboratory, Berkeley, California 94720 (Received 1 April 1998) The hollow plasma channel

Wurtele, Jonathan

25

Frequency chirp and pulse shape effects in self-modulated laser wakefield accelerators  

SciTech Connect

The effect of asymmetric laser pulses on plasma wave excitation in a self-modulated laser wakefield accelerator is examined. Laser pulse shape and frequency chirp asymmetries, controlled experimentally in the laser system through a grating pair compressor, are shown to strongly enhance measured electron yields for certain asymmetries. It is shown analytically that a positive (negative) frequency chirp enhances (suppresses) the growth rate of the Raman forward scattering and near-forward Raman sidescatter instabilities, but is of minimal importance for the experimental parameters. Temporal laser pulse shapes with fast rise times (< plasma period) are shown to generate larger wakes (compared to slow rise time pulses) which seed the growth of the plasma wave, resulting in enhanced electron yield.

Schroeder, C.B.; Esarey, E.; Geddes, C.G.R.; Toth, Cs.; Shadwick, B.A.; van Tilborg, J.; Faure, J.; Leemans, W.P.

2002-11-07T23:59:59.000Z

26

Emittance Measurements of Trapped Electrons from a Plasma Wakefield Accelerator  

SciTech Connect

Recent electron beam driven plasma wakefield accelerator experiments carried out at SLAC showed trapping of plasma electrons. These trapped electrons appeared on an energy spectrometer with smaller transverse size than the beam driving the wake. A connection is made between transverse size and emittance; due to the spectrometer's resolution, this connection allows for placing an upper limit on the trapped electron emittance. The upper limit for the lowest normalized emittance measured in the experiment is 1 mm {center_dot} mrad.

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

2007-06-28T23:59:59.000Z

27

Physics of Laser-driven plasma-based acceleration  

SciTech Connect

The physics of plasma-based accelerators driven by short-pulse lasers is reviewed. This includes the laser wake-field accelerator, the plasma beat wave accelerator, the self-modulated laser wake-field accelerator, and plasma waves driven by multiple laser pulses. The properties of linear and nonlinear plasma waves are discussed, as well as electron acceleration in plasma waves. Methods for injecting and trapping plasma electrons in plasma waves are also discussed. Limits to the electron energy gain are summarized, including laser pulse direction, electron dephasing, laser pulse energy depletion, as well as beam loading limitations. The basic physics of laser pulse evolution in underdense plasmas is also reviewed. This includes the propagation, self-focusing, and guiding of laser pulses in uniform plasmas and plasmas with preformed density channels. Instabilities relevant to intense short-pulse laser-plasma interactions, such as Raman, self-modulation, and hose instabilities, are discussed. Recent experimental results are summarized.

Esarey, Eric; Schroeder, Carl B.

2003-06-30T23:59:59.000Z

28

Measurement of the Decelerating Wake in a Plasma Wakefield Accelerator  

SciTech Connect

Recent experiments at SLAC have shown that high gradient acceleration of electrons is achievable in meter scale plasmas. Results from these experiments show that the wakefield is sensitive to parameters in the electron beam which drives it. In the experiment the bunch lengths were varied systematically at constant charge. The effort to extract a measurement of the decelerating wake from the maximum energy loss of the electron beam is discussed.

Blumenfeld, I.; Decker, F. J.; Hogan, M. J.; Ischebeck, R.; Iverson, R. H.; Kirby, N.; Siemann, R. H.; Walz, D. R. [Stanford Linear Accelerator Center, Stanford University, Stanford, California 94305 (United States); Clayton, C. E.; Huang, C.; Joshi, C.; Lu, W.; Marsh, K. A.; Mori, W. B.; Zhou, M. [University of California, Los Angeles, California 90095 (United States); Katsouleas, T.; Muggli, P.; Oz, E. [University of Southern California, Los Angeles, California 90089 (United States)

2009-01-22T23:59:59.000Z

29

Mesurement of the Decelerating Wake in a Plasma Wakefield Accelerator  

SciTech Connect

Recent experiments at SLAC have shown that high gradient acceleration of electrons is achievable in meter scale plasmas. Results from these experiments show that the wakefield is sensitive to parameters in the electron beam which drives it. In the experiment the bunch lengths were varied systematically at constant charge. The effort to extract a measurement of the decelerating wake from the maximum energy loss of the electron beam is discussed.

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

2008-09-24T23:59:59.000Z

30

Beam Head Erosion in Self-Ionized Plasma Wakefield Accelerators  

SciTech Connect

In the recent plasma wakefield accelerator experiments at SLAC, the energy of the particles in the tail of the 42 GeV electron beam were doubled in less than one meter [1]. Simulations suggest that the acceleration length was limited by a new phenomenon--beam head erosion in self-ionized plasmas. In vacuum, a particle beam expands transversely in a distance given by {beta}*. In the blowout regime of a plasma wakefield [2], the majority of the beam is focused by the ion channel, while the beam head slowly spreads since it takes a finite time for the ion channel to form. It is observed that in self-ionized plasmas, the head spreading is exacerbated compared to that in pre-ionized plasmas, causing the ionization front to move backward (erode). A simple theoretical model is used to estimate the upper limit of the erosion rate for a bi-gaussian beam by assuming free expansion of the beam head before the ionization front. Comparison with simulations suggests that half this maximum value can serve as an estimate for the erosion rate. Critical parameters to the erosion rate are discussed.

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

2008-01-28T23:59:59.000Z

31

Laser wakefield simulation using a speed-of-light frame envelope model  

E-Print Network (OSTI)

Laser wakefield simulation using a speed-of-light frame envelope model B. Cowan , D. Bruhwiler , E. By propagating the laser envelope in a frame moving at the speed of light, dispersive errors can be avoided

Geddes, Cameron Guy Robinson

32

Self-Guided Laser Wakefield Acceleration beyond 1 GeV Using Ionization-Induced Injection  

SciTech Connect

The concepts of matched-beam, self-guided laser propagation and ionization-induced injection have been combined to accelerate electrons up to 1.45 GeV energy in a laser wakefield accelerator. From the spatial and spectral content of the laser light exiting the plasma, we infer that the 60 fs, 110 TW laser pulse is guided and excites a wake over the entire 1.3 cm length of the gas cell at densities below 1.5x10{sup 18} cm{sup -3}. High-energy electrons are observed only when small (3%) amounts of CO{sub 2} gas are added to the He gas. Computer simulations confirm that it is the K-shell electrons of oxygen that are ionized and injected into the wake and accelerated to beyond 1 GeV energy.

Clayton, C. E.; Joshi, C.; Lu, W.; Marsh, K. A.; Mori, W. B.; Pak, A.; Tsung, F. S. [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); Ralph, J. E.; Albert, F.; Glenzer, S. H.; Froula, D. H. [L-399, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States); Fonseca, R. A.; Martins, S. F.; Silva, L. O. [GoLP/IPFN-LA, Instituto Superior Tecnico, Lisboa (Portugal); Pollock, B. B.; Ross, J. S. [L-399, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States); MAE Department, University of California, San Diego, La Jolla, California 92093 (United States)

2010-09-03T23:59:59.000Z

33

Measurement of the Betatron Radiation Spectrum Coming From a Laser Wakefield Accelerator  

SciTech Connect

A Laser Wakefield Accelerator (LWFA) is under development at Lawrence Livermore National Laboratory (LLNL) to produce electron bunches with GeV class energy and energy spreads of a few-percent. The ultimate goal is to provide a bright and compact photon source for high energy density physics. The interaction of a high power (200 TW), short pulse (50 fs) laser with neutral He gas can generate quasi-monoenergetic electron beams at energies up to 1 GeV. The laser pulse can be self-guided over a dephasing length of 1 cm (for a plasma density of 1.5 x 10{sup 18} cm{sup -3}) overcoming the limitation of vacuum diffraction. Betatron radiation is emitted while the accelerated electrons undergo oscillations in the wakefield electrostatic field. Here we present electron spectra measurements with a two screen spectrometer allowing to fix the ambiguities due to electron deflections at the plasma exit. They have measured monoenergetic electron beams above 300 MeV. Furthermore a forward directed x-ray beam is observed. The measured betatron spectrum agrees well with the calculated spectrum in the synchrotron asymptotic limit (SAL) using the measured electron beam parameters.

Leurent, V; Michel, P; Clayton, C E; Pollock, B; Doeppner, T; Wang, T L; Ralph, J; Pak, A; Marsh, K; Joshi, C; Tynan, G R; Divol, L; Palastro, J P; Glenzer, S H; Froula, D H

2008-08-12T23:59:59.000Z

34

Meter scale plasma source for plasma wakefield experiments  

SciTech Connect

High accelerating gradients generated by a high density electron beam moving through plasma has been used to double the energy of the SLAC electron beam [1]. During that experiment, the electron current density was high enough to generate its own plasma without significant head erosion. In the newly commissioned FACET facility at SLAC, the peak current will be lower and without pre-ionization, head erosion will be a significant challenge for the planned experiments. In this work we report on our design of a meter scale plasma source for these experiments to effectively avoid the problem of head erosion. The plasma source is based on a homogeneous metal vapor gas column that is generated in a heat pipe oven [2]. A lithium oven over 30 cm long at densities over 10{sup 17} cm{sup -3} has been constructed and tested at UCLA. The plasma is then generated by coupling a 10 TW short pulse Ti:Sapphire laser into the gas column using an axicon lens setup. The Bessel profile of the axicon setup creates a region of high intensity that can stretch over the full length of the gas column with approximately constant diameter. In this region of high intensity, the alkali metal vapor is ionized through multi-photon ionization process. In this manner, a fully ionized meter scale plasma of uniform density can be formed. Methods for controlling the plasma diameter and length will also be discussed.

Vafaei-Najafabadi, N.; Shaw, J. L.; Marsh, K. A.; Joshi, C.; Hogan, M. J. [Department of Electrical Engineering, University of California Los Angeles, Los Angeles, CA 90095 (United States); SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States)

2012-12-21T23:59:59.000Z

35

Effect of plasma inhomogeneity on plasma wakefield acceleration driven by long bunches  

SciTech Connect

Effects of plasma inhomogeneity on self-modulating proton bunches and accelerated electrons were studied numerically. The main effect is the change of the wakefield wavelength which results in phase shifts and loss of accelerated particles. This effect imposes severe constraints on density uniformity in plasma wakefield accelerators driven by long particle bunches. The transverse two stream instability that transforms the long bunch into a train of micro-bunches is less sensitive to density inhomogeneity than are the accelerated particles. The bunch freely passes through increased density regions and interacts with reduced density regions.

Lotov, K. V. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk, Russia and Novosibirsk State University, 630090 Novosibirsk (Russian Federation); Pukhov, A. [Institut fuer Theoretische Physik I, Heinrich-Heine-Universitaet Duesseldorf, 40225 Duesseldorf (Germany); Caldwell, A. [Max-Planck-Institut fuer Physik, 80805 Muenchen (Germany)

2013-01-15T23:59:59.000Z

36

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

SciTech Connect

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.

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

2009-06-02T23:59:59.000Z

37

UNDULATOR-BASED LASER WAKEFIELD ACCELERATOR ELECTRON BEAM DIAGNOSTIC  

SciTech Connect

to couple the THUNDER undulator to the LOASIS Lawrence Berkeley National Laboratory (LBNL) laser wakefield accelerator (LWFA). Currently the LWFA has achieved quasi-monoenergetic electron beams with energies up to 1 GeV. These ultra-short, high-peak-current, electron beams are ideal for driving a compact XUV free electron laser (FEL). Understanding the electron beam properties such as the energy spread and emittance is critical for achieving high quality light sources with high brightness. By using an insertion device such as an undulator and observing changes in the spontaneous emission spectrum, the electron beam energy spread and emittance can be measured with high precision. The initial experiments will use spontaneous emission from 1.5 m of undulator. Later experiments will use up to 5 m of undulator with a goal of a high gain, XUV FEL.

Bakeman, M.S.; Fawley, W.M.; Leemans, W. P.; Nakamura, K.; Robinson, K.E.; Schroeder, C.B.; Toth, C.

2009-05-04T23:59:59.000Z

38

Efficient operating mode of the plasma wakefield accelerator  

SciTech Connect

A new operating mode of the plasma wakefield accelerator is found at which high efficiency of the driver-to-witness energy exchange can be achieved simultaneously with high transformer ratio and low energy spread. The efficient acceleration is realized in the blowout regime with a high-current moderate-length driver, if most of the driver and the whole witness are inside the cavern, and the beams are shaped to flatten the profile of the longitudinal electric field. The efficient regime can be demonstrated with state-of-the-art electron beams, but requires a longitudinal compression of the drive beam, high density plasma, and precise control of driver and witness shapes.

Lotov, K.V. [Budker Institute of Nuclear Physics, 630090 Novosibirsk (Russian Federation)

2005-05-15T23:59:59.000Z

39

Excitation of two-dimensional plasma wakefields by trains of equidistant particle bunches  

SciTech Connect

Nonlinear effects responsible for elongation of the plasma wave period are numerically studied with the emphasis on two-dimensionality of the wave. The limitation on the wakefield amplitude imposed by detuning of the wave and the driver is found.

Lotov, K. V. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk, Russia and Novosibirsk State University, 630090 Novosibirsk (Russian Federation)] [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk, Russia and Novosibirsk State University, 630090 Novosibirsk (Russian Federation)

2013-08-15T23:59:59.000Z

40

Spectroscopy of betatron radiation emitted from laser-produced wakefield accelerated electronsa...  

E-Print Network (OSTI)

laser facilities in which the nature divergence and total x-ray flux of the betatron radiation has been is able to discern changes of the betatron emission x-ray spec- trum with differing laser parametersSpectroscopy of betatron radiation emitted from laser-produced wakefield accelerated electronsa

Geddes, Cameron Guy Robinson

Note: This page contains sample records for the topic "laser plasma wakefield" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Monte Carlo Characterization of a Pulsed Laser-Wakefield Driven Monochromatic  

E-Print Network (OSTI)

Monte Carlo Characterization of a Pulsed Laser-Wakefield Driven Monochromatic X-Ray Source S. D determination of the incident X-ray energy by using unfolding techniques. I. INTRODUCTION HE Diocles laser light from the same laser system, producing monochromatic X-rays with energy and spectral width

Umstadter, Donald

42

Properties of Trapped Electron Bunches in a Plasma Wakefield Accelerator  

SciTech Connect

Plasma-based accelerators use the propagation of a drive bunch through plasma to create large electric fields. Recent plasma wakefield accelerator (PWFA) experiments, carried out at the Stanford Linear Accelerator Center (SLAC), successfully doubled the energy for some of the 42 GeV drive bunch electrons in less than a meter; this feat would have required 3 km in the SLAC linac. This dissertation covers one phenomenon associated with the PWFA, electron trapping. Recently it was shown that PWFAs, operated in the nonlinear bubble regime, can trap electrons that are released by ionization inside the plasma wake and accelerate them to high energies. These trapped electrons occupy and can degrade the accelerating portion of the plasma wake, so it is important to understand their origins and how to remove them. Here, the onset of electron trapping is connected to the drive bunch properties. Additionally, the trapped electron bunches are observed with normalized transverse emittance divided by peak current, {epsilon}{sub N,x}/I{sub t}, below the level of 0.2 {micro}m/kA. A theoretical model of the trapped electron emittance, developed here, indicates that the emittance scales inversely with the square root of the plasma density in the non-linear 'bubble' regime of the PWFA. This model and simulations indicate that the observed values of {epsilon}{sub N,x}/I{sub t} result from multi-GeV trapped electron bunches with emittances of a few {micro}m and multi-kA peak currents. These properties make the trapped electrons a possible particle source for next generation light sources. This dissertation is organized as follows. The first chapter is an overview of the PWFA, which includes a review of the accelerating and focusing fields and a survey of the remaining issues for a plasma-based particle collider. Then, the second chapter examines the physics of electron trapping in the PWFA. The third chapter uses theory and simulations to analyze the properties of the trapped electron bunches. Chapters four and five present the experimental diagnostics and measurements for the trapped electrons. Next, the sixth chapter introduces suggestions for future trapped electron experiments. Then, Chapter seven contains the conclusions. In addition, there is an appendix chapter that covers a topic which is extraneous to electron trapping, but relevant to the PWFA. This chapter explores the feasibility of one idea for the production of a hollow channel plasma, which if produced could solve some of the remaining issues for a plasma-based collider.

Kirby, Neil; /SLAC

2009-10-30T23:59:59.000Z

43

Tunable Electron Multibunch Production in Plasma Wakefield Accelerators  

E-Print Network (OSTI)

Synchronized, independently tunable and focused $\\mu$J-class laser pulses are used to release multiple electron populations via photo-ionization inside an electron-beam driven plasma wave. By varying the laser foci in the laboratory frame and the position of the underdense photocathodes in the co-moving frame, the delays between the produced bunches and their energies are adjusted. The resulting multibunches have ultra-high quality and brightness, allowing for hitherto impossible bunch configurations such as spatially overlapping bunch populations with strictly separated energies, which opens up a new regime for light sources such as free-electron-lasers.

Hidding, B; Wittig, G; Aniculaesei, C; Jaroszynski, D; McNeil, B W J; Campbell, L T; Islam, M R; Ersfeld, B; Sheng, Z -M; Xi, Y; Deng, A; Rosenzweig, J B; Andonian, G; Murokh, A; Hogan, M J; Bruhwiler, D L; Cormier, E

2014-01-01T23:59:59.000Z

44

Physics of laser-driven plasma-based electron accelerators E. Esarey, C. B. Schroeder, and W. P. Leemans  

E-Print Network (OSTI)

Physics of laser-driven plasma-based electron accelerators E. Esarey, C. B. Schroeder, and W. P Laser-driven plasma-based accelerators, which are capable of supporting fields in excess of 100 GV/m, are reviewed. This includes the laser wakefield accelerator, the plasma beat wave accelerator, the self

Geddes, Cameron Guy Robinson

45

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

ScienceCinema (OSTI)

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.

Andrei Seryi

2010-01-08T23:59:59.000Z

46

Scaling of the Longitudinal Electric Field and Transformer Ratio in a Nonlinear Plasma Wakefield Accelerator  

SciTech Connect

The scaling of the two important figures of merit, the transformer ratio T and the longitudinal electric field E{sub z}, with the peak drive-bunch current I{sub p}, in a nonlinear plasma wakefield accelerator is presented for the first time. The longitudinal field scales as I{sub P}{sup 0.623{+-}0.007}, in good agreement with nonlinear wakefield theory ({approx}I{sub P}{sup 0.5}), while the unloaded transformer ratio is shown to be greater than unity and scales weakly with the bunch current. The effect of bunch head erosion on both parameters is also discussed.

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

2012-06-12T23:59:59.000Z

47

Emittance and Current of Electrons Trapped in a Plasma Wakefield Accelerator  

SciTech Connect

In recent experiments plasma electrons became trapped in a plasma wakefield accelerator (PWFA). The transverse size of these trapped electrons on a downstream diagnostic yields an upper limit measurement of transverse normalized emittance divided by peak current, {epsilon}{sub N,{sub x}}/I. The lowest upper limit for {epsilon}{sub N,{sub x}}/I measured in the experiment is 1.3{center_dot}10{sup -10} m/A.

Kirby, N.; Blumenfeld, I.; Decker, F. J.; Hogan, M. J.; Ischebeck, R.; Iverson, R. H.; Siemann, R. H.; Walz, D. R. [Stanford Linear Accelerator Center, Stanford University, Stanford, California 94305 (United States); Clayton, C. E.; Huang, C.; Joshi, C.; Lu, W.; Marsh, K. A.; Mori, W. B.; Zhou, M. [University of California, Los Angeles, California 90095 (United States); Katsouleas, T.; Muggli, P.; Oz, E. [University of Southern California, Los Angeles, California 90089 (United States); Martins, S. [GoLP/IPFN, Instituto Superior Tecnico (Portugal)

2009-01-22T23:59:59.000Z

48

Downramp-assisted underdense photocathode electron bunch generation in plasma wakefield accelerators  

E-Print Network (OSTI)

It is shown that the requirements for high quality electron bunch generation and trapping from an underdense photocathode in plasma wakefield accelerators can be substantially relaxed through localizing it on a plasma density downramp. This depresses the phase velocity of the accelerating electric field until the generated electrons are in phase, allowing for trapping in shallow trapping potentials. As a consequence the underdense photocathode technique is applicable by a much larger number of accelerator facilities. Furthermore, dark current generation is effectively suppressed.

Knetsch, Alexander; Wittig, Georg; Groth, Henning; Xi, Yunfeng; Deng, Aihua; Rosenzweig, James Benjamin; Bruhwiler, David Leslie; Smith, Johnathan; Jaroszynski, Dino Anthony; Sheng, Zheng-Ming; Manahan, Grace Gloria; Xia, Guoxing; Jamison, Steven; Hidding, Bernhard

2014-01-01T23:59:59.000Z

49

Modeling of 10 GeV-1 TeV laser-plasma accelerators using Lorentz boosted simulations  

E-Print Network (OSTI)

Modeling of 10 GeV-1 TeV laser-plasma accelerators using Lorentz boosted simulations J.-L. Vay,1,a-plasma wakefield accelerators in an optimal frame of reference [J.-L. Vay, Phys. Rev. Lett. 98, 130405 (2007 of plasma accelerators to very high energies and accurately models the laser evolution and the accelerated

Geddes, Cameron Guy Robinson

50

Computational studies and optimization of wakefield accelerators  

E-Print Network (OSTI)

optimization of wakefield accelerators C. G. R. Geddes 1 ,from the U.S. -LHC Accelerator Research Program (LARP),driven plasma wakefield accelerators produce accelerating

Geddes, C.G.R.

2010-01-01T23:59:59.000Z

51

Electron Bunch Length Measurements in the E-167 Plasma Wakefield Experiment  

SciTech Connect

Bunch length is of prime importance to beam driven plasma wakefield acceleration experiments due to its inverse relationship to the amplitude of the accelerating wake. We present here a summary of work done by the E167 collaboration measuring the SLAC ultra-short bunches via autocorrelation of coherent transition radiation. We have studied material transmission properties and improved our autocorrelation traces using materials with better spectral characteristics.

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

2007-03-27T23:59:59.000Z

52

Effect of the laser wavefront in a laser-plasma accelerator  

E-Print Network (OSTI)

A high repetition rate electron source was generated by tightly focusing kHz, few-mJ laser pulses into an underdense plasma. This high intensity laser-plasma interaction led to stable electron beams over several hours but with strikingly complex transverse distributions even for good quality laser focal spots. Analysis of the experimental data, along with results of PIC simulations demonstrate the role of the laser wavefront on the acceleration of electrons. Distortions of the laser wavefront cause spatial inhomogeneities in the out-of-focus laser distribution and consequently, the laser pulse drives an inhomogenous transverse wakefield whose focusing/defocusing properties affect the electron distribution. These findings explain the experimental results and suggest the possibility of controlling the electron spatial distribution in laser-plasma accelerators by tailoring the laser wavefront.

Beaurepaire, B; Bocoum, M; Bhle, F; Jullien, A; Rousseau, J-P; Lefrou, T; Douillet, D; Iaquaniello, G; Lopez-Martens, R; Lifschitz, A; Faure, J

2015-01-01T23:59:59.000Z

53

SLAC-PUB-8352 E-157: A 1.4 Meterlong Plasma Wakefield Acceleration Experiment Using a  

E-Print Network (OSTI)

beam of 2 x 1010 electrons in a 0.65mm long bunch is propagated through a 1.4m long Lithium plasma gradients, much in excess of 1 GeV/m, but over rather small ( acceleration of electrons by plasma wakefield acceleration with gradients in excess of 100 MeV/m over

54

Spectrum bandwidth narrowing of Thomson scattering X-rays with energy chirped electron beams from laser wakefield acceleration  

SciTech Connect

We study incoherent Thomson scattering between an ultrashort laser pulse and an electron beam accelerated from a laser wakefield. The energy chirp effects of the accelerated electron beam on the final radiation spectrum bandwidth are investigated. It is found that the scattered X-ray radiation has the minimum spectrum width and highest intensity as electrons are accelerated up to around the dephasing point. Furthermore, it is proposed that the electron acceleration process inside the wakefield can be studied by use of 90 Thomson scattering. The dephasing position and beam energy chirp can be deduced from the intensity and bandwidth of the scattered radiation.

Xu, Tong; Chen, Min, E-mail: minchen@sjtu.edu.cn; Li, Fei-Yu; Yu, Lu-Le [Key Laboratory for Laser Plasmas (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China)] [Key Laboratory for Laser Plasmas (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Sheng, Zheng-Ming, E-mail: zmsheng@sjtu.edu.cn [Key Laboratory for Laser Plasmas (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China) [Key Laboratory for Laser Plasmas (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Zhang, Jie [Key Laboratory for Laser Plasmas (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China) [Key Laboratory for Laser Plasmas (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, CAS, Beijing 100190 (China)

2014-01-06T23:59:59.000Z

55

Control of seeding phase for a cascaded laser wakefield accelerator with gradient injection  

SciTech Connect

We demonstrated experimentally the seeding-phase control for a two-stage laser wakefield accelerator with gradient injection. By optimizing the seeding phase of electrons into the second stage, electron beams beyond 0.5 GeV with a 3% rms energy spread were produced over a short acceleration distance of ?2 mm. Peak energy of the electron beam was further extended beyond 1 GeV by lengthening the second acceleration stage to 5 mm. Time-resolved magnetic field measurements via magneto-optical Faraday polarimetry allowed us to monitor the processes of electron seeding and acceleration in the second stage.

Wang, Wentao; Li, Wentao; Liu, Jiansheng; Wang, Cheng; Chen, Qiang; Zhang, Zhijun; Qi, Rong; Leng, Yuxin; Liang, Xiaoyan; Liu, Yanqi; Lu, Xiaoming; Wang, Cheng; Li, Ruxin; Xu, Zhizhan [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences (CAS), Shanghai 201800 (China)] [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences (CAS), Shanghai 201800 (China)

2013-12-09T23:59:59.000Z

56

The status and evolution of plasma wakefield particle accelerators  

Science Journals Connector (OSTI)

...respectively. This electric field will tend to focus the rest of the electron beam that resides...If the density length product of the plasma is large enough, the electron beam can focus within the plasma itself and indeed undergo multiple focusing...

2006-01-01T23:59:59.000Z

57

Self-truncated ionization injection and consequent monoenergetic electron bunches in laser wakefield acceleration  

SciTech Connect

The ionization-induced injection in laser wakefield acceleration has been recently demonstrated to be a promising injection scheme. However, the energy spread controlling in this mechanism remains a challenge because continuous injection in a mixed gas target is usually inevitable. Here, we propose that by use of certain initially unmatched laser pulses, the electron injection can be constrained to the very front region of the mixed gas target, typically in a length of a few hundreds micrometers determined by the laser self-focusing and the wake deformation. As a result, the produced electron beam has narrow energy spread and meanwhile contains tens of pC in charge. Both multidimensional simulations and theoretical analysis illustrate the effectiveness of this scheme.

Zeng, Ming; Zhang, Jie [Key Laboratory for Laser Plasmas (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China)] [Key Laboratory for Laser Plasmas (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Chen, Min, E-mail: minchen@sjtu.edu.cn [Key Laboratory for Laser Plasmas (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China) [Key Laboratory for Laser Plasmas (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Department of Mathematics, Institute of Natural Sciences, and MOE-LSC, Shanghai Jiao Tong University, Shanghai 20040 (China); Sheng, Zheng-Ming, E-mail: zmsheng@sjtu.edu.cn [Key Laboratory for Laser Plasmas (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China) [Key Laboratory for Laser Plasmas (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Mori, Warren B. [University of California, Los Angeles, California 90095 (United States)] [University of California, Los Angeles, California 90095 (United States)

2014-03-15T23:59:59.000Z

58

Study of laser plasma interactions in the relativistic regime  

SciTech Connect

We discuss the first experimental demonstration of electron acceleration by a laser wakefield over instances greater than a Rayleigh range (or the distance a laser normally propagates in vacuum). A self-modulated laser wakefield plasma wave is shown to have a field gradient that exceeds that of an RF linac by four orders of magnitude (E => 200 GV/m) and accelerates electrons with over 1-nC of charge per bunch in a beam with space-charge-limited emittance (1 mm-mrad). Above a laser power threshold, a plasma channel, created by the intense ultrashort laser pulse (I approx. 4 x1018 W/CM2, gamma = 1 micron, r = 400 fs), was found to increase the laser propagation distance, decrease the electron beam divergence, and increase the electron energy. The plasma wave, directly measured with coherent Thomson scattering is shown to damp-due to beam loading-in a duration of 1.5 ps or approx. 100 plasma periods. These results may have important implications for the proposed fast ignitor concept.

Umstadter, D.

1997-08-13T23:59:59.000Z

59

A Proposal for a 1 GeV Plasma-Wakefield Acceleration Experiment at SLAC T. Katsouleas, S. Lee, USC  

E-Print Network (OSTI)

, USC Los Angeles, CA 90089-0484 S. Chattopadhyay, W. Leemans, LBNL R. Assmann, P. Chen, F.J. Decker, R. Iverson, T. Kotseroglou, P. Raimondi, T. Raubenheimer, S. Rokni, R.H. Siemann, D. Walz, D. Whittum, SLAC C. Clayton, C. Joshi, K. Marsh, W. Mori, G. Wang, UCLA Abstract A plasma-based wakefield acceleration (PWFA

60

Electron Acceleration Experiments by Using a Density-tapered Capillary Plasma Source  

Science Journals Connector (OSTI)

We have developed a density-tapered capillary plasma source for high energy electron generation by using the laser wakefield acceleration, where the dephasing problem will be...

Suk, Hyyong; Nam, Inhyuk; Kim, Minseok; Lee, Seungwoo; Lee, Taehee

Note: This page contains sample records for the topic "laser plasma wakefield" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

Electron diffraction using ultrafast electron bunches from a laser-wakefield accelerator at kHz repetition rate  

SciTech Connect

We show that electron bunches in the 50-100 keV range can be produced from a laser wakefield accelerator using 10 mJ, 35 fs laser pulses operating at 0.5 kHz. It is shown that using a solenoid magnetic lens, the electron bunch distribution can be shaped. The resulting transverse and longitudinal coherence is suitable for producing diffraction images from a polycrystalline 10 nm aluminum foil. The high repetition rate, the stability of the electron source, and the fact that its uncorrelated bunch duration is below 100 fs make this approach promising for the development of sub-100 fs ultrafast electron diffraction experiments.

He, Z.-H.; Thomas, A. G. R.; Nees, J. A.; Hou, B.; Krushelnick, K. [Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48106-2099 (United States)] [Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48106-2099 (United States); Beaurepaire, B.; Malka, V.; Faure, J. [Laboratoire d'Optique Appliquee, ENSTA-CNRS-Ecole Polytechnique, UMR 7639, 91761 Palaiseau (France)] [Laboratoire d'Optique Appliquee, ENSTA-CNRS-Ecole Polytechnique, UMR 7639, 91761 Palaiseau (France)

2013-02-11T23:59:59.000Z

62

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

SciTech Connect

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.

Ali, S. [National Centre for Physics (NCP), Quaid-e-Azam University Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan)] [National Centre for Physics (NCP), Quaid-e-Azam University Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Khan, S. [National Centre for Physics (NCP), Quaid-e-Azam University Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan) [National Centre for Physics (NCP), Quaid-e-Azam University Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Department of Physics, Gomal University, Dera Ismail Khan 29050 (Pakistan)

2013-07-15T23:59:59.000Z

63

Gas lens laser produced plasma  

Science Journals Connector (OSTI)

A gas lens is used to focus a megawatt ruby laser beam on to a target to create a plasma. By using focal plane photographs and Faraday cup plasma diagnostics, the focusing ability of a...

Notcutt, Mark; Waltham, J A; Michaelis, M M; Cunningham, P F; Cazalet, R S

1989-01-01T23:59:59.000Z

64

Generation of wakefields by whistlers in spin quantum magnetoplasmas  

SciTech Connect

The excitation of electrostatic wakefields in a magnetized spin quantum plasma by the classical and the spin-induced ponderomotive force (CPF and SPF, respectively) due to whistler waves is reported. The nonlinear dynamics of the whistlers and the wakefields is shown to be governed by a coupled set of nonlinear Schroedinger and driven Boussinesq-like equations. It is found that the quantum force associated with the Bohm potential introduces two characteristic length scales, which lead to the excitation of multiple wakefields in a strongly magnetized dense plasma (with a typical magnetic field strength B{sub 0} or approx. 10{sup 9} T and particle density n{sub 0} > or approx. 10{sup 36} m{sup -3}), where the SPF strongly dominates over the CPF. In other regimes, namely, B{sub 0} < or approx. 10{sup 8} T and n{sub 0} < or approx. 10{sup 35} m{sup -3}, where the SPF is comparable to the CPF, a plasma wakefield can also be excited self-consistently with one characteristic length scale. Numerical results reveal that the wakefield amplitude is enhanced by the quantum tunneling effect; however, it is lowered by the external magnetic field. Under appropriate conditions, the wakefields can maintain high coherence over multiple plasma wavelengths and thereby accelerate electrons to extremely high energies. The results could be useful for particle acceleration at short scales, i.e., at nanometer and micrometer scales, in magnetized dense plasmas where the driver is the whistler wave instead of a laser or a particle beam.

Misra, A. P.; Brodin, G.; Marklund, M. [Department of Physics, Umeaa University, SE-901 87 Umeaa (Sweden); Shukla, P. K. [Department of Physics, Umeaa University, SE-901 87 Umeaa (Sweden); RUB International Chair, International Centre for Advanced Studies in Physical Sciences, Faculty of Physics and Astronomy, Ruhr University Bochum, D-44780 Bochum (Germany)

2010-12-15T23:59:59.000Z

65

Improvements to laser wakefield accelerated electron beam stability, divergence, and energy spread using three-dimensional printed two-stage gas cell targets  

SciTech Connect

High intensity, short pulse lasers can be used to accelerate electrons to ultra-relativistic energies via laser wakefield acceleration (LWFA) [T. Tajima and J. M. Dawson, Phys. Rev. Lett. 43, 267 (1979)]. Recently, it was shown that separating the injection and acceleration processes into two distinct stages could prove beneficial in obtaining stable, high energy electron beams [Gonsalves et al., Nat. Phys. 7, 862 (2011); Liu et al., Phys. Rev. Lett. 107, 035001 (2011); Pollock et al., Phys. Rev. Lett. 107, 045001 (2011)]. Here, we use a stereolithography based 3D printer to produce two-stage gas targets for LWFA experiments on the HERCULES laser system at the University of Michigan. We demonstrate substantial improvements to the divergence, pointing stability, and energy spread of a laser wakefield accelerated electron beam compared with a single-stage gas cell or gas jet target.

Vargas, M.; Schumaker, W.; He, Z.-H.; Zhao, Z.; Behm, K.; Chvykov, V.; Hou, B.; Krushelnick, K.; Maksimchuk, A.; Yanovsky, V.; Thomas, A. G. R., E-mail: agrt@umich.edu [Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48109 (United States)

2014-04-28T23:59:59.000Z

66

LASER-PLASMA-ACCELERATOR-BASED GAMMA GAMMA COLLIDERS  

E-Print Network (OSTI)

LASER-PLASMA-ACCELERATOR-BASED ?? COLLIDERS ? C. B.linear col- lider based on laser-plasma-accelerators arediscussed, and a laser-plasma-accelerator-based gamma-

Schroeder, C. B.

2010-01-01T23:59:59.000Z

67

Laser Plasma Particle Accelerators: Large Fields for Smaller Facility Sources  

E-Print Network (OSTI)

of high- gradient, laser plasma particle accelerators.accelerators that use laser-driven plasma waves. Theseleft) showing the laser (red), plasma wake density (purple-

Geddes, Cameron G.R.

2010-01-01T23:59:59.000Z

68

Staging laser plasma accelerators for increased beam energy  

E-Print Network (OSTI)

Staging Laser Plasma Accelerators for Increased Beam EnergyStaging laser plasma accelerators is an efficient way ofcompact laser-plasma accelerators to generate particle

Panasenko, Dmitriy

2010-01-01T23:59:59.000Z

69

Terahertz radiation as a bunch diagnostic for laser-wakefield-accelerated electron bunches  

SciTech Connect

Experimental results are reported from two measurement techniques (semiconductor switching and electro-optic sampling) that allow temporal characterization of electron bunches produced by a laser-driven plasma-based accelerator. As femtosecond electron bunches exit the plasma-vacuum interface, coherent transition radiation (at THz frequencies) is emitted. Measuring the properties of this radiation allows characterization of the electron bunches. Theoretical work on the emission mechanism is presented, including a model that calculates the THz wave form from a given bunch profile. It is found that the spectrum of the THz pulse is coherent up to the 200 {micro}m thick crystal (ZnTe) detection limit of 4 THz, which corresponds to the production of sub-50 fs (rms) electron bunch structure. The measurements demonstrate both the shot-to-shot stability of bunch parameters that are critical to THz emission (such as total charge and bunch length), as well as femtosecond synchronization among bunch, THz pulse, and laser beam.

van Tilborg, Jeroen; Schroeder, Carl; Filip, Catalin; Toth, Csaba; Geddes, Cameron; Fubiani, Gwenael; Esarey, Eric; Leemans, Wim

2011-06-17T23:59:59.000Z

70

Laser-Plasma Acceleration of Electrons and Plasma Diagnostics at High Laser Fields  

E-Print Network (OSTI)

would open the prospect of building x-ray free-electron lasers and linear colliders hundreds of timesLaser-Plasma Acceleration of Electrons and Plasma Diagnostics at High Laser Fields Mike Downer: Laser-plasma acceleration is now entering an era of petawatt lasers, tenuous plasmas and multi

Shvets, Gennady

71

VOLUME 78, NUMBER 16 P H Y S I C A L R E V I E W L E T T E R S 21 APRIL 1997 Electron Acceleration by a Laser Wakefield in a Relativistically Self-Guided Channel  

E-Print Network (OSTI)

, x-ray lasers, and ultrahigh-gradient electron accelerators [2]. In the latter case, the field by a Laser Wakefield in a Relativistically Self-Guided Channel R. Wagner, S.-Y. Chen, A. Maksimchuk, and D-modulated laser wakefield is discussed. Above a power threshold, a relativistically self-guided channel from

Umstadter, Donald

72

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

SciTech Connect

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.

Cho, Myung-Hoon [School of Natural Science, UNIST, BanYeon-Ri 100, Ulju-gun, Ulsan 689-798 (Korea, Republic of)] [School of Natural Science, UNIST, BanYeon-Ri 100, Ulju-gun, Ulsan 689-798 (Korea, Republic of); Kim, Young-Kuk; Hur, Min Sup [School of Electrical and Computer Engineering, UNIST, BanYeon-Ri 100, Ulju-gun, Ulsan 689-798 (Korea, Republic of)] [School of Electrical and Computer Engineering, UNIST, BanYeon-Ri 100, Ulju-gun, Ulsan 689-798 (Korea, Republic of)

2013-09-15T23:59:59.000Z

73

Nonlinear laser energy depletion in laser-plasma accelerators  

E-Print Network (OSTI)

Lee- mans, in Advanced Accelerator Concepts, Eleventh Work-in laser-plasma accelerators ? B. A. Shadwick, 1, C. B.ac- celerators. Laser-plasma accelerators, for example, have

Shadwick, B.A.

2009-01-01T23:59:59.000Z

74

Laser Guiding for GeV Laser-Plasma Accelerators  

E-Print Network (OSTI)

Overview of plasma-based accelerator concepts. IEEE Trans.using laser wake?eld accelerators. Meas. Sci. Technol. 12,for GeV laser-plasma accelerators. In Advanced Accelerator

Leemans, Wim; Esarey, Eric; Geddes, Cameron; Schroeder, C.B.; Toth, Csaba

2005-01-01T23:59:59.000Z

75

DEVELOPMENT OF WATER JET PLASMA MIRROR FOR STAGING OF LASER PLASMA ACCELERATORS  

E-Print Network (OSTI)

STAGING OF LASER PLASMA ACCELERATORS ? Dmitriy Panasenko,Staging Laser Plasma Accelerators (LPAs) is necessary in4]. INTRODUCTION Laser Plasma Accelerators (LPAs) have now

Panasenko, Dmitriy

2010-01-01T23:59:59.000Z

76

Laser wakefield simulation using a speed-of-light frame envelope model  

E-Print Network (OSTI)

Laser wake?eld simulation using a speed-of-light frameAbstract. Simulation of laser wake?eld accelerator (LWFA)extend hundreds of laser wave- lengths transversely and many

Cowan, B.

2010-01-01T23:59:59.000Z

77

Quasi-monoenergetic Electron Beams from Laser-plasma Acceleration by Ionization-induced Injection in Low- density Pure Nitrogen  

E-Print Network (OSTI)

We report a laser wakefield acceleration of electron beams up to 130 MeV from laser-driven 4-mm long nitrogen gas jet. By using a moderate laser intensity (3.5*10^18 W.cm^(-2) ) and relatively low plasma densities (0.8*10^18 cm^(-3) to 2.7*10^18 cm^(-3)) we have achieved a stable regime for laser propagation and consequently a stable generation of electron beams. We experimentally studied the dependence of the drive laser energy on the laser-plasma channel and electron beam parameters. The quality of the generated electron beams is discussed within the framework of the ionization-induced injection mechanism.

Tao, Mengze; Li, Song; Mirzaie, Mohammad; Chen, Liming; He, Fei; Cheng, Ya; Zhang, Jie

2014-01-01T23:59:59.000Z

78

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

SciTech Connect

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 regimeregarding the trapped chargehas 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.

Rassou, S.; Bourdier, A.; Drouin, M. [CEA, DAM, DIF, 91297 Arpajon (France)

2014-08-15T23:59:59.000Z

79

Application of a Laser-Wakefield Driven Monochromatic Photon Source to  

E-Print Network (OSTI)

) is a 100-TW, 30-fs pulsed Ti:sapphire laser system. Diocles routinely provides electron beams exhibiting

Umstadter, Donald

80

Laser wakefield generated X-ray probe for femtosecond time-resolved measurements of ionization states of warm dense aluminum  

SciTech Connect

We have developed a laser wakefield generated X-ray probe to directly measure the temporal evolution of the ionization states in warm dense aluminum by means of absorption spectroscopy. As a promising alternative to the free electron excited X-ray sources, Betatron X-ray radiation, with femtosecond pulse duration, provides a new technique to diagnose femtosecond to picosecond transitions in the atomic structure. The X-ray probe system consists of an adjustable Kirkpatrick-Baez (KB) microscope for focusing the Betatron emission to a small probe spot on the sample being measured, and a flat Potassium Acid Phthalate Bragg crystal spectrometer to measure the transmitted X-ray spectrum in the region of the aluminum K-edge absorption lines. An X-ray focal spot size of around 50 ?m was achieved after reflection from the platinum-coated 10-cm-long KB microscope mirrors. Shot to shot positioning stability of the Betatron radiation was measured resulting in an rms shot to shot variation in spatial pointing on the sample of 16 ?m. The entire probe setup had a spectral resolution of ?1.5 eV, a detection bandwidth of ?24 eV, and an overall photon throughput efficiency of the order of 10{sup ?5}. Approximately 10 photons were detected by the X-ray CCD per laser shot within the spectrally resolved detection band. Thus, it is expected that hundreds of shots will be required per absorption spectrum to clearly observe the K-shell absorption features expected from the ionization states of the warm dense aluminum.

Mo, M. Z.; Chen, Z.; Tsui, Y. Y.; Fedosejevs, R. [Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta T6G 2V4 (Canada)] [Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta T6G 2V4 (Canada); Fourmaux, S.; Saraf, A.; Otani, K.; Kieffer, J. C. [INRS-EMT, Universit du Qubec, 1650 Lionel Boulet, Varennes, Qubec J3X 1S2 (Canada)] [INRS-EMT, Universit du Qubec, 1650 Lionel Boulet, Varennes, Qubec J3X 1S2 (Canada); Ng, A. [Department of Physics and Astronomy, University of British Columbia, British Columbia V6T 1Z1 (Canada)] [Department of Physics and Astronomy, University of British Columbia, British Columbia V6T 1Z1 (Canada)

2013-12-15T23:59:59.000Z

Note: This page contains sample records for the topic "laser plasma wakefield" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Evolution of pulse shapes during compressor scans in a CPA system and control of electron acceleration in plasmas  

SciTech Connect

The skewness of the envelope function of 20 - 100 femtosecond Ti:sapphire laser pulses has been controlled by appropriate choice of the higher order special phase coefficients, and used for optimization of a plasma wakefield electron accelerator.

Toth, Csaba; de Groot, Joeri; van Tilborg, Jeroen; Geddes, Cameron G.R.; Faure, Jerome; Catravas, Palma; Schroeder, Carl; Shadwick, B.A.; Esarey, Eric; Leemans, Wim

2002-05-12T23:59:59.000Z

82

High-repetition Rate Wakefield Electron Source Driven by Few-millijoule Ultrashort Laser Pulses  

Science Journals Connector (OSTI)

10 mJ ultrafast laser pulses acting on gas flow from capillary nozzles generate stable 100 keV electron beams at 500 Hz. Particle-in-cell simulations indicate that slow high amplitude...

He, Zhaohan; Hou, Bixue; Easter, James; Krushelnick, Karl; Nees, John A; Thomas, Alexander

83

Charge Diagnostics for Laser Plasma Accelerators  

E-Print Network (OSTI)

the 1989 Particle Accelerator Conference, IEEE, Piscataway,Diagnostics for Laser Plasma Accelerators K . Nakamura, A .ALS) synchrotron booster accelerator. The sensitivity of the

Nakamura, K.

2011-01-01T23:59:59.000Z

84

Laser induced fluorescence measurements of spheromak plasmas.  

E-Print Network (OSTI)

??This thesis reports the results of investigations intended to further the understanding of the formation and evolution of spheromak plasmas via the use of laser (more)

Pracko, Steven Edmund

2007-01-01T23:59:59.000Z

85

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

Office of Scientific and Technical Information (OSTI)

experiments that showed the great potential of plasma accelerators. The FACET ii test facility at SLAC will, in the period 2012-2016, further study several issues that are...

86

MeV-Energy X Rays from Inverse Compton Scattering with Laser-Wakefield Accelerated Electrons  

Science Journals Connector (OSTI)

We report the generation of MeV x rays using an undulator and accelerator that are both driven by the same 100-terawatt laser system. The laser pulse driving the accelerator and the scattering laser pulse are independently optimized to generate a high energy electron beam (>200??MeV) and maximize the output x-ray brightness. The total x-ray photon number was measured to be ?1107, the source size was 5???m, and the beam divergence angle was ?10??mrad. The x-ray photon energy, peaked at 1MeV (reaching up to 4MeV), exceeds the thresholds of fundamental nuclear processes (e.g., pair production and photodisintegration).

S. Chen; N. D. Powers; I. Ghebregziabher; C. M. Maharjan; C. Liu; G. Golovin; S. Banerjee; J. Zhang; N. Cunningham; A. Moorti; S. Clarke; S. Pozzi; D. P. Umstadter

2013-04-10T23:59:59.000Z

87

Plasma-based Accelerator with Magnetic Compression  

SciTech Connect

Electron dephasing is a major gain-inhibiting effect in plasma-based accelerators. A novel method is proposed to overcome dephasing, in which the modulation of a modest (#24; O(10 kG)), axial, uniform magnetic field in the acceleration channel leads to densification of the plasma through magnetic compression, enabling direct, time-resolved control of the plasma wave properties. The methodology is broadly applicable and can be optimized to improve the leading acceleration approaches, including plasma beat-wave, plasma wakefield, and laser wakefield acceleration. The advantages of magnetic compression compared to other proposed schemes to overcome dephasing are identified.

Paul F. Schmit and Nathaniel J. Fisch

2012-06-28T23:59:59.000Z

88

Multi-GeV Energy Gain in a Plasma-Wakefield Accelerator M. J. Hogan,1  

E-Print Network (OSTI)

. Katsouleas,3 P. Krejcik,1 W. Lu,2 K. A. Marsh,2 W. B. Mori,2 P. Muggli,3 C. L. O'Connell,1 E. Oz,3 R. H,2 F. J. Decker,1 S. Deng,3 P. Emma,1 C. Huang,2 R. H. Iverson,1 D. K. Johnson,2 C. Joshi,2 T regime is reached when the electron bunch density nb N=23=2z2 r is greater than the plasma density np

Jalali. Bahram

89

Lasers as a tool for plasma diagnostics  

SciTech Connect

Lasers can be used as non-perturbative probes to measure many plasma parameters. Plasma refractivity is primarily a function of electron density, and interferometric measurements of phase changes with either pulsed or CW lasers can determine this parameter with spatial or temporal resolution over several orders of magnitude sensitivity by using laser wavelengths from the near uv to the far infrared. Laser scattering from free electrons yields the most fundamental electron temperature measurements in the plasma parameter range where individual scattering events are uncorrelated in phase and ion temperature or plasma wave and turbulence structure in the opposite limit. Laser scattering from bound electrons can be many orders of magnitude larger if the laser is matched to appropriate resonance frequencies and can be used in specialized circumstances for measuring low-ionized impurity or dominant species neutral concentrations and velocities.

Jahoda, F.C.

1981-01-01T23:59:59.000Z

90

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

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.

Mo, M. Z.; Ali, A.; Fedosejevs, R. [Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta T6G 2V4 (Canada)] [Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta T6G 2V4 (Canada); Fourmaux, S.; Lassonde, P.; Kieffer, J. C. [INRS-EMT, Universite du Quebec, 1650 Lionel Boulet, Varennes, Quebec J3X 1S2 (Canada)] [INRS-EMT, Universite du Quebec, 1650 Lionel Boulet, Varennes, Quebec J3X 1S2 (Canada)

2013-04-01T23:59:59.000Z

91

LASER-PLASMA-ACCELERATOR-BASED COLLIDERS C. B. Schroeder  

E-Print Network (OSTI)

LASER-PLASMA-ACCELERATOR-BASED COLLIDERS C. B. Schroeder , E. Esarey, Cs. T´oth, C. G. R. Geddes-generation linear col- lider based on laser-plasma-accelerators are discussed, and a laser-plasma-accelerator gamma-gamma () collider is considered. An example of the parameters for a 0.5 TeV laser-plasma-accelerator collider

Geddes, Cameron Guy Robinson

92

Laser Facilities, Laser-Plasmas & Diagnostics Plasmas Division  

E-Print Network (OSTI)

of freely moving ions and free electrons. Figure 1: The large NOVA laser at Lawrence Livermore National Facility (NIF) is the world's largest and highest-energy laser (Figure 2). It houses 192 intense laser and of a single wavelength. There are a large number of Figure 2: NIF from above & the target chamber. Figure 4

Strathclyde, University of

93

The role of the gas/plasma plume and self-focusing in a gas-filled capillary discharge waveguide for high-power laser-plasma applications  

E-Print Network (OSTI)

The role of the gas/plasma plume at the entrance of a gas-filled capillary discharge plasma waveguide in increasing the laser intensity has been investigated. Distinction is made between neutral gas and hot plasma plumes that, respectively, develop before and after discharge breakdown. Time-averaged measurements show that the on-axis plasma density of a fully expanded plasma plume over this region is similar to that inside the waveguide. Above the critical power, relativistic and ponderomotive selffocusing lead to an increase in the intensity, which can be nearly a factor of 2 compared with the case without a plume. When used as a laser plasma wakefield accelerator, the enhancement of intensity can lead to prompt electron injection very close to the entrance of the waveguide. Self-focusing occurs within two Rayleigh lengths of the waveguide entrance plane in the region, where the laser beam is converging. Analytical theory and numerical simulations show that, for a density of 3.01018 cm3, the peak normalized...

Ciocarlan, C.; Islam, M. R.; Ersfeld, B.; Abuazoum, S.; Wilson, R.; Aniculaesei, C.; Welsh, G. H.; Vieux, G.; Jaroszynski, D. A.

2013-01-01T23:59:59.000Z

94

Extreme-ultraviolet radiation transport in small scale length laser-produced tin plasmas  

E-Print Network (OSTI)

Laser Plasma . Handbook of Plasma Physics, ed. A. RubenchikLaser Plasma . Handbook of Plasma Physics, ed. A. RubenchikLaser Plasma . Handbook of Plasma Physics, ed. A. Rubenchik

Sequoia, Kevin Lamar Williams

2009-01-01T23:59:59.000Z

95

Laser-plasma interactions for fast ignition  

E-Print Network (OSTI)

In the electron-driven fast-ignition approach to inertial confinement fusion, petawatt laser pulses are required to generate MeV electrons that deposit several tens of kilojoules in the compressed core of an imploded DT shell. We review recent progress in the understanding of intense laser plasma interactions (LPI) relevant to fast ignition. Increases in computational and modeling capabilities, as well as algorithmic developments have led to enhancement in our ability to perform multi-dimensional particle-in-cell (PIC) simulations of LPI at relevant scales. We discuss the physics of the interaction in terms of laser absorption fraction, the laser-generated electron spectra, divergence, and their temporal evolution. Scaling with irradiation conditions such as laser intensity are considered, as well as the dependence on plasma parameters. Different numerical modeling approaches and configurations are addressed, providing an overview of the modeling capabilities and limitations. In addition, we discuss the compa...

Kemp, A J; Debayle, A; Johzaki, T; Mori, W B; Patel, P K; Sentoku, Y; Silva, L O

2013-01-01T23:59:59.000Z

96

Relativistic laser channeling in plasmas for fast ignition  

Science Journals Connector (OSTI)

We report an experimental observation suggesting plasma channel formation by focusing a relativistic laser pulse into a long-scale-length preformed plasma. The channel direction coincides with the laser axis. Laser light transmittance measurement indicates laser channeling into the high-density plasma with relativistic self-focusing. A three-dimensional particle-in-cell simulation reproduces the plasma channel and reveals that the collimated hot-electron beam is generated along the laser axis in the laser channeling. These findings hold the promising possibility of fast heating a dense fuel plasma with a relativistic laser pulse.

A. L. Lei, A. Pukhov, R. Kodama, T. Yabuuchi, K. Adumi, K. Endo, R. R. Freeman, H. Habara, Y. Kitagawa, K. Kondo, G. R. Kumar, T. Matsuoka, K. Mima, H. Nagatomo, T. Norimatsu, O. Shorokhov, R. Snavely, X. Q. Yang, J. Zheng, and K. A. Tanaka

2007-12-18T23:59:59.000Z

97

Laser Plasma Particle Accelerators: Large Fields for Smaller Facility Sources  

E-Print Network (OSTI)

essential understanding of accelerator physics to advanceof high- gradient, laser plasma particle accelerators.to conventional particle accelerators, plasmas can sustain

Geddes, Cameron G.R.

2010-01-01T23:59:59.000Z

98

Summary Report of Working Group 6: Laser-Plasma Acceleration  

E-Print Network (OSTI)

be an important focus of laser-plasma acceleration researchfocus. In both cases, light regions of the image ionized and heated the plasma,

Leemans, Wim P.; Downer, Michael; Siders, Craig

2008-01-01T23:59:59.000Z

99

Staging Laser Plasma Accelerators for Increased Beam Energy  

E-Print Network (OSTI)

Staging Laser Plasma Accelerators for Increased Beam Energy D. Panasenko, A. J. Shu, C. B., Berkeley, California 94720, USA Abstract. Staging laser plasma accelerators is an efficient way of mitigating laser pump depletion in laser driven accelerators and necessary for reaching high energies

Geddes, Cameron Guy Robinson

100

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

SciTech Connect

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.

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

2011-12-01T23:59:59.000Z

Note: This page contains sample records for the topic "laser plasma wakefield" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Tapered plasma channels to phase-lock accelerating and focusing forces in laser-plasma accelerators  

E-Print Network (OSTI)

elds in laser plasma accelerators using higher order modes,collider, in Advanced Accelerator Concepts, edited by C. B.forces in laser-plasma accelerators W. Rittershofer, 1, a)

Rittershofer, W.

2010-01-01T23:59:59.000Z

102

Laser plasma focus produced in a ring target  

Science Journals Connector (OSTI)

A new geometry for generating a laser?produced plasma is presented. A toroidalmirror is used to focus a CO2laser beam on the inside wall of a copper ring target. The plasma produced converges at the center of the ring where an axial plasma focus is formed. High?speed photography shows details of a plasma generated at a distance from the target surface. This new geometry could have important applications in the field of x?ray lasers.

G. Saint?Hilaire; Z. Szili

1976-01-01T23:59:59.000Z

103

Transverse dynamics of an intense electron bunch traveling through a pre-ionized plasma  

SciTech Connect

The propagation of a relativistic electron bunch through a plasma is an important problem in both plasma-wakefield acceleration and laser-wakefield acceleration. In those situations, the charge of the accelerated bunch is usually large enough to drive a relativistic wakefield, which then affects the transverse dynamics of the bunch itself. Yet to date, there is no fully relativistic, fully electromagnetic model that describes the generation of this wakefield and its feedback on the bunch. In this article, we derive a model which takes into account all the relevant relativistic and electromagnetic effects involved in the problem. A very good agreement is found between the model and the results of particle-in-cell simulations. The implications of high-charge effects for the transport of the bunch are discussed in detail.

Lehe, R., E-mail: remi.lehe@ensta.fr; Thaury, C.; Lifschitz, A.; Rax, J.-M.; Malka, V. [Laboratoire d'Optique Applique, ENSTA-CNRS-Ecole Polytechnique, UMR 7639, 91761 Palaiseau (France)] [Laboratoire d'Optique Applique, ENSTA-CNRS-Ecole Polytechnique, UMR 7639, 91761 Palaiseau (France)

2014-04-15T23:59:59.000Z

104

Optics for X-Ray Laser and Laser Plasma Soft X-Ray Radiation  

Science Journals Connector (OSTI)

Focusing X-ray grazing incidence optics for X-ray laser and laser plasma soft X-ray radiation has been studied. ... computer code. Parabolic axisymmetric mirror for focusing Princeton X-ray laser beam and ellipso...

L. Pina; A. Inneman; R. Hudec

1996-01-01T23:59:59.000Z

105

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

E-Print Network (OSTI)

used at the world's first x-ray free electron laser (FEL) at the LCLS at SLAC, and the lower energyThe BErkeley Lab Laser Accelerator (BELLA): A 10 GeV Laser Plasma Accelerator W.P. Leemansa,b,c , R, USA Abstract. An overview is presented of the design of a 10 GeV laser plasma accelerator (LPA

Geddes, Cameron Guy Robinson

106

Dynamics of intense laser propagation in underdense plasma: Polarization dependence  

SciTech Connect

We present a comprehensive numerical study of the dynamics of an intense laser pulse as it propagates through an underdense plasma in two and three dimensions. By varying the background plasma density and the polarization of the laser beam, significant differences are found in terms of energy transport and dissipation, in agreement with recently reported experimental results. Below the threshold for relativistic self-focusing, the plasma and laser dynamics are observed to be substantially insensitive to the initial laser polarization, since laser transport is dominated by ponderomotive effects. Above this threshold, relativistic effects become important, and laser energy is dissipated either by plasma heating (p-polarization) or by trapping of electromagnetic energy into plasma cavities (s-polarization) or by a combination of both (circular polarization). Besides the fundamental interest of this study, the results presented are relevant to applications such as plasma-based accelerators, x-ray lasers, and fast-ignition inertial confinement fusion.

Singh, D. K.; Fiuza, F.; Silva, L. O. [GoLP, Instituto de Plasmas e Fusao Nuclear - Laboratorio Associado, Instituto Superior Tecnico, 1049-001 Lisboa (Portugal); Davies, J. R. [Fusion Science Center, Laboratory for Laser Energetics and Mechanical Engineering, University of Rochester, New York 14623 (United States); Sarri, G. [School of Mathematics and Physics, The Queens University of Belfast, Belfast BT7 1NN (United Kingdom)

2012-07-15T23:59:59.000Z

107

Summary Report of Working Group 6: Laser-Plasma Acceleration  

SciTech Connect

A summary is given of presentations and discussions in theLaser-Plasma Acceleration Working Group at the 2006 Advanced AcceleratorConcepts Workshop. Presentation highlights include: widespreadobservation of quasi-monoenergetic electrons; good agreement betweenmeasured and simulated beam properties; the first demonstration oflaser-plasma acceleration up to 1 GeV; single-shot visualization of laserwakefield structure; new methods for measuring<100 fs electronbunches; and new methods for "machining" laser-plasma acceleratorstructures. Discussion of future direction includes: developing a roadmapfor laser-plasma acceleration beyond 1 GeV; a debate over injection andguiding; benchmarking simulations with improved wake diagnostics;petawatt laser technology for future laser-plasmaaccelerators.

Leemans, Wim P.; Downer, Michael; Siders, Craig

2006-07-01T23:59:59.000Z

108

Laser-produced plasma-wall interaction O. RENNER,1  

E-Print Network (OSTI)

Laser-produced plasma-wall interaction O. RENNER,1 R. LISKA,2 AND F.B. ROSMEJ3,4 1 Institute, France (RECEIVED 30 August 2009; ACCEPTED 21 September 2009) Abstract Jets of laser­generated plasma surfaces (walls). The pilot experiments carried out on the iodine laser system (5­200 J, 0.44 mm, 0

Liska, Richard

109

Plasma Channel Diagnostic Based on Laser Centroid Oscillations  

E-Print Network (OSTI)

THz [4] to free electron laser (FEL) x-ray sources [5] and Thomson scattering gamma ray sources [6Plasma Channel Diagnostic Based on Laser Centroid Oscillations A. J. Gonsalves, K. Nakamura, C. Lin for measuring the properties of discharge-based plasma channels by monitoring the centroid location of a laser

Geddes, Cameron Guy Robinson

110

Laser-Matter Interaction Above the Plasma Ignition Threshold Intensity  

Science Journals Connector (OSTI)

In this chapter we present the process of laser-matter interaction above the plasma ignition threshold intensity. The physics of the pulsed laser ablation process at high intensities is very complex since it invo...

Mihai Stafe; Aurelian Marcu; Niculae N. Puscas

2014-01-01T23:59:59.000Z

111

Laser-Matter Interaction Below the Plasma Ignition Threshold Intensity  

Science Journals Connector (OSTI)

In this chapter we present the process of laser-matter interaction below the plasma ignition threshold intensity. When the high power laser radiation characterized by electric field intensities around ...

Mihai Stafe; Aurelian Marcu; Niculae N. Puscas

2014-01-01T23:59:59.000Z

112

Electron Beam Charge Diagnostics for Laser Plasma Accelerators  

E-Print Network (OSTI)

the 1989 Particle Accelerator Conference (IEEE, Piscataway,the 1993 Particle Accelerator Conference (IEEE, Piscataway,Diagnostics for Laser Plasma Accelerators K. Nakamura, 1 A.

Nakamura, Kei

2012-01-01T23:59:59.000Z

113

Collaborative Research: Instability and transport of laser beam in plasma  

SciTech Connect

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.

Rose, Harvey Arnold [New Mexico Consortium; Lushnikov, Pavel [University of New Mexico

2014-11-18T23:59:59.000Z

114

Princeton Plasma Physics Lab - Laser diagnostics  

NLE Websites -- All DOE Office Websites (Extended Search)

laser-diagnostics The Multi-Point 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. en Premiere issue of "Quest" magazine details PPPL's strides toward fusion energy and advances in plasma science http://www.pppl.gov/news/2013/09/premiere-issue-quest-magazine-details-pppls-strides-toward-fusion-energy-and-advances-0

115

Control of Laser Plasma Based Accelerators up to 1 GeV  

SciTech Connect

This dissertation documents the development of a broadband electron spectrometer (ESM) for GeV class Laser Wakefield Accelerators (LWFA), the production of high quality GeV electron beams (e-beams) for the first time in a LWFA by using a capillary discharge guide (CDG), and a statistical analysis of CDG-LWFAs. An ESM specialized for CDG-LWFAs with an unprecedented wide momentum acceptance, from 0.01 to 1.1 GeV in a single shot, has been developed. Simultaneous measurement of e-beam spectra and output laser properties as well as a large angular acceptance (> {+-} 10 mrad) were realized by employing a slitless scheme. A scintillating screen (LANEX Fast back, LANEX-FB)--camera system allowed faster than 1 Hz operation and evaluation of the spatial properties of e-beams. The design provided sufficient resolution for the whole range of the ESM (below 5% for beams with 2 mrad divergence). The calibration between light yield from LANEX-FB and total charge, and a study on the electron energy dependence (0.071 to 1.23 GeV) of LANEX-FB were performed at the Advanced light source (ALS), Lawrence Berkeley National Laboratory (LBNL). Using this calibration data, the developed ESM provided a charge measurement as well. The production of high quality electron beams up to 1 GeV from a centimeter-scale accelerator was demonstrated. The experiment used a 310 {micro}m diameter gas-filled capillary discharge waveguide that channeled relativistically-intense laser pulses (42 TW, 4.5 x 10{sup 18} W/cm{sup 2}) over 3.3 centimeters of sufficiently low density ({approx_equal} 4.3 x 10{sup 18}/cm{sup 3}) plasma. Also demonstrated was stable self-injection and acceleration at a beam energy of {approx_equal} 0.5 GeV by using a 225 {micro}m diameter capillary. Relativistically-intense laser pulses (12 TW, 1.3 x 10{sup 18}W/cm{sup 2}) were guided over 3.3 centimeters of low density ({approx_equal} 3.5 x 10{sup 18}/cm{sup 3}) plasma in this experiment. A statistical analysis of the CDG-LWFAs performance was carried out. By taking advantage of the high repetition rate experimental system, several thousands of shots were taken in a broad range of the laser and plasma parameters. An analysis program was developed to sort and select the data by specified parameters, and then to evaluate performance statistically. The analysis suggested that the generation of GeV-level beams comes from a highly unstable and regime. By having the plasma density slightly above the threshold density for self injection, (1) the longest dephasing length possible was provided, which led to the generation of high energy e-beams, and (2) the number of electrons injected into the wakefield was kept small, which led to the generation of high quality (low energy spread) e-beams by minimizing the beam loading effect on the wake. The analysis of the stable half-GeV beam regime showed the requirements for stable self injection and acceleration. A small change of discharge delay t{sub dsc}, and input energy E{sub in}, significantly affected performance. The statistical analysis provided information for future optimization, and suggested possible schemes for improvement of the stability and higher quality beam generation. A CDG-LWFA is envisioned as a construction block for the next generation accelerator, enabling significant cost and size reductions.

Nakamura, Kei

2007-12-03T23:59:59.000Z

116

Comparison of optical emission from nanosecond and femtosecond laser produced plasma in atmosphere and vacuum conditions  

E-Print Network (OSTI)

Comparison of optical emission from nanosecond and femtosecond laser produced plasma in atmosphere Laser-induced breakdown spectroscopy Laser-produced plasma Plasma dynamics Femtosecond laser ablation In this study we examine the emission from brass plasma produced by ns and fs laser ablation under both vacuum

Harilal, S. S.

117

Laser Copper Plasma X-ray Source Debris Characterization  

E-Print Network (OSTI)

Laser Copper Plasma X-ray Source Debris Characterization A Thesis Presented by David Hurley 3, 2007 Vice President for Research and Dean of Graduate studies #12;Abstract Laser copper plasma for x-ray lithography. Copper debris in the form of vapor, ions, dust, and high-speed particles

Huston, Dryver R.

118

Broadband Single-Shot Electron Spectrometer for GeV-Class Laser Plasma Based Accelerators  

E-Print Network (OSTI)

of the 2007 Particle Accelerator Conference, p. 2978,Class Laser Plasma Based Accelerators K. Nakamura, ? W. Wan,Laser-plasma-based accelerators can provide electrons over a

Nakamura, K.

2008-01-01T23:59:59.000Z

119

Observation of laser satellites in a plasma produced by a femtosecond laser pulse  

E-Print Network (OSTI)

that the laser x-ray satellites were predicted more than 20 years ago, they had not been observed until veryObservation of laser satellites in a plasma produced by a femtosecond laser pulse S. A. Pikuz P. N­459 10 October 1997 Laser satellites are detected in the emission spectra of magnesium and aluminum

Umstadter, Donald

120

Differential laser absorption spectroscopy of uranium in an atmospheric pressure laser-induced plasma  

Science Journals Connector (OSTI)

A two-beam differential laser absorption technique is used to measure U238 absorption spectra with high signal-to-noise ratios in an atmospheric pressure laser-induced plasma....

Taylor, N R; Phillips, M C

2014-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "laser plasma wakefield" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Nonlinear resonance absorption of laser in an inhomogeneous plasma  

SciTech Connect

A formalism of nonlinear resonance absorption of p-polarized laser in a plasma with density gradient is developed. The nonlinearity is taken to arise through the relativistic mass effect. As the laser incident at an angle to the density gradient approaches the turning point, dielectric swelling leads to field enhancement, causing strong electron mass enhancement and reduction in local plasma frequency. When the critical layer is within a laser wavelength away from the turning point, the laser field is greatly enhanced at the critical layer and absorption of the laser is strongly affected by the nonlinear effect.

Rajouria, Satish Kumar; K K, Magesh Kumar; Tripathi, V. K. [Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016 (India)] [Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016 (India)

2013-08-15T23:59:59.000Z

122

OPTICAL EMISSION DIAGNOSTICS OF LASER PRODUCED PLASMA FROM  

E-Print Network (OSTI)

OPTICAL EMISSION DIAGNOSTICS OF LASER PRODUCED PLASMA FROM GRAPHITE AND YBa2Cu30 7 HARILAL. s irradiances, ionization occurs which leads to the plasma formation. Spectroscopic studies of optical emission and the resulting plasma. Optical emission spectroscopy is a technique which analyzes the light emitted from

Harilal, S. S.

123

Infrared nanosecond laser-metal ablation in atmosphere: Initial plasma during laser pulse and further expansion  

SciTech Connect

We have investigated the dynamics of the nanosecond laser ablated plasma within and after the laser pulse irradiation using fast photography. A 1064 nm, 15 ns laser beam was focused onto a target made from various materials with an energy density in the order of J/mm{sup 2} in atmosphere. The plasma dynamics during the nanosecond laser pulse were observed, which could be divided into three stages: fast expansion, division into the primary plasma and the front plasma, and stagnation. After the laser terminated, a critical moment when the primary plasma expansion transited from the shock model to the drag model was resolved, and this phenomenon could be understood in terms of interactions between the primary and the front plasmas.

Wu, Jian; Wei, Wenfu; Li, Xingwen; Jia, Shenli; Qiu, Aici [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Shaanxi 710049 (China)] [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Shaanxi 710049 (China)

2013-04-22T23:59:59.000Z

124

Wavefront-sensor-based electron density measurements for laser-plasma accelerators  

E-Print Network (OSTI)

for laser-plasma accelerators G. R. Plateau, ? N. H. Matlis,driven plasma-wake?eld accelerator depends on the plasmaof the laser-plasma accelerator. It is shown that direct

Plateau, Guillaume

2010-01-01T23:59:59.000Z

125

Ultrafast electron beam imaging of femtosecond laser-induced plasma  

NLE Websites -- All DOE Office Websites (Extended Search)

Ultrafast electron beam imaging of femtosecond laser-induced plasma Ultrafast electron beam imaging of femtosecond laser-induced plasma dynamics Title Ultrafast electron beam imaging of femtosecond laser-induced plasma dynamics Publication Type Journal Article Year of Publication 2010 Authors Li, Junjie, Xuan Wang, Zhaoyang Chen, Richard Clinite, Samuel S. Mao, Pengfei Zhu, Zhengming Sheng, Jie Zhang, and Jianming Cao Journal Journal of Applied Physics Volume 107 Issue 8 Date Published 03/2010 Keywords copper, electron beam applications, high-speed optical techniques, laser ablation, plasma diagnostics, plasma production by laser Abstract Plasma dynamics in the early stage of laser ablation of a copper target are investigated in real time by making ultrafast electron shadow images and electron deflectometry measurements. These complementary techniques provide both a global view and a local perspective of the associated transient electric field and charge expansion dynamics. The results reveal that the charge cloud above the target surface is composed predominantly of thermally ejected electrons and that it is self-expanding, with a fast front-layer speed exceeding 107 m/s. The average electric field strength of the charge cloud induced by a pump fluence of 2.2 J/cm2 is estimated to be ∼ 2.4×105 V/m.

126

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

DOE Patents (OSTI)

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.

Sher, Mark H. (Los Altos, CA); Macklin, John J. (Stanford, CA); Harris, Stephen E. (Palo Alto, CA)

1989-09-26T23:59:59.000Z

127

Stable plateau formation and Brillouin suppression in laser plasma  

SciTech Connect

Among the variety of ponderomotively induced density structures in laser produced plasmas in one dimension, it is shown by particle-in-cell simulations that the stable plateau formation at critical, subcritical, and above critical density is possible. Stimulated Brillouin backscattering is suppressed with increasing laser intensity.

Mulser, P. [Theoretical Quantum Electronics (TQE), Technische Universitaet Darmstadt, D-64289 Darmstadt (Germany); Weng, S. M. [Theoretical Quantum Electronics (TQE), Technische Universitaet Darmstadt, D-64289 Darmstadt (Germany); Department of Physics, Ludwig-Maximilians-Universitaet Muenchen, D-80333 Munich (Germany)

2010-10-15T23:59:59.000Z

128

Novel techniques of laser acceleration: from structures to plasmas  

Science Journals Connector (OSTI)

...numerical aperture was used to focus the mid-IR beam. A set of...omega=0.95, a crit initial plasma wave amplitude, u 0=0.08...PHY-0114336 administered by the FOCUS Center at the University of...laser-excited relativistic electron plasma waves. Phys. Rev. Lett...

2006-01-01T23:59:59.000Z

129

Time evolution of colliding laser produced magnesium plasmas investigated using a pinhole camera  

E-Print Network (OSTI)

suitable conditions for x-ray amplification in a laser produced plasma.24 When two plasmas collide, variTime evolution of colliding laser produced magnesium plasmas investigated using a pinhole camera S for publication 14 February 2001 Time resolved studies of colliding laser produced magnesium plasmas are performed

Harilal, S. S.

130

Charge-exchange collisions in interpenetrating laser-produced magnesium plasmas  

E-Print Network (OSTI)

Charge-exchange collisions in interpenetrating laser-produced magnesium plasmas S.S. HARILAL,1 C charge-exchange collisions between highly charged Mg ions in colliding laser-produced magnesium plasmas magnesium plasmas. 1. INTRODUCTION Several applications of laser-produced plasmas involve an experimental

Harilal, S. S.

131

Measurements of laser-plasma instability relevant to ignition hohlraums  

SciTech Connect

The potential for laser-plasma instability is a serious concern for indirect-drive inertial confinement fusion (ICF), where laser beams illuminate the interior of a cavity (called a hohlraum) to produce x-rays for imploding a fusion capsule symmetrically. The speckled nature of laser beams used in ICF is an important factor in laser-plasma instability processes. For example, models which calculate the spatial growth of convective instability by properly accounting for the laser speckles successfully predict the observed onsets of backscattering due to stimulated Brillouin and Raman scattering instabilities (SBS and SRS). Assuming pump depletion as the only saturation mechanism in these models results in very large predicted levels of SBS and SRS backscattering from the long-scale plasmas expected in ignition hohlraums. However, in the long-scale plasmas studied in the Nova and Trident lasers [E. M. Campbell, Rev. Sci. Instrum. {bold 57}, 2101 (1986) and N. K. Moncur {ital et al.}, Appl. Opt. {bold 34}, 4274 (1995)], SRS and SBS are observed to saturate much below the levels expected from pump depletion. While the mechanism of SBS saturation is not understood at present, the observations of SRS saturation are qualitatively understood. {copyright} {ital 1997 American Institute of Physics.}

Fernandez, J.C.; Bauer, B.S.; Cobble, J.A.; DuBois, D.F.; Kyrala, G.A.; Montgomery, D.S.; Rose, H.A.; Vu, H.X.; Watt, R.G.; Wilde, B.H.; Wilke, M.D.; Wood, W.M. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Failor, B.H. [Physics International, San Leandro, California 94577 (United States)] [Physics International, San Leandro, California 94577 (United States); Kirkwood, R.; MacGowan, B.J. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)] [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

1997-05-01T23:59:59.000Z

132

Control of Laser Plasma Based Accelerators up to 1 GeV  

E-Print Network (OSTI)

Based Accelerators . . . . . . . . . . . . . . . . . . 11Guided Laser Wake?eld Accelerator . 76 Low Power Guidingusing laser wake?eld accelerators. Phys. Plasmas, 8(5):2510

Nakamura, Kei

2008-01-01T23:59:59.000Z

133

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

SciTech Connect

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.

Schroeder, Carl; Esarey, Eric; Benedetti, Carlo; Leemans, Wim

2013-08-06T23:59:59.000Z

134

LASER-ELECTRON COMPTON INTERACTION IN PLASMA CHANNELS  

SciTech Connect

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, we 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. We demonstrate the advantages of the channeled LSS approach by the example of the prospective polarized positron source for Japan Linear Collider.

POGORELSKY,I.V.

1998-10-01T23:59:59.000Z

135

Laser diagnostics | Princeton Plasma Physics Lab  

NLE Websites -- All DOE Office Websites (Extended Search)

the Lawrence Livermore National Laboratory with the goal of igniting a propagating thermonuclear burn wave in DT fuel leading to energy gain (defined as fusion yieldinput laser...

136

Design Considerations for Plasma Accelerators Driven by Lasers or Particle Beams  

E-Print Network (OSTI)

collider," in Advanced Accelerator Concepts, edited by C .Considerations for Plasma Accelerators Driven by Lasers orUSA Abstract. Plasma accelerators may be driven by the

Schroeder, C. B.

2011-01-01T23:59:59.000Z

137

Measurement of Plasma Density in a Gas-Filled Ionizing Laser Focus.  

E-Print Network (OSTI)

??We use an interferometric method for measuring the plasma density in a laser-induced plasma as a function of time. Any changes in the density within (more)

Heilmann, Nathan Edward

2012-01-01T23:59:59.000Z

138

Wavefront-sensor-based electron density measurements for laser-plasma accelerators  

E-Print Network (OSTI)

After imaging the plasma to a primary focus shortly afterfocus was 1 mm above the nozzle. The laser pulse excited a plasma

Plateau, Guillaume

2010-01-01T23:59:59.000Z

139

Generation of electron beams from a laser-based advanced accelerator at Shanghai Jiao Tong University  

E-Print Network (OSTI)

At Shanghai Jiao Tong University, we have established a research laboratory for advanced acceleration research based on high-power lasers and plasma technologies. In a primary experiment based on the laser wakefield acceleration (LWFA) scheme, multi-hundred MeV electron beams having a reasonable quality are generated using 20-40 TW, 30 femtosecond laser pulses interacting independently with helium, neon, nitrogen and argon gas jet targets. The laser-plasma interaction conditions are optimized for stabilizing the electron beam generation from each type of gas. The electron beam pointing angle stability and divergence angle as well as the energy spectra from each gas jet are measured and compared.

Elsied, Ahmed M M; Li, Song; Mirzaie, Mohammad; Sokollik, Thomas; Zhang, Jie

2014-01-01T23:59:59.000Z

140

Anomalous Heating of a Plasma by a Laser  

Science Journals Connector (OSTI)

As lasers have an ability to deliver a large amount of energy very rapidly to matter, one can produce a plasma of thermonuclear temperature by laser bombardment of matter. We observed a neutron yield from a solid deuterium target irradiated by the beam of a glass laser, which had a power of 20 GW for 2 nsec. The theoretically estimated threshold laser power for anomalous heating owing to the parametric instability was in agreement with the experimental result. Above this threshold, an increase in the electron temperature, the appearance of a fast-ion group, and an anomaly in the reflection of light from the plasma were observed. These phenomena were closely correlated with the neutron yield. At the high-temperature region above a few hundred electron volts, the anomalous heating plays an essential role in reaching the fusion-reaction temperature.

C. Yamanaka; T. Yamanaka; T. Sasaki; K. Yoshida; M. Waki; H. B. Kang

1972-12-01T23:59:59.000Z

Note: This page contains sample records for the topic "laser plasma wakefield" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Laser produced plasma diagnostics by cavity ringdown spectroscopy and applications  

SciTech Connect

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.

Milosevic, S. [Institute of Physics, Zagreb (Croatia)

2012-05-25T23:59:59.000Z

142

Gas dynamic effects on formation of carbon dimers in laser-produced plasmas  

E-Print Network (OSTI)

production, carbon laser-produced plasma (LPP) research was a main focus over the last several years.1

Harilal, S. S.

143

Desired Improvements in Laser-Plasma Accelerators  

NLE Websites -- All DOE Office Websites (Extended Search)

experiment: one CO2-driven SWABSiC prebunches the beam, the other one diagnoses Laser and Beam Damage: Dielectrics vs. Metals vs. Semiconductors From Du and Byer (1999)....

144

A transmission grating spectrograph and its application in both laser plasma and plasma focus  

Science Journals Connector (OSTI)

A new transmission gratingspectrograph for soft x-raymeasurement in pulsed plasmas was designed and studied. The spectrograph has an adjustment system with three degrees of freedom together with an electronic-controlled camera. This design makes it easy to align and use for laser-produced plasmas or the plasma focus. The spectrograph provides spatially resolved spectrum in two dimensions and has a wavelength range of 0.330 nm. A transmission grating was used to obtain spatially resolved spectra from plasmas produced by laser-irradiated solid target and gas filled plasma focus. Such a spectrograph is suitable for coupling with a soft x-ray streak camera or a soft x-ray charge coupled device detector for time-resolved studies.

X. Feng; M. H. Liu; S. Lee

1997-01-01T23:59:59.000Z

145

Efficient laser-overdense plasma coupling via surface plasma waves and steady magnetic field generation  

SciTech Connect

The efficiency of laser overdense plasma coupling via surface plasma wave excitation is investigated. Two-dimensional particle-in-cell simulations are performed over a wide range of laser pulse intensity from 10{sup 15} to 10{sup 20} W cm{sup -2}{mu}m{sup 2} with electron density ranging from 25 to 100n{sub c} to describe the laser interaction with a grating target where a surface plasma wave excitation condition is fulfilled. The numerical studies confirm an efficient coupling with an enhancement of the laser absorption up to 75%. The simulations also show the presence of a localized, quasi-static magnetic field at the plasma surface. Two interaction regimes are identified for low (I{lambda}{sup 2} < 10{sup 17} W cm{sup -2}{mu}m{sup 2}) and high (I{lambda}{sup 2} > 10{sup 17} W cm{sup -2}{mu}m{sup 2}) laser pulse intensities. At ''relativistic'' laser intensity, steady magnetic fields as high as {approx}580 MG {mu}m/{lambda}{sub 0} at 7 x 10{sup 19} W cm{sup -2}{mu}m{sup 2} are obtained in the simulations.

Bigongiari, A. [CEA/DSM/LSI, CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France); TIPS/LULI, Universite Paris 6, CNRS, CEA, Ecole Polytechnique, 3, rue Galilee 94200, Ivry-sur-Seine (France); Raynaud, M. [CEA/DSM/LSI, CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Riconda, C. [TIPS/LULI, Universite Paris 6, CNRS, CEA, Ecole Polytechnique, 3, rue Galilee 94200, Ivry-sur-Seine (France); Heron, A. [CPHT, CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Macchi, A. [Consiglio Nazionale delle Ricerche, Istituto Nazionale di Ottica (CNR/INO), Dipartimento di Fisica ''E. Fermi'', Largo B. Pontecorvo 3, 56127 Pisa (Italy)

2011-10-15T23:59:59.000Z

146

Excitation of promising nuclear fusion reactions in picosecond laser plasmas  

SciTech Connect

The results of experiments devoted to studying the excitation of the promising nuclear fusion reactions {sup 6}Li(d, {alpha}){sup 4}He, {sup 3}He(d, p){sup 4}He, {sup 11}B(p, 3{alpha}), and {sup 7}Li(p, {alpha}){sup 4}He, along with the standard reaction D(d, n){sup 3}He, in picosecond laser plasmas are presented. For the first time, it was shown that these reactions may proceed at a moderate laser-radiation intensity of 2 x 10{sup 18} W/cm{sup 2}, the respective yield being 2 x 10{sup 3} to 10{sup 5} per laser pulse. A brief survey of the main processes responsible for the generation of fast electrons and fast ions (protons) at the front surface of the target and for the excitation of nuclear fusion reactions is given. The calculated and experimental results on the yield from nuclear fusion reactions in picosecond laser plasmas are compared. The possibilities for optimizing the yield from the promising fusion reactions excited in femto- and picosecond laser plasmas are discussed.

Belyaev, V. S.; Vinogradov, V. I.; Matafonov, A. P., E-mail: Matafonov@mtu-net.ru; Rybakov, S. M. [Central Research Institute of Machine Building (Russian Federation); Krainov, V. P. [Moscow Institute for Physics and Technology (State University) (Russian Federation); Lisitsa, V. S. [Russian Research Centre Kurchatov Institute, Institute of Nuclear Fusion (Russian Federation); Andrianov, V. P.; Ignatiev, G. N. [Research Institute for Pulse Technology (NIIPT) (Russian Federation); Bushuev, V. S.; Gromov, A. I.; Rusetsky, A. S.; Dravin, V. A. [Russian Academy of Sciences, Lebedev Institute of Physics (Russian Federation)

2009-07-15T23:59:59.000Z

147

The effect of plasma channel on the self-distortion of laser pulse propagating through the collisional plasma channel  

Science Journals Connector (OSTI)

Abstract In the present paper, laser pulse distortion/breakup and the effect of the plasma channel on the laser propagation through the collisional plasma have been studied by using moment theory approach. Second order nonlinear differential equations of the beam width parameter have been derived for the propagation of the laser through uniform homogenous plasma and preformed plasma channel having parabolic density profile. Differential equations of beam width parameter have been solved numerically using Runge Kutta method. It has been observed from analysis that when the laser pulse propagates through the homogenous plasma, the low intensity front and rear parts of the laser get defocused/diffracted and the high intensity central/main portion of the laser pulse gets self-guided. As a result of this, the laser pulse gets distorted. This distortion of the laser has not been observed when the laser pulse is propagated through the plasma channel having density minimum at the axis and maximum at the edges. The laser pulse is guided as a whole, even the low intensity front and rear parts of the laser are also guided. Therefore, the plasma channel is useful to prevent the distortion/breakup of the laser.

Navpreet Singh; Arvinder Singh

2014-01-01T23:59:59.000Z

148

Effects of excitation laser wavelength on Ly-a and He-a line emission from nitrogen plasmas  

E-Print Network (OSTI)

are soft x-ray lasers,6,7 laser-produced plasma (LPP) sources,8­11 and higher har- monics from laser heatedEffects of excitation laser wavelength on Ly-a and He-a line emission from nitrogen plasmas S. S November 2012; accepted 27 December 2012; published online 11 January 2013) Laser-produced nitrogen plasmas

Harilal, S. S.

149

High energy heavy ion jets emerging from laser plasma generated by long pulse laser beams from  

E-Print Network (OSTI)

, Albuquerque, New Mexico. ~Received 21 February 2005; Accepted 20 April 2005! Abstract High energy heavy ions to the fast ion emission process. The interest in laser plasmas and interaction phenomena of heavy ion beams!. Thus there is a tradition to investigate accelerator related issues like beam transport phenomena

150

Pulse shaping of transversely excited atmospheric CO2 laser using a simple plasma shutter  

E-Print Network (OSTI)

Pulse shaping of transversely excited atmospheric CO2 laser using a simple plasma shutter Noah excited atmospheric CO2 laser consists of a sharp spike followed by a long, drawn out tail region spanning applications because it decreases the average power of the laser pulse. We employ a pinhole plasma shutter

Harilal, S. S.

151

Experimental investigation of ultraviolet laser induced plasma density and temperature evolution in air  

E-Print Network (OSTI)

and collisional cascade processes for pressures ranging from 40 Torr to 5 atm. A laser shadowgraphy diagnosticExperimental investigation of ultraviolet laser induced plasma density and temperature evolution July 2008 We present measurements and analysis of laser induced plasma neutral densities

Scharer, John E.

152

Plasma channel diagnostic based on laser centroid oscillationsa... A. J. Gonsalves,b  

E-Print Network (OSTI)

for radia- tion sources--ranging from coherent terahertz4 to free elec- tron laser FEL x-ray sources5Plasma channel diagnostic based on laser centroid oscillationsa... A. J. Gonsalves,b K. Nakamura, C the properties of discharge-based plasma channels by monitoring the centroid location of a laser beam exiting

Geddes, Cameron Guy Robinson

153

Design Considerations for Plasma Accelerators Driven by Lasers or Particle Beams  

E-Print Network (OSTI)

Design Considerations for Plasma Accelerators Driven by Lasers or Particle Beams C. B. Schroeder, E of an intense laser or the space-charge force of a charged particle beam. The implications for accelerator design and the different physical mechanisms of laser-driven and beam-driven plasma acceleration

Geddes, Cameron Guy Robinson

154

Improved ion acceleration via laser surface plasma waves excitation  

SciTech Connect

The possibility of enhancing the emission of the ions accelerated in the interaction of a high intensity ultra-short (<100 fs) laser pulse with a thin target (<10?{sub 0}), via surface plasma wave excitation is investigated. Two-dimensional particle-in-cell simulations are performed for laser intensities ranging from 10{sup 19} to 10{sup 20} Wcm{sup ?2}?m{sup 2}. The surface wave is resonantly excited by the laser via the coupling with a modulation at the target surface. In the cases where the surface wave is excited, we find an enhancement of the maximum ion energy of a factor ?2 compared to the cases where the target surface is flat.

Bigongiari, A. [CEA/DSM/LSI, CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France) [CEA/DSM/LSI, CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France); TIPS/LULI, Universit Paris 6, CNRS, CEA, Ecole Polytechnique, 3, rue Galile, 94200 Ivry-sur-Seine (France); Raynaud, M. [CEA/DSM/LSI, CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France)] [CEA/DSM/LSI, CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Riconda, C. [TIPS/LULI, Universit Paris 6, CNRS, CEA, Ecole Polytechnique, 3, rue Galile, 94200 Ivry-sur-Seine (France)] [TIPS/LULI, Universit Paris 6, CNRS, CEA, Ecole Polytechnique, 3, rue Galile, 94200 Ivry-sur-Seine (France); Hron, A. [CPHT, CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France)] [CPHT, CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France)

2013-05-15T23:59:59.000Z

155

Fusion reactions initiated by laser-accelerated particle beams in a laser-produced plasma  

E-Print Network (OSTI)

The advent of high-intensity pulsed laser technology enables the generation of extreme states of matter under conditions that are far from thermal equilibrium. This in turn could enable different approaches to generating energy from nuclear fusion. Relaxing the equilibrium requirement could widen the range of isotopes used in fusion fuels permitting cleaner and less hazardous reactions that do not produce high energy neutrons. Here we propose and implement a means to drive fusion reactions between protons and boron-11 nuclei, by colliding a laser-accelerated proton beam with a laser-generated boron plasma. We report proton-boron reaction rates that are orders of magnitude higher than those reported previously. Beyond fusion, our approach demonstrates a new means for exploring low-energy nuclear reactions such as those that occur in astrophysical plasmas and related environments.

Labaune, C; Depierreux, S; Goyon, C; Loisel, G; Yahia, V; Rafelski, J

2013-01-01T23:59:59.000Z

156

Title of Dissertation: MODELING LASER PULSE EVOLUTION IN IONIZING GAS AND PLASMA WITH  

E-Print Network (OSTI)

ABSTRACT Title of Dissertation: MODELING LASER PULSE EVOLUTION IN IONIZING GAS AND PLASMA to model propagation in tenuous gas and plasma and we provide relevant information about the validation energy distribution. #12;MODELING LASER PULSE EVOLUTION IN IONIZING GAS AND PLASMA WITH APPILCATION

Anlage, Steven

157

Nonlinear relativistic interaction of an ultrashort laser pulse with a cold plasma  

E-Print Network (OSTI)

J Fisch. . . . Princeton Plasma Physics Laboratory, Princeton University, Princeton, New JerseyNonlinear relativistic interaction of an ultrashort laser pulse with a cold plasma J M Raxa) and N that results when intense ( 10" W/cm* and above) and ultrashort (one plasma period or shorter) laser pulse

158

Saturation of multi-laser beams laser-plasma instabilities from stochastic ion heating  

SciTech Connect

Cross-beam energy transfer (CBET) has been used as a tool on the National Ignition Facility (NIF) since the first energetics experiments in 2009 to control the energy deposition in ignition hohlraums and tune the implosion symmetry. As large amounts of power are transferred between laser beams at the entrance holes of NIF hohlraums, the presence of many overlapping beat waves can lead to stochastic ion heating in the regions where laser beams overlap [P. Michel et al., Phys. Rev. Lett. 109, 195004 (2012)]. This increases the ion acoustic velocity and modifies the ion acoustic waves dispersion relation, thus reducing the plasma response to the beat waves and the efficiency of CBET. This pushes the plasma oscillations driven by CBET in a regime where the phase velocities are much smaller than both the electron and ion thermal velocities. CBET gains are derived for this new regime and generalized to the case of multi ion species plasmas.

Michel, P.; Williams, E. A.; Divol, L.; Berger, R. L.; Glenzer, S. H.; Callahan, D. A. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)] [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Rozmus, W. [Theoretical Physics Institute, University of Alberta, Edmonton, Alberta T6G2G7 (Canada) [Theoretical Physics Institute, University of Alberta, Edmonton, Alberta T6G2G7 (Canada); Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

2013-05-15T23:59:59.000Z

159

Experimental demonstration of wakefield effects in a THz planar...  

NLE Websites -- All DOE Office Websites (Extended Search)

energy chirp compensation * Self-wake energy modulation wakefield structure spectro meter Shaped beam energy chirped Shape + energy chirp energy change via self-wakefield...

160

Experimental demonstration of wakefield effects in a THz planar...  

NLE Websites -- All DOE Office Websites (Extended Search)

ATF Users' Meetings, April 26 - 27, 2012 Wakefield Mapping wakefield structure spectro meter drive beam witness Experimental drive + witness visualization Spectrometer measurement...

Note: This page contains sample records for the topic "laser plasma wakefield" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Laser-Energy Transfer and Enhancement of Plasma Waves and Electron Beams by Interfering High-Intensity Laser Pulses  

E-Print Network (OSTI)

Laser-Energy Transfer and Enhancement of Plasma Waves and Electron Beams by Interfering High-Intensity) The effects of interference due to crossed laser beams were studied experimentally in the high- intensity regime. Two ultrashort (400 fs), high-intensity (4 1017 and 1:6 1018 W=cm2) and 1 m wavelength laser

Umstadter, Donald

162

Demonstration of Laser Induced X-Ray Generation in an Expanding Laser Produced Plasma  

Science Journals Connector (OSTI)

X-ray emission at 10 nm stimulated by visible laser radiation at 614.2 nm in a beryllium laser produced plasma was investigated. A method of laser induced quenching of metastable ions was applied to He-like Be2+ ions in the 1s2s 1S0 state. Laser excitation to the 1s2p 1P1 state was followed by an intense x-ray emission at a resonance 1s2 1S0-1s2p 1P1 transition. Time, angular, and polarization characteristics of the radiation were studied; a linear polarization and a dipole type angular distribution have been found. The total energy radiated in a 1.5 ns pulse amounted to 10 ?J.

D. M. Simanovskii, A. N. Gladskikh, L. A. Shmaenok, and S. V. Bobashev

1996-07-29T23:59:59.000Z

163

Creation of electron-positron plasma with superstrong laser field  

E-Print Network (OSTI)

We present a short review of recent progress in studying QED effects of interaction of ultra-relativistic laser pulses with vacuum and $e^-e^+$ plasma. The development of laser technologies promises very rapid growth of laser intensities in close future already. Two exawatt class facilities (ELI and XCELS, Russia) in Europe are already in the planning stage. Realization of these projects will make available a laser of intensity $\\sim 10^{26}$W/cm$^2$ or even higher. Therefore, discussion of nonlinear optical effects in vacuum are becoming urgent for experimentalists and are currently gaining much attention. We show that, in spite of the fact that the respective field strength is still essentially less than $E_S=m^2c^3/e\\hbar=1.32\\cdot 10^{16}$V/cm, the nonlinear vacuum effects will be accessible for observation at ELI and XCELS facilities. The most promissory for observation is the effect of pair creation by laser pulse in vacuum. It is shown, that at intensities $\\sim 5\\cdot 10^{25}$W/cm$^2$, creation even o...

Narozhny, N B

2013-01-01T23:59:59.000Z

164

Wear resistance of laser cladding and plasma spray welding layer on stainless steel surface  

Science Journals Connector (OSTI)

The effect of coatings, which are formed with laser cladding and plasma spray welding on 1Cr18Ni9Ti base metal, on wear resistance is studied, A 5-kW transverse flowing CO2 laser...

Wang, Xinlin; Shi, Shihong; Zheng, Qiguang

2004-01-01T23:59:59.000Z

165

Optically-ionized plasma recombination x-ray lasers  

SciTech Connect

Design studies for recombination x-ray lasers based on plasmas ionized by high intensity, short pulse optical lasers are presented. Transient lasing on n = 3 to n = 2 transitions in Lithium-like Neon allows for moderately short wavelengths ({le} 100{angstrom}) without requiring ionizing intensities associated with relativistic electron quiver energies. The electron energy distribution following the ionizing pulse affects directly the predicted gains for this resonance transition. Efficiencies of 10{sup {minus}6} or greater are found for plasma temperatures in the vicinity of 40 eV. Simulation studies of parametric heating phenomena relating to stimulated Raman and Compton scattering are presented. For electron densities less than about 2.5 {times} 10{sup 20} cm{sup {minus}3} and peak driver intensity of 2 {times} 10{sup 17} W/cm{sup 2} at 0.25 {mu}m with pulse length of 100 fsec, the amount of electron heating is found to be marginally significant. For Lithium-like Aluminum, the required relativistic ionizing intensity gives excessive electron heating and reduced efficiency, thereby rendering this scheme impractical for generating shorter wavelength lasing ({le} 50{angstrom}) in the transient case. Following the transient lasing phase, a slow hydrodynamic expansion into the surrounding cool plasma is accompanied by quasi-static gain on the n = 4 to n = 3 transition in Lithium-like Neon. Parametric heating effects on gain optimization in this regime are also discussed. 18 refs., 6 figs.

Amendt, P.; Eder, D.C.; Wilks, S.C.; Dunning, M.J.; Keane, C.J.

1991-01-18T23:59:59.000Z

166

Recent Advances in Plasma Acceleration  

SciTech Connect

The costs and the time scales of colliders intended to reach the energy frontier are such that it is important to explore new methods of accelerating particles to high energies. Plasma-based accelerators are particularly attractive because they are capable of producing accelerating fields that are orders of magnitude larger than those used in conventional colliders. In these accelerators a drive beam, either laser or particle, produces a plasma wave (wakefield) that accelerates charged particles. The ultimate utility of plasma accelerators will depend on sustaining ultra-high accelerating fields over a substantial length to achieve a significant energy gain. More than 42 GeV energy gain was achieved in an 85 cm long plasma wakefield accelerator driven by a 42 GeV electron drive beam in the Final Focus Test Beam (FFTB) Facility at SLAC. Most of the beam electrons lose energy to the plasma wave, but some electrons in the back of the same beam pulse are accelerated with a field of {approx}52 GV/m. This effectively doubles their energy, producing the energy gain of the 3 km long SLAC accelerator in less than a meter for a small fraction of the electrons in the injected bunch. Prospects for a drive-witness bunch configuration and high-gradient positron acceleration experiments planned for the SABER facility will be discussed.

Hogan, Mark

2007-03-19T23:59:59.000Z

167

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

E-Print Network (OSTI)

We present results of the first tunable Compton backscattering (CBS) x-ray source that is based on the easily aligned combination of a laser-plasma accelerator (LPA) and a plasma mirror (PM). The LPA is driven in the blowout regime by 30 TW, 30 fs laser pulses, and produces high-quality, tunable, quasi-monoenergetic electron beams. A thin plastic film near the gas jet exit efficiently retro-reflects the LPA driving pulse with relativistic intensity into oncoming electrons to produce $2\\times10^{7}$ CBS x-ray photons per shot with 10-20 mrad angular divergence and 50 % (FWHM) energy spread without detectable bremsstrahlung background. The x-ray central energy is tuned from 75 KeV to 200 KeV by tuning the LPA e-beam central energy. Particle-in-cell simulations of the LPA, the drive pulse/PM interaction and CBS agree well with measurements.

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

2014-01-01T23:59:59.000Z

168

Evolution of ?-SiC in laser-generated plasmas  

Science Journals Connector (OSTI)

A relevant issue in fusion reactors is to choose materials for plasma facing components such that an acceptable lifetime is guaranteed. Silicon carbide is among the very few materials that appear promising to resist harsh environmental conditions including high thermal loads, strong chemical erosion and severe energetic particle bombardment. Thin films, around 130nm thick, of cubic silicon carbide (?-SiC) were pulsed laser deposited on Si (100) substrates at 1173K, at fluences ranging from 3 to 9Jcm?2. The films deposited at 6Jcm?2 appear the most compact, homogeneous, crack free, with a reduced density of particulate and droplets at the surface. Such films were irradiated by different plasmas, generated by ns and fs laser pulses respectively, corresponding to deposited intensities between 108Wcm?2 and 1018Wcm?2. The compositional, morphological and microstructural evolution of irradiated ?-SiC films were investigated by energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), vibrational spectroscopies (IR and Raman) and transmission electron microscopy (TEM). Under both irradiation conditions the films remain well adherent to the substrates, showing thermal and mechanical stability. The samples loose only a minor fraction of carbon. However, all irradiations induce meaningful changes of surface morphology, qualitatively different between the ns and fs pulses. In the former an evident columnar structure develops at the crater edges; in the latter, after a single pulse, a wavy structure was observed whose periodicity is nearly identical to the laser wavelength. Under both kinds of irradiation ?-SiC shows meaningful chemical and structural stability in highly energetic, aggressive plasma ambient.

L. Gemini; D. Margarone; T. Mocek; F. Neri; S. Trusso; P.M. Ossi

2013-01-01T23:59:59.000Z

169

Laser scattering from long scalelength plasmas on Omega. Final report  

SciTech Connect

In this project, the authors accomplished the tasks called for in the revised statement of work associated with this grant. Specifically, they accomplished: (1) active participation in the design of long-scalelength plasmas for Omega and in experiments to characterize these plasmas; (2) development of software that permits the rapid evaluation of laser-scattering diagnostic possibilities involving the standard parametric instabilities. It must be able to account for all 60 beams in Omega in addition to a probe beam and variable detector locations; and (3) design, purchase of components for, and assembly of instrumentation to make such measurements, providing for long-term versatility in the type of measurement. The project background and these accomplishments are discussed.

Drake, R.P. [Univ. of Michigan, Ann Arbor, MI (United States); Seka, W.; Craxton, R.S. [Univ. of Rochester, NY (United States); Bauer, B.S. [Univ. of Nevada, Reno, NV (United States)

1998-12-31T23:59:59.000Z

170

Dielectric Wakefield Accelerator to drive the future FEL Light Source.  

SciTech Connect

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.

Jing, C.; Power, J.; Zholents, A. (Accelerator Systems Division (APS)); ( HEP); (LLC)

2011-04-20T23:59:59.000Z

171

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

SciTech Connect

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.

Jafari Milani, M. R., E-mail: mrj.milani@gmail.com [Plasma Physics Research School, Tehran (Iran, Islamic Republic of); Department of Energy Engineering and Physics, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); 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); Farahbod, A. H. [Plasma Physics Research School, Tehran (Iran, Islamic Republic of)

2014-06-15T23:59:59.000Z

172

Laser-based diagnostics for condensation in laser-ablated copper plasmas  

SciTech Connect

We are investigating the thermodynamic conditions under which condensation occurs in laser-ablated copper plasma plumes. The plasma is created by XeCl excimer laser ablation (308 nm, 350 mJ/pulse) at power densities from 500--1000 MW/cm{sup 2}. The atomic vapor expands rapidly into backing pressures of helium ranging from 0--50 torr. The backing gas serves to slow the vapor before it rarefies and provides a third body to stabilize collision complexes between vapor atoms to produce small cluster species. The formation of these small clusters is indicative of the onset of condensation, a process which, under the proper conditions, eventually forms macroscopic particulate in the plume. We use laser-induced fluorescence (LIF) to probe both atomic copper and the copper dimer molecule, Cu{sub 2}. Velocities of atomic Cu have been obtained by a time-of-flight method under varying conditions of backing gas pressure. At low pressure (10 mtorr), the atomic Cu velocity peaks at approximately 2 {times} 10{sup 6} cm/s. Excitation scans of the Cu{sub 2} A {minus} X (0,0) and (1,1) bands yield both a rotational temperature and a vibrational temperature. Direct laser beam absorption is used to determine the number density of atomic copper. Rayleigh scattering from particulate is easily observable under conditions favorable to particulate production. The Cu{sub 2} LIF and Rayleigh-scattered signals disappear instantaneously in the absence of the ablation laser pulse indicating that the particulate is formed during a single laser shot. 10 refs., 9 figs.

Sappey, A.D.; Gamble, T.K.

1991-01-01T23:59:59.000Z

173

Low-temperature atmospheric pressure argon plasma treatment and hybrid laser-plasma ablation of barite crown and heavy flint glass  

Science Journals Connector (OSTI)

We report on atmospheric pressure argon plasma-based surface treatment and hybrid laser-plasma ablation of barite crown glass N-BaK4 and heavy flint glass SF5. By pure plasma...

Gerhard, Christoph; Roux, Sophie; Brckner, Stephan; Wieneke, Stephan; Vil, Wolfgang

2012-01-01T23:59:59.000Z

174

High energy density micro plasma bunch from multiple laser interaction with thin target  

SciTech Connect

Three-dimensional particle-in-cell simulation is used to investigate radiation-pressure driven acceleration and compression of small solid-density plasma by intense laser pulses. It is found that multiple impacts by presently available short-pulse lasers on a small hemispheric shell target can create a long-living tiny quasineutral monoenergetic plasma bunch of very high energy density.

Xu, Han [National Laboratory for Parallel and Distributed Processing, College of Computer Science, National University of Defense Technology, Changsha 410073 (China); Shanghai Institute of Optics and Fine Mechanics, Shanghai 201800 (China); Yu, Wei; Luan, S. X.; Xu, Z. Z. [Shanghai Institute of Optics and Fine Mechanics, Shanghai 201800 (China); Yu, M. Y., E-mail: myyu@zju.edu.cn [Physics Department, Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China); Institute for Theoretical Physics I, Ruhr University, Bochum D-44780 (Germany); Cai, H. B.; Zhou, C. T. [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China); Yang, X. H.; Yin, Y.; Zhuo, H. B. [College of Science, National University of Defense Technology, Changsha (China); Wang, J. W. [Shanghai Institute of Optics and Fine Mechanics, Shanghai 201800 (China); Institute of Laser Engineering, Osaka University, Osaka 565-0871 (Japan); Murakami, M. [Institute of Laser Engineering, Osaka University, Osaka 565-0871 (Japan)

2014-01-13T23:59:59.000Z

175

Comparison of EUV spectral and ion emission features from laser-produced Sn and Li plasmas  

E-Print Network (OSTI)

Comparison of EUV spectral and ion emission features from laser- produced Sn and Li plasmas R. W. Coons, D. Campos, M. Crank, S. S. Harilal, and A. Hassanein School of Nuclear Engineering, and Center, and the kinetic energies and fluxes of ions at various laser intensities for both Sn and Li plasmas. The maximum

Harilal, S. S.

176

Supra-bubble regime for laser acceleration of cold electron beams in tenuous plasma  

E-Print Network (OSTI)

Supra-bubble regime for laser acceleration of cold electron beams in tenuous plasma V. I. Geyko,1 I 2010 Relativistic electrons can be accelerated by an ultraintense laser pulse in the "supra-bubble" regime, that is, in the blow-out regime ahead of the plasma bubble as opposed to the conventional method

177

Late-time particle emission from laser-produced graphite plasma S. S. Harilal,a)  

E-Print Network (OSTI)

-produced carbon plasma. Furthermore, in the design of Tokamaks for nuclear fusion, graphite has been proposedLate-time particle emission from laser-produced graphite plasma S. S. Harilal,a) A. Hassanein online 6 September 2011) We report a late-time "fireworks-like" particle emission from laser

Harilal, S. S.

178

Monte Carlo calculations of pair production in high-intensity laser-plasma interactions  

E-Print Network (OSTI)

Gamma-ray and electron-positron pair production will figure prominently in laser-plasma experiments with next generation lasers. Using a Monte Carlo approach we show that straggling effects arising from the finite recoil an electron experiences when it emits a high energy photon, increase the number of pairs produced on further interaction with the laser fields.

Roland Duclous; John Kirk; Anthony Bell

2010-10-21T23:59:59.000Z

179

Quasitransient backward Raman amplification of powerful laser pulses in dense plasmas with multicharged ions  

E-Print Network (OSTI)

are found. The calculation, applicable to infrared, ultraviolet, soft x-ray, and x-ray laser pulses, takes technique is also applicable to shorter wavelength laser pulses including x-ray pulses for which CPA cannotQuasitransient backward Raman amplification of powerful laser pulses in dense plasmas

180

Surface heating of wire plasmas using laser-irradiated cone geometries  

E-Print Network (OSTI)

constructed (National Ignition Facility and Laser M´egaJoule). The energy can be transported over surprisinglyLETTERS Surface heating of wire plasmas using laser-irradiated cone geometries J. S. GREEN1,2 , K Graduate School of Engineering, Osaka University, Suita, 565-0871 Osaka, Japan 9 Institute of Laser

Loss, Daniel

Note: This page contains sample records for the topic "laser plasma wakefield" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

A PLASMA CHANNEL BEAM CONDITIONER FOR A FREE ELECTRON LASER  

E-Print Network (OSTI)

plasma focusing and plasma accel- eration, but further beam compression is not required. The resulting

Wurtele, Jonathan

182

COUNTER PROPAGATION OF ELECTRON AND CO2 LASER BEAMS IN A PLASMA CHANNEL.  

SciTech Connect

A high-energy CO{sub 2} laser is channeled in a capillary discharge. Occurrence of guiding conditions at a relatively low plasma density (<10{sup 18} cm{sup -3}) is confirmed by MHD simulations. Divergence of relativistic electron beam changes depending on the plasma density. Counter-propagation of the electron and laser beams inside the plasma channel results in intense x-ray generation.

HIROSE,T.; POGORELSKY,I.V.; BEN ZVI,I.; YAKIMENKO,V.; KUSCHE,K.; SIDDONS,P.; KUMITA,T.; KAMIYA,Y.; ZIGLER,A.; GREENBERG,B.; ET AL

2002-11-12T23:59:59.000Z

183

Observation and modelling of hollow multicharged ion x-ray spectra radiated by laser produced plasma  

SciTech Connect

The role of the highly charged hollow ions in the X-Ray emission plasma spectTa is investigated for 2 cases: (1) plasma obtained under inadiation of Ar clusters by ultrashort laser pulses and (2) Mg-plasma heated by a short-wavelength long (nanosecond) laser pulse. Experimental measurements are presented. Calculations in support of these measurements have been performed using a detailed atomic kinetics model with the ion distributions found from solution of the time-dependent rate equations.

Colgan, James P [Los Alamos National Laboratory; Abdallah, Joseph [Los Alamos National Laboratory; Faenov, A Ya [JAPAN/RUSSIA; Pikuz, T A [JAPAN/RUSSIA; Akobelev, I Yu [JAPAN/RUSSIA; Fukuda, Y [JAPAN/RUSSIA

2008-01-01T23:59:59.000Z

184

Theory of ionization-induced trapping in laser-plasma accelerators M. Chen, E. Esarey,a)  

E-Print Network (OSTI)

Theory of ionization-induced trapping in laser-plasma accelerators M. Chen, E. Esarey,a) C. B) Ionization injection in a laser-plasma accelerator is studied analytically and by multi-dimensional particle acceleration. For a broad laser pulse, ionization injection requires a minimum normalized laser field of a0 ' 1

Geddes, Cameron Guy Robinson

185

Experimental scaling law for mass ablation rate from a Sn plasma generated by a 1064 nm laser  

E-Print Network (OSTI)

. INTRODUCTION Laser produced Sn plasma, in its role as an efficient extreme ultraviolet EUV x-ray sourceExperimental scaling law for mass ablation rate from a Sn plasma generated by a 1064 nm laser depth in planar Sn targets irradiated with a pulsed 1064 nm laser was investigated over laser

Najmabadi, Farrokh

186

First Demonstration of Staged Laser Acceleration  

NLE Websites -- All DOE Office Websites (Extended Search)

Laser Wakefield Acceleration Driven by a CO 2 Laser (STELLA-LW) W. D. Kimura ATF Users' Meeting Jan. 8, 2004 Work was supported by the U.S. Department of Energy, Grant Nos....

187

Laser-rf creation and diagnostics of seeded atmospheric pressure air and nitrogen plasmas  

E-Print Network (OSTI)

Laser-rf creation and diagnostics of seeded atmospheric pressure air and nitrogen plasmas Siqi Luo to the ambient air. The atmospheric-pressure plasma is then maintained with the 13.56 MHz rf power. Using of atmospheric-pressure air plasmas The kinetics of reactions and transitions in atmospheric- pressure air

Scharer, John E.

188

Computational modeling of laser-plasma interactions: Pulse self-modulation and energy transfer between intersecting laser pulses  

Science Journals Connector (OSTI)

The nonlinear interaction of intense femtosecond laser pulses with a self-induced plasma channel in air and the energy transfer between two intersecting laser pulses were simulated using the finite-difference time-domain particle-in-cell method. Implementation of a simple numerical code enabled modeling of various phenomena, including pulse self-modulation in the spatiotemporal and spectral domains, conical emission, and energy transfer between two intersecting laser beams. The mechanism for energy transfer was found to be related to a plasma waveguide array induced by Moir patterns of the interfering electric fields. The simulation results provide a persuasive replication and explanation of previous experimental results, when carried out under comparable physical conditions, and lead to prediction of others. This approach allows us to further examine the effect of the laser and plasma parameters on the simulation results and to investigate the underlying physics.

Rotem Kupfer; Boris Barmashenko; Ilana Bar

2013-07-17T23:59:59.000Z

189

Time-resolved spectroscopy of plasma plumes: A versatile approach for optimization of high-order harmonic generation in laser plasma  

SciTech Connect

The time-resolved studies of laser-produced Ag, In, Pt, V, Mn, and Ga plasmas are presented from the point of view of plasma application as the nonlinear optical medium for high-order harmonic generation of laser radiation. We show that optimization of plasma formation using this technique allows the enhancement of harmonic generation efficiency and extension of maximal harmonic order.

Ganeev, R. A. [Institut national de la recherche scientifique, Centre Energie, Materiaux et Telecommunications, 1650 Lionel-Boulet, Varennes, Quebec J3X 1S2 (Canada); Institute of Electronics, Akademgorodok, 33 Dormon Yoli street, Tashkent 100125 (Uzbekistan); Elouga Bom, L. B.; Ozaki, T. [Institut national de la recherche scientifique, Centre Energie, Materiaux et Telecommunications, 1650 Lionel-Boulet, Varennes, Quebec J3X 1S2 (Canada)

2011-08-15T23:59:59.000Z

190

High-order harmonic generation from plasma plume pumped by 400 nm wavelength laser  

SciTech Connect

The authors present their study on high-order harmonic generation pumped by 400 nm wavelength laser from plasma plumes produced on the surfaces of various solid-state targets. The maximum harmonic cutoff was observed for Be plasma (31st harmonic, {lambda}=12.9 nm). They compared these results with harmonic generation pumped by 800 nm wavelength laser. The authors demonstrated single harmonic enhancement for Cr, Sn, Sb, and Mn plasmas. They also studied the use of varying the chirp of the pump laser to control the enhancement of single harmonics within the plateau.

Ganeev, Rashid A.; Elouga Bom, Luc B.; Ozaki, Tsuneyuki [Institut National de la Recherche Scientifique, Energie, Materiaux et Telecommunications, 1650 Lionel-Boulet, Varennes, Quebec J3X 1S2 (Canada) and Scientific Association Akadempribor, Academy of Sciences of Uzbekistan, Akademgorodok, Tashkent 100125 (Uzbekistan); Institut National de la Recherche Scientifique, Energie, Materiaux et Telecommunications, 1650 Lionel-Boulet, Varennes, Quebec J3X 1S2 (Canada)

2007-09-24T23:59:59.000Z

191

Titanium nitride thin films deposited by reactive pulsed-laser ablation in RF plasma  

Science Journals Connector (OSTI)

Titanium nitride thin films were deposited on Si (100) substrates by pulsed laser ablation of a titanium target in a N2 atmosphere (gas pressure approx. 10 Pa) using a doubled frequency Nd:YAG laser (532 nm) also assisted by a 13.56-MHz radio frequency (RF) plasma. Deposition was carried out at various substrate temperatures ranging from 373 up to 873 K and films were analyzed by X-ray diffractometry, scanning electron microscopy and optical emission spectroscopy. A comparison between the normal pulsed laser deposition (PLD) and the RF plasma-assisted PLD showed the influence of the plasma on the structural characteristics of the thin films.

A. Giardini; V. Marotta; S. Orlando; G.P. Parisi

2002-01-01T23:59:59.000Z

192

Few-cycle optical probe-pulse for investigation of relativistic laser-plasma interactions  

SciTech Connect

The development of a few-cycle optical probe-pulse for the investigation of laser-plasma interactions driven by a Ti:sapphire, 30 Terawatt (TW) laser system is described. The probe is seeded by a fraction of the driving laser's energy and is spectrally broadened via self-phase modulation in a hollow core fiber filled with a rare gas, then temporally compressed to a few optical cycles via chirped mirrors. Shadowgrams of the laser-driven plasma wave created in relativistic electron acceleration experiments are presented with few-fs temporal resolution, which is shown to be independent of post-interaction spectral filtering of the probe-beam.

Schwab, M. B.; Svert, A.; Polz, J.; Schnell, M.; Rinck, T.; Mller, M.; Hansinger, P. [Insitut fr Optik und Quantenelektronik, Max-Wien-Platz 1, 07743 Jena (Germany)] [Insitut fr Optik und Quantenelektronik, Max-Wien-Platz 1, 07743 Jena (Germany); Jckel, O.; Paulus, G. G.; Kaluza, M. C. [Insitut fr Optik und Quantenelektronik, Max-Wien-Platz 1, 07743 Jena (Germany) [Insitut fr Optik und Quantenelektronik, Max-Wien-Platz 1, 07743 Jena (Germany); Helmholtz-Institut Jena, Frbelstieg 3, 07743 Jena (Germany); Veisz, L. [Max-Planck-Institut fr Quantenoptik, Hans-Kopfermann-Strae 1, 85748 Garching (Germany)] [Max-Planck-Institut fr Quantenoptik, Hans-Kopfermann-Strae 1, 85748 Garching (Germany)

2013-11-04T23:59:59.000Z

193

Hollow screw like drill in plasma using an intense Laguerre Gaussian laser  

E-Print Network (OSTI)

With the development of ultra intense laser technology, MeV ions from the laser foil interaction have been obtained by different mechanisms, such as target normal sheath acceleration, radiation pressure acceleration, collisionless shock acceleration, breakout afterburner, and a combination of different mechanisms. These energetic ion beams can be applied in fast ignition for inertial confinement fusion, medical therapy, and proton imaging. However, these ions are mainly accelerated in the laser propagation direction, and the ion acceleration in an azimuthal orientation is scarcely mentioned. Here, a doughnut Laguerre Gaussian LG laser is used for the first time to study the laser plasma interaction in the relativistic intensity regime in three dimensional particle in cell simulations. Studies have shown that a novel rotation of the plasma is produced from the hollow screw like drill of a LG mode laser. The angular momentum of the protons in the longitudinal direction produced by the LG laser is remarkably enh...

Wang, Wenpeng; Zhang, Xiaomei; Zhang, Lingang; Shi, Yin; Xu, Zhizhan

2014-01-01T23:59:59.000Z

194

Terahertz generation by two cross focused laser beams in collisional plasmas  

SciTech Connect

The role of two cross-focused spatial-Gaussian laser beams has been studied for the high power and efficient terahertz (THz) radiation generation in the collisional plasma. The nonlinear current at THz frequency arises on account of temperature dependent collision frequency of electrons with ions in the plasma and the presence of a static electric field (applied externally in the plasma) and density ripple. Optimisation of laser-plasma parameters gives the radiated THz power of the order of 0.23??MW.

Sharma, R. P., E-mail: rpsharma@ces.iitd.ernet.in; Singh, Ram Kishor, E-mail: ram007kishor@gmail.com [Centre for Energy Studies, Indian Institute of Technology Delhi, New Delhi 110016 (India)

2014-07-15T23:59:59.000Z

195

Plasma spectroscopy of H, Li, and Na in plumes resulting from laser-induced droplet explosion  

Science Journals Connector (OSTI)

The plasma emission resulting from laser-induced breakdown of large transparent H2O droplets (with and without NaCl or LiCl) has been spectrally and spatially resolved along...

Eickmans, Johannes H; Hsieh, Wen-Feng; Chang, Richard K

1987-01-01T23:59:59.000Z

196

Plasma density ramp for relativistic self-focusing of an intense laser  

Science Journals Connector (OSTI)

It is known that a high-power laser propagating through an underdense plasma can acquire a minimum spot size due to relativistic self-focusing. Beyond the focus, the nonlinear...

Gupta, Devki N; Hur, Min S; Hwang, Ilmoon; Suk, Hyyong; Sharma, Ashok K

2007-01-01T23:59:59.000Z

197

Investigation and characterization of single hot spot laser-plasma interactions  

E-Print Network (OSTI)

Control of parametric laser-plasma interactions (LPI) is essential to the success of inertial confinement fusion (ICF). Through a research collaboration with the Los Alamos National Laboratory (LANL), we have had the ...

Focia, Ronald J

2002-01-01T23:59:59.000Z

198

Spectroscopic studies of XeCl-laser-induced plasma on Ti targets in nitrogen containing atmospheres  

Science Journals Connector (OSTI)

This work deals with the study of a plasma produced by intense XeCl-excimer-laser irradiation of a titanium surface in nitrogen-containing atmospheres. We observed that the optical emission spectra ... from irrad...

M. L. De Giorgi; J. Hermann; A. Luches; A. Perrone; L. Renna

1994-06-01T23:59:59.000Z

199

Characterization of single and colliding laser-produced plasma bubbles using Thomson scattering and proton radiography  

E-Print Network (OSTI)

Time-resolved measurements of electron and ion temperatures using Thomson scattering have been combined with proton radiography data for comprehensive characterization of individual laser-produced plasma bubbles or the ...

Rosenberg, Michael Jonathan

200

Laser Ablation Inductively Coupled Plasma Mass Spectrometry Measurement of Isotope Ratios in Depleted Uranium Contaminated Soils  

Science Journals Connector (OSTI)

Laser ablation of pressed soil pellets was examined as a means of direct sample introduction to enable inductively coupled plasma mass spectrometry (ICP-MS) screening of soils for...

Seltzer, Michael D

2003-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "laser plasma wakefield" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Development of Focused Laser Plasma X-ray Beam for Radiobiological Applications  

Science Journals Connector (OSTI)

We have started to develop a laser plasma x-ray microbeam irradiation system, and demonstrated a preliminary study of the cell survival and gamma-H2AX focus formation in the culture...

NISHIKINO, Masaharu; SATO, Katsutoshi; OHSHIMA, Shinsuke; HASEGAWA, Noboru; ISHINO, Masahiko; KAWACHI, Tetsuya; OKANO, Yasuaki; NUMASAKI, Hodaka; TESHIMA, Teruki; Nishimura, Hiroaki

202

PLASMA WAKEFIELD ACCELERATION UTILIZING MULTIPLE ELECTRON BUNCHES  

E-Print Network (OSTI)

. Yakimenko, Brookhaven National Lab., Upton, NY W. D. Kimura, STI Optronics, Bellevue, WA Abstract We

Brookhaven National Laboratory

203

Hydrodynamic Scaling Analysis of Nuclear Fusion driven by ultra-intense laser-plasma interactions  

E-Print Network (OSTI)

We discuss scaling laws of fusion yields generated by laser-plasma interactions. The yields are found to scale as a function of the laser power. The origin of the scaling law in the laser driven fusion yield is derived in terms of hydrodynamic scaling. We point out that the scaling properties can be attributed to the laser power dependence of three terms: the reaction rate, the density of the plasma and the projected range of the plasma particle in the target medium. The resulting scaling relations have a predictive power that enables estimating the fusion yield for a nuclear reaction which has not been investigated by means of the laser accelerated ion beams.

Sachie Kimura; Aldo Bonasera

2011-09-23T23:59:59.000Z

204

Laser-driven hole boring and gamma-ray emission in high-density plasmas  

E-Print Network (OSTI)

Ion acceleration in laser-produced dense plasmas is a key topic of many recent investigations thanks to its potential applications. Besides, at forthcoming laser intensities ($I \\gtrsim 10^{23} \\text{W}\\,\\text{cm}^{-2}$) interaction of laser pulses with plasmas can be accompanied by copious gamma-ray emission. Here we demonstrate the mutual influence of gamma-ray emission and ion acceleration during relativistic hole boring in high-density plasmas with ultra-intense laser pulses. If gamma-ray emission is abundant, laser pulse reflection and hole-boring velocity are lower and gamma-ray radiation pattern is narrower than in the case of low emission. Conservation of energy and momentum allows one to elucidate the effects of gamma-ray emission which are more pronounced at higher hole-boring velocities.

Nerush, Evgeny

2014-01-01T23:59:59.000Z

205

Two-dimensional space-resolved emission spectroscopy of laser ablation plasma in water  

SciTech Connect

We developed a method for two-dimensional space-resolved emission spectroscopy of laser-induced plasma in water to investigate the spatial distribution of atomic species involved in the plasma. Using this method, the laser ablation plasma produced on a Cu target in 5 mM NaCl aqueous solution was examined. The emission spectrum varied considerably depending on the detecting position. The temperature and the atomic density ratio N{sub Na}/N{sub Cu} at various detecting positions were evaluated by fitting emission spectra to a theoretical model based on the Boltzmann distribution. We are successful in observing even a small difference between the distributions of the plasma parameters along the directions vertical and horizontal to the surface. The present approach gives direct information for sound understanding of the behavior of laser ablation plasma produced on a solid surface in water.

Matsumoto, Ayumu; Tamura, Ayaka; Fukami, Kazuhiro; Ogata, Yukio H. [Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011 (Japan); Sakka, Tetsuo [Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510 (Japan)

2013-02-07T23:59:59.000Z

206

Enhancement of x-ray line emission from plasmas produced by short high-intensity laser double pulses  

E-Print Network (OSTI)

Enhancement of x-ray line emission from plasmas produced by short high-intensity laser double laser-produced plasmas are bright ultrafast line x-ray sources potentially suitable for different onto a solid target into the x-ray emission is significantly enhanced when a laser prepulse precedes

Limpouch, Jiri

207

Dynamics of laser-produced Sn-based plasmas for a monochromatic 13.5 nm extreme ultraviolet source  

E-Print Network (OSTI)

the critical density, a narrower EUV x-ray spectrum and a higher conversion efficiency from laserDynamics of laser-produced Sn-based plasmas for a monochromatic 13.5 nm extreme ultraviolet source-0417 ABSTRACT Dynamics of laser-produced Sn-based plasmas were investigated for a monochromatic EUV lithography

Najmabadi, Farrokh

208

Electron acceleration by a circularly polarized laser pulse in a plasma K. P. Singha)  

E-Print Network (OSTI)

Electron acceleration by a circularly polarized laser pulse in a plasma K. P. Singha) Department of electrons in an axial static field are presented. The electron rotates around the propagation direction occurs between the electrons and electric field of the laser pulse for two optimum values of the magnetic

Roy, Subrata

209

Enhanced Laser-Light Absorption by Optical Resonance in Inhomogeneous Plasma  

Science Journals Connector (OSTI)

The collisional absorption of laser radiation by a planar plasma was calculated using the classical physical optics of absorbing media. In most regions of interest to thermonuclear fusion, the enhanced absorption of p-polarized radiation by optical resonanceparticularly at high temperatures and long laser wavelengthcompletely dominates the ordinary absorption due to inverse bremsstrahlung.

Marvin M. Mueller

1973-03-26T23:59:59.000Z

210

Emission characteristics and dynamics of C2 from laser produced graphite plasma  

E-Print Network (OSTI)

Emission characteristics and dynamics of C2 from laser produced graphite plasma S. S. Harilal, Riju 1996; accepted for publication 20 December 1996 The emission features of laser ablated graphite plume diagnostic technique. Time resolved optical emission spectroscopy is employed to reveal the velocity

Harilal, S. S.

211

Diagnostics and analyses of decay process in laser produced tetrakis,,dimethyl-amino...ethylene plasma  

E-Print Network (OSTI)

Diagnostics and analyses of decay process in laser produced tetrakis,,dimethyl-amino...ethylene dimethyl-amino ethylene TMAE . The plasma is characterized as high electron density (1013 ­1012 cm 3 organic gas, tetrakis dimethyl-amino ethylene, which can be single-photon ionized by a 193 nm laser, so

Scharer, John E.

212

Feasibility of Laser Induced Plasma Micro-machining Kumar Pallav1  

E-Print Network (OSTI)

associated with µ-EDM and conventional ultra-short laser micro-machining processes. The limitations in µ-EDM: µ-EDM, Laser, Dielectric, Plasma, Micro-machining. 1.0 Introduction Micro-manufacturing encompasses widely recognized that the major limitations of µ-EDM are [1-3]: (1) the inability to micro-machine non

Boyer, Edmond

213

CO2-Laser-Excited Langmuir Turbulence in a Dense-Plasma Focus  

Science Journals Connector (OSTI)

We report on ruby-laser scattering measurements of Langmuir turbulence excited in a high-density plasma by a CO2 laser pump. The observations are reasonably consistent with a new theoretical treatment of the convective electron-ion decay instability at equal electron and ion temperatures.

M. J. Forrest; P. D. Morgan; N. J. Peacock; K. Kuriki; M. V. Goldman; T. Rudolph

1976-12-20T23:59:59.000Z

214

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

SciTech Connect

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.

Xia Xiongping; Yi Lin [Department of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Xu Bin [Department of Mathematics and Information Sciences, North China Institute of Water Conservancy and Hydroelectric Power, Zhengzhou 450011 (China); Lu Jianduo [Department of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Hubei Province Key Laboratory of Systems Science in Metallurgical Process, Wuhan University of Science and Technology, Wuhan 430081 (China)

2011-10-15T23:59:59.000Z

215

Plasma density inside a femtosecond laser filament in air: Strong dependence on external focusing  

E-Print Network (OSTI)

Plasma density inside a femtosecond laser filament in air: Strong dependence on external focusing­16 . The plasma generation balances the self-focusing effect and leads to a limited peak intensity 17­19 along, Germany Received 10 March 2006; published 27 September 2006 Our experiment shows that external focusing

Becker, Andreas

216

Laser beat wave excitation of terahertz radiation in a plasma slab  

SciTech Connect

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??m, one obtains the THz intensity ?1?GW/cm{sup 2} at 3 THz radiation frequency.

Chauhan, Santosh; Parashar, Jetendra, E-mail: j.p.parashar@gmail.com [Department of Applied Physics, Samrat Ashok Technological Institute, Vidisha 464001, Madhya Pradesh (India)

2014-10-15T23:59:59.000Z

217

Increasing the transformer ratio at the Argonne wakefield accelerator  

Science Journals Connector (OSTI)

The transformer ratio is defined as the ratio of the maximum energy gain of the witness bunch to the maximum energy loss experienced by the drive bunch (or a bunch within a multidrive bunch train). This plays an important role in the collinear wakefield acceleration scheme. A high transformer ratio is desirable since it leads to a higher overall efficiency under similar conditions (e.g. the same beam loading, the same structure, etc.). One technique to enhance the transformer ratio beyond the ordinary limit of 2 is to use a ramped bunch train. The first experimental demonstration observed a transformer ratio only marginally above 2 due to the mismatch between the drive microbunch length and the frequency of the accelerating structure [C. Jing, A. Kanareykin, J. Power, M. Conde, Z. Yusof, P. Schoessow, and W. Gai, Phys. Rev. Lett. 98, 144801 (2007)]. Recently, we revisited this experiment with an optimized microbunch length using a UV laser stacking technique at the Argonne Wakefield Accelerator facility and measured a transformer ratio of 3.4. Measurements and data analysis from these experiments are presented in detail.

C. Jing, J. G. Power, M. Conde, W. Liu, Z. Yusof, A. Kanareykin, and W. Gai

2011-02-16T23:59:59.000Z

218

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

SciTech Connect

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.

Habibi, M. [Department of Physics, Shirvan Branch, Islamic Azad University, Shirvan (Iran, Islamic Republic of); Ghamari, F. [Department of Physics, Khorramabad Branch, Islamic Azad University, Khorramabad (Iran, Islamic Republic of)

2012-10-15T23:59:59.000Z

219

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

DOE Patents (OSTI)

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.

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

1992-12-29T23:59:59.000Z

220

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

DOE Patents (OSTI)

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.

Augustoni, Arnold L. (Albuquerque, NM); Gerardo, James B. (Albuquerque, NM); Raymond, Thomas D. (Albuquerque, NM)

1992-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "laser plasma wakefield" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Mapping return currents in laser-generated Z-pinch plasmas using proton deflectometry  

SciTech Connect

Dynamic return currents and electromagnetic field structure in laser-generated Z-pinch plasmas have been measured using proton deflectometry. Experiments were modeled to accurately interpret deflections observed in proton radiographs. Current flow is shown to begin on axis and migrate outwards with the expanding coronal plasma. Magnetic field strengths of {approx}1 T are generated by currents that increase from {approx}2 kA to {approx}7 kA over the course of the laser pulse. Proton deflectometry has been demonstrated to be a practical alternative to other magnetic field diagnostics for these types of plasmas.

Manuel, M. J.-E.; Sinenian, N.; Seguin, F. H.; Li, C. K.; Frenje, J. A.; Rinderknecht, H. G.; Casey, D. T.; Zylstra, A. B.; Petrasso, R. D. [Plasma Science and Fusion Center, MIT, Cambridge, Massachusetts 02144 (United States); Beg, F. N. [Department of Mechanical and Aerospace Engineering, University of California, San Diego, California 92093-0411 (United States)

2012-05-14T23:59:59.000Z

222

Lattice-Boltzmann simulation of laser interaction with weakly ionized helium plasmas  

SciTech Connect

This paper presents a lattice Boltzmann method for laser interaction with weakly ionized plasmas considering electron impact ionization and three-body recombination. To simulate with physical properties of plasmas, the authors' previous work on the rescaling of variables is employed and the electromagnetic fields are calculated from the Maxwell equations by using the finite-difference time-domain method. To calculate temperature fields, energy equations are derived separately from the Boltzmann equations. In this way, we attempt to solve the full governing equations for plasma dynamics. With the developed model, the continuous-wave CO{sub 2} laser interaction with helium is simulated successfully.

Li Huayu; Ki, Hyungson [Department of Mechanical Engineering, Michigan State University, East Lansing, Michigan 48824-1226 (United States); School of Mechanical and Advanced Materials Engineering, Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

2010-07-15T23:59:59.000Z

223

Isentropic expansion of copper plasma in Mbar pressure range at Luch laser facility  

SciTech Connect

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 impedancematching method. A theoretical analysis and quantum simulations show that in our experiments strongly coupled quantum plasma is generated.

Bel'kov, S. A.; Derkach, V. N.; Garanin, S. G.; Mitrofanov, E. I.; Voronich, I. N. [Russian Federal Nuclear Center VNIIEF, Sarov (Russian Federation); Fortov, V. E.; Levashov, P. R.; Minakov, D. V. [Joint Institute for High Temperatures, Moscow, Russia and Moscow Institute of Physics and Technology (State University), Dolgoprudny (Russian Federation)

2014-01-21T23:59:59.000Z

224

Intermittent laser-plasma interactions and hot electron generation in shock ignition  

SciTech Connect

We study laser-plasma interactions and hot electron generation in the ignition phase of shock ignition through 1D and 2D particle-in-cell simulations in the regime of long density scale length and moderately high laser intensity. These long-term simulations show an intermittent bursting pattern of laser-plasma instabilities, resulting from a coupling of the modes near the quarter-critical-surface and those in the lower density region via plasma waves and laser pump depletion. The majority of the hot electrons are found to be from stimulated Raman scattering and of moderate energies. However, high energy electrons of preheating threat can still be generated from the two-plasmon-decay instability.

Yan, R.; Li, J. [Department of Mechanical Engineering and Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14627 (United States); Ren, C. [Department of Mechanical Engineering and Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14627 (United States); Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627 (United States)

2014-06-15T23:59:59.000Z

225

Plasma analyses during femtosecond laser ablation of Ti, Zr, and Hf  

SciTech Connect

Femtosecond laser ablation of Ti, Zr, and Hf has been investigated by means of in situ plasma diagnostics. Fast imaging was used to characterize the plasma plume expansion on a nanosecond time scale. In addition, time- and space-resolved optical emission spectroscopy was employed to determine the plume composition and the characteristic expansion velocities of plasma species. It is shown that two plume components with different expansion velocities are generated by the interaction of ultrashort laser pulses with metals. The composition and the expansion behavior of the two components have been analyzed as a function of laser fluence and target material. The results are discussed in terms of mechanisms responsible for ablation by ultrashort laser pulses.

Grojo, D.; Hermann, J.; Perrone, A. [LP3-UMR 6182 Centre National de la Recherche Scientifique, Faculte des Sciences de Luminy, Case 917, 13288 Marseille Cedex 9 (France); University of Lecce, Physics Department and National Nanotechnology Laboratory, 73100-Lecce (Italy)

2005-03-15T23:59:59.000Z

226

Ultra-High Gradient Dielectric Wakefield Accelerator Experiments  

SciTech Connect

Ultra-high gradient dielectric wakefield accelerators are a potential option for a linear collider afterburner since they are immune to the ion collapse and electron/positron asymmetry problems implicit in a plasma based afterburner. The first phase of an experiment to study the performance of dielectric Cerenkov wakefield accelerating structures at extremely high gradients in the GV/m range has been completed. The experiment took advantage of the unique SLAC FFTB electron beam and its ultra-short pulse lengths and high currents (e.g., {sigma}{sub z} = 20 {micro}m at Q = 3 nC). The FFTB electron beam was successfully focused down and sent through short lengths of fused silica capillary tubing (ID = 200 {micro}m/OD = 325 {micro}m). The pulse length of the electron beam was varied to produce a range of electric fields between 2 and 20 GV/m at the inner surface of the dielectric tubes. We observed a sharp increase in optical emissions from the capillaries in the middle part of this surface field range which we believe indicates the transition between sustainable field levels and breakdown. If this initial interpretation is correct, the surfaced fields that were sustained equate to on axis accelerating field of several GV/m. In future experiments being developed for the SLAC SABER and BNL ATF we plan to use the coherent Cerenkov radiation emitted from the capillary tube as a field strength diagnostic and demonstrate GV/m range particle energy gain.

Thompson, M C; Badakov, H; Rosenzweig, J B; Travish, G; Hogan, M; Ischebeck, R; Kirby, N; Siemann, R; Walz, D; Muggli, P; Scott, A; Yoder, R

2006-08-04T23:59:59.000Z

227

Ultra-High Gradient Dielectric Wakefield Accelerator Experiments  

SciTech Connect

Ultra-high gradient dielectric wakefield accelerators are a potential option for a linear collider afterburner since they are immune to the ion collapse and electron/positron asymmetry problems implicit in a plasma based afterburner. The first phase of an experiment to study the performance of dielectric Cerenkov wakefield accelerating structures at extremely high gradients in the GV/m range has been completed. The experiment took advantage of the unique SLAC FFTB electron beam and its ultra-short pulse lengths and high currents (e.g., {sigma}z = 20 {mu}m at Q = 3 nC). The FFTB electron beam was successfully focused down and sent through short lengths of fused silica capillary tubing (ID = 200 {mu}m / OD = 325 {mu}m). The pulse length of the electron beam was varied to produce a range of electric fields between 2 and 20 GV/m at the inner surface of the dielectric tubes. We observed a sharp increase in optical emissions from the capillaries in the middle part of this surface field range which we believe indicates the transition between sustainable field levels and breakdown. If this initial interpretation is correct, the surfaced fields that were sustained equate to on axis accelerating field of several GV/m. In future experiments being developed for the SLAC SABER and BNL ATF we plan to use the coherent Cerenkov radiation emitted from the capillary tube as a field strength diagnostic and demonstrate GV/m range particle energy gain.

Thompson, M. C. [Lawrence Livermore National Laboratory, Livermore, California, 90095 (United States); Badakov, H.; Rosenzweig, J. B.; Travis, G. [UCLA Department of Physics and Astronomy, Los Angeles, California, 90095 (United States); Hogan, M.; Ischebeck, R.; Kirby, N.; Siemann, R.; Walz, D. [Stanford Linear Accelerator Center, Stanford, California, 94309 (United States); Muggli, P. [University of Southern California Los Angeles, California, 90089 (United States); Scott, A. [UCSB Department of Physics, Santa Barbara, California, 93106 (United States); Yoder, R. [Manhattan College, Riverdale, New York, 10471 (United States)

2006-11-27T23:59:59.000Z

228

Raman Amplification of Laser Pulses in Microcapillary Plasmas  

E-Print Network (OSTI)

of overcoming the power limit of current chirped-pulse-amplification (CPA) CP641, X-Ray Lasers 2002: 8th International Conference on X-Ray Lasers, edited by J. J. Rocca et al. > 2002American Institute of Physics 0 of the optics. Such Raman amplifiers can be useful to produce ultra-intense laser pulses for pumping soft x-ray

229

Ignition characteristics of methane/air premixed mixture by microwave-enhanced laser-induced breakdown plasma  

Science Journals Connector (OSTI)

A microwave-enhanced plasma generation technique was combined with laser-induced ignition to improve ignition characteristics. A locally intensified microwave field was formed near the...

Nishiyama, Atsushi; Moon, Ahsa; Ikeda, Yuji; Hayashi, Jun; Akamatsu, Fumiteru

2013-01-01T23:59:59.000Z

230

Kilotesla Magnetic Assisted Fast Laser Ignited Boron-11 Hydrogen Fusion with Nonlinear Force Driven Ultrahigh Accelerated Plasma Blocks  

Science Journals Connector (OSTI)

Nuclear fusion with confinement by available kilotesla magnetic fields ... combination of this approach with the established ultrahigh laser acceleration of plasma blocks driven by nonlinear (ponderomotive) forc...

P. Lalousis; S. Moustaizis; H. Hora; G. H. Miley

2014-09-01T23:59:59.000Z

231

Focused excimer laser initiated, radio frequency sustained high pressure air plasmas  

SciTech Connect

Measurements and analysis of air breakdown processes and plasma production by focusing 193 nm, 300 mJ, 15 MW high power laser radiation inside a 6 cm diameter helical radio frequency (RF) coil are presented. Quantum resonant multi-photon ionization (REMPI) and collisional cascade laser ionization processes are exploited that have been shown to produce high-density (n{sub e} {approx} 7 x 10{sup 16}/cm{sup 3}) cylindrical seed plasmas at 760 Torr. Air breakdown in lower pressures (from 7-22 Torr), where REMPI is the dominant laser ionization process, is investigated using an UV 18 cm focal length lens, resulting in a laser flux of 5.5 GW/cm{sup 2} at the focal spot. The focused laser power absorption and associated shock wave produce seed plasmas for sustainment by the RF (5 kW incident power, 1.5 s) pulse. Measurements of the helical RF antenna load impedance in the inductive and capacitive coupling regimes are obtained by measuring the loaded antenna reflection coefficient. A 105 GHz interferometer is used to measure the plasma electron density and collision frequency. Spectroscopic measurements of the plasma and comparison with the SPECAIR code are made to determine translational, rotational, and vibrational neutral temperatures and the associated neutral gas temperature. From this and the associated measurement of the gas pressure the electron temperature is obtained. Experiments show that the laser-formed seed plasma allows RF sustainment at higher initial air pressures (up to 22 Torr) than that obtained via RF-only initiation (<18 Torr) by means of a 0.3 J UV laser pulse.

Giar, Ryan; Scharer, John [Department of Electrical Engineering, University of Wisconsin-Madison, 506 Engineering Research Building, 1500 Engineering Drive, Madison, Wisconsin 53706 (United States)

2011-11-15T23:59:59.000Z

232

Ultraviolet versus infrared: Effects of ablation laser wavelength on the expansion of laser-induced plasma into one-atmosphere argon gas  

SciTech Connect

Laser-induced plasma from an aluminum target in one-atmosphere argon background has been investigated with ablation using nanosecond ultraviolet (UV: 355 nm) or infrared (IR: 1064 nm) laser pulses. Time- and space-resolved emission spectroscopy was used as a diagnostics tool to have access to the plasma parameters during its propagation into the background, such as optical emission intensity, electron density, and temperature. The specific feature of nanosecond laser ablation is that the pulse duration is significantly longer than the initiation time of the plasma. Laser-supported absorption wave due to post-ablation absorption of the laser radiation by the vapor plume and the shocked background gas plays a dominant role in the propagation and subsequently the behavior of the plasma. We demonstrate that the difference in absorption rate between UV and IR radiations leads to different propagation behaviors of the plasma produced with these radiations. The consequence is that higher electron density and temperature are observed for UV ablation. While for IR ablation, the plasma is found with lower electron density and temperature in a larger and more homogenous axial profile. The difference is also that for UV ablation, the background gas is principally evacuated by the expansion of the vapor plume as predicted by the standard piston model. While for IR ablation, the background gas is effectively mixed to the ejected vapor at least hundreds of nanoseconds after the initiation of the plasma. Our observations suggest a description by laser-supported combustion wave for the propagation of the plasma produced by UV laser, while that by laser-supported detonation wave for the propagation of the plasma produced by IR laser. Finally, practical consequences of specific expansion behavior for UV or IR ablation are discussed in terms of analytical performance promised by corresponding plasmas for application with laser-induced breakdown spectroscopy.

Ma Qianli; Motto-Ros, Vincent; Laye, Fabrice; Yu Jin [Universite de Lyon, F-69622, Lyon, France, Universite Lyon 1, Villeurbanne, CNRS, UMR5579, LASIM (France); Lei Wenqi; Bai Xueshi; Zheng Lijuan; Zeng Heping [State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai (China)

2012-03-01T23:59:59.000Z

233

Structure of an exploding laser-produced plasma  

SciTech Connect

Currents and instabilities associated with an expanding dense plasma embedded in a magnetized background plasma are investigated by direct volumetric probe measurements of the magnetic field and floating potential. A diamagnetic cavity is formed and found to collapse rapidly compared to the expected magnetic diffusion time. The three-dimensional current density within the expanding plasma includes currents along the background magnetic field, in addition to the diamagnetic current. Correlation measurements reveal that flutelike structures at the plasma surface translate with the expanding plasma across the magnetic field and extend into the current system that sustains the diamagnetic cavity, possibly contributing to its collapse.

Collette, A. [Laboratory for Atmospheric and Space Physics, UCB 392, Boulder, Colorado 80309 (United States); Gekelman, W. [Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, California 90095 (United States)

2011-05-15T23:59:59.000Z

234

Interaction of explosively driven dense plasmas with a low-intensity laser radiation  

Science Journals Connector (OSTI)

The results of first experiments on reflectivity of polarized light on an explosively driven dense xenon plasma are presented. The study of polarized reflectivity properties of the plasma was accomplished using a laser light of wavelength ? = 1064 nm and at incident angles ? = 030. With density ? = 2.7 g cm?3, pressure P = 10.5 GPa and temperatures up to T ~ 3?104 K of the investigated plasma, conditions with strong Coulomb interaction (the nonideality parameter up to ? ~ 2.0) were present. Reflectivities, which were calculated via the Helmholtz equation incorporating a density profile for the plasma surface, are compared to the experimental results.

Yu Zaporozhets; V Mintsev; V Gryaznov; V Fortov; H Reinholz; G Rpke

2009-01-01T23:59:59.000Z

235

Thomson scattering measurement of a shock in laser-produced counter-streaming plasmas  

SciTech Connect

We report the first direct measurement of temporally and spatially resolved plasma temperatures at a shock as well as its spatial structure and propagation in laser-produced counter-streaming plasmas. Two shocks are formed in counter-streaming collisionless plasmas early in time, and they propagate opposite directions. This indicates the existence of counter-streaming collisionless flows to keep exciting the shocks, even though the collisional effects increase later in time. The shock images are observed with optical diagnostics, and the upstream and downstream plasma parameters of one of the shocks are measured using Thomson scattering technique.

Morita, T.; Kuramitsu, Y.; Moritaka, T. [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan)] [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan); Sakawa, Y.; Takabe, H. [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan) [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan); Graduate School of Science, Osaka University, 1-1 Machikane-yama, Toyonaka, Osaka 560-0043 (Japan); Tomita, K.; Nakayama, K.; Inoue, K.; Uchino, K. [Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1, Kasugakoen, Kasuga, Fukuoka 816-8580 (Japan)] [Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1, Kasugakoen, Kasuga, Fukuoka 816-8580 (Japan); Ide, T.; Tsubouchi, K. [Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan)] [Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); Nishio, K.; Ide, H.; Kuwada, M. [Graduate School of Science, Osaka University, 1-1 Machikane-yama, Toyonaka, Osaka 560-0043 (Japan)] [Graduate School of Science, Osaka University, 1-1 Machikane-yama, Toyonaka, Osaka 560-0043 (Japan)

2013-09-15T23:59:59.000Z

236

Summary Report of Working Group 1: Laser-Plasma Acceleration  

E-Print Network (OSTI)

structure providing a linear mechanism with potential to harness low-energy laser systems [11 94720, USA Department of Electrical Engineering, University of California, Los Angeles, Westwood, CA

Geddes, Cameron Guy Robinson

237

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

E-Print Network (OSTI)

of the plasma target will be the vacuum focus location ofFinal Focus Diagnostic (High Power),' a meter-scale plasma

Leemans, W.P.

2011-01-01T23:59:59.000Z

238

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

SciTech Connect

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.

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)

2014-08-15T23:59:59.000Z

239

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

SciTech Connect

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.

Khudik, V., E-mail: vkhudik@physics.utexas.edu; Yi, S. A.; Siemon, C.; Shvets, G. [Department of Physics and Institute for Fusion Studies, University of Texas at Austin, One University Station C1500, Austin, Texas 78712 (United States)] [Department of Physics and Institute for Fusion Studies, University of Texas at Austin, One University Station C1500, Austin, Texas 78712 (United States)

2014-01-15T23:59:59.000Z

240

Controlling plasma distributions as driving forces for ion migration during fs laser writing  

E-Print Network (OSTI)

The properties of structures written inside dielectrics with high repetition rate femtosecond lasers are known to depend strongly on the complex interplay of a large number of writing parameters. Recently, ion migration within the laser-excited volume has been identified as a powerful mechanism for changing the local element distribution and producing efficient optical waveguides. In this work it is shown that the transient plasma distribution induced during laser irradiation is a reliable monitor for predicting the final refractive index distribution of the waveguide caused by ion migration. By performing in-situ plasma emission microscopy during the writing process inside a La-phosphate glass it is found that the long axis of the plasma distribution determines the axis of ion migration, being responsible for the local refractive index increase. This observation is also valid when strong positive or negative spherical aberration is induced, greatly deforming the focal volume and inverting the index profile. ...

Fernandez, Toney Teddy; Hoyo, Jesus; Sotillo, Belen; Fernandez, Paloma; Solis, Javier

2014-01-01T23:59:59.000Z

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241

41.8-nm Xe8+ laser driven in a plasma waveguide  

Science Journals Connector (OSTI)

An experimental demonstration of an optical field ionization short-wavelength laser driven in a gas-filled capillary-discharge waveguide is described in detail. Guiding of high-intensity laser pulses has previously been demonstrated with this type of waveguide for capillary discharges in hydrogen. For the present experiments xenon gas was mixed with the hydrogen, and strong lasing on the 4d95d-4d95p transition in Xe8+ at 41.8nm was observed. Under optimum conditions the short-wavelength laser output achieved with the waveguide was found to be greater than that from a Xe gas cell. Measurements of the transmission of the pump laser pulses through the waveguide show that the short-wavelength laser signal was greatest under conditions for which the pump laser pulses were well guided. Simulations of the propagation of the pump laser radiation are presented for a range of initial plasma conditions, and these indicate that the laser-plasma interaction length achieved was greatly increased compared to that which can be achieved in a gas cell.

A. Butler; A. J. Gonsalves; C. M. McKenna; D. J. Spence; S. M. Hooker; S. Sebban; T. Mocek; I. Betttaibi; B. Cros

2004-08-30T23:59:59.000Z

242

Development of a Time-resolved Soft X-ray Spectrometer for Laser Produced Plasma Experiments  

SciTech Connect

A 2400 line/mm variable spaced grating spectrometer (VSG) has been used to measure soft x-ray emission (8-22 {angstrom}) from laser-produced plasma experiments at Lawrence Livermore National Laboratory's Compact Multipulse Terrawatt (COMET) Laser Facility. The spectrometer was coupled to a Kentech x-ray streak camera to study the temporal evolution of soft x-rays emitted from the back of mylar and copper foils irradiated at 10{sup 15} W/cm{sup 2}. The instrument demonstrated a resolving power of {approx} 120 at 19 {angstrom} with a time resolution of 31 ps. The time-resolved copper emission spectrum was consistent with a photodiode monitoring the laser temporal pulse shape and indicated that the soft x-ray emission follows the laser heating of the target. The time and spectral resolution of this diagnostic make it useful for studies of high temperature plasmas.

Cone, K V; Dunn, J; Schneider, M B; Baldis, H A; Brown, G V; Emig, J; James, D L; May, M J; Park, J; Shepherd, R; Widmann, K

2010-05-12T23:59:59.000Z

243

Development of a time-resolved soft x-ray spectrometer for laser produced plasma experiments  

SciTech Connect

A 2400 lines/mm variable-spaced grating spectrometer has been used to measure soft x-ray emission (8-22 A) from laser-produced plasma experiments at Lawrence Livermore National Laboratory's Compact Multipulse Terrawatt (COMET) Laser Facility. The spectrometer was coupled to a Kentech x-ray streak camera to study the temporal evolution of soft x rays emitted from the back of the Mylar and the copper foils irradiated at 10{sup 15} W/cm{sup 2}. The instrument demonstrated a resolving power of {approx}120 at 19 A with a time resolution of 31 ps. The time-resolved copper emission spectrum was consistent with a photodiode monitoring the laser temporal pulse shape and indicated that the soft x-ray emission follows the laser heating of the target. The time and spectral resolutions of this diagnostic make it useful for studies of high temperature plasmas.

Cone, K. V.; Park, J. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); University of California at Davis, Davis, California 95616 (United States); Dunn, J.; Schneider, M. B.; Brown, G. V.; Emig, J.; James, D. L.; May, M. J.; Shepherd, R.; Widmann, K. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Baldis, H. A. [University of California at Davis, Davis, California 95616 (United States)

2010-10-15T23:59:59.000Z

244

Laser Channeling in Millimeter-Scale Underdense Plasmas of Fast-Ignition Targets  

Science Journals Connector (OSTI)

Two dimensional particle-in-cell simulations show that laser channeling in millimeter-scale underdense plasmas is a highly nonlinear and dynamic process involving longitudinal plasma buildup, laser hosing, channel bifurcation and self-correction, and electron heating to relativistic temperatures. The channeling speed is much less than the linear group velocity of the laser. The simulations find that low-intensity channeling pulses are preferred to minimize the required laser energy but with an estimated lower bound on the intensity of I?51018??W/cm2 if the channel is to be established within 100ps. The channel is also shown to significantly increase the transmission of an ignition pulse.

G. Li, R. Yan, C. Ren, T.-L. Wang, J. Tonge, and W. B. Mori

2008-03-24T23:59:59.000Z

245

X-ray backlight measurement of preformed plasma by kJ-class petawatt LFEX laser  

SciTech Connect

Foot and pedestal pulses that precede the main pulse from a high-intensity laser greatly affect laser-plasma interactions. Especially in fast ignition schemes, preceding pulses generate a plasma prior to irradiation by the main pulse. This results in a too energetic and divergent electron beam being generated in the preformed plasma, which reduces the energy coupling efficiency from the heating laser to the dense fuel core. A preformed plasma with a density scale length of 40-60 {mu}m was observed by a time- and space-resolved x-ray backlight technique using the LFEX laser system at the Institute of Laser Engineering, Osaka University. Preceding pulses (i.e., the foot and pedestal) of the LFEX were characterized by comparing observations with calculations results obtained using a two-dimension (2D) radiation-hydrodynamic simulation code. In a separate experiment, the 2D code was benchmarked with the experimentally observed hydrodynamic behavior of a gold plasma produced by a nanosecond laser pulse that mimicked foot and pedestal pulses (intensity: 1 Multiplication-Sign 10{sup 11}-1 Multiplication-Sign 10{sup 12}W/cm{sup 2}). The preceding pulses were estimated to have an intensity of 1 Multiplication-Sign 10{sup 12}-10{sup 13}W/cm{sup 2}, a duration of 2.0 ns, and a spot diameter at the target of 200-600 {mu}m by comparing the measured hydrodynamics of the preformed plasma with that calculated by the 2D hydrodynamic simulation code.

Ohira, Shinji; Fujioka, Shinsuke; Nagatomo, Hideo; Matsuo, Satoshi; Morio, Noboru; Kawanaka, Jyunji; Nakata, Yoshiki; Miyanaga, Noriaki; Shiraga, Hiroyuki; Nishimura, Hiroaki; Azechi, Hiroshi [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita Osaka 565-0871 (Japan); Sunahara, Atsushi [Institute for Laser Technology, 2-6 Yamada-oka, Suita Osaka 565-0871 (Japan); Johzaki, Tomoyuki [Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi Hiroshima 739-8527 (Japan)

2012-09-15T23:59:59.000Z

246

Ion expansion characteristics from a KrF-laser-produced plasma  

Science Journals Connector (OSTI)

Two groups of ions are observed in an aluminum plasma produced by focusing a Raman-compressed KrF-laser beam (268 nm) on thick planar targets in the intensity range 510111013 W/cm2. The angular distribution, velocity distribution, energy partition between the two groups, and scaling of the ion velocities with laser intensity are presented. The role of lateral energy transport in generating the two groups of ions is discussed.

P. D. Gupta; Y. Y. Tsui; R. Popil; R. Fedosejevs; A. A. Offenberger

1986-05-01T23:59:59.000Z

247

High-Power, Kilojoule Class Laser Channeling in Millimeter-Scale Underdense Plasma  

SciTech Connect

Experiments were performed using the Omega EP laser, operating at 740 J of energy in 8 ps (90 TW), which provides extreme conditions relevant to fast ignition studies. A carbon and hydrogen plasma plume was used as the underdense target and the interaction of the laser pulse propagating and channeling through the plasma was imaged using proton radiography. The early time expansion, channel evolution, filamentation, and self-correction of the channel was measured on a single shot via this method. A channel wall modulation was observed and attributed to surface waves. After around 50 ps, the channel had evolved to show bubblelike structures, which may be due to postsoliton remnants.

Willingale, L.; Thomas, A. G. R.; Maksimchuk, A.; Zulick, C.; Krushelnick, K. [Center for Ultrafast Optical Science, University of Michigan, 2200 Bonisteel Boulevard, Ann Arbor, Michigan 48109 (United States); Nilson, P. M.; Craxton, R. S.; Sangster, T. C.; Stoeckl, C. [University of Rochester-Laboratory for Laser Energetics, Rochester, New York 14623 (United States); Cobble, J. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Norreys, P. A.; Scott, R. H. H. [STFC, Rutherford Appleton Laboratory, Central Laser Facility, Oxfordshire, OX11 0QX (United Kingdom)

2011-03-11T23:59:59.000Z

248

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

SciTech Connect

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.

Sepehri Javan, N., E-mail: sepehri-javan@uma.ac.ir [Department of physics, University of Mohaghegh Ardabili, PO Box 179, Ardabil (Iran, Islamic Republic of)

2014-10-15T23:59:59.000Z

249

Monitoring of Focus Position During Laser Processing based on Plasma Emission  

Science Journals Connector (OSTI)

Abstract The effects of lens-to-sample distance on plasma emission induced during laser processing were investigated. For tight focusing conditions, a local minimum value of emission intensity was observed for opaque materials. It was attributed to a reduction of ablation efficiency due to saturation. This effect can lead to identify the lens-to-sample distance that produces the highest fluence on the sample. A strategy to detect the working focus position based on monitoring the intensity of plasma emission was proposed. Variations of laser energy, pulse overlap and material type were also studied.

D. Diego-Vallejo; D. Ashkenasi; H.J. Eichler

2013-01-01T23:59:59.000Z

250

X-ray laser frequency near-doubling and generation of tunable coherent x rays in plasma  

E-Print Network (OSTI)

X-ray laser frequency near-doubling and generation of tunable coherent x rays in plasma P. L plasmas in which efficient x-ray laser frequency near-doubling is expected for a number of available x-ray of coherent x rays and tunable optical radiation may result in tunable coherent x-ray radiation powerful

Kaplan, Alexander

251

Observation of neutronless fusion reactions in picosecond laser plasmas V. S. Belyaev, A. P. Matafonov, and V. I. Vinogradov  

E-Print Network (OSTI)

, Russia V. S. Lisitsa Institute of Nuclear Fusion, RSC "Kurchatov Institute," 123182 Moscow, Russia A. SObservation of neutronless fusion reactions in picosecond laser plasmas V. S. Belyaev, A. P fusion reactions 11 B+p in plasmas produced by picosecond laser pulses with the peak intensity of 2 1018

252

Origin of protons accelerated by an intense laser and the dependence of their energy on the plasma density  

Science Journals Connector (OSTI)

We study the high-energy (14 MeV) proton production from a slab plasma irradiated by a ultrashort high-power laser. In our 2.5-dimensional particle-in-cell simulations, a p-polarized laser beam of 1.61019 W/cm2, 300 fs, ?L=1.053 ?m, illuminates a slab plasma normally; the slab plasma consists of a hydrogen plasma, and the target plasma thickness and the laser spot size are 2.5?L and 5?L, respectively. The simulation results show that an emitted proton energy depends on the slab plasma density, and three kinds of high-energy proton beams are generated at the target plasma surfaces: one kind of the proton beams is produced at the laser-illuminated target surface and accelerated to the same laser-incident side. The second is generated at the target surface opposite to the laser-illuminated target surface and is accelerated outward on the same side. The third is generated at the laser-illuminated target surface and accelerated to the opposite side while passing through the target plasma. The simulations also show a mechanism of proton accelerations. In an overdense plasma, laser energy goes to energies of hot electrons and magnetic fields in part; the electrons oscillate around the slab plasma so that a static electric field is generated and consequently protons are extracted. The magnetic field generated in the slab plasma exists longer and heats up the plasma electrons to sustain the static electric field even after the laser termination.

Takashi Nakamura and Shigeo Kawata

2003-02-06T23:59:59.000Z

253

Radiation sources based on laserplasma interactions  

Science Journals Connector (OSTI)

...the ALPHA-X beam final focus onto the entrance to the plasma channel the bunch is stretched...from the cathode to final focus at the position of the plasma-channel has been simulated...projection is shown at the focus. The curved cathode reduces...

2006-01-01T23:59:59.000Z

254

Simulations of Jitter Coupling due to Wakefields in the FACET Linac  

SciTech Connect

Facilities for Accelerator Science and Experimental Test Beams (FACET) is a proposed facility at SLAC that would use the initial two-thirds of the linac to transport e{sup +} and e{sup -} beams to an experimental region. A principal use of this facility is to identify the optimum method for accelerating positrons in a beam driven plasma wakefield accelerator. To study this, a positron bunch, followed an RF-cycle later by an electron bunch, will be accelerated to an asymmetric chicane designed to move the positrons behind the electrons, and then on to the plasma wakefield test stand. A major focus of study was the coupling of jitter of the positron bunch to the electron bunch via linac wakes. Lucretia is a Matlab toolbox for the simulation of electron beam transport systems, capable of multi-bunch tracking and wakefield calculations. With the exception of the lack of support for tracking of electrons and positrons within a single bunch train, it was well suited to the jitter coupling studies. This paper describes the jitter studies, including modifications made to Lucretia to correctly simulate tracking of mixed-species bunch trains through a lattice of magnetic elements and EM wakes.

Molloy, Stephen

2009-10-30T23:59:59.000Z

255

High-resolution X-ray spectroscopy of hollow atoms created in plasma heated by subpicosecond laser radiation  

SciTech Connect

The investigations of ultrashort (0.4-0.6 ps) laser pulse radiation interaction with solid targets have been carried out. The Trident subpicosecond laser system was used for plasma creation. The X-ray plasma emission was investigated with the help of high-resolution spectrographs with spherically bent mica crystals. It is shown that when high contrast ultrashort laser pulses were used for plasma heating its emission spectra could not be explained in terms of commonly used theoretical models, and transitions in so called {open_quotes}hollow atoms{close_quotes} must be taken into account for adequate description of plasma radiation.

Faenov, A.Ya.; Magunov, A.I.; Pikuz, T.A. [Multicharged Ions Spectra Data Center of VNIIFTRI, Moscow (Russian Federation)] [and others

1997-10-01T23:59:59.000Z

256

Laser-induced plasma ignition studies in a model scramjet engine  

Science Journals Connector (OSTI)

An experimental investigation of the behavior of laser-induced plasma (LIP) ignition for scramjet inlet injection is presented. The presented results demonstrate for the first time, that LIP can be used to promote the formation of hydroxyl in a hypersonic flow. The temporal evolution of the LIP-ignited region is monitored using the planar laser-induced fluorescence technique on the hydroxyl radical. This study is the first laser spark study in a hypersonic flow, shown to generate combustion products where they would not otherwise occur.

Stefan Brieschenk; Sean OByrne; Harald Kleine

2013-01-01T23:59:59.000Z

257

Laser-rf creation and diagnostics of seeded atmospheric pressure air and nitrogen plasmas  

Science Journals Connector (OSTI)

A laser initiation and radio frequency (rf) sustainment technique has been developed and improved from our previous work to create and sustain large-volume high-pressure air and nitrogen plasmas. This technique utilizes a laser-initiated 15 mTorr partial pressure tetrakis (dimethylamino) ethylene seed plasma with a 75 Torr background gas pressure to achieve high-pressure air/nitrogen plasma breakdown and reduce the rf power requirement needed to sustain the plasma. Upon the laser plasma initiation the chamber pressure is raised to 760 Torr in 0.5 s through a pulsed gas valve and the end of the chamber is subsequently opened to the ambient air. The atmospheric-pressure plasma is then maintained with the 13.56 MHz rf power. Using this technique large-volume ( 1000 ? cm 3 ) high electron density (on the order of 10 11 12 ? cm ? 3 ) 760 Torr air and nitrogen plasmas have been created while rf power reflection is minimized during the entire plasma pulse utilizing a dynamic matching method. This plasma can project far away from the antenna region (30 cm) and the rf power budget is 5 ? W / cm 3 . Temporal evolution of the plasma electron density and total electron-neutral collision frequency during the pulsed plasma is diagnosed using millimeter waveinterferometry. Optical emission spectroscopy(OES) aided by SPECAIR a special OES simulation program for air-constituent plasmas is used to analyze the radiating species and thermodynamic characteristics of the plasma. Rotational and vibrational temperatures of 4400 4600 100 ? K are obtained from the emission spectra from the N 2 ( 2 + ) and N 2 + ( 1 ? ) transitions by matching the experimental spectrum results with the SPECAIR simulation results. Based on the relation between the electron collision frequency and the neutral density utilizing millimeter waveinterferometry the electron temperature of the 760 Torr nitrogen plasma is found to be 8700 100 ? K ( 0.75 0.1 ? eV ) . Therefore the plasma deviates significantly from local thermal equilibrium.

Siqi Luo; C. Mark Denning; John E. Scharer

2008-01-01T23:59:59.000Z

258

Laser-rf creation and diagnostics of seeded atmospheric pressure air and nitrogen plasmas  

SciTech Connect

A laser initiation and radio frequency (rf) sustainment technique has been developed and improved from our previous work to create and sustain large-volume, high-pressure air and nitrogen plasmas. This technique utilizes a laser-initiated, 15 mTorr partial pressure tetrakis (dimethylamino) ethylene seed plasma with a 75 Torr background gas pressure to achieve high-pressure air/nitrogen plasma breakdown and reduce the rf power requirement needed to sustain the plasma. Upon the laser plasma initiation, the chamber pressure is raised to 760 Torr in 0.5 s through a pulsed gas valve, and the end of the chamber is subsequently opened to the ambient air. The atmospheric-pressure plasma is then maintained with the 13.56 MHz rf power. Using this technique, large-volume (1000 cm{sup 3}), high electron density (on the order of 10{sup 11-12} cm{sup -3}), 760 Torr air and nitrogen plasmas have been created while rf power reflection is minimized during the entire plasma pulse utilizing a dynamic matching method. This plasma can project far away from the antenna region (30 cm), and the rf power budget is 5 W/cm{sup 3}. Temporal evolution of the plasma electron density and total electron-neutral collision frequency during the pulsed plasma is diagnosed using millimeter wave interferometry. Optical emission spectroscopy (OES) aided by SPECAIR, a special OES simulation program for air-constituent plasmas, is used to analyze the radiating species and thermodynamic characteristics of the plasma. Rotational and vibrational temperatures of 4400-4600{+-}100 K are obtained from the emission spectra from the N{sub 2}(2+) and N{sub 2}{sup +}(1-) transitions by matching the experimental spectrum results with the SPECAIR simulation results. Based on the relation between the electron collision frequency and the neutral density, utilizing millimeter wave interferometry, the electron temperature of the 760 Torr nitrogen plasma is found to be 8700{+-}100 K (0.75{+-}0.1 eV). Therefore, the plasma deviates significantly from local thermal equilibrium.

Luo Siqi; Denning, C. Mark; Scharer, John E. [Electrical and Computer Engineering, University of Wisconsin--Madison, Madison, Wisconsin 53705 (United States)

2008-07-01T23:59:59.000Z

259

Production of a keV X-Ray Beam from Synchrotron Radiation in Relativistic Laser-Plasma Interaction  

E-Print Network (OSTI)

Production of a keV X-Ray Beam from Synchrotron Radiation in Relativistic Laser-Plasma Interaction demonstrate that a beam of x-ray radiation can be generated by simply focusing a single high- intensity laser spectral range) [6]. Laser-driven K x-ray sources [7­9] radiate subnanometer wavelength radiation

Umstadter, Donald

260

A technique has been developed to accurately align a laser beam through a plasma channel by minimizing the  

E-Print Network (OSTI)

for radiation sources ­ ranging from coherent THz to free electron laser (FEL) x-ray sources and ThomsonAbstract A technique has been developed to accurately align a laser beam through a plasma channel by minimizing the shift in laser centroid and angle at the channel outptut. If only the shift in centroid

Geddes, Cameron Guy Robinson

Note: This page contains sample records for the topic "laser plasma wakefield" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

X-Ray Radiation from Nonlinear Thomson Scattering of an Intense Femtosecond Laser on Relativistic Electrons in a Helium Plasma  

E-Print Network (OSTI)

X-Ray Radiation from Nonlinear Thomson Scattering of an Intense Femtosecond Laser on Relativistic laser beam on plasma electrons. A collimated x-ray radiation with a broad continuous spectrum peaked by the ultraintense laser fields. The results show the existence of several physical mecha- nisms for the x-ray

Umstadter, Donald

262

Control of focusing fields in laser-plasma accelerators using higher-order modes E. Cormier-Michel,1,* E. Esarey,1  

E-Print Network (OSTI)

of intense laser pulses in plasma channels [1] has many applications, including x-ray lasers [2], highControl of focusing fields in laser-plasma accelerators using higher-order modes E. Cormier-order laser modes are analyzed as a method to control focusing forces and improve the electron bunch quality

Geddes, Cameron Guy Robinson

263

Attraction and repulsion of multi-color laser beams in plasmas: a computational study  

SciTech Connect

The nonlinear interaction of high-power multi-color laser beams in plasmas is investigated numerically. Both the relativistic mass increase and the driven plasma wave contribute to the mutual beam-beam interaction and to the development of the electromagnetic cascade. The propagation of the individual cascade sidebands is modelled in the paraxial approximation. The resulting set of coupled nonlinear envelope equations is solved numerically using a newly developed pseudospectral method. We predict that two beams intersecting in the plasma can either attract or deflect each other depending on whether their frequency detuning is slightly below or above the electron Langmuir frequency.

Yi, S. A.; Kalmykov, S.; Shvets, G. [Department of Physics and Institute for Fusion Studies, University of Texas at Austin, One University Station C1500, Austin, Texas 78712 (United States)

2009-01-22T23:59:59.000Z

264

Experimental basis for laser-plasma interactions in ignition hohlraums at the National Ignition Facility  

SciTech Connect

A series of laser plasma interaction experiments at OMEGA (LLE, Rochester) using gas-filled hohlraums shed light on the behavior of stimulated Raman scattering and stimulated Brillouin scattering at various plasma conditions encountered in indirect drive ignition designs. We present detailed experimental results that quantify the density, temperature, and intensity thresholds for both of these instabilities. In addition to controlling plasma parameters, the National Ignition Campaign relies on optical beam smoothing techniques to mitigate backscatter. We show that polarization smoothing is effective at controlling backscatter. These results provide an experimental basis for forthcoming experiments on National Ignition Facility.

Froula, D H; Divol, L; London, R A; Berger, R L; Doeppner, T; Meezan, N B; Ralph, J; Ross, J S; Suter, L J; Glenzer, S H

2009-11-12T23:59:59.000Z

265

Note: Characterization of the plasma parameters of a capillary discharge-produced plasma channel waveguide to guide an intense laser pulse  

SciTech Connect

We demonstrated the production of an optical waveguide in a capillary discharge-produced plasma using a cylindrical capillary. Plasma parameters of its waveguide were characterized by use of both a Nomarski laser interferometer and a hydrogen plasma line spectrum. A space-averaged maximum temperature of 3.3 eV with electron densities of the order of 10{sup 17} cm{sup -3} was observed at a discharge time of 150 ns and a maximum discharge current of 400 A. An ultrashort, intense laser pulse was guided by use of this plasma channel.

Higashiguchi, Takeshi; Yugami, Noboru [Department of Advanced Interdisciplinary Sciences and Center for Optical Research and Education (CORE), Utsunomiya University, Yoto 7-1-2, Utsunomiya, Tochigi 321-8585 (Japan); CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kanagawa, Saitama 332-0012 (Japan); Hikida, Masafumi; Terauchi, Hiromitsu; Bai Jinxiang [Department of Advanced Interdisciplinary Sciences and Center for Optical Research and Education (CORE), Utsunomiya University, Yoto 7-1-2, Utsunomiya, Tochigi 321-8585 (Japan); Kikuchi, Takashi [Department of Electrical Engineering, Nagaoka University of Technology, Kami-tomiokamachi 1603-1, Nagaoka, Niigata 940-2188 (Japan); Tao Yezheng [Center for Energy Research, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0438 (United States)

2010-04-15T23:59:59.000Z

266

Beam manipulation by self-wakefield at ATF  

NLE Websites -- All DOE Office Websites (Extended Search)

Committee and the ATF Users' Meetings, April 26 - 27, 2012 Outline 1. Enhanced Transformer Ratio demonstration (wakefield mapping with the shaped beam) 2. Tunable beam energy...

267

Suppression of stochastic pulsation in laser-plasma interaction by smoothing methods  

SciTech Connect

The control of the very complex behavior of a plasma with laser interaction by smoothing with induced spatial incoherence or other methods was related to improving the lateral uniformity of the irradiation. While this is important, it is shown from numerical hydrodynamic studies that the very strong temporal pulsation (stuttering) will mostly be suppressed by these smoothing methods too.

Hora, H. (PS-Division, CERN, CH1211 Geneva 23 (Switzerland)); Aydin, M. (Department of Theoretical Physics, University of New South Wales, Kensington 2033 (Australia))

1992-04-15T23:59:59.000Z

268

Emission characteristics and dynamics of the stagnation layer in colliding laser produced plasmas  

E-Print Network (OSTI)

Emission characteristics and dynamics of the stagnation layer in colliding laser produced plasmas P been investigated using time and space resolved optical emission spectroscopies and spectrally and angularly resolved fast imaging. The emission results highlight a difference in neutral atom and ion

Harilal, S. S.

269

Dynamics of plasma formation during quasicontinuous laser irradiation of metals in high-pressure nitrogen atmospheres  

Science Journals Connector (OSTI)

This is a study of target destruction and the dynamics of surface plasma formation during the interaction of quasicontinuous laser...q = 17 MW/cm2..., ? ? 1.5 msec) with D16T duraluminum and bismuth in nitrogen

V. I. Nasonov; Yu. A. Chivel

2009-11-01T23:59:59.000Z

270

Scaling laws for collisionless laser-plasma interactions of relevance for laboratory astrophysics  

SciTech Connect

Scaling laws for interaction of ultra-intense laser beams with a collisionless plasmas are discussed. Special attention is paid to the problem of the collective ion acceleration. Symmetry arguments in application to the generation of the poloidal magnetic field are presented. A heuristic model for evaluating the magnetic field strength is proposed.

Ryutov, D D; Rermington, B A

2006-04-04T23:59:59.000Z

271

Analysis of atomic and ion debris features of laser-produced Sn and Li plasmas  

E-Print Network (OSTI)

Analysis of atomic and ion debris features of laser-produced Sn and Li plasmas R. W. Coons,a S. S. Harilal, D. Campos, and A. Hassanein School of Nuclear Engineering and Center for Materials Under Extreme provide a CE nearly twice that of Li. However, the kinetic energies of Sn ions are considerably higher

Harilal, S. S.

272

Neutron production by fast protons from ultraintense laser-plasma interactions  

E-Print Network (OSTI)

intense laser-plasma interactions, have been used to induce nuclear reactions in low-Z materials and used to induce nuclear reactions in zinc and boron samples. The numbers of 11 C, 66 Ga, 67 Ga, 68 Ga experimentally determined proton energy spectra, the production of neutrons via p,n reactions in various targets

Strathclyde, University of

273

Demonstration of electron beam focusing by a laser-plasma lens  

E-Print Network (OSTI)

Laser-plasma technology promises a drastic reduction of the size of high energy electron accelerators. It could make free electron lasers available to a broad scientific community, and push further the limits of electron accelerators for high energy physics. Furthermore the unique femtosecond nature of the source makes it a promising tool for the study of ultra-fast phenomena. However, applications are hindered by the lack of suitable lens to transport this kind of high-current electron beams, mainly due to their divergence. Here we show that this issue can be solved by using a laser-plasma lens, in which the field gradients are five order of magnitude larger than in conventional optics. We demonstrate a reduction of the divergence by nearly a factor of three, which should allow for an efficient coupling of the beam with a conventional beam transport line.

Thaury, Cdric; Dpp, Andreas; Lehe, Remi; Lifschitz, Agustin; Phuoc, Kim Ta; Gautier, Julien; Goddet, Jean-Philippe; Tafzi, Amar; Flacco, Alessandro; Tissandier, Fabien; Sebban, Stphane; Rousse, Antoine; Malka, Victor

2014-01-01T23:59:59.000Z

274

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

SciTech Connect

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.

Braenzel, J.; Schnrer, M.; Steinke, S.; Priebe, G.; Sandner, W. [Max-Born-Institut fr Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Str. 2A, 12489 Berlin (Germany)] [Max-Born-Institut fr Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Str. 2A, 12489 Berlin (Germany); Andreev, A. [Max-Born-Institut fr Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Str. 2A, 12489 Berlin (Germany) [Max-Born-Institut fr Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Str. 2A, 12489 Berlin (Germany); Vavilov State Optical Institute, Birzhevaya line 4, 199034 St. Petersburg (Russian Federation); Platonov, K. [Vavilov State Optical Institute, Birzhevaya line 4, 199034 St. Petersburg (Russian Federation)] [Vavilov State Optical Institute, Birzhevaya line 4, 199034 St. Petersburg (Russian Federation)

2013-08-15T23:59:59.000Z

275

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

DOE Patents (OSTI)

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.

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

1996-11-19T23:59:59.000Z

276

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

DOE Patents (OSTI)

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.

Kublak, Glenn D. (124 Turquoise Way, Livermore, Alameda County, CA 94550); Richardson, Martin C. (CREOL

1996-01-01T23:59:59.000Z

277

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

SciTech Connect

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.

Afhami, Saeedeh; Eslami, Esmaeil, E-mail: eeslami@iust.ac.ir [Department of Physics, Iran University of Science and Technology (IUST), Narmak, Tehran, 16846-13114 (Iran, Islamic Republic of)

2014-08-15T23:59:59.000Z

278

Hot-electron generation from laserpre-plasma interactions in cone-guided fast ignition  

SciTech Connect

Two-dimensional particle-in-cell (PIC) simulations were performed for the cone-in-shell integrated fast-ignition experiments at the Omega Laser Facility [W. Theobald et al., Phys. Plasmas 18, 056305 (2011)]. The initial plasma density profile in the PIC simulations was taken from hydrodynamic simulations of the prepulse interaction with the gold cone. Hot-electron generation from laserpre-plasma interactions and transport up to 100 the critical density (n{sub c}) was studied. The simulation showed a mean divergence half-angle of 68 and 50% absorption for the hot electrons. The simulation results show that the generated hot electrons were dominated in number by low-energy electrons but in energy by multi-MeV electrons. Electron transport between 5 and 100 n{sub c} was ballistic. In the late stage of the simulation, all the results were largely independent of polarization, indicating a stochastic hot-electrongeneration mechanism.

Li, J.; Davies, J. R. [Laboratory for Laser Energetics and Fusion Science Center, 250 East River Road, Rochester, New York 14623-1299 (United States) [Laboratory for Laser Energetics and Fusion Science Center, 250 East River Road, Rochester, New York 14623-1299 (United States); Department of Mechanical Engineering, University of Rochester, Rochester, New York 14627 (United States); Ma, T. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States) [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Department of Mechanical and Aerospace Engineering, University of California-San Diego, La Jolla, California 92093 (United States); Mori, W. B.; Tonge, J. [Department of Physics and Astronomy, University of California, Los Angeles, California 90095 (United States)] [Department of Physics and Astronomy, University of California, Los Angeles, California 90095 (United States); Ren, C. [Laboratory for Laser Energetics and Fusion Science Center, 250 East River Road, Rochester, New York 14623-1299 (United States) [Laboratory for Laser Energetics and Fusion Science Center, 250 East River Road, Rochester, New York 14623-1299 (United States); Department of Mechanical Engineering, University of Rochester, Rochester, New York 14627 (United States); Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627 (United States); Solodov, A. A.; Theobald, W. [Laboratory for Laser Energetics and Fusion Science Center, 250 East River Road, Rochester, New York 14623-1299 (United States)] [Laboratory for Laser Energetics and Fusion Science Center, 250 East River Road, Rochester, New York 14623-1299 (United States)

2013-05-15T23:59:59.000Z

279

Measurement of xenon plasma properties in an ion thruster using laser Thomson scattering technique  

SciTech Connect

This paper reports on the development of a method for measuring xenon plasma properties using the laser Thomson scattering technique, for application to ion engine system design. The thresholds of photo-ionization of xenon plasma were investigated and the number density of metastable atoms, which are photo-ionized by a probe laser, was measured using laser absorption spectroscopy, for several conditions. The measured threshold energy of the probe laser using a plano-convex lens with a focal length of 200 mm was 150 mJ for a xenon mass flow rate of 20 {mu}g/s and incident microwave power of 6 W; the probe laser energy was therefore set as 80 mJ. Electron number density was found to be (6.2 {+-} 0.4) Multiplication-Sign 10{sup 17} m{sup -3} and electron temperature was found to be 2.2 {+-} 0.4 eV at a xenon mass flow rate of 20 {mu}g/s and incident microwave power of 6 W. The threshold of the probe laser intensity against photo-ionization in a miniature xenon ion thruster is almost constant for various mass flow rates, since the ratio of population of the metastable atoms to the electron number density is little changed.

Yamamoto, N.; Tomita, K.; Sugita, K.; Kurita, T.; Nakashima, H.; Uchino, K. [Kyushu University, 6-1 Kasuga-kouen, Kasuga, Fukuoka 816-8580 (Japan)

2012-07-15T23:59:59.000Z

280

Optimizing conversion efficiency and reducing ion energy in a laser-produced Gd plasma  

SciTech Connect

We have demonstrated an efficient extreme ultraviolet (EUV) source at 6.7 nm by irradiating Gd targets with 0.8 and 1.06 {mu}m laser pulses of 140 fs to 10 ns duration. Maximum conversion efficiency of 0.4% was observed within a 0.6% bandwidth. A Faraday cup observed ion yield and time of flight signals for ions from plasmas generated by each laser. Ion kinetic energy was lower for shorter pulse durations, which yielded higher electron temperatures required for efficient EUV emission, due to higher laser intensity. Picosecond laser pulses were found to be the best suited to 6.7 nm EUV source generation.

Cummins, Thomas; Li Bowen; O'Gorman, Colm; Dunne, Padraig; Sokell, Emma; O'Sullivan, Gerry [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Otsuka, Takamitsu [Department of Advanced Interdisciplinary Sciences, Center for Optical Research and Education (CORE), and Optical Technology Innovation Center (OpTIC), Utsunomiya University, Yoto 7-1-2, Utsunomiya, Tochigi 321-8585 (Japan); Yugami, Noboru; Higashiguchi, Takeshi [Department of Advanced Interdisciplinary Sciences, Center for Optical Research and Education (CORE), and Optical Technology Innovation Center (OpTIC), Utsunomiya University, Yoto 7-1-2, Utsunomiya, Tochigi 321-8585 (Japan); Japan Science and Technology Agency, CREST, 4-1-8 Honcho, Kanagawa, Saitama 332-0012 (Japan); Jiang Weihua [Department of Electrical Engineering, Nagaoka University of Technology, Kami-tomiokamachi 1603-1, Nagaoka, Niigata 940-2188 (Japan); Endo, Akira [Research Institute for Science and Engineering, Waseda University, Okubo 3-4-1, Shinjuku, Tokyo 169-8555 (Japan)

2012-02-06T23:59:59.000Z

Note: This page contains sample records for the topic "laser plasma wakefield" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Laser plasma formation assisted by ultraviolet pre-ionization  

SciTech Connect

We present experimental and modeling studies of air pre-ionization using ultraviolet (UV) laser pulses and its effect on laser breakdown of an overlapped near-infrared (NIR) pulse. Experimental studies are conducted with a 266?nm beam (fourth harmonic of Nd:YAG) for UV pre-ionization and an overlapped 1064?nm NIR beam (fundamental of Nd:YAG), both having pulse duration of ?10?ns. Results show that the UV beam produces a pre-ionized volume which assists in breakdown of the NIR beam, leading to reduction in NIR breakdown threshold by factor of >2. Numerical modeling is performed to examine the ionization and breakdown of both beams. The modeled breakdown threshold of the NIR, including assist by pre-ionization, is in reasonable agreement with the experimental results.

Yalin, Azer P., E-mail: ayalin@engr.colostate.edu; Dumitrache, Ciprian [Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado 80523 (United States); Wilvert, Nick [Sandia Laboratory, Albuquerque, New Mexico 87123 (United States); Joshi, Sachin [Cummins Inc., Columbus, Indiana 47201 (United States); Shneider, Mikhail N. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544 (United States)

2014-10-15T23:59:59.000Z

282

Resonant third-harmonic generation of a short-pulse laser from electron-hole plasmas  

SciTech Connect

In semiconductors, free carriers are created in pairs in inter-band transitions and consist of an electron and its corresponding hole. At very high carrier densities, carrier-carrier collisions dominate over carrier-lattice collisions and carriers begin to behave collectively to form plasma. Here, we apply a short-pulse laser to generate third-harmonic radiation from a semiconductor plasma (electron-hole plasma) in the presence of a transverse wiggler magnetic-field. The process of third-harmonic generation of an intense short-pulse laser is resonantly enhanced by the magnetic wiggler, i.e., wiggler magnetic field provides the necessary momentum to third-harmonic photons. In addition, a high-power laser radiation, propagating through a semiconductor imparts an oscillatory velocity to the electrons and exerts a ponderomotive force on electrons at the third-harmonic frequency of the laser. This oscillatory velocity produces a third-harmonic longitudinal current. And due to the beating of the longitudinal electron velocity and the wiggler magnetic field, a transverse third-harmonic current is produced that drives third-harmonic electromagnetic radiation. It is finally observed that for a specific wiggler wave number value, the phase-matching conditions for the process are satisfied, leading to resonant enhancement in the energy conversion efficiency.

Kant, Niti [Department of Physics, Lovely Professional University, Phagwara, Punjab 144 402 (India); Nandan Gupta, Devki [Department of Physics and Astrophysics, University of Delhi, Delhi 110 007 (India); Suk, Hyyong [Advanced Photonics Research Institute (APRI) and Graduate Program of Photonics and Applied Physics, Gwangju Institute of Science and Technology, Gwangju 500 712 (Korea, Republic of)

2012-01-15T23:59:59.000Z

283

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

SciTech Connect

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.

Crank, M.; Harilal, S. S.; Hassan, S. M.; Hassanein, A. [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

2012-02-01T23:59:59.000Z

284

Instantaneous x-ray radiation energy from laser produced polystyrene plasmas for shock ignition conditions  

SciTech Connect

Laser target energy coupling mechanism is crucial in the shock ignition (SI) scheme, and x-ray radiation energy is a non-negligible portion of the laser produced plasma energy. To evaluate the x-ray radiation energy amount at conditions relevant to SI scheme, instantaneous x-ray radiation energy is investigated experimentally with continuum phase plates smoothed lasers irradiating layer polystyrene targets. Comparative laser pulses without and with shock spike are employed. With the measured x-ray angular distribution, full space x-ray radiation energy and conversion efficiency are observed. Instantaneous scaling law of x-ray conversion efficiency is obtained as a function of laser intensity and time. It should be pointed out that the scaling law is available for any laser pulse shape and intensity, with which irradiates polystyrene planar target with intensity from 2 10{sup 14} to 1.8 10{sup 15} W/cm{sup 2}. Numerical analysis of the laser energy transformation is performed, and the simulation results agree with the experimental data.

Shang, Wanli; Wei, Huiyue; Li, Zhichao; Yi, Rongqing; Zhu, Tuo; Song, Tianmin; Huang, Chengwu; Yang, Jiamin [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China)] [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China)

2013-10-15T23:59:59.000Z

285

Investigations of laser plasmas dynamics by means of real and virtual Langmuir probes  

SciTech Connect

In this paper we propose a novel technique for LPP-Laser Produced Plasmas investigation, combining high time resolved measurements using compact Langmuir Probes with the output of a theoretical model called HYBLAS developed on purpose, which is able to simulate the charged particles collected by a so-called virtual probe. It will be shown that with an appropriate experimental set-up and with the use of a Matlab software able to accurately analyze the experimental I-V curves, laser plasmas can be investigated properly even if the probe is placed very close to the target surface. This permits not only to study the plume expansion with a high temporal resolution, but also to estimate correctly the self-generated coulomb electric field inside the plume and to detect the inner structure of the the first upcoming expanding plasma. HYBLAS is able to predict and describe the plume expansion at relatively low power densities and is a powerful method to compare directly the experimental current signals with the numerical results if the initial conditions are settled properly. A direct comparison of the theoretical data with the experimental ones realized on different metal targets shows that our method is able to predict properly the overall plasma expansion in the nanosecond laser pulse duration regime. The virtual probe method was moreover tested by comparing the numerical results with another numerical code called MULTI, which simulate the expansion by combining the hydrodynamics equations to a multigroup method in order to include the radiation transport. (authors)

Gambino, N.; Mascali, D.; Tudisco, S.; Anzalone, A.; Gammino, S.; Musumeci, F.; Spitaleri, A.

2011-07-01T23:59:59.000Z

286

Transverse Effect due to Short-range Resistive Wall Wakefield  

SciTech Connect

For accelerator designs with ultra short electron beams, beam dynamics study has to invoke the short-range wakefields. In this paper, we first obtain the short-range dipole mode resistive wall wakefield. Analytical approach is then developed to study the single bunch transverse beam dynamics due to this short-range resistive wall wake. The results are applied to the LCLS undulator.

Juhao Wu; Alex Chao; Jean Delayen

2007-06-18T23:59:59.000Z

287

Energy Loss and Charge Transfer of Argon in a Laser-Generated Carbon Plasma  

Science Journals Connector (OSTI)

This Letter reports on the measurement of the energy loss and the projectile charge states of argon ions at an energy of 4??MeV/u penetrating a fully ionized carbon plasma. The plasma of ne?1020??cm-3 and Te?180??eV is created by two laser beams at ?Las=532??nm incident from opposite sides on a thin carbon foil. The resulting plasma is spatially homogenous and allows us to record precise experimental data. The data show an increase of a factor of 2 in the stopping power which is in very good agreement with a specifically developed MonteCarlo code, that allows the calculation of the heavy ion beams charge state distribution and its energy loss in the plasma.

A. Frank, A. Blaevi?, V. Bagnoud, M. M. Basko, M. Brner, W. Cayzac, D. Kraus, T. Heling, D. H. H. Hoffmann, A. Ortner, A. Otten, A. Pelka, D. Pepler, D. Schumacher, An. Tauschwitz, and M. Roth

2013-03-12T23:59:59.000Z

288

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

SciTech Connect

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.

Patil, S. D., E-mail: sdpatil-phy@rediffmail.com [Department of Physics, Devchand College, Arjunnagar, Kolhapur 591 269 (India); Takale, M. V. [Department of Physics, Doodhsakhar Mahavidyalaya, Bidri, Kolhapur 416 208 (India)

2014-06-15T23:59:59.000Z

289

Multiple-beam laserplasma interactions in inertial confinement fusion  

SciTech Connect

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.

Myatt, J. F., E-mail: jmya@lle.rochester.edu; Zhang, J.; Maximov, A. V. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Department of Mechanical Engineering, University of Rochester, Rochester, New York 14627 (United States); Short, R. W.; Seka, W.; Edgell, D. H.; Michel, D. T.; Igumenshchev, I. V. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Froula, D. H. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627-0171 (United States); Hinkel, D. E.; Michel, P.; Moody, J. D. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808 (United States)

2014-05-15T23:59:59.000Z

290

Coupling between High-Frequency Plasma Waves in Laser-Plasma Interactions  

Science Journals Connector (OSTI)

Experimental evidence for the coupling between two electron plasma waves having nearly the same frequency but greatly differing in wave number is presented using time and wave-number resolved spectra of Thomson scattered light from the plasma. The qualitative features of the measured w(t,k) spectra are predicted by a Lagrangian fluid description and reproduced in particle simulations. These show that the daughter waves generated in this mode coupling process take the energy preferentially from the large k wave without significantly affecting the small k plasma wave.

M. J. Everett; A. Lal; C. E. Clayton; W. B. Mori; T. W. Johnston; C. Joshi

1995-03-20T23:59:59.000Z

291

Third harmonic stimulated Raman backscattering of laser in a magnetized plasma  

SciTech Connect

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.

Paknezhad, Alireza [Physics Department, Shabestar Branch, Islamic Azad University, Shabestar (Iran, Islamic Republic of)] [Physics Department, Shabestar Branch, Islamic Azad University, Shabestar (Iran, Islamic Republic of); Dorranian, Davoud [Laser Lab., Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)] [Laser Lab., Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)

2013-09-15T23:59:59.000Z

292

Extremely high-pressure generation and compression with laser implosion plasmas  

SciTech Connect

We have tested a scheme for using laser implosion plasmas to generate pressures in the gigabar (100 TPa) regime. Cone-in-shell targets employed in fast ignition of inertial confinement fusion were irradiated to create a high-pressure source for compression of materials. The imploded plasmas pushed a foil embedded on the tip of a cone. The pressure was estimated from the shock velocity into the material; the shock velocity was obtained from an optical measurement. The measured shock velocity of the foil was above 100 km/s, corresponding to a pressure greater than 1 Gbar.

Shigemori, K.; Hironaka, Y.; Nagatomo, H.; Fujioka, S.; Azechi, H. [Institute of Laser Engineering, Osaka University, 2-6 Yamada-Oka, Suita, Osaka 565-0871 (Japan)] [Institute of Laser Engineering, Osaka University, 2-6 Yamada-Oka, Suita, Osaka 565-0871 (Japan); Sunahara, A. [Institute for Laser Technology, 2-6 Yamada-Oka, Suita, Osaka 565-0871 (Japan)] [Institute for Laser Technology, 2-6 Yamada-Oka, Suita, Osaka 565-0871 (Japan); Kadono, T. [University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahata-nishi-ku, Kitakyushu, Fukuoka 807-8555 (Japan)] [University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahata-nishi-ku, Kitakyushu, Fukuoka 807-8555 (Japan); Shimizu, K. [Center for Quantum Science and Technology under Extreme Conditions, Osaka University, 1-3 Machikaneyama-Cho, Toyonaka 560-0831 (Japan)] [Center for Quantum Science and Technology under Extreme Conditions, Osaka University, 1-3 Machikaneyama-Cho, Toyonaka 560-0831 (Japan)

2013-05-06T23:59:59.000Z

293

Spectral characteristics of ultra-short laser pulses in plasma amplifiers  

SciTech Connect

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.

Riconda, C. [LULI, Universit Pierre et Marie CurieEcole PolytechniqueCNRSCEA, 75252 Paris (France)] [LULI, Universit Pierre et Marie CurieEcole PolytechniqueCNRSCEA, 75252 Paris (France); Weber, S. [IZEST, Ecole PolytechniqueCEA, 91128 Palaiseau (France) [IZEST, Ecole PolytechniqueCEA, 91128 Palaiseau (France); Institute of Physics of the ASCR, ELI-Beamlines, 18221 Prague (Czech Republic); Lancia, L. [SAPIENZA, University of Rome, Dip. SBAI, 00161 Rome (Italy) [SAPIENZA, University of Rome, Dip. SBAI, 00161 Rome (Italy); INFNSez. RomaSAPIENZA, University of Rome, 00185 Rome (Italy); Marqus, J.-R.; Fuchs, J. [LULI, CNRSEcole PolytechniqueUniversit Pierre et Marie CurieCEA, 91128 Palaiseau (France)] [LULI, CNRSEcole PolytechniqueUniversit Pierre et Marie CurieCEA, 91128 Palaiseau (France); Mourou, G. A. [IZEST, Ecole PolytechniqueCEA, 91128 Palaiseau (France)] [IZEST, Ecole PolytechniqueCEA, 91128 Palaiseau (France)

2013-08-15T23:59:59.000Z

294

Model for electron cooling by radiation losses in plasmas: application to soft x-ray laser development  

SciTech Connect

We present a simple model which may be used to evaluate the suitability of different ions for rapid plasma cooling by line radiation in recombination pumped x-ray laser schemes.

Skinner, C.H.; Keane, C.

1986-02-01T23:59:59.000Z

295

Compact scanning soft-x-ray microscope using a laser-produced plasma source and normal-incidence multilayer mirrors  

Science Journals Connector (OSTI)

We have constructed a scanning soft-x-ray microscope that uses a laser-produced plasma as the soft-x-ray source and normal-incidence multilayer-coated mirrors in a Schwarzschild...

Trail, J A; Byer, R L

1989-01-01T23:59:59.000Z

296

Longitudinal instabilities affecting the moving critical layer laser-plasma ion accelerators  

E-Print Network (OSTI)

In this work we analyze the longitudinal instabilities of propagating acceleration structures that are driven by a relativistically intense laser at the moving plasma critical layer [1]. These instabilities affect the energy-spectra of the accelerated ion-beams in propagating critical layer acceleration schemes [2][3]. Specifically, using analytical theory and PIC simulations we look into three fundamental physical processes and their interplay that are crucial to the understanding of energy spectral control by making the laser-plasma ion accelerators stable. The interacting processes are (i) Doppler-shifted ponderomotive bunching [1][4] (ii) potential quenching by beam-loading [2] and (iii) two-stream instabilities. These phenomenon have been observed in simulations analyzing these acceleration processes [5][6][7]. From the preliminary models and results we present in this work, we can infer measures by which these instabilities can be controlled [8] for improving the energy-spread of the beams.

Sahai, Aakash Ajit

2014-01-01T23:59:59.000Z

297

Studies of Intense Laser Propagation in Channels for Extended Length Plasma Accelerators  

E-Print Network (OSTI)

. Wurtele, G. Shvets Massachusetts Institute of Technology, Cambridge, MA 02139 Abstract Progress profile. That is, n0(y) = 0 for y a In this section we consider the more that the wakefield accelerator scheme can be effective, but only if the beam load is placed on the first accelerating

Wurtele, Jonathan

298

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

SciTech Connect

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.

Ma, T

2010-04-21T23:59:59.000Z

299

Polarization and Angular Dependence of 1.06-?m Laser-Light Absorption by Planar Plasmas  

Science Journals Connector (OSTI)

An enclosing "box" calorimeter has been used to measure the polarization and angular dependence of 1.06-?m laser-light absorption under experimental conditions approximating those assumed by Estabrook, Valeo, and Kruer in their simulations; i.e., ?1016 W/cm2 plane waves incident on a planar plasma. A clear resonance absorption maximum was observed for p-but not for s-polarized incident radiation as predicted.

K. R. Manes, V. C. Rupert, J. M. Auerbach, P. Lee, and J. E. Swain

1977-08-01T23:59:59.000Z

300

Large-solid-angle illuminators for extreme ultraviolet lithography with laser plasmas  

SciTech Connect

Laser Plasma Sources (LPSS) of extreme ultraviolet radiation are an attractive alternative to synchrotron radiation sources for extreme ultraviolet lithography (EUVL) due to their modularity, brightness, and modest size and cost. To fully exploit the extreme ultraviolet power emitted by such sources, it is necessary to capture the largest possible fraction of the source emission half-sphere while simultaneously optimizing the illumination stationarity and uniformity on the object mask. In this LDRD project, laser plasma source illumination systems for EUVL have been designed and then theoretically and experimentally characterized. Ellipsoidal condensers have been found to be simple yet extremely efficient condensers for small-field EUVL imaging systems. The effects of aberrations in such condensers on extreme ultraviolet (EUV) imaging have been studied with physical optics modeling. Lastly, the design of an efficient large-solid-angle condenser has been completed. It collects 50% of the available laser plasma source power at 14 nm and delivers it properly to the object mask in a wide-arc-field camera.

Kubiak, G.D.; Tichenor, D.A. [Sandia National Labs., Livermore, CA (United States); Sweatt, W.C.; Chow, W.W. [Sandia National Labs., Albuquerque, NM (United States)

1995-06-01T23:59:59.000Z

Note: This page contains sample records for the topic "laser plasma wakefield" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

Controlled Electron Injection into Plasma Accelerators and SpaceCharge Estimates  

SciTech Connect

Plasma based accelerators are capable of producing electron sources which are ultra-compact (a few microns) and high energies (up to hundreds of MeVs) in much shorter distances than conventional accelerators. This is due to the large longitudinal electric field that can be excited without the limitation of breakdown as in RF structures.The characteristic scale length of the accelerating field is the plasma wavelength and for typical densities ranging from 1018 - 1019 cm-3, the accelerating fields and scale length can hence be on the order of 10-100GV/m and 10-40 mu m, respectively. The production of quasimonoenergetic beams was recently obtained in a regime relying on self-trapping of background plasma electrons, using a single laser pulse for wakefield generation. In this dissertation, we study the controlled injection via the beating of two lasers (the pump laser pulse creating the plasma wave and a second beam being propagated in opposite direction) which induce a localized injection of background plasma electrons. The aim of this dissertation is to describe in detail the physics of optical injection using two lasers, the characteristics of the electron beams produced (the micrometer scale plasma wavelength can result in femtosecond and even attosecond bunches) as well as a concise estimate of the effects of space charge on the dynamics of an ultra-dense electron bunch with a large energy spread.

Fubiani, Gwenael J.

2005-09-01T23:59:59.000Z

302

Inductively Coupled Plasma: Fundamental Particle Investigations with Laser Ablation and Applications in Magnetic Sector Mass Spectrometry  

SciTech Connect

Particle size effects and elemental fractionation in laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) are investigated with nanosecond and femtosecond laser ablation, differential mobility analysis, and magnetic sector ICP-MS. Laser pulse width was found to have a significant influence on the LA particle size distribution and the elemental composition of the aerosol and thus fractionation. Emission from individual particles from solution nebulization, glass, and a pressed powder pellet are observed with high speed digital photography. The presence of intact particles in an ICP is shown to be a likely source of fractionation. A technique for the online detection of stimulated elemental release from neural tissue using magnetic sector ICP-MS is described. Detection limits of 1 {micro}g L{sup -1} or better were found for P, Mn, Fe, Cu, and Zn in a 60 {micro}L injection in a physiological saline matrix.

Nathan Joe Saetveit

2008-08-18T23:59:59.000Z

303

Low-Emittance Electron Bunches from a Laser-Plasma Accelerator Measured using Single-Shot X-Ray Spectroscopy  

E-Print Network (OSTI)

Low-Emittance Electron Bunches from a Laser-Plasma Accelerator Measured using Single-Shot X-Ray,8], x-ray [9­11], and -ray radiation [12,13]. The electron density wave gener- ated by an intense laser manuscript received 15 February 2012; published 10 August 2012) X-ray spectroscopy is used to obtain single

Geddes, Cameron Guy Robinson

304

Inverse bremsstrahlung heating rate for dense plasmas in laser fields  

SciTech Connect

We report a theoretical analysis of inverse bremsstrahlung heating rate in the eikonal approximation. The present analysis is performed for a dense plasma using the screened electron-ion interaction potential for the ion charge state Z{sub i} = 1 and for both the weak and strong plasma screening cases. We have also compared the eikonal results with the first Born approximation (FBA) [M. Moll et al., New J. Phys. 14, 065010 (2012)] calculation. We find that the magnitudes of inverse bremsstrahlung heating rate within the eikonal approximation (EA) are larger than the FBA values in the weak screening case (? = 0.03 a.u.) in a wide range of field strength for three different initial electron momenta (2, 3, and 4 a.u.). But for strong screening case (? = 0.3 a.u.), the heating rates predicted by the two approximations do not differ much after reaching their maximum values. Furthermore, the individual contribution of photoemission and photoabsorption processes to heating rate is analysed for both the weak and strong screening cases. We find that the single photoemission and photoabsorption rates are the same throughout the field strength while the multiphoton absorption process dominates over the multiphoton emission process beyond the field strength ? 410{sup 8} V/cm. The present study of the dependence of heating rate on the screening parameter ranging from 0.01 to 20 shows that whereas the heating rate predicted by the EA is greater than the FBA up to the screening parameter ? = 0.3 a.u., the two approximation methods yield results which are nearly identical beyond the above value.

Dey, R. [D-203, Samruddhi Residency, Motera, Ahmedabad-380009, Gujarat (India)] [D-203, Samruddhi Residency, Motera, Ahmedabad-380009, Gujarat (India); Roy, A. C. [School of Mathematical Sciences, Ramakrishna Mission Vivekananda University, Belur Math 711202, West Bengal (India)] [School of Mathematical Sciences, Ramakrishna Mission Vivekananda University, Belur Math 711202, West Bengal (India)

2013-07-15T23:59:59.000Z

305

Dynamics of plasma expansion and shockwave formation in femtosecond laser-ablated aluminum plumes in argon gas at atmospheric pressures  

E-Print Network (OSTI)

plasma expansion into a background gas at atmospheric pressure is cru- cial for many engineeringDynamics of plasma expansion and shockwave formation in femtosecond laser-ablated aluminum plumes in argon gas at atmospheric pressures Alexander Miloshevsky, Sivanandan S. Harilal, Gennady Miloshevsky

Harilal, S. S.

306

Plasma-wall interaction studies with optimized laser-produced jets  

SciTech Connect

The production of the laser-produced plasma jets at burnt-through low-Z foils was optimized by using three-frame interferometry. When striking secondary targets, these jets of energetic particles represent an efficient tool for the investigation of transient phenomena at surfaces of the plasma-exposed solids. Two sets of precisely measured x-ray spectroscopic data demonstrate diagnostic potential of the collimated jets in the plasma-wall interaction studies: Blue Doppler shifts of the Al jet self-emission visualize ion deceleration in the near-wall region. Local depressions found in Al Ly{gamma} profiles emitted from Al/Si(PMMA) targets indicate charge exchange between the Al XIII and fully stripped C ions.

Renner, O.; Krousky, E.; Smid, M. [Institute of Physics ASCR, 18221 Prague (Czech Republic); Pisarczyk, T.; Chodukowski, T.; Kalinowska, Z. [Institute of Plasma Physics and Laser Microfusion, 01-497 Warsaw (Poland); Pisarczyk, P. [Warsaw University of Technology, ICS, 00-665 Warsaw (Poland); Ullschmied, J. [Institute of Plasma Physics ASCR, 18200 Prague 8 (Czech Republic); Dalimier, E. [Sorbonne Universites, Pierre et Marie Curie, UMR 7605, LULI, 75252 Paris (France)

2011-09-15T23:59:59.000Z

307

Wakefield Municipal Gas and Light Department - Residential Conservation  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Wakefield Municipal Gas and Light Department - Residential Wakefield Municipal Gas and Light Department - Residential Conservation Services Program Wakefield Municipal Gas and Light Department - Residential Conservation Services Program < Back Eligibility Residential Savings Category Home Weatherization Commercial Weatherization Sealing Your Home Heating & Cooling Commercial Heating & Cooling Cooling Appliances & Electronics Design & Remodeling Windows, Doors, & Skylights Manufacturing Commercial Lighting Lighting Water Heating Maximum Rebate Energy Audit Recommended Measures: $300 Programmable Thermostats: 2 units Program Info State Massachusetts Program Type Utility Rebate Program Rebate Amount Energy Audit Recommended Measures: 25% of total cost Refrigerators: $50 Clothes Washer: $50 Dishwasher: $50 Room AC: $50

308

Method and apparatus for fast laser pulse detection using gaseous plasmas  

DOE Patents (OSTI)

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.

McLellan, Edward J. (Los Alamos, NM); Webb, John A. (Albuquerque, NM)

1984-01-01T23:59:59.000Z

309

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

DOE Patents (OSTI)

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.

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

1981-06-18T23:59:59.000Z

310

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

SciTech Connect

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.

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

2014-07-13T23:59:59.000Z

311

Relativistic nonlinear dynamics of an intense laser beam propagating in a hot electron-positron magnetoactive plasma  

SciTech Connect

The present study is devoted to investigation of the nonlinear dynamics of an intense laser beam interacting with a hot magnetized electron-positron plasma. Propagation of the intense circularly polarized laser beam along an external magnetic field is studied using a relativistic two-fluid model. A modified nonlinear Schrdinger equation is derived based on the quasi-neutral approximation, which is valid for hot plasma. Light envelope solitary waves and modulation instability are studied, for one-dimensional case. Using a three-dimensional model, spatial-temporal development of laser pulse is investigated. Occurrence of some nonlinear phenomena such as self-focusing, self-modulation, light trapping, and filamentation of laser pulse is discussed. Also the effect of external magnetic field and plasma temperature on the nonlinear evolution of these phenomena is studied.

Sepehri Javan, N.; Adli, F. [Department of Physics, Faculty of Sciences, University of Mohaghegh Ardabili, P.O. Box 179, Ardabil 56199-11367 (Iran, Islamic Republic of)] [Department of Physics, Faculty of Sciences, University of Mohaghegh Ardabili, P.O. Box 179, Ardabil 56199-11367 (Iran, Islamic Republic of)

2013-06-15T23:59:59.000Z

312

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

SciTech Connect

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.

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)

2014-10-15T23:59:59.000Z

313

Wakefields in SLAC linac collimators  

Science Journals Connector (OSTI)

When a beam travels near collimator jaws, it gets an energy loss and a transverse kick due to the backreaction of the beam field diffracted from the jaws. The effect becomes very important for an intense short bunch when a tight collimation of the background beam halo is required. In the Linac Coherent Light Source at SLAC a collimation system is used to protect the undulators from radiation due to particles in the beam halo. The halo is most likely formed from gun dark current or dark current in some of the accelerating sections. However, collimators are also responsible for the generation of wake fields. The wake field effect from the collimators not only brings an additional energy jitter and change in the trajectory of the beam, but it also rotates the beam on the phase plane, which consequently leads to a degradation of the performance of the Free Electron Laser at the Linac Coherent Light Source. In this paper, we describe a model of the wake field radiation in the SLAC linac collimators. We use the results of a numerical simulation to illustrate the model. Based on the model, we derive simple formulas for the bunch energy loss and the average kick. We also present results from experimental measurements that confirm our model.

A. Novokhatski; F.-J. Decker; H. Smith; M. Sullivan

2014-12-02T23:59:59.000Z

314

The effects of pre-formed plasma on the generation and transport of fast electrons in relativistic laser-solid interactions  

E-Print Network (OSTI)

Mason. Ignition and high gain with ultrapowerful lasers.high power lasers, especially in the fast ignition relevantlaser-plasma interactions, fast-electron generation, and transport in fast ignition.

Paradkar, Bhooshan S.

2012-01-01T23:59:59.000Z

315

Optical breakdown threshold investigation of 1064 nm laser induced air plasmas  

SciTech Connect

We present the theoretical and experimental measurements and analysis of the optical breakdown threshold for dry air by 1064 nm infrared laser radiation and the significance of the multiphoton and collisional cascade ionization process on the breakdown threshold measurements over pressures range from 10 to 2000 Torr. Theoretical estimates of the breakdown threshold laser intensities and electric fields are obtained using two distinct theories namely multiphoton and collisional cascade ionization theories. The theoretical estimates are validated by experimental measurements and analysis of laser induced breakdown processes in dry air at a wavelength of 1064 nm by focusing 450 mJ max, 6 ns, 75 MW max high-power 1064 nm IR laser radiation onto a 20 {mu}m radius spot size that produces laser intensities up to 3 - 6 TW/cm{sup 2}, sufficient for air ionization over the pressures of interest ranging from 10 to 2000 Torr. Analysis of the measured breakdown threshold laser intensities and electric fields are carried out in relation with classical and quantum theoretical ionization processes, operating pressures. Comparative analysis of the laser air breakdown results at 1064 nm with corresponding results of a shorter laser wavelength (193 nm) [M. Thiyagarajan and J. E. Scharer, IEEE Trans. Plasma Sci. 36, 2512 (2008)] and a longer microwave wavelength (10{sup 8} nm) [A. D. MacDonald, Microwave Breakdown in Gases (Wiley, New York, 1966)]. A universal scaling analysis of the breakdown threshold measurements provided a direct comparison of breakdown threshold values over a wide range of frequencies ranging from microwave to ultraviolet frequencies. Comparison of 1064 nm laser induced effective field intensities for air breakdown measurements with data calculated based on the collisional cascade and multiphoton breakdown theories is used successfully to determine the scaled collisional microwave portion. The measured breakdown threshold of 1064 nm laser intensities are then scaled to classical microwave breakdown theory after correcting for the multiphoton ionization process for different pressures and good agreement, regarding both pressure dependence and breakdown threshold electric fields, is obtained. The effect of the presence of submicron particles on the 1064 nm breakdown threshold was also investigated. The measurements show that higher breakdown field is required, especially at lower pressures, and in close agreement with classical microwave breakdown theory and measurements in air.

Thiyagarajan, Magesh; Thompson, Shane [Plasma Engineering Research Lab (PERL), College of Science and Engineering, Texas A and M University-Corpus Christi, Texas 78412 (United States)

2012-04-01T23:59:59.000Z

316

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

SciTech Connect

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.

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)

2014-06-15T23:59:59.000Z

317

Time-resolved electron thermal conduction by probing of plasma formation in transparent solids with high power subpicosecond laser pulses  

SciTech Connect

This dissertation work includes a series of experimental measurements in a search for better understanding of high temperature (10{sup 4}-10{sup 6}K) and high density plasmas (10{sup 22}-10{sup 24}cm{sup {minus}3}) produced by irradiating a transparent solid target with high intensity (10{sup 13} - 10{sup 15}W/cm{sup 2}) and subpicosecond (10{sup {minus}12}-10{sup {minus}13}s) laser pulses. Experimentally, pump and probe schemes with both frontside (vacuum-plasma side) and backside (plasma-bulk material side) probes are used to excite and interrogate or probe the plasma evolution, thereby providing useful insights into the plasma formation mechanisms. A series of different experiments has been carried out so as to characterize plasma parameters and the importance of various nonlinear processes. Experimental evidence shows that electron thermal conduction is supersonic in a time scale of the first picosecond after laser irradiation, so fast that it was often left unresolved in the past. The experimental results from frontside probing demonstrate that upon irradiation with a strong (pump) laser pulse, a thin high temperature ({approximately}40eV) super-critical density ({approximately}10{sup 23}/cm{sup 3}) plasma layer is quickly formed at the target surface which in turn becomes strongly reflective and prevents further transmission of the remainder of the laser pulse. In the bulk region behind the surface, it is also found that a large sub-critical ({approximately}10{sup 18}/cm{sup 3}) plasma is produced by inverse Bremsstrahlung absorption and collisional ionization. The bulk underdense plasma is evidenced by large absorption of the backside probe light. A simple and analytical model, modified from the avalanche model, for plasma evolution in transparent materials is proposed to explain the experimental results. Elimination of the bulk plasma is then experimentally illustrated by using targets overcoated with highly absorptive films.

Vu, B.T.V.

1994-02-01T23:59:59.000Z

318

Operating Regime for a Backward Raman Laser Amplifier in Preformed Plasma  

SciTech Connect

A critical issue in the generation of ultra-intense, ultra-short laser pulses by backward Raman scattering in plasma is the stability of the pumping pulse to premature backscatter from thermal fluctuations in the preformed plasma. Malkin et al. [V.M. Malkin, et al., Phys. Rev. Lett. 84 (6):1208-1211, 2000] demonstrated that density gradients may be used to detune the Raman resonance in such a way that backscatter of the pump from thermal noise can be stabilized while useful Raman amplification persists. Here plasma conditions for which the pump is stable to thermal Raman backscatter in a homogeneous plasma and the density gradients necessary to stabilize the pump for other plasma conditions are quantified. Other ancillary constraints on a Raman amplifier are also considered to determine a specific region in the Te-he plane where Raman amplification is feasible. By determining an operability region, the degree of uncertainty in density or temperature tolerable for an experimental Raman amplifier is thus also identified. The fluid code F3D, which includes the effects of thermal fluctuations, is used to verify these analytic estimates.

Daniel S. Clark; Nathaniel J. Fisch

2003-02-06T23:59:59.000Z

319

The Influence of spot size on the expansion dynamics of nanosecond-laser-produced copper plasmas in atmosphere  

SciTech Connect

Laser produced copper plasmas of different spot sizes in air were investigated using fast photography and optical emission spectroscopy (OES). The laser energy was 33 mJ. There were dramatic changes in the plasma plume expansion into the ambient air when spot sizes changed from {approx}0.1 mm to {approx}0.6 mm. A stream-like structure and a hemispherical structure were, respectively, observed. It appeared that the same spot size resulted in similar expansion dynamics no matter whether the target was located in the front of or behind the focal point, although laser-induced air breakdown sometimes occurred in the latter case. Plasma plume front positions agree well with the classic blast wave model for the large spot-size cases, while an unexpected stagnation of {approx}80 ns occurred after the laser pulse ends for the small spot size cases. This stagnation can be understood in terms of the evolution of enhanced plasma shielding effects near the plasma front. Axial distributions of plasma components by OES revealed a good confinement effect. Electron number densities were estimated and interpreted using the recorded Intensified Charge Coupled Device (ICCD) images.

Li, Xingwen; Wei, Wenfu; Wu, Jian; Jia, Shenli; Qiu, Aici [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, No. 28 XianNing West Road, Xi'an, Shaanxi Province 710049 (China)] [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, No. 28 XianNing West Road, Xi'an, Shaanxi Province 710049 (China)

2013-06-28T23:59:59.000Z

320

Laser-based diagnostic for tracing magnetic-field lines in spheromaks and other self-organized magnetically confined plasmas  

Science Journals Connector (OSTI)

We are in the process of testing a technique for measuring the magnetic-field line topology in magnetically confined plasmas. The basic idea is to use a high-powerful short-pulse laser to launch a burst of energetic (?100 keV) electrons from a target passing through the plasma of interest; these electrons then generally follow field lines until they strike a solid surface where a burst of x rays is produced and then detected. The field line connection length can be determined from the time delay between the laser pulse and the burst of x rays. The topology of the field lines can be inferred by measuring the connection length as a function of initial target location inside the plasma. Measuring the spatial distribution of the x-ray production will provide further information on the field topology including the effects of magnetic-field fluctuations and stochasticity. The work will eventually include testing the appropriate x-ray detectors measuring the background x-ray emission in a spheromak plasma measuring the energetic electron production by a short-pulse high-power laser and making preliminary measurements of the edge field line topology in the Sustained Spheromak Physics Experiment using a pulsed electron-beam source as a prototype for a laser-based source. This technique may have broad application to a variety of plasma configurations and provide physics data applicable to a wide range of plasma physics problems.

H. S. McLean; D. N. Hill; D. D. Ryutov; H. Chen

2003-01-01T23:59:59.000Z

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321

Alumina reduction by laser sustained plasma for aluminum-based renewable energy cycling  

Science Journals Connector (OSTI)

A novel alumina (Al 2O3) reduction technique for a renewable energy cycling system based on aluminum is proposed. Al 2O3 powder was fed into laser-sustained plasma and thermally dissociated. The produced Al was expanded to supersonic speeds through a nozzle. From the Al and argon line distributions in the flow direction it was found that Al remained in the dissociated state. A water-cooled copper tube was inserted in the flow to collect Al. X-ray analysis indicated that elemental Al was observed on the surface of the tube. The maximum value of the estimated reduction efficiency was 5%.

Kimiya Komurasaki

2013-01-01T23:59:59.000Z

322

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

SciTech Connect

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.

Modi, K. V., E-mail: kvmodi.iitd@gmail.com [Centre for Energy Studies, Indian Institute of Technology Delhi, Delhi 110016 (India); Mechanical Engineering Department, Government Engineering College Valsad, Gujarat 396001 (India); Tiwary, Prem Pyari, E-mail: prempyari@gmail.com [Centre for Energy Studies, Indian Institute of Technology Delhi, Delhi 110016 (India); Department of Physics and Computer Science, Dayal Bagh Educational Institute (Deemed University), Dayal Bagh, Agra 282005 (India); Singh, Ram Kishor, E-mail: ram007kishor@gmail.com; Sharma, R. P., E-mail: rpsharma@ces.iitd.ac.in [Centre for Energy Studies, Indian Institute of Technology Delhi, Delhi 110016 (India); Satsangi, V. R. [Department of Physics and Computer Science, Dayal Bagh Educational Institute (Deemed University), Dayal Bagh, Agra 282005 (India)

2014-10-15T23:59:59.000Z

323

Study of nanosecond laser-produced plasmas in atmosphere by spatially resolved optical emission spectroscopy  

SciTech Connect

We investigate the evolution of the species from both the target and the air, and the plasma parameter distribution of the nanosecond laser-produced plasmas in atmospheric air. The technique used is spatially resolved optical emission spectroscopy. It is argued that the N II from the air, which is distributed over a wider region than the target species in the early stages of the discharge, is primarily formed by the shock wave. The ionized species have a larger expansion velocity than the excited atoms in the first ?100 ns, providing direct evidence for space-charge effects. The electron density decreases with the distance from the target surface in the early stages of the discharge, and both the electron density and the excited temperature variation in the axial direction are found to become insignificant at later stages.

Wei, Wenfu; Wu, Jian; Li, Xingwen; Jia, Shenli; Qiu, Aici [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, No. 28 XianNing West Road, Xi'an, Shaanxi Province 710049 (China)] [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, No. 28 XianNing West Road, Xi'an, Shaanxi Province 710049 (China)

2013-09-21T23:59:59.000Z

324

Nitrogen doping in pulsed laser deposited ZnO thin films using dense plasma focus  

Science Journals Connector (OSTI)

Pulsed laser deposition synthesized ZnO thin films, grown at 400C substrate temperature in different oxygen gas pressures, were irradiated with 6 shots of pulsed nitrogen ions obtained from 2.94kJ dense plasma focus to achieve the nitrogen doping in ZnO. Structural, compositional and optical properties of as-deposited and nitrogen ion irradiated ZnO thin films were investigated to confirm the successful doping of nitrogen in irradiated samples. Spectral changes have been seen in the nitrogen irradiated ZnO thin film samples from the low temperature PL measurements. Free electron to acceptor emissions can be observed from the irradiated samples, which hints towards the successful nitrogen doping in films. Compositional analysis by X-ray photoelectron spectroscopy and corresponding shifts in binding energy core peaks of oxygen and nitrogen confirmed the successful use of plasma focus device as a novel source for nitrogen ion doping in ZnO thin films.

S. Karamat; R.S. Rawat; T.L. Tan; P. Lee; S.V. Springham; E. Ghareshabani; R. Chen; H.D. Sun

2011-01-01T23:59:59.000Z

325

Time-resolved plasma measurements in Ge-doped silica exposed to infrared femtosecond laser  

SciTech Connect

Using a time-resolved interferometric technique, we study the laser-induced carrier-trapping dynamics in SiO{sub 2} and Ge-doped SiO{sub 2}. The fast trapping of electrons in the band gap is associated with the formation of self-trapped excitons (STE). The STE trapping is doping dependent in SiO{sub 2}. The mean trapping time of electrons excited in the conduction band was found to be significantly lower in Ge-doped silica (75 {+-} 5 fs) when compared to pure silica (155 {+-} 5 fs). At our concentration level, this indicates that the plasma properties are determined by the presence of easily ionizable states such as the presence of Ge atoms in the glass network. Therefore, we suggest that in Ge-doped silica there exist an additional trapping pathway that leads to a significantly faster excitons trapping and a higher plasma density when compared to undoped silica.

Lancry, M.; Poumellec, B. [LPCES/ICMMO, UMR CNRS-UPS 8182, Universite Paris Sud 11, Batiment 410, 91405 Orsay (France); Groothoff, N.; Canning, J. [Interdisciplinary Photonics Laboratories, School of Chemistry, University of Sydney, 206 NIC, ATP, Eveleigh, NSW, 1340 (Australia); Guizard, S.; Fedorov, N. [Laboratoire des Solides Irradies/CEA IRAMIS, Ecole Polytechnique, Palaiseau (France)

2011-12-15T23:59:59.000Z

326

Demonstration of the 101st harmonic generated from a laser-produced manganese plasma  

SciTech Connect

We demonstrate the generation of the 101st harmonic (wavelength {lambda}=7.9 nm) from manganese plasma, which is generated using the plasma high-order harmonic technique. We also investigate the variation of the high-order harmonic distribution from the manganese plasma plume as a function of the prepulse and main pulse intensities. The harmonic cutoff was at the 31st order, for pump intensities below the barrier suppression intensity for singly charged Mn ions. However, by using higher prepulse and main pulse intensities, the harmonic cutoff was extended to the 101st order, with an appearance of second plateau for harmonics higher than the 31st order. In this case, the low-order harmonics decreased in intensity, or completely disappeared, and the spectrum for wavelengths longer than 27.6 nm was dominated by plasma line emission. The origin of the harmonics appearing at this short wavelength plateau is attributed to the interaction of the intense main pump laser field with doubly charged manganese ions.

Ganeev, R. A. [Institut National de la Recherche Scientifique, Centre Energie, Materiaux et Telecommunications, 1650 Lionel-Boulet, Varennes, Quebec, J3X 1S2 (Canada); Scientific Association Akadempribor, Academy of Sciences of Uzbekistan, Akademgorodok, Tashkent 100125 (Uzbekistan); Bom, L. B. Elouga; Kieffer, J.-C.; Ozaki, T. [Institut National de la Recherche Scientifique, Centre Energie, Materiaux et Telecommunications, 1650 Lionel-Boulet, Varennes, Quebec, J3X 1S2 (Canada); Suzuki, M.; Kuroda, H. [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan)

2007-08-15T23:59:59.000Z

327

AUGMENTING COMPUTER MUSIC WITH JUST-IN-TIME COMPILATION Wesley Smith, Graham Wakefield  

E-Print Network (OSTI)

AUGMENTING COMPUTER MUSIC WITH JUST-IN-TIME COMPILATION Wesley Smith, Graham Wakefield University of California Santa Barbara Media Arts and Technology whsmith|wakefield@mat.ucsb.edu ABSTRACT We discuss

California at Santa Barbara, University of

328

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

SciTech Connect

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.

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)

2013-07-15T23:59:59.000Z

329

Effects of CSR Generated from Upstream Bends in a Laser Plasma Storage Ring  

SciTech Connect

The recent proposal [1] of a Laser Plasma Storage Ring (LPSR) envisions the use of a laser-plasma (LP) acceleration module to inject an electron beam into a compact 500 MeV storage ring. Electron bunches generated by LP methods are naturally very short (tens of femtoseconds), presenting peak currents on the order of 10 kA or higher. Of obvious concern is the impact of collective effects and in particular Coherent Synchrotron Radiation (CSR) on the beam dynamics in the storage ring. Available simulation codes (e.g. Elegant [2]) usually include transient CSR effects but neglect the contribution of radiation emitted from trailing magnets. In a compact storage ring, with dipole magnets close to each other, cross talking between different magnets could in principle be important.In this note we investigate this effect for the proposed LPSR and show that, in fact, this effect is relatively small. However our analysis also indicates that CSR effects in general would be quite strong and deserve a a careful study.

Mitchell, C.; Qiang, J.; Venturini, M.

2013-08-28T23:59:59.000Z

330

Optical emission studies of nitrogen plasma generated by IR CO2 laser pulses  

Science Journals Connector (OSTI)

Large-scale plasma produced in nitrogen gas at room temperature and pressures ranging from 4 ? 103 to 1.2 ? 105 Pa by high-power laser-induced dielectric breakdown (LIDB) has been investigated. Time-integrated optical nitrogen gas spectra excited from a CO2 laser have been measured and analysed. The spectrum of the generated plasma is dominated by the emission of strong N+ and N and very weak N2+ atomic lines and molecular features of N+2(B2?+uX2?+g), N+2(D2?gA2?u), N2(C3?uB3?g) and very weak N2(B3?gA3?+u). The relative intensities of the 00 band heads in the N2(CB) and N+2(BX) systems are very weak as compared with the chemiluminescence spectrum of nitrogen formed in a glow discharge. An excitation temperature Texc = 21?000 1300 K was calculated by means of the relative intensity of ionized nitrogen atomic lines assuming local thermodynamic equilibrium. Optical breakdown threshold intensities in N2 at 9.621 m have been determined. The physical processes leading to the LIDB of nitrogen in the power density range 0.4 J ?2 have been analysed. From our experimental observations we can suggest that, although the first electrons must appear via multiphoton ionization or natural ionization, electron cascade is the main mechanism responsible for the LIDB in nitrogen.

J J Camacho; J M L Poyato; L Daz; M Santos

2007-01-01T23:59:59.000Z

331

Increased Saturated Levels of Stimulated Brillouin Scattering of a Laser by Seeding a Plasma with an External Light Source  

SciTech Connect

The reflectivity of laser light due to stimulated Brillouin scattering (SBS) from long-scale plasmas normally saturates when the laser intensity is increased sufficiently. Nevertheless a significant increase in the SBS reflectivity back into the beam cone results from a subtle change in the target geometry, done for the purpose of seeding SBS. The key element is apparently the injection into the plasma of a modest external electromagnetic seed at a wavelength near that of the scattered light. {copyright} {ital 1998} {ital The American Physical Society}

Fernandez, J.C.; Bauer, B.S.; Bradley, K.S.; Cobble, J.A.; Montgomery, D.S.; Watt, R.G.; Bezzerides, B.; Focia, R.; Goldman, S.R.; Harris, D.B.; Lindman, E.L.; Rose, H.A.; Wallace, J.; Wilde, B.H. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Estabrook, K.G. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)] [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

1998-09-01T23:59:59.000Z

332

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

SciTech Connect

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.

Jha, Pallavi; Agrawal, Ekta [Department of Physics, University of Lucknow, Lucknow-226007 (India)

2014-05-15T23:59:59.000Z

333

Numerical and simulation study of terahertz radiation generation by laser pulses propagating in the extraordinary mode in magnetized plasma  

SciTech Connect

A one-dimensional numerical model for studying terahertz radiation generation by intense laser pulses propagating, in the extraordinary mode, through magnetized plasma has been presented. The direction of the static external magnetic field is perpendicular to the polarization as well as propagation direction of the laser pulse. A transverse electromagnetic wave with frequency in the terahertz range is generated due to the presence of the magnetic field. Further, two-dimensional simulations using XOOPIC code show that the THz fields generated in plasma are transmitted into vacuum. The fields obtained via simulation study are found to be compatible with those obtained from the numerical model.

Jha, Pallavi; Kumar Verma, Nirmal [Department of Physics, University of Lucknow, Lucknow-226007 (India)

2014-06-15T23:59:59.000Z

334

Collisional absorption of laser light in under-dense plasma: The role of Coulomb logarithm  

SciTech Connect

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.

Kundu, M. [Institute for Plasma Research, Bhat, Gandhinagar 382 428, Gujarat (India)] [Institute for Plasma Research, Bhat, Gandhinagar 382 428, Gujarat (India)

2014-01-15T23:59:59.000Z

335

Two photon absorption laser induced fluorescence measurements of neutral density in a helicon plasma  

SciTech Connect

We have developed a new diagnostic based on two-photon absorption laser induced fluorescence (TALIF). We use a high intensity (5?MW/cm{sup 2}), narrow bandwidth (0.1?cm{sup ?1}) laser to probe the ground state of neutral hydrogen, deuterium and krypton with spatial resolution better than 0.2?cm, a time resolution of 10?ns, and a measurement cadence of 20?Hz. Here, we describe proof-of-principle measurements in a helicon plasma source that demonstrate the TALIF diagnostic is capable of measuring neutral densities spanning four orders of magnitude; comparable to the edge neutral gradients predicted in the DIII-D tokamak pedestal. The measurements are performed in hydrogen and deuterium plasmas and absolute calibration is accomplished through TALIF measurements in neutral krypton. The optical configuration employed is confocal, i.e., both light injection and collection are accomplished with a single lens through a single optical port in the vacuum vessel. The wavelength resolution of the diagnostic is sufficient to separate hydrogen and deuterium spectra and we present measurements from mixed hydrogen and deuterium plasmas that demonstrate isotopic abundance measurements are feasible. Time resolved measurements also allow us to explore the evolution of the neutral hydrogen density and temperature and effects of wall recycling. We find that the atomic neutral density grows rapidly at the initiation of the discharge, reaching the steady-state value within 1?ms. Additionally, we find that neutral hydrogen atoms are born with 0.08?eV temperatures, not 2?eV as is typically assumed.

Galante, M. E.; Magee, R. M.; Scime, E. E. [Department of Physics, West Virginia University, Morgantown, West Virginia 26506 (United States)] [Department of Physics, West Virginia University, Morgantown, West Virginia 26506 (United States)

2014-05-15T23:59:59.000Z

336

Comment on 'Dynamics of an electron driven by relativistically intense laser radiation' [Phys. Plasmas 15, 023104 (2008)  

SciTech Connect

Galkin et al. [Phys. Plasmas 15, 023104 (2008)] presented the comparison of the electron dynamics in the cases of the linear and circular polarizations of the optical fields. They assume that the longitudinal component of the laser field can be neglected in the case of longitudinal displacement less than the Rayleigh range. In this comment, we point out that the longitudinal component must be considered for the minimum spot size less than 10 times wavelength for linearly polarized laser pulse and for the minimum spot size less than 15 times wavelength for circularly polarized laser pulse.

Tian Youwei; Bao Gang; Zheng Ying; Yang Jianping [College of Science, Nanjing University of Posts and Telecommunications, Nanjing 210046 (China); Yu Wei; Wang Xin [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)

2010-06-15T23:59:59.000Z

337

Increasing the upper-limit intensity and temperature range for thermal self-focusing of a laser beam by using plasma density ramp-up  

SciTech Connect

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.

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)

2014-03-15T23:59:59.000Z

338

Application of maximum likelihood methods to laser Thomson scattering measurements of low density plasmas  

SciTech Connect

Laser Thomson scattering (LTS) is an established plasma diagnostic technique that has seen recent application to low density plasmas. It is difficult to perform LTS measurements when the scattered signal is weak as a result of low electron number density, poor optical access to the plasma, or both. Photon counting methods are often implemented in order to perform measurements in these low signal conditions. However, photon counting measurements performed with photo-multiplier tubes are time consuming and multi-photon arrivals are incorrectly recorded. In order to overcome these shortcomings a new data analysis method based on maximum likelihood estimation was developed. The key feature of this new data processing method is the inclusion of non-arrival events in determining the scattered Thomson signal. Maximum likelihood estimation and its application to Thomson scattering at low signal levels is presented and application of the new processing method to LTS measurements performed in the plume of a 2-kW Hall-effect thruster is discussed.

Washeleski, Robert L.; Meyer, Edmond J. IV; King, Lyon B. [Michigan Technological University, Houghton, Michigan 49931 (United States)] [Michigan Technological University, Houghton, Michigan 49931 (United States)

2013-10-15T23:59:59.000Z

339

Ion flux enhancements and oscillations in spatially confined laser produced aluminum plasmas  

SciTech Connect

Ion signals from laser produced plasmas (LPPs) generated inside aluminum rectangular cavities at a fixed depth d?=?2?mm and varying width, x?=?1.0, 1.6, and 2.75?mm were obtained by spatially varying the position of a negatively biased Langmuir probe. Damped oscillatory features superimposed on Maxwellian distributed ion signals were observed. Depending on the distance of the probe from the target surface, three to twelve fold enhancements in peak ion density were observed via confinement of the LPP, generated within rectangular cavities of varying width which constrained the plasma plume to near one dimensional expansion in the vertical plane. The effects of lateral spatial confinement on the expansion velocity of the LPP plume front, the temperature, density and expansion velocity of ions, enhancement of ion flux, and ion energy distribution were recorded. The periodic behavior of ion signals was analyzed and found to be related to the electron plasma frequency and electron-ion collision frequency. The effects of confinement and enhancement of various ion parameters and expansion velocities of the LPP ion plume are explained on the basis of shock wave theory.

Singh, S. C., E-mail: subhash.laserlab@gmail.com; Fallon, C.; Hayden, P.; Yeates, P.; Costello, J. T. [National Centre for Plasma Science and Technology and School of Physical Sciences, Dublin City University, Dublin 9 (Ireland); Mujawar, M. [School of Physics, Trinity College, Dublin 2 (Ireland)

2014-09-15T23:59:59.000Z

340

Laser-Beam-Scattering Measurement of Ion Temperature in a ?-Pinch Plasma and Evidence for Thermonuclear Reactions  

Science Journals Connector (OSTI)

Results are reported on an experiment to measure the ion temperature in a 100-kJ ?-pinch deuterium plasma. A ruby laser was used for scattering observations at 5 and 90 using multichannel spectrum analyzers and gave n=1.051017 cm-3 and Ti=300 eV. An independent measurement of the density was made by means of Rayleigh scattering. The neutron yield from the plasma was measured to be 8108 sec-1. The observed neutron emission was compared with that expected from a plasma with an ion temperature of 300 eV and was found to be of thermonuclear origin.

P. K. John

1972-08-01T23:59:59.000Z

Note: This page contains sample records for the topic "laser plasma wakefield" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

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

Science Journals Connector (OSTI)

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 indexn 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-organizedplasma studied here. Instead it can be readily applied to other configurations that produce measurable gradients of refractive index by local gas heating and opens new diagnostics prospects particularly for microplasmas.

J. Schfer; R. Foest; S. Reuter; T. Kewitz; J. perka; K.-D. Weltmann

2012-01-01T23:59:59.000Z

342

Effect of shockwave-induced density jump on laser plasma interactions in low-pressure ambient air  

E-Print Network (OSTI)

and Aerospace Engineering and the Center for Energy Research, University of California San Diego, 9500 Gilman significantly reduce laser energy absorbed in the solid plasma. The ionization of the density jump was confirmed , extreme ultraviolet lithography (EUVL) source 3 , and inertial fusion energy (IFE) 4 . During

Tillack, Mark

343

Integrated Kinetic Simulation of Laser-Plasma Interactions, Fast-Electron Generation and Transport in Fast Ignition  

SciTech Connect

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.

Kemp, A; Cohen, B; Divol, L

2009-11-16T23:59:59.000Z

344

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

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.

Perdian, David C.

2009-08-19T23:59:59.000Z

345

Resonance laser-plasma excitation of coherent terahertz phonons in the bulk of fluorine-bearing crystals under high-intensity femtosecond laser irradiation  

SciTech Connect

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)

Potemkin, F V; Mareev, E I [International Laser Center, M. V. Lomonosov Moscow State University, Moscow (Russian Federation); Khodakovskii, N G [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Mikheev, P M

2013-08-31T23:59:59.000Z

346

Application of Plasma Waveguides to High Energy Accelerators  

SciTech Connect

The eventual success of laser-plasma based acceleration schemes for high-energy particle physics will require the focusing and stable guiding of short intense laser pulses in reproducible plasma channels. For this goal to be realized, many scientific issues need to be addressed. These issues include an understanding of the basic physics of, and an exploration of various schemes for, plasma channel formation. In addition, the coupling of intense laser pulses to these channels and the stable propagation of pulses in the channels require study. Finally, new theoretical and computational tools need to be developed to aid in the design and analysis of experiments and future accelerators. Here we propose a 3-year renewal of our combined theoretical and experimental program on the applications of plasma waveguides to high-energy accelerators. During the past grant period we have made a number of significant advances in the science of laser-plasma based acceleration. We pioneered the development of clustered gases as a new highly efficient medium for plasma channel formation. Our contributions here include theoretical and experimental studies of the physics of cluster ionization, heating, explosion, and channel formation. We have demonstrated for the first time the generation of and guiding in a corrugated plasma waveguide. The fine structure demonstrated in these guides is only possible with cluster jet heating by lasers. The corrugated guide is a slow wave structure operable at arbitrarily high laser intensities, allowing direct laser acceleration, a process we have explored in detail with simulations. The development of these guides opens the possibility of direct laser acceleration, a true miniature analogue of the SLAC RF-based accelerator. Our theoretical studies during this period have also contributed to the further development of the simulation codes, Wake and QuickPIC, which can be used for both laser driven and beam driven plasma based acceleration schemes. We 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.

Milchberg, Howard M

2013-03-30T23:59:59.000Z

347

Town of Wakefield, Massachusetts (Utility Company) | Open Energy  

Open Energy Info (EERE)

Wakefield Wakefield Place Massachusetts Utility Id 19979 Utility Location Yes Ownership M NERC Location NPCC NERC NPCC Yes Activity Buying Transmission Yes Activity Distribution Yes Activity Retail Marketing Yes Activity Bundled Services Yes References EIA Form EIA-861 Final Data File for 2010 - File1_a[1] LinkedIn Connections CrunchBase Profile No CrunchBase profile. Create one now! This article is a stub. You can help OpenEI by expanding it. Utility Rate Schedules Grid-background.png Commercial Rate B Commercial Domestic Electric Rate A Residential Power Rate C Industrial Average Rates Residential: $0.1510/kWh Commercial: $0.1410/kWh Industrial: $0.1240/kWh References ↑ "EIA Form EIA-861 Final Data File for 2010 - File1_a" Retrieved from "http://en.openei.org/w/index.php?title=Town_of_Wakefield,_Massachusetts_(Utility_Company)&oldid=41183

348

Town of Wakefield, Virginia (Utility Company) | Open Energy Information  

Open Energy Info (EERE)

Wakefield, Virginia (Utility Company) Wakefield, Virginia (Utility Company) Jump to: navigation, search Name Town of Wakefield Place Virginia Utility Id 19978 Utility Location Yes Ownership M NERC Location SERC NERC SERC Yes Activity Distribution Yes References EIA Form EIA-861 Final Data File for 2010 - File1_a[1] LinkedIn Connections CrunchBase Profile No CrunchBase profile. Create one now! This article is a stub. You can help OpenEI by expanding it. Utility Rate Schedules Grid-background.png Commercial Commercial Large Service Demand Industrial Out Town Residential Elec Residential Residential Residential Small Commercial Demand Commercial Average Rates Residential: $0.0855/kWh Commercial: $0.0855/kWh References ↑ "EIA Form EIA-861 Final Data File for 2010 - File1_a" Retrieved from

349

Observation of Megagauss-Field Topology Changes due to Magnetic Reconnection in Laser-Produced Plasmas  

SciTech Connect

The spatial structure and temporal evolution of megagauss magnetic fields generated by interactions of up to 4 laser beams with matter were studied with an innovative, time-gated proton radiography method that produces images of unprecedented clarity because it uses an isotropic, truly monoenergetic backlighter (14.7-MeV protons from D{sup 3}He nuclear fusion reactions). Quantitative field maps reveal precisely and directly, for the first time, changes in the magnetic topology due to reconnection in a high-energy-density plasma (n{sub e}{approx}10{sup 20}-10{sup 22} cm{sup -3}, T{sub e}{approx}1 keV)

Li, C. K.; Seguin, F. H.; Frenje, J. A.; Rygg, J. R.; Petrasso, R. D.; Town, R. P. J.; Landen, O. L.; Knauer, J. P.; Smalyuk, V. A. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)

2007-08-03T23:59:59.000Z

350

Absorption of laser light in overdense plasmas by sheath inverse bremsstrahlung  

SciTech Connect

The original sheath inverse bremsstrahlung model [P. J. Catto and R. M. More, 1977] is modified by including the vxB term in the equation of motion. It is shown that the present results axe significantly different from those derived without the vxB term. The vxB term is also important in interpreting the absorption mechanism. If the vxB term were neglected, the absorption of the light would be incorrectly interpreted as an increase in the transverse electron temperature. This would violate the conservation of the transverse components of the canonical momentum, in the case of a normally incident laser light. It is also shown that both the sheath inverse bremsstrahlung and the anomalous skin effect are limiting cases of the same collisionless absorption mechanism. Finally, results from PIC plasma simulations are compared with the absorption coefficient calculated from the linear theory.

Yang, T.Y.B.; Kruer, W.L.; More, R.M.

1994-11-01T23:59:59.000Z

351

Interferometric and schlieren characterization of the plasmas and shock wave dynamics during laser-triggered discharge in atmospheric air  

SciTech Connect

This paper describes our efforts to reveal the underlying physics of laser-triggered discharges in atmospheric air using a Mach-Zehnder interferometer and schlieren photography. Unlike the hemispherical shock waves that are produced by laser ablation, bell-like morphologies are observed during laser-triggered discharges. Phase shifts are recovered from the interferograms at a time of 1000?ns by the 2D fast Fourier transform method, and then the values of the refractive index are deduced using the Abel inversion. An abundance of free electrons is expected near the cathode surface. The schlieren photographs visualize the formation of stagnation layers at ?600?ns in the interaction zones of the laser- and discharge-produced plasmas. Multiple reflected waves are observed at later times with the development of shock wave propagations. Estimations using the Taylor-Sedov self-similar solution indicated that approximately 45.8% and 51.9% of the laser and electrical energies are transferred into the gas flow motions, respectively. Finally, numerical simulations were performed, which successfully reproduced the main features of the experimental observations, and provided valuable insights into the plasma and shock wave dynamics during the laser-triggered discharge.

Wei, Wenfu; Li, Xingwen, E-mail: xwli@mail.xjtu.edu.cn; Wu, Jian; Yang, Zefeng; Jia, Shenli; Qiu, Aici [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Shaanxi 710049 (China)

2014-08-15T23:59:59.000Z

352

Time-resolved visible and extreme ultraviolet spectroscopy of laser-produced tin plasma  

E-Print Network (OSTI)

and copper plasma temperature in one atmosphere of argonand copper plasma electron temperature in one atmosphere ofand copper plasma electron temperature in one atmosphere of

O'Shay, Joseph Fred

2007-01-01T23:59:59.000Z

353

Measurements of Collimator Wakefields at End Station A  

SciTech Connect

The angular deflection of a 28.5 GeV electron beam passing off-axis between the jaws of a collimator, generating a transverse wakefield, were measured in End Station A (ESA) at SLAC. In total, fifteen different configurations of collimator geometry and material were tested: some were chosen for compatibility with previous measurements while others served to study the effect of geometry and taper angles (geometrical contribution to the wakefield) and the effect of the material resistivity (resistive contribution) to the imparted kick. This paper summarises the last update of preliminary experimental results before they are finalised. The reconstructed kick factor is compared to analytical calculations and simulations.

Fernandez-Hernando, J.L.; /Daresbury; Molloy, S.; /SLAC; Smith, J.D.A.; /Cockcroft Inst. Accel. Sci. Tech.; Watson, Nigel Keith; /Birmingham U.

2011-11-01T23:59:59.000Z

354

Relativistic solitary waves with phase modulation embedded in long laser pulses in plasmas  

SciTech Connect

We investigate the existence of nonlinear phase-modulated relativistic solitary waves embedded in an infinitely long circularly polarized electromagnetic wave propagating through a plasma. These states are exact nonlinear solutions of the 1-dimensional Maxwell-fluid model for a cold plasma composed of electrons and ions. The solitary wave, which consists of an electromagnetic wave trapped in a self-generated Langmuir wave, presents a phase modulation when the group velocity V and the phase velocity V{sub ph} of the long circularly polarized electromagnetic wave do not match the condition VV{sub ph} = c{sup 2}. The main properties of the waves as a function of their group velocities, wavevectors, and frequencies are studied, as well as bifurcations of the dynamical system that describes the waves when the parameter controlling the phase modulation changes from zero to a finite value. Such a transition is illustrated in the limit of small amplitude waves where an analytical solution for a grey solitary wave exists. The solutions are interpreted as the stationary state after the collision of a long laser pulse with an isolated solitary wave.

Sanchez-Arriaga, G.; Siminos, E.; Lefebvre, E. [CEA, DAM, DIF, 91297 Arpajon (France)

2011-08-15T23:59:59.000Z

355

Specific features of microheterogeneous plasma produced by irradiation of a polymer aerogel target with an intense 500-ps-long laser pulse  

SciTech Connect

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-?m 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.

Borisenko, N. G.; Merkulev, Yu. A.; Orekhov, A. S., E-mail: orekhov@sci.lebedev.ru [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Chaurasia, S.; Tripathi, S.; Munda, D. S.; Dhareshwar, L. J. [Bhabha Atomic Research Centre, High-Pressure and Synchrotron Radiation Physics Division (India)] [Bhabha Atomic Research Centre, High-Pressure and Synchrotron Radiation Physics Division (India); Pimenov, V. G.; Sheveleva, E. E. [Russian Academy of Sciences, Zelinksy Institute of Organic Chemistry (Russian Federation)] [Russian Academy of Sciences, Zelinksy Institute of Organic Chemistry (Russian Federation)

2013-08-15T23:59:59.000Z

356

Particle-in-cell simulations of magnetic reconnection in laser-plasma experiments on Shenguang-II facility  

SciTech Connect

Recently, magnetic reconnection has been realized in high-energy-density laser-produced plasmas. Plasma bubbles with self-generated magnetic fields are created by focusing laser beams to small-scale spots on a foil. The bubbles expand into each other, which may then drive magnetic reconnection. The reconnection experiment in laser-produced plasmas has also been conducted at Shenguang-II (SG-II) laser facility, and the existence of a plasmoid was identified in the experiment [Dong et al., Phys. Rev. Lett. 108, 215001 (2012)]. In this paper, by performing two-dimensional (2-D) particle-in-cell simulations, we investigate such a process of magnetic reconnection based on the experiment on SG-II facility, and a possible explanation for the formation of the plasmoid is proposed. The results show that before magnetic reconnection occurs, the bubbles squeeze strongly each other and a very thin current sheet is formed. The current sheet is unstable to the tearing mode instability, and we can then observe the formation of plasmoid(s) in such a multiple X-lines reconnection.

Lu, San; Lu, Quanming; Huang, Can; Wang, Shui [CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Science, University of Science and Technology of China, Hefei 230026 (China)] [CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Science, University of Science and Technology of China, Hefei 230026 (China); Dong, Quanli [School of Physics and Optoelectronic Engineering, Ludong University, Yantai 264025 (China)] [School of Physics and Optoelectronic Engineering, Ludong University, Yantai 264025 (China); Zhu, Jianqiang [CAS Key Laboratory for High Power Laser Physics, Chinese Academy of Sciences, Shanghai 201800 (China)] [CAS Key Laboratory for High Power Laser Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Sheng, Zhengming; Zhang, Jie [Key Laboratory for Laser Plasmas (MoE) and Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China)] [Key Laboratory for Laser Plasmas (MoE) and Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China)

2013-11-15T23:59:59.000Z

357

CO{sub 2} laser-based dispersion interferometer utilizing orientation-patterned gallium arsenide for plasma density measurements  

SciTech Connect

A dispersion interferometer based on the second-harmonic generation of a carbon dioxide laser in orientation-patterned gallium arsenide has been developed for measuring electron density in plasmas. The interferometer includes two nonlinear optical crystals placed on opposite sides of the plasma. This instrument has been used to measure electron line densities in a pulsed radio-frequency generated argon plasma. A simple phase-extraction technique based on combining measurements from two successive pulses of the plasma has been used. The noise-equivalent line density was measured to be 1.7 10{sup 17} m{sup ?2} in a detection bandwidth of 950 kHz. One of the orientation-patterned crystals produced 13 mW of peak power at the second-harmonic wavelength from a carbon dioxide laser with 13 W of peak power. Two crystals arranged sequentially produced 58 mW of peak power at the second-harmonic wavelength from a carbon dioxide laser with 37 W of peak power.

Bamford, D. J.; Cummings, E. A.; Panasenko, D. [Physical Sciences Inc., 6652 Owens Drive, Pleasanton, California 94588 (United States)] [Physical Sciences Inc., 6652 Owens Drive, Pleasanton, California 94588 (United States); Fenner, D. B.; Hensley, J. M. [Physical Sciences Inc., 20 New England Business Center, Andover, Massachusetts 01810 (United States)] [Physical Sciences Inc., 20 New England Business Center, Andover, Massachusetts 01810 (United States); Boivin, R. L.; Carlstrom, T. N.; Van Zeeland, M. A. [General Atomics, P.O. Box 85608, San Diego, California 92186 (United States)] [General Atomics, P.O. Box 85608, San Diego, California 92186 (United States)

2013-09-15T23:59:59.000Z

358

PLASMA WAKEFIELD ACCELERATION EXPERIMENTS USING TWO SUBPICOSECOND ELECTRON BUNCHES*  

E-Print Network (OSTI)

. Yakimenko,3 1 University of Southern California, Los Angeles, CA, USA 2 STI Optronics, Inc., Bellevue, WA

Brookhaven National Laboratory

359

Multi-bunch Plasma Wakefield Acceleration at ATF  

NLE Websites -- All DOE Office Websites (Extended Search)

280 MeV1.4m, e- and e+ - ANL: 15 MeV30cm, >50% beam energy extracted - ATF: .6 MeVcm, focus and acceleration phases * Realizations require multi-bunches - Afterburner: 2 - NLC...

360

Electron generation and transport in intense relativistic laser-plasma interactions relevant to fast ignition ICF  

E-Print Network (OSTI)

as a step towards laser fusion ignition, Nature, 412 (2001),tip. Full scale fast ignition laser systems are envisionedmodified. Full scale fast ignition laser systems of 100 kJ

Ma, Tammy Yee Wing

2010-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "laser plasma wakefield" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

USING LUA FOR AUDIOVISUAL COMPOSTION Graham Wakefield Wesley Smith  

E-Print Network (OSTI)

USING LUA FOR AUDIOVISUAL COMPOSTION Graham Wakefield Wesley Smith University of California Santa Barbara Media Arts and Technology Program Santa Barbara, California, USA ABSTRACT In this paper, we/MSP/Jitter [27], PureData [19], etc.) are popular choices for composing interactive digital media works because

California at Santa Barbara, University of

362

Modeling laser wakefield accelerators in a Lorentz boosted frame  

E-Print Network (OSTI)

on axis, beam average energy history and momentum spread aton the mean beam energy histories and on the longitudinalgave the same beam energy history within a few percents, and

Vay, J.-L.

2010-01-01T23:59:59.000Z

363

Modeling laser wakefield accelerators in a Lorentz boosted frame  

E-Print Network (OSTI)

on axis, beam average energy history and momentum spread aton the mean beam energy histories and on the lon- gitudinalgave the same beam energy history within a few percents, and

Vay, J.-L.

2010-01-01T23:59:59.000Z

364

Advances in laser driven accelerator R&D  

SciTech Connect

Current activities (last few years) at different laboratories, towards the development of a laser wakefield accelerator (LWFA) are reviewed, followed by a more in depth discussion of results obtained at the L'OASIS laboratory of LBNL. Recent results on laser guiding of relativistically intense beams in preformed plasma channels are discussed. The observation of mono-energetic beams in the 100 MeV energy range, produced by a channel guided LWFA at LBNL, is described and compared to results obtained in the unguided case at LOA, RAL and LBNL. Analysis, aided by particle-in-cell simulations, as well as experiments with various plasma lengths and densities, indicate that tailoring the length of the accelerator has a very beneficial impact on the electron energy distribution. Progress on laser triggered injection is reviewed. Results are presented on measurements of bunch duration and emittance of the accelerated electron beams, that indicate the possibility of generating femtosecond duration electron bunches. Future challenges and plans towards the development of a 1 GeV LWFA module are discussed.

Leemans, Wim

2004-08-23T23:59:59.000Z

365

The use of ultraviolet Thomson scattering as a versatile diagnostic for detailed measurements of a collisional laser produced plasma  

SciTech Connect

Collective Thomson scattering from ion-acoustic waves at 266nm is used to obtain spatially resolved, two-dimensional electron density, sound speed, and radial drift profiles of a collisional laser plasma. An ultraviolet diagnostic wavelength minimizes the complicating effects of inverse bremsstrahlung and refractive turning in the coronal region of interest, where the electron densities approach n{sub c}/10. Laser plasmas of this type are important because they model some of the aspects of the plasmas found in high-gain laser-fusion pellets irradiated by long pulse widths where the laser light is absorbed mostly in the corona. The experimental results and LASNEX simulations agree within a percent standard deviation of 40% for the electron density and 50% for the sound speed and radial drift velocity. Thus it is shown that the hydrodynamics equations with classical coefficients and the numerical approximations in LASNEX are valid models of laser-heated, highly collisional plasmas. The versatility of Thomson scattering is expanded upon by extending existing theory with a Fokker-Planck based model to include plasmas that are characterized by (0 {le} k{sub ia}{lambda}{sub ii} {le} {infinity}) and ZT{sub e}/T{sub i}, where k{sub ia} is the ion- acoustic wave number, {lambda}{sub ii} is the ion-ion mean free path, Z is the ionization state of the plasma, and T{sub e}, T{sub i} are the electron and ion temperatures in electron volts respectively. The model is valid for plasmas in which the electrons are approximately collisionless, (k{sub ia}{lambda}{sub ei}, k{sub ia}{lambda}{sub ee} {ge} 1), and quasineutrality holds, ({alpha} {much_gt}1), where {alpha} = 1/k{lambda}{sub DE} and {lambda}{sub DE} is the electron Debye length. This newly developed model predicts the lineshape of the ion-acoustic Thomson spectra and when fit to experimental data provides a direct measurement of the relative thermal flow velocity between the electrons and ions.

Tracy, M.D.

1993-01-08T23:59:59.000Z

366

Characterisation of electron beams from laser-driven particle accelerators  

SciTech Connect

The development, understanding and application of laser-driven particle accelerators require accurate measurements of the beam properties, in particular emittance, energy spread and bunch length. Here we report measurements and simulations showing that laser wakefield accelerators can produce beams of quality comparable to conventional linear accelerators.

Brunetti, E.; Manahan, G. G.; Shanks, R. P.; Islam, M. R.; Ersfeld, B.; Anania, M. P.; Cipiccia, S.; Issac, R. C.; Vieux, G.; Welsh, G. H.; Wiggins, S. M.; Jaroszynski, D. A. [Physics Department, University of Strathclyde, Glasgow G4 0NG (United Kingdom)

2012-12-21T23:59:59.000Z

367

5. Kodama, R. et al. Fast heating of ultrahigh-density plasma as a step towards laser fusion ignition. Nature 412, 798802 (2001).  

E-Print Network (OSTI)

5. Kodama, R. et al. Fast heating of ultrahigh-density plasma as a step towards laser fusion. J. Geophys. Res. 100, 23567­23581 (1995). 13. Hirahara, M. et al. Acceleration and heating of cold

Davis, James C.

368

Comparative study of laser-induced plasma emission of hydrogen from zircaloy-2 samples in atmospheric and low pressure ambient helium gas  

Science Journals Connector (OSTI)

An experimental study has been performed to demonstrate the advantage of employing ambient helium gas in the spectral quality improvement of hydrogen emission in laser-induced plasma from zircaloy-2 samples at...

M. Pardede; R. Hedwig; M.M. Suliyanti; Z.S. Lie; T.J. Lie

2007-11-01T23:59:59.000Z

369

Laser-induced plasma cloud interaction and ice multiplication under cirrus cloud conditions  

Science Journals Connector (OSTI)

...electrode free by high-power ultrashort laser...AIDA). High-power lasers allow producing...above a critical power of 36 GW in air...respectively. (A) Chamber gas phase temperature...laser-induced ice generation is apparent from...s. The laser was fired at t = 400 s when the...

Thomas Leisner; Denis Duft; Ottmar Mhler; Harald Saathoff; Martin Schnaiter; Stefano Henin; Kamil Stelmaszczyk; Massimo Petrarca; Raphalle Delagrange; Zuoqiang Hao; Johannes Lder; Yannick Petit; Philipp Rohwetter; Jrme Kasparian; Jean-Pierre Wolf; Ludger Wste

2013-01-01T23:59:59.000Z

370

WENO schemes applied to the quasi-relativistic Vlasov--Maxwell model for laser-plasma interaction  

E-Print Network (OSTI)

In this paper we focus on WENO-based methods for the simulation of the 1D Quasi-Relativistic Vlasov--Maxwell (QRVM) model used to describe how a laser wave interacts with and heats a plasma by penetrating into it. We propose several non-oscillatory methods based on either Runge--Kutta (explicit) or Time-Splitting (implicit) time discretizations. We then show preliminary numerical experiments.

Vecil, Francesco; Labrunie, Simon

2014-01-01T23:59:59.000Z

371

Plasmawall interaction in laser inertial fusion reactors: novel proposals for radiation tests of first wall materials  

Science Journals Connector (OSTI)

Dry-wall laser inertial fusion (LIF) chambers will have to withstand strong bursts of fast charged particles which will deposit tens of kJm?2 and implant more than 1018particlesm?2 in a few microseconds at a repetition rate of some Hz. Large chamber dimensions and resistant plasma-facing materials must be combined to guarantee the chamber performance as long as possible under the expected threats: heating, fatigue, cracking, formation of defects, retention of light species, swelling and erosion. Current and novel radiation resistant materials for the first wall need to be validated under realistic conditions. However, at present there is a lack of facilities which can reproduce such ion environments.This contribution proposes the use of ultra-intense lasers and high-intense pulsed ion beams (HIPIB) to recreate the plasma conditions in LIF reactors. By target normal sheath acceleration, ultra-intense lasers can generate very short and energetic ion pulses with a spectral distribution similar to that of the inertial fusion ion bursts, suitable to validate fusion materials and to investigate the barely known propagation of those bursts through background plasmas/gases present in the reactor chamber. HIPIB technologies, initially developed for inertial fusion driver systems, provide huge intensity pulses which meet the irradiation conditions expected in the first wall of LIF chambers and thus can be used for the validation of materials too.

J Alvarez Ruiz; A Rivera; K Mima; D Garoz; R Gonzalez-Arrabal; N Gordillo; J Fuchs; K Tanaka; I Fernndez; F Briones; J Perlado

2012-01-01T23:59:59.000Z

372

Visualizing electromagnetic fields in laser-produced counter-streaming plasma experiments for collisionless shock laboratory astrophysics  

SciTech Connect

Collisionless shocks are often observed in fast-moving astrophysical plasmas, formed by non-classical viscosity that is believed to originate from collective electromagnetic fields driven by kinetic plasma instabilities. However, the development of small-scale plasma processes into large-scale structures, such as a collisionless shock, is not well understood. It is also unknown to what extent collisionless shocks contain macroscopic fields with a long coherence length. For these reasons, it is valuable to explore collisionless shock formation, including the growth and self-organization of fields, in laboratory plasmas. The experimental results presented here show at a glance with proton imaging how macroscopic fields can emerge from a system of supersonic counter-streaming plasmas produced at the OMEGA EP laser. Interpretation of these results, plans for additional measurements, and the difficulty of achieving truly collisionless conditions are discussed. Future experiments at the National Ignition Facility are expected to create fully formed collisionless shocks in plasmas with no pre-imposed magnetic field.

Kugland, N. L.; Ross, J. S.; Glenzer, S. H.; Huntington, C.; Martinez, D.; Plechaty, C.; Remington, B. A.; Ryutov, D. D.; Park, H.-S. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States)] [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States); Chang, P.-Y.; Fiksel, G.; Froula, D. H. [Laboratory for Laser Energetics, University of Rochester, 250 E. River Road, Rochester, New York 14636 (United States)] [Laboratory for Laser Energetics, University of Rochester, 250 E. River Road, Rochester, New York 14636 (United States); Drake, R. P.; Grosskopf, M.; Kuranz, C. [Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States)] [Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States); Gregori, G.; Meinecke, J.; Reville, B. [Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom)] [Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Koenig, M.; Pelka, A. [Laboratoire pour l'Utilisation des Lasers Intenses (LULI), cole Polytechnique-Univ, Paris VI, 91128 Palaiseau (France)] [Laboratoire pour l'Utilisation des Lasers Intenses (LULI), cole Polytechnique-Univ, Paris VI, 91128 Palaiseau (France); and others

2013-05-15T23:59:59.000Z

373

Specific features of microheterogeneous plasma produced by irradiation of a polymer aerogel target with an intense 500-ps-long laser pulse  

Science Journals Connector (OSTI)

The properties of microheterogeneous plasma produced by irradiation of a polymer aerogel target with an intense (1014 W/cm3) short (0.5 ps) 1.064-?m laser pulse were studied. It is found that, even at plasma dens...

N. G. Borisenko; Yu. A. Merkulev; A. S. Orekhov; S. Chaurasia

2013-08-01T23:59:59.000Z

374

Emission features of femtosecond laser ablated carbon plasma in ambient K. F. Al-Shboul, S. S. Harilal, and A. Hassanein  

E-Print Network (OSTI)

Emission features of femtosecond laser ablated carbon plasma in ambient helium K. F. Al-Shboul, S carbon species in the plume were obtained using time of flight emission spectroscopy. These contours 2013; published online 30 April 2013) We investigated the optical emission features of plasmas produced

Harilal, S. S.

375

Verification of a XeCl* laser model by measurement of the plasma conductivity  

Science Journals Connector (OSTI)

Measurements of current, voltage, and laser emission of an X-ray preionized selfsustained XeCl* laser discharge using Ne:Xe:HCl gas mixtures are compared with predictions of spatially homogeneous model calculatio...

G. Stielow; Th. Hammer; W. Btticher

1988-12-01T23:59:59.000Z

376

Spectrum and conversion efficiency measurements of suprathermal electrons from relativistic laser plasma interactions  

E-Print Network (OSTI)

Fast Ignition is an alternative scheme for Inertial Confinement Fusion (ICF) that uses a petawatt laser to ignite a hot spot in precompressed fuel. The laser delivers its energy into relativistic electrons at the critical ...

Chen, Cliff D. (Cliff Ding Yu)

2009-01-01T23:59:59.000Z

377

Stark-tuned, far-infrared laser for high-frequency plasma diagnostics  

Science Journals Connector (OSTI)

A Stark-tuned optically pumped far-infrared CH3OH laser operating at 119 ?m has been built. The laser is designed to operate at high power while exhibiting a well-separated...

Mansfield, D K; Krug, Peter A; Vocaturo, M; Guttadora, L; Rockmore, M; Micai, K

1992-01-01T23:59:59.000Z

378

Cushman & Wakefield Environmental Challenge | ENERGY STAR Buildings &  

NLE Websites -- All DOE Office Websites (Extended Search)

Cushman & Wakefield Environmental Challenge Cushman & Wakefield Environmental Challenge Secondary menu About us Press room Contact Us Portfolio Manager Login Facility owners and managers Existing buildings Commercial new construction Industrial energy management Small business Service providers Service and product providers Verify applications for ENERGY STAR certification Design commercial buildings Energy efficiency program administrators Commercial and industrial program sponsors Associations State and local governments Federal agencies Tools and resources Training In this section How can we help you? Build an energy program Improve building and plant performance Earn the ENERGY STAR and other recognition Benchmark energy use ENERGY STAR in action Communicate and educate ENERGY STAR communications toolkit Bring Your Green to Work with ENERGY STAR

379

Transverse wakefields due to asymmetric protrusions into a vacuum chamber  

Science Journals Connector (OSTI)

Abstract We analyze the effect of a wakefield caused by an asymmetric protrusion inside the accelerator vacuum chamber. The asymmetry leads to a transverse kick on the beam and an increase of the projected transverse beam emittance. Calculations are done for a model rectangular protrusion in a vacuum chamber of rectangular cross-section. Based on our analysis, numerical estimates are given for the SuperKEKB accelerator in KEK, Japan, and TLEP-W proposal at CERN.

Gennady Stupakov; Demin Zhou

2014-01-01T23:59:59.000Z

380

Comparison of Laser (LMS), Californium-252 Plasma Desorption (252Cf-PDMS), Fast Atom Bombardment (FAB), Secondary Ion (SIMS), and Field Desorption (FD) Mass Spectra of a Series of Internal Salts  

Science Journals Connector (OSTI)

Comparison of the mass spectral techniques of Laser (LMS), Californium-252 Plasma Desorption (252Cf-PDMS), Secondary Ion (SIMS), Fast Atom Bombardment (FAB), and Field...

Balasanmugam, Kesagapillai; Viswanadham, Somayajula Kasi; Hercules, David M; Cotter, Robert J; Heller, David; Benninghoven, A; Sichtermann, W; Anders, V; Keough, T; Macfarlane, Ronald D; McNeal, Catherine J

1987-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "laser plasma wakefield" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Stimulated Raman scattering of beat wave of two counter-propagating X-mode lasers in a magnetized plasma  

SciTech Connect

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.

Verma, Kanika; Sajal, Vivek, E-mail: vsajal@rediffmail.com; Varshney, Prateek; Kumar, Ravindra; Sharma, Navneet K. [Department of Physics and Materials Science and Engineering, Jaypee Institute of Information Technology, Noida 201307, UP (India)] [Department of Physics and Materials Science and Engineering, Jaypee Institute of Information Technology, Noida 201307, UP (India)

2014-02-15T23:59:59.000Z

382

Optimization of extreme ultraviolet photons emission and collection in mass-limited laser produced plasmas for lithography application  

SciTech Connect

The progress in development of commercial system for next generation EUV lithography requires, among other factors, significant improvement in EUV photon sources such as discharge produced plasma (DPP) and laser produced plasma (LPP) devices. There are still many uncertainties in determining the optimum device since there are many parameters for the suitable and efficient energy source and target configuration and size. Complex devices with trigger lasers in DPP or with pre-pulsing in LPP provide wide area for optimization in regards to conversion efficiency (CE) and components lifetime. We considered in our analysis a promising LPP source configuration using 10-30 {mu}m tin droplet targets, and predicted conditions for the most efficient EUV radiation output and collection as well as calculating photons source location and size. We optimized several parameters of dual-beam lasers and their relationship to target size. We used our HEIGHTS comprehensive and integrated full 3D simulation package to study and optimize LPP processes with various target sizes to maximize the CE of the system.

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

2012-08-01T23:59:59.000Z

383

Outline History Basic Theory Research Future Accelerators References Brief Overview of Wakefield  

E-Print Network (OSTI)

Outline History Basic Theory Research Future Accelerators References Brief Overview of Wakefield Acceleration Eugene S. Evans1 November 9, 2010 1 University of California, Berkeley Eugene S. Evans Brief Overview of Wakefield Acceleration #12;Outline History Basic Theory Research Future Accelerators References

Budker, Dmitry

384

Vlasov simulations of kinetic enhancement of Raman backscatter in laser fusion plasmas  

E-Print Network (OSTI)

Stimulated Raman scattering (SRS) is studied in plasmas relevant to inertial confinement fusion (ICF). The Eulerian Vlasov-Maxwell code ELVIS was developed and run for this purpose. Plasma waves are heavily Landau damped ...

Strozzi, D. J. (David J.)

2006-01-01T23:59:59.000Z

385

Bow shocks formed by plasma collisions in laser irradiated semi-cylindrical cavities  

E-Print Network (OSTI)

the axis to form a dense bright plasma focus. Later in time a long lasting bow shock is observed to develop a location near the cavity axis, where it collides forming a bright high density plasma focus

Rocca, Jorge J.

386

Study of 18 keV K-? x-ray emission from high intensity femtosecond laser produced plasma  

SciTech Connect

We report an experimental study on the optimization of a laser plasma based x-ray source of ultra-short duration K-? line radiation. The interaction of pulses from a CPA based Ti:sapphire laser (10 TW, 45 fs, 10 Hz) system with magnesium, titanium, iron and copper solid target generates bright 1-8 keV K-? x-ray radiation. The x-ray yield was optimized with the laser pulse duration (at fixed fluence) which is varied in the range of 45 fs to 1.4 ps. It showed a maximum at laser pulse duration of ?740 fs, 420 fs, 350 and 250 fs for Mg (1.3 keV), Ti (4.5 keV), Fe (6.4 keV) and Cu (8.05 keV) respectively. The x-ray yield is observed to be independent of the sign of the chirp. The scaling of the K-? yield (I{sub x} ? I{sub L}{sup ?}) for 45 fs and optimized pulse duration were measured for laser intensities in the region of 3 10{sup 14} 8 10{sup 17}. The x-ray yield shows a much faster scaling exponent ? = 1.5, 2.1, 2.4 and 2.6 for Mg, Ti, Fe and Cu respectively at optimized pulse duration compared to scaling exponent of 0.65, 1.3, 1.5, and 1.7 obtained for 45 fs duration laser pulses. The laser to x-ray energy conversion efficiencies obtained for different target materials are ?{sub Mg} = 1.2 10{sup ?5}, ?{sub Ti} = 3.1 10{sup ?5}, ?{sub Fe} = 2.7 10{sup ?5}, ?{sub Cu} = 1.9 10{sup ?5}. The results have been explained from the efficient generation of optimal energy hot electrons at longer laser pulse duration. The faster scaling observed at optimal pulse duration indicates that the x-ray source is generated at the target surface and saturation of x-ray emission would appear at larger laser fluence. An example of utilization of the source for measurement of shock-wave profiles in a silicon crystal by time resolved x-ray diffraction is also presented.

Arora, V., E-mail: arora@rrcat.gov.in; Naik, P. A.; Chakera, J. A.; Bagchi, S.; Tayyab, M.; Gupta, P. D. [Laser Plasma Division, Raja Rammana Centre for Advanced Technology, Indore 452 013 (India)] [Laser Plasma Division, Raja Rammana Centre for Advanced Technology, Indore 452 013 (India)

2014-04-15T23:59:59.000Z

387

Formation of laser plasma channels in a stationary gas A. Dunaevsky  

E-Print Network (OSTI)

a high-current arc discharge leads to overdense plasma near the front pinhole and further refraction-current glow discharge initiated in the chamber improves the uniformity of the plasma channel slightly, while fluctuation of the plasma density is nez ne a0 p , 1 where a0=eE/mc is normalized electric field in the beam

388

DD nuclear fusion induced by laser-generated plasma at 1016Wcm?2 intensity  

Science Journals Connector (OSTI)

Deuterated polyethylene targets (CD2-monomer), as thin and thick films, were laser irradiated in a vacuum at 1016Wcm?2 intensity. The produced plasma was monitored in situ using the Thomson parabola spectrometer, ion collectors and SiC semiconductor detectors. For thin targets irradiated under target-normal-sheath-acceleration conditions, laser accelerated deuterons with energies higher than 3.0MeV were measured along the normal to the target surface. Characteristic emissions at 3.0 and 2.5MeV for protons and neutrons, respectively, have been detected confirming the production of nuclear fusion events. The evidence of nuclear fusion effects was evaluated and discussed.

Lorenzo Torrisi; Salvatore Cavallaro; Maria Cutroneo; Josef Krasa; Daniel Klir

2014-01-01T23:59:59.000Z

389

Generation of very high-frequency waves by up-conversion in a plasma-loaded free-electron laser  

Science Journals Connector (OSTI)

A free-electron laser loaded with a plasma is able to resonate at two different frequencies. The two waves are copropagating, one with positive slippage while the other has negative slippage. We deduce the nonlinear partial differential equations describing the interaction between the two waves in the slowly-varying-envelope approximation. By injecting a signal at the low frequency, a strong signal is produced at the harmonically related high frequency, with a lethargy time much smaller than that of the spontaneous vacuum emission. This effect could be applied in the generation of very short wavelength radiation, up to the range of hard x rays.

V. Petrillo and C. Maroli

2000-12-01T23:59:59.000Z

390

High-energy x-ray microscopy of laser-fusion plasmas at the National Ignition Facility  

SciTech Connect

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.

Koch, J.A.; Landen, O.L.; Hammel, B.A. [and others

1997-08-26T23:59:59.000Z

391

Femtosecond electron and x-ray generation by laser and plasma-based sources  

E-Print Network (OSTI)

Although conventional electron sources (photocathode orof these conventional electron sources. Novel schemes which11, 2000 These laser-electron beam sources o?er some unique

Esarey, E.; Leemans, W.P.

2000-01-01T23:59:59.000Z

392

Influence of magnetic field on laser-produced barium plasmas: Spectral and dynamic behaviour of neutral and ionic species  

SciTech Connect

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{sup ?5?}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{sup 2}. 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.

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)

2014-10-21T23:59:59.000Z

393

Extreme ultraviolet spectroscopy and modeling of Cu on the SSPX Spheromak and laser plasma Sparkya)  

Science Journals Connector (OSTI)

Impurities play a critical role in magnetic fusion research. In large quantities impurities can cool and dilute plasma creating problems for achieving ignition and burn; however in smaller amounts the impurities could provide valuable information about several plasma parameters through the use of spectroscopy. Many impurity ions radiate within the extreme ultraviolet(EUV) range. Here we report on spectra from the silver flat field spectrometer which was implemented at the Sustained Spheromak Physics experiment (SSPX) to monitor ion impurity emissions. The chamber within the SSPX was made of Cu which makes M-shell Cu a prominent impurity signature. The Spect3D spectral analysis code was utilized to identify spectral features in the range of 115315 and to more fully understand the plasma conditions. A second set of experiments was carried out on the compact laser-plasma x-ray/EUV facility Sparky at UNR with Cu flat targets used. The EUVspectra were recorded between 40300 and compared with results from SSPX.

M. E. Weller; A. S. Safronova; J. Clementson; V. L. Kantsyrev; U. I. Safronova; P. Beiersdorfer; E. E. Petkov; P. G. Wilcox; G. C. Osborne

2012-01-01T23:59:59.000Z

394

Submillimeter-resolution radiography of shielded structures with laser-accelerated electron beams  

E-Print Network (OSTI)

Submillimeter-resolution radiography of shielded structures with laser-accelerated electron beams (Received 24 March 2010; published 14 October 2010) We investigate the use of energetic electron beams beam (with energy >100 MeV) was generated by the process of laser-wakefield acceleration through

Umstadter, Donald

395

Photocathode Studies at the Argonne Wakefield Accelerator  

NLE Websites -- All DOE Office Websites (Extended Search)

Quantum Quantum Efficiency Photocathodes for the AWA High Energy Physics Division, ANL Zikri Yusof, Manoel Conde, Felipe Franchini Matt Virgo DOE Review April 26-27 2007 Energy Systems Division, ANL 2 PHOTOCATHODE REQUIREMENT FOR BUNCH TRAIN For the near future, creation of charge bunch train of 16 bunches in a single RF pulse 50 nC 16 micro pulses 5 eV Laser 10 mJ Want 50 nC in each charge microbunch. This is equal to ~ 3×10 11 electrons. * 10 mJ of laser energy per pulse; * Estimate 80% loss due to beam splitter, mirrors, etc.; * Beam is split into 16 micro pulses; * Number of photons in each micro pulse is ~1.5×10 14 . QE of photocathode to be able to supply that amount of charge: % 2 . 0 10 2 10 5 . 1 10 3 3 14 11 = × ≈ × × = - QE Need high QE photocathode - choose Cs 2 Te 770 ps 3 Cs 2 Te RECIPE

396

3-D particle-in-cell simulations for quasi-phase matched direct laser electron acceleration in density-modulated plasma waveguides  

E-Print Network (OSTI)

Quasi-phase matched direct laser acceleration (DLA) of electrons can be realized with guided, radially polarized laser pulses in density-modulated plasma waveguides. A 3-D particle-in-cell model has been developed to describe the interactions among the laser field, injected electrons, and the background plasma in the DLA process. Simulations have been conducted to study the scheme in which seed electron bunches with moderate energies are injected into a plasma waveguide and the DLA is performed by use of relatively low-power (0.5-2 TW) laser pulses. Selected bunch injection delays with respect to the laser pulse, bunch lengths, and bunch transverse sizes have been studied in a series of simulations of DLA in a plasma waveguide. The results show that the injection delay is important for controlling the final transverse properties of short electron bunches, but it also affects the final energy gain. With a long injected bunch length, the enhanced ion-focusing force helps to collimate the electrons and a relativ...

Lin, M -W; Chen, S -H; Jovanovic, I

2014-01-01T23:59:59.000Z

397

Calibration of laser ablation inductively coupled plasma mass spectrometry using dried solution aerosols for the quantitative analysis of solid samples  

SciTech Connect

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.

Leach, J.

1999-02-12T23:59:59.000Z

398

Coulomb driven energy boost of heavy ions for laser plasma acceleration  

E-Print Network (OSTI)

An unprecedented increase of kinetic energy of laser accelerated heavy ions is demonstrated. Ultra thin gold foils have been irradiated by an ultra short laser pulse at an intensity of $6\\times 10^{19}$ W/cm$^{2}$. Highly charged gold ions with kinetic energies up to $> 200$ MeV and a bandwidth limited energy distribution have been reached by using $1.3$ Joule laser energy on target. $1$D and $2$D Particle in Cell simulations show how a spatial dependence on the ions ionization leads to an enhancement of the accelerating electrical field. Our theoretical model considers a varying charge density along the target normal and is capable of explaining the energy boost of highly charged ions, leading to a higher efficiency in laser acceleration of heavy ions.

Braenzel, J; Platonov, K; Klingsporn, M; Ehrentraut, L; Sandner, W; Schnrer, M

2014-01-01T23:59:59.000Z

399

Design Considerations for Plasma Accelerators Driven by Lasers or Particle Beams  

E-Print Network (OSTI)

al. , Phys. Rev. ST Accel. Beams, submitted, (2010). 15. A.D . Kimura, Phys. Rev. ST Accel. Beams 13, 24. C . Jing, A .Driven by Lasers or Particle Beams C . B . Schroeder, E .

Schroeder, C. B.

2011-01-01T23:59:59.000Z

400

Plasma-Density Determination from X-Ray Radiography of Laser-Driven Spherical Implosions  

E-Print Network (OSTI)

The fuel layer density of an imploding laser-driven spherical shell is inferred from framed x-ray radiographs. The density distribution is determined by using Abel inversion to compute the radial distribution of the opacity ...

Frenje, Johan A.

Note: This page contains sample records for the topic "laser plasma wakefield" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
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to obtain the most current and comprehensive results.


401

A vibrationally compensated far infrared laser interferometer for plasma density measurements  

Science Journals Connector (OSTI)

A modulated far-infrared laser interferometer which is presently operating on the PDX experiment at Princeton is described. The interferometer geometry permits the characterization of inside D, outside D a...

D. K. Mansfield; L. C. Johnson

1980-12-01T23:59:59.000Z

402

Investigation of focusing of relativistic electron and positron bunches moving in cold plasma. Final report  

SciTech Connect

This document is the final report on a project to study focusing effects of relativistic beams of electrons and positrons interacting with a cold plasma. The authors consider three different models for the overdense cold plasma - electron bunch interaction. They look at coulomb effects, wakefield effects, bunch parameters, and the effects of trains of pulses on focusing properties.

Amatuni, A.Ts.; Elbakian, S.S.; Khachatryan, A.G.; Sekhpossian, E.V.

1995-03-01T23:59:59.000Z

403

Absorption, Double Layers, and Dynamics at Laser-Plasma Interaction and Pellet Fusion Gains With Reheat  

Science Journals Connector (OSTI)

Absorption by Coulomb collisions has been studied comparing the classical low frequency limit, the QED result and the anomalous resistivity case. A derivation of the two-fluid plasma equations for HF monochromati...

L. Cicchitelli; R. Dragila; K. I. Golden

1984-01-01T23:59:59.000Z

404

Instability Versus Equilibrium Propagation of a Laser Beam in Plasma Pavel M. Lushnikov1,2  

E-Print Network (OSTI)

) at the National Ignition Facility (NIF) [1]. NIF's plasma environment, in the indirect drive approach to ICF, has that of actual experiments, as in the idealized ``top hat'' model of NIF optics: j ^EEkj const; k

Lushnikov, Pavel

405

Ultrafast Electron Dynamics in Gold in the Presence of Laser Excited Surface Plasma Waves  

SciTech Connect

Surface plasmon excitation with ultrashort intense laser pulses enhances efficiently laser absorption in metals and creates local high fields and non-equilibrium hot electrons population that have attractivity for numerous applications such as the development of intense sources of high-energy particles or photons and in the fast ignitor scheme in the framework of inertial fusion. In this context, the knowledge of the dynamics of relaxation of the collective electrons behavior is of importance. Using gold grating, we have investigated electrons relaxation in the presence of laser excited surface plasmon waves using a multiple-wavelengh femtosecond pump-probe technique. The results yield evidence of longer relaxation time in the presence of the collective excitation than that of individual electronic states.

Raynaud, M. [CEA/DSM/IRAMIS/LSI, Ecole Polytechnique, 91128 Palaiseau (France); Geoffroy, G.; Perdrix, M. [CEA/DSM/IRAMIS/SPAM, 91191 Gif-sur-Yvette (France); Martin, P. [CELIA, Universite Bordeaux 1-CEA-CNRS, 33405 Talence (France)

2010-02-02T23:59:59.000Z

406

E-Print Network 3.0 - accelerator system accelerator Sample Search...  

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and Fusion Center, High-Energy-Density Physics Group Collection: Plasma Physics and Fusion ; Physics 80 Visual Exploration of Turbulent Combustion and Laser-Wakefield...

407

E-Print Network 3.0 - acceleration foran electron Sample Search...  

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Physics and Fusion ; Physics 10 The Application of Radiation and Particle Beams from Laser Plasma Wakefield Accelerators to Oncology Summary: to recent improvements in...

408

E-Print Network 3.0 - accelerator applications university Sample...  

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university Page: << < 1 2 3 4 5 > >> 1 The Application of Radiation and Particle Beams from Laser Plasma Wakefield Accelerators to Oncology Summary: The Application of...

409

Observation of Stimulated Raman Scattering from 20-psec Laser-Produced Plasmas  

Science Journals Connector (OSTI)

Raman scattering spectra obtained with 20-psec 1.064-?m laser pulses incident at 45 on nickel-foil targets show an intensity-dependent red shift relative to the subharmonic of the laser frequency. In conjunction with temperature data deduced from x-ray measurements, the results imply a change from the absolute to the convective instability with increasing intensity. The observation of Raman scattering is correlated with the appearance of a high-energy tail in the x-ray spectrum above 100 keV.

K. A. Nugent and B. Luther-Davies

1982-12-27T23:59:59.000Z

410

Temperature measurements of fusion plasmas produced by petawatt laser-irradiated D2-3He or CD4-3He clustering gases  

E-Print Network (OSTI)

Two different methods have been employed to determine the plasma temperature in a laser-cluster fusion experiment on the Texas Petawatt laser. In the first, the temperature was derived from time-of-flight data of deuterium ions ejected from exploding D2 or CD4 clusters. In the second, the temperature was measured from the ratio of the rates of two different nuclear fusion reactions occurring in the plasma at the same time: D(d, 3He)n and 3He(d, p)4He. The temperatures determined by these two methods agree well, which indicates that: i) The ion energy distribution is not significantly distorted when ions travel in the disassembling plasma; ii) The kinetic energy of deuterium ions, especially the hottest part responsible for nuclear fusion, is well described by a near-Maxwellian distribution.

Bang, W; Bonasera, A; Dyer, G; Quevedo, H J; Hagel, K; Schmidt, K; Consoli, F; De Angelis, R; Andreoli, P; Gaul, E; Bernstein, A C; Donovan, M; Barbarino, M; Kimura, S; Mazzocco, M; Sura, J; Natowitz, J B; Ditmire, T

2013-01-01T23:59:59.000Z

411

Spectroscopic investigations of hard x-ray emission from 120 ps laser-produced plasmas at intensities near 10{sup 17} W cm{sup {minus}2}  

SciTech Connect

Spectroscopic investigations of the x-ray emission of plasmas heated by 120 ps, frequency doubled pulses from the JANUS Nd: glass laser are presented. High Z K-shell spectra emitted from slab targets heated to near 10{sup 17} W cm{sup {minus}2} intensity are investigated. High resolution ({gamma}/{Delta}{gamma}>5000) x-ray spectra of multicharged ions of H-like Ti, Co, Ni, Cu, and also H-like Sc in the spectral range 1.5--3.0 {angstrom} are obtained in single laser shots using a spherically bent Mica crystal spectrograph with a 186 mm radius of curvature. The spectra- have one dimensional spatial resolution of about 25{mu}m and indicate that the size of the emission zone of the resonance, transitions is <25{mu}m. Simultaneous x-ray images of the plasma from a charge-coupled device pinhole camera confirmed that the plasma x-ray emission is from a similar sized source. Survey spectra {gamma}/{Delta}{gamma}=500--1000) taken with a flat LiF (200) crystal spectrometer with a charge-coupled device detector complement the high resolution data. Two dimensional LASNEX modeling of the laser target conditions indicate that the high K-shell charge states are produced in the hot dense region of the plasma with electron temperature >2 keV and density{approximately}10{sup 22} cm{sup {minus}3}. These experiments demonstrate that with modest laser energy, plasmas heated by high-intensity 120 ps lasers provide a very bright source of hard {approximately}8 keV x-ray emission.

Dunn, J.; Young, B.K.F.; Osterheld, A.L.; Foord, M.E.; Walling, R.S.; Stewart, R.E. [Lawrence Livermore National Lab., CA (United States); Faenov, A.Y. [VINIFTRI, Mendeleevo, Moscow Region (Russian Federation)

1995-11-01T23:59:59.000Z

412

The interaction of polarized microwaves with planar arrays of femtosecond laser-produced plasma filaments in air  

SciTech Connect

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.

Marian, Anca; El Morsli, Mbark; Vidal, Francois; Payeur, Stephane; Kieffer, Jean-Claude [INRS-Energie, Materiaux et Telecommunications, Universite du Quebec, Varennes, Quebec J3X 1S2 (Canada); Chateauneuf, Marc; Theberge, Francis; Dubois, Jacques [Defense R and D Canada Valcartier, Quebec G3J 1X5 (Canada)

2013-02-15T23:59:59.000Z

413

Laser-driven, magnetized quasi-perpendicular collisionless shocks on the Large Plasma Devicea)  

E-Print Network (OSTI)

and Astronomy, University of California - Los Angeles, Los Angeles, California 90095, USA 2 Los Alamos National Plasma Device [Gekelman et al., Rev. Sci. Instrum. 62, 2875 (1991)] at the University of California, Los environments, including supernovae remnants, coronal mass ejections, the solar wind, and iono- spheric

California at Los Angles, University of

414

Nonlinear and Multi-Wave Effects in Fast-Scale Laser-Plasma Interactions  

E-Print Network (OSTI)

shift of the wave and the incoherent energy associated with developing the final, phase-mixed state. These Bernstein-Greene-Kruskal (BGK) type waves naturally arise in weakly driven, thermal plasmas, and extend shift of the wave, in agreement with recent numerical results. Energy conservation is employed

Wurtele, Jonathan

415

Modeling of plasma-controlled evaporation and surface condensation of Al induced by 1.06 and 0.248 {mu}m laser radiations  

SciTech Connect

Phase transition on the surface of an aluminum target and vapor plasma induced by laser irradiation in the nanosecond regime at the wavelengths of 1.06 {mu}m in the infrared range and 0.248 {mu}m in the ultraviolet range with an intensity of 10{sup 8}-10{sup 9} W/cm{sup 2} in vacuum are analyzed. Special attention is paid to the wavelength dependence of the observed phenomena and the non-one-dimensional effects caused by the nonuniform (Gaussian) laser intensity distribution and the lateral expansion of the plasma plume. A transient two-dimensional model is used which includes conductive heat transfer in the condensed phase, radiative gas dynamics, and laser radiation transfer in the plasma as well as surface evaporation and back condensation at the phase interface. It was shown that distinctions in phase transition dynamics for the 1.06 and 0.248 {mu}m radiations result from essentially different characteristics of the laser-induced plasmas. For the 1.06 {mu}m radiation, evaporation stops after the formation of hot optically thick plasma, can occasionally resume at a later stage of the pulse, and proceeds nonuniformly in the spot area, and the major contribution to the mass removal occurs in the outer part of the irradiated region. Plasma induced by the 0.248 {mu}m laser is colder and partially transparent since it transmits 30%-70% of the incident radiation; therefore evaporation does not stop but continues in the subsonic regime with the Mach number of about 0.1. The amount of evaporated matter that condenses back to the surface is as high as 15%-20% and less than 10% for the 1.06 and 0.248 {mu}m radiations, respectively. For a beam radius smaller than {approx}100 {mu}m, the screening and retarding effect of the plasma weakens because of the lateral expansion, thickness of the removed layer increases, and condensation after the end of the pulse is not observed. Comparison of the numerical and experimental results on the removed layer thickness has shown, in particular, the importance of accounting for the plasma effect to predict the correct trends for radiation intensity and beam radius.

Mazhukin, V. I.; Nossov, V. V.; Smurov, I. [Institute of Mathematical Modeling of RAS, 4a Miusskaya Square, 125047 Moscow (Russian Federation); Ecole Nationale d'Ingenieurs de Saint-Etienne, 58 rue Jean Parot, 42023 Saint-Etienne Cedex 2 (France)

2007-01-15T23:59:59.000Z

416

Comment on Observation of neutronless fusion reactions in picosecond laser plasmas  

Science Journals Connector (OSTI)

The paper by Belyaev et al. [Phys. Rev. E 72, 026406 (2005)] reported the first experimental observation of alpha particles produced in the thermonuclear reaction B11(p,?)B8e induced by laser irradiation on a B11 polyethylene (CH2) composite target. The laser used in the experiment is characterized by a picosecond pulse duration and a peak of intensity of 21018?W/cm2. We suggest that both the background-reduction method adopted in their detection system and the choice of the detection energy region of the reaction products are possibly inadequate. Consequently the total yield reported underestimates the true yield. Based on their observation, we give an estimation of the total yield to be higher than their conclusion, i.e., of the order of 105? per shot.

S. Kimura; A. Anzalone; A. Bonasera

2009-03-26T23:59:59.000Z

417

Cushman & Wakefields Client Solutions Group presents:  

NLE Websites -- All DOE Office Websites (Extended Search)

OCTOBER 2009 OCTOBER 2009 Updated January 2010 A CALL TO ACTION TO IMPROVE THE ENVIRONMENTAL EFFICIENCY OF CUSHMAN &WAKEFIELD'S MANAGED PROPERTIES Take the C&W Environmental Challenge and help us find out: * Who can quantify improvements in environmental performance over time? * Who can take environmental performance to the next level? * Which buildings are the highest performers across C&W managed portfolio? WHAT IS THE C&W ENVIRONMENTAL CHALLENGE? WHY PARTICIPATE? IMPROVE YOUR BOTTOM LINE: Increased energy and water efficiency, and reduced waste in commercial real estate can reduce operating expenses and increase property asset value. DO YOUR PART TO ADDRESS CLIMATE CHANGE: Commercial buildings generate about 17% of total greenhouse gas emissions.

418

Tunable Radiation Source by Coupling Laser-Plasma-Generated Electrons to a Periodic Structure  

SciTech Connect

Near-infrared radiation around 1000 nm generated from the interaction of a high-density MeV electron beam, obtained by impinging an intense ultrashort laser pulse on a solid target, with a metal grating is observed experimentally. Theoretical modeling and particle-in-cell simulation suggest that the radiation is caused by the Smith-Purcell mechanism. The results here indicate that tunable terahertz radiation with tens GV/m field strength can be achieved by using appropriate grating parameters.

Jin, Z. [Photon Pioneers Center, Osaka University, 2-1 Yamada-oka, Suita, Osaka, 565-0871 (Japan); Chen, Z. L.; Kon, A.; Nakatsutsumi, M. [Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka, 565-0871 (Japan); Zhuo, H. B. [Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka, 565-0871 (Japan); School of Science, National University of Defense Technology, Changsha 410073 (China); Wang, H. B.; Zhang, B. H.; Gu, Y. Q.; Wu, Y. C.; Zhu, B.; Wang, L. [National Key Laboratory of Laser Fusion, CAEP, Mianyang 621900 (China); Yu, M. Y. [Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China); Institute for Theoretical Physics I, Ruhr University, Bochum D-44780 (Germany); Sheng, Z. M. [Key Laboratory for Laser Plasmas (Ministry of Education) and Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China); Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, CAS, Beijing 100080 (China); Kodama, R. [Photon Pioneers Center, Osaka University, 2-1 Yamada-oka, Suita, Osaka, 565-0871 (Japan); Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka, 565-0871 (Japan); Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka, 565-0871 (Japan)

2011-12-23T23:59:59.000Z

419

Relativistic self-focusing of ultra-high intensity X-ray laser beams in warm quantum plasma with upward density profile  

SciTech Connect

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.

Habibi, M., E-mail: habibi.physics@gmail.com [Young Researchers and Elite Club, Shirvan Branch, Islamic Azad University, Shirvan (Iran, Islamic Republic of); Ghamari, F. [Young Researchers and Elite Club, Khorramabad Branch, Islamic Azad University, Khorramabad (Iran, Islamic Republic of)

2014-05-15T23:59:59.000Z

420

Influence of prepulse plasma formation on neutron production from the laser-target interaction  

SciTech Connect

The interaction of an intense ultrashort pulse laser with a planar uniform target was studied with a two-dimensional relativistic electromagnetic particle-in-cell method to determine the acceleration of deuterons and production of neutrons. A Au-CD{sub 2} double-layer planar target with thickness of {approx}1 {mu}m and a preplasma of variable length was used to generate high-energy deuterons as a precursor for neutron production. The deuteron energy and angular distributions and the neutron production from D(d,n)-{sup 3}He nuclear fusion reactions were studied as a function of the preplasma scale length and target thickness. For very thin (submicron) targets the preplasma increases the neutron yield only marginally, but for realistic targets with thickness of a few microns the preplasma enhances the neutron yield by two orders of magnitude. Both the average deuteron energy and neutron yield peak at an optimum preplasma scale length L{sub p}{sup opt}{approx_equal}1/k{sub 0} (k{sub 0} laser wave vector), which is of the order of one inverse laser wave vector.

Davis, J.; Petrov, G. M. [Naval Research Laboratory, Plasma Physics Division, 4555 Overlook Avenue SW, Washington, DC 20375 (United States)

2008-08-15T23:59:59.000Z

Note: This page contains sample records for the topic "laser plasma wakefield" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

Ionization-induced blue shift of KrF laser pulses in an underdense plasma  

Science Journals Connector (OSTI)

The ionization-induced blue-shifted spectra for helium, neon, and nitrogen have been measured at various gas densities up to 51020 cm-3 at a vacuum intensity of 81016 W/cm2 for picosecond KrF laser pulses at 248 nm. A 1-mm diameter gas jet target was used in the experiment to minimize the refraction of the laser beam and thus higher laser intensities were obtained in the gas than in previously reported experiments. For helium, a distinct shifted peak was observed at intermediate densities which was not seen before. For helium and nitrogen, spectra were also measured of the light scattered outside of the original focal cone angle. In this region there was little signal for electron densities below 21020 cm-3 consistent with limited refraction at lower densities and at higher densities the spectra were predominantly blue shifted. These results indicate the importance of refraction in the correct interpretation of ionization blue-shifted spectra. 1996 The American Physical Society.

Y. M. Li and R. Fedosejevs

1996-08-01T23:59:59.000Z

422

Power law decay of harmonic spectra in ultrarelativistic laser-plasma interactions  

SciTech Connect

Particle-in-cell simulations have been used to explore the transition from the m{sup -8/3} decay in the power emitted by high harmonics to a regime for which the harmonic power P{sub m{approx}}m{sup -p}, where m denotes the harmonic number and p=5/3 or, less commonly, p=4/3. The deviation from the p=8/3 spectrum is interpreted as a consequence of the degree to which emission at the plasma frequency and its harmonics contribute to the spectrum. The research reported here explores conditions under which these deviations arise.

Boyd, T. J. M. [Centre for Theoretical Physics, University of Essex, Colchester CO4 3SQ (United Kingdom); Ondarza-Rovira, R. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, Mexico 11801, Distrito Federal (Mexico)

2010-08-15T23:59:59.000Z

423

Comment on 'Stimulated Raman scattering of laser from periodically spaced nanoparticles' [Phys. Plasmas 16, 093106 (2009)  

SciTech Connect

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.

Maraghechi, B. [Department of Physics, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran (Iran, Islamic Republic of); Chakhmachi, A. [Plasma Physics and Nuclear Fusion Research School, Nuclear Science and Technology Research Institute, Atomic Energy Organization of Iran, P.O. Box 14155-1339, Tehran (Iran, Islamic Republic of)

2010-08-15T23:59:59.000Z

424

Tunable THz Generation by the Interaction of a Super-luminous Laser Pulse with Biased Semiconductor Plasma  

SciTech Connect

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 interaction results in the emission of an electromagnetic wave at the plasma frequency of the ionization front. The device resembles the well-known DARC plasma device with two significant differences. First, the frozen wave is on a semiconductor crystal and not on a gas (Azulene Vapor). Second, the ionizing front is super-luminous. These differences result in a device with superior tunability, efficiency, compactness and flexibility. The paper concludes with examples of THz imaging using the MPCA.

Papadopoulos, K. [BAE Systems-ATI, University of Maryland, College Park MD 20742 (United States); Zigler, A. [BAE Systems-ATI, Hebrew University (Israel)

2006-01-03T23:59:59.000Z

425

Low-energy x-ray and electron physics and applications to diagnostics development for laser-produced plasma research. Final report, April 30, 1980-April 29, 1981  

SciTech Connect

This final report describes a collaborative extension of an ongoing research program in low-energy x-ray and electron physics into particular areas of immediate need for the diagnostics of plasmas as involved in laser-produced fusion research. It has been for the continued support for one year of a post-doctoral research associate and for three student research assistants who have been applied to the following specific efforts: (1) the continuation of our research on the absolute characterization of x-ray photocathode systems for the 0.1 to 10 keV photon energy region. The research results were applied collaboratively to the design, construction and calibration of photocathodes for time-resolved detection with the XRD and the streak and framing cameras; (2) the design, construction and absolute calibration of optimized, bolt-on spectrographs for the absolute measurement of laser-produced plasma spectra.

Henke, B.L.

1981-08-01T23:59:59.000Z

426

High-resolution measurements of the spatial and temporal evolution of megagauss magnetic fields created in intense short-pulse laser-plasma interactions  

SciTech Connect

A pump-probe polarimetric technique is demonstrated, which provides a complete, temporally and spatially resolved mapping of the megagauss magnetic fields generated in intense short-pulse laser-plasma interactions. A normally incident time-delayed probe pulse reflected from its critical surface undergoes a change in its ellipticity according to the magneto-optic Cotton-Mouton effect due to the azimuthal nature of the ambient self-generated megagauss magnetic fields. The temporal resolution of the magnetic field mapping is typically of the order of the pulsewidth, limited by the laser intensity contrast, whereas a spatial resolution of a few ?m is achieved by this optical technique. High-harmonics of the probe can be employed to penetrate deeper into the plasma to even near-solid densities. The spatial and temporal evolution of the megagauss magnetic fields at the target front as well as at the target rear are presented. The ?m-scale resolution of the magnetic field mapping provides valuable information on the filamentary instabilities at the target front, whereas probing the target rear mirrors the highly complex fast electron transport in intense laser-plasma interactions.

Chatterjee, Gourab, E-mail: gourab@tifr.res.in; Singh, Prashant Kumar; Adak, Amitava; Lad, Amit D.; Kumar, G. Ravindra, E-mail: grk@tifr.res.in [Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai 400 005 (India)

2014-01-15T23:59:59.000Z

427

Pre-annealing effects of n+/p and p+/n junction formed by plasma doping (PLAD) and laser annealing  

SciTech Connect

In this paper, we demonstrated ultra-shallow junction formed by plasma doping (PLAD) and laser annealing. PLAD may be considered as an alternative doping method for the sub 45 technology node due to the possibility of low energy doping and high throughput. However, PLAD has various problems due to the incorporated hydrogen or fluorine. Incorporated hydrogen generally increases damage in the Si substrate and junction depth. Incorporated fluorine also retards dopant activation and increases deactivation behavior after post-annealing. In order to improve the effect of incorporated ions, we applied pre-annealing prior to laser annealing in PLAD samples. By employing low temperature pre-annealing, we can improve electrical characteristics such as low sheet resistance and high activation rates, and also reduce the junction depth after laser annealing.

Heo, Sungho; Baek, Sungkweon; Lee, Dongkyu; Hasan, Musarrat; Hwang, Hyunsang [Department of Materials Science and Engineering, Gwangju Institute of Science and Technology, no. 1, Oryong-dong, Buk-gu, Gwangju, 500-712 (Korea, Republic of)

2006-11-13T23:59:59.000Z

428

Deposition of yttria-stabilized zirconia thermal barrier coatings by laser-assisted plasma coating at atmospheric pressure.  

E-Print Network (OSTI)

??This thesis details the design and construction of a microwave generation system, and a coaxial cylindrical plasma torch, where an atmospheric-pressure plasma (APP) can be (more)

Ouyang, Zihao

2011-01-01T23:59:59.000Z

429

Effects of initially energetic electrons on relativistic laser-driven electron plasma waves  

SciTech Connect

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.

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)

2014-02-15T23:59:59.000Z

430

Relative phase interactions of two copropagating laser beams in underdense plasmas at different intensities and spot sizes  

SciTech Connect

The mutual interactions of two copropagating laser beams at a relative phase are studied using a two-dimensional fluid code. The interactions are investigated in underdense plasma at selected beam configurations and beam parameters for two separate nonlinearities, i.e., the ponderomotive and the relativistic nonlinearity. The selected beam configurations are introduced by different initial transverse spot size perturbations (finite and infinite) and different initial transversal intensity distributions (nonuniform and uniform) over those spot sizes and the selected beam parameters are given by different initial beam intensities relevant to each nonlinearity. In the ponderomotive nonlinearity, simulation results show that no mutual interactions are demonstrated between the copropagating beams regardless of the initial beam configurations and parameters. In nonlinear relativistic simulations, the mutual interactions between the beams are clearly observed, a mutual repulsion is formed in the presence of initial intensities that are nonuniformly distributed over finite spot sizes, and an effective strongly modulated mutual attraction takes places in the presence of initial intensities that are uniformly distributed over infinite spot sizes. Moreover, it is found in these simulations that increasing the initial beam intensities improves the attraction properties between the copropagationg beams.

Mahdy, A. I. [Department of Plasma and Nuclear Fusion, Nuclear Research Centre, Atomic Energy Authority, 13759 Cairo (Egypt)

2010-06-15T23:59:59.000Z

431

Production of extended plasma channels in atmospheric air by amplitude-modulated UV radiation of GARPUN-MTW Ti : sapphire-KrF laser. Part 2. Accumulation of plasma electrons and electric discharge control  

SciTech Connect

The problem of the production of extended ({approx}1 m) plasma channels is studied in atmospheric air by amplitude-modulated laser pulses of UV radiation, which are a superposition of a subpicosecond USP train amplified in a regenerative KrF amplifier with an unstable confocal resonator and a quasi-stationary lasing pulse. The USPs possess a high (0.2-0.3 TW) peak power and efficiently ionise oxygen molecules due to multiphoton ionisation, and the quasi-stationary lasing pulse, which has a relatively long duration ({approx}100 ns), maintains the electron density at a level n{sub e} = (3-5) Multiplication-Sign 10{sup 14} cm{sup -3} by suppressing electron attachment to oxygen. Experiments in laser triggering of high-voltage electric discharges suggest that the use of combined pulses results in a significant lowering of the breakdown threshold and enables controlling the discharge trajectory with a higher efficiency in comparison with smooth pulses. It was shown that controlled breakdowns may develop with a delay of tens of microseconds relative to the laser pulse, which is many orders of magnitude greater than the lifetime of free electrons in the laser-induced plasma. We propose a mechanism for this breakdown, which involves speeding-up of the avalanche ionisation of the air by negative molecular oxygen ions with a low electron binding energy ({approx}0.5 eV) and a long lifetime ({approx}1 ms), which are produced upon cessation of the laser pulse. (extreme light fields and their applications)

Zvorykin, V D; Ionin, Andrei A; Levchenko, A O; Mesyats, Gennadii A; Seleznev, L V; Sinitsyn, D V; Smetanin, Igor V; Sunchugasheva, E S; Ustinovskii, N N; Shutov, A V [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2013-04-30T23:59:59.000Z

432

2012 SG Peer Review - Day 2 Panel Discussion: Matt Wakefield, EPRI  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Matt Wakefield Matt Wakefield Senior Program Manager, Smart Grid June 7, 2012 Overview & Industry Coordination of EPRI IntelliGrid & Security Research & Smart Grid Demonstrations 2 © 2012 Electric Power Research Institute, Inc. All rights reserved. IntelliGrid Program Information & Communication Technologies (ICT) to Enable..... The IntelliGrid Program conducts research, development and demonstrations on the Information and Communications Technologies (ICT) that Enable Smart Grid applications IntelliGrid * Transmission * Distribution * End-Use (AMI/DR) 3 © 2012 Electric Power Research Institute, Inc. All rights reserved. * Reliability and performance characteristics the various technology

433

Molecular Dynamics for Low Temperature Plasma-Surface Interaction David B. Graves a)  

E-Print Network (OSTI)

considerable problems as well. Controlled nuclear fusion devices employing highly energetic, hot, magnetized, plasma lamps, plasma lasers, and many other applications of plasmas, are often challenged by plasma

Boyer, Edmond

434

Nonlinear plasma wave in magnetized plasmas  

SciTech Connect

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.

Bulanov, Sergei V. [Kansai Photon Science Institute, JAEA, Kizugawa, Kyoto 619-0215 (Japan) [Kansai Photon Science Institute, JAEA, Kizugawa, Kyoto 619-0215 (Japan); Prokhorov Institute of General Physics, Russian Academy of Sciences, Moscow 119991 (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny, Moscow region 141700 (Russian Federation); Esirkepov, Timur Zh.; Kando, Masaki; Koga, James K. [Kansai Photon Science Institute, JAEA, Kizugawa, Kyoto 619-0215 (Japan)] [Kansai Photon Science Institute, JAEA, Kizugawa, Kyoto 619-0215 (Japan); Hosokai, Tomonao; Zhidkov, Alexei G. [Photon Pioneers Center, Osaka University, 2-8 Yamadaoka, Suita, Osaka 565-0871 (Japan) [Photon Pioneers Center, Osaka University, 2-8 Yamadaoka, Suita, Osaka 565-0871 (Japan); Japan Science and Technology Agency, CREST, 2-1, Yamadaoka, Suita, Osaka 565-0871 (Japan); Kodama, Ryosuke [Photon Pioneers Center, Osaka University, 2-8 Yamadaoka, Suita, Osaka 565-0871 (Japan) [Photon Pioneers Center, Osaka University, 2-8 Yamadaoka, Suita, Osaka 565-0871 (Japan); Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)

2013-08-15T23:59:59.000Z

435

Coupling of laser energy into plasma channels D. A. Dimitrov, R. E. Giacone, D. L. Bruhwiler, and R. Busby  

E-Print Network (OSTI)

ramp leads to an actual focus at the top of the ramp due to plasma focusing, resulting in reduced spot

Geddes, Cameron Guy Robinson

436

An improved approach for hydrogen analysis in metal samples using single laser-induced gas plasma and target plasma at helium atmospheric pressure  

Science Journals Connector (OSTI)

We report in this paper the results of an experimental study on hydrogen analysis of solid samples in high pressure helium ambient gas employing the basic scheme of laser induced breakdown spectroscopy (LIBS)....

S.N. Abdulmadjid; M.M. Suliyanti; K.H. Kurniawan; T.J. Lie; M. Pardede

2006-01-01T23:59:59.000Z

437

LuaAV: Extensibility and Heterogeneity for Audiovisual Graham WAKEFIELD and Wesley SMITH and Charles ROBERTS  

E-Print Network (OSTI)

LuaAV: Extensibility and Heterogeneity for Audiovisual Computing Graham WAKEFIELD and Wesley SMITH and Charles ROBERTS Media Arts and Technology, University of California Santa Barbara Santa Barbara, CA 93110 providing the flexibility and temporal accuracy demanded by interactive audio-visual media. Code generation

California at Santa Barbara, University of

438

Figure 1: Artificially colored image of the plasma produced with a cylindrical lens. The laser travels in the Z-  

E-Print Network (OSTI)

-dimension to form a long focus. Progress on Plasma Lens Experiments at the Final Focus Test Beam* P. Kwok2, P. Chen of the supersonic gas jet as the plasma source, and study on focused beam size measurement techniques. Most demonstrate plasma focusing in a setting close to the true high energy collider with negligible induced

McDonald, Kirk

439

Betatron radiation based measurement of the electron-beam size in a wakefield accelerator  

SciTech Connect

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.

Schnell, Michael; Saevert, Alexander; Reuter, Maria [Institut fuer Optik und Quantenelektronik, Friedrich- Schiller- Universitaet, Jena (Germany); and others

2012-07-09T23:59:59.000Z

440

Laser research shows promise for cancer treatment  

NLE Websites -- All DOE Office Websites (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....

Note: This page contains sample records for the topic "laser plasma wakefield" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Numerical modeling of quasitransient backward Raman amplification of laser pulses in moderately undercritical plasmas with multicharged ions  

SciTech Connect

It was proposed recently that powerful optical laser pulses could be efficiently compressed through backward Raman amplification in ionized low density solids, in spite of strong damping of the resonant Langmuir wave. It was argued that, even for nonsaturated Landau damping of the Langmuir wave, the energy transfer from the pump laser pulse to the amplified seed laser pulse can nevertheless be highly efficient. This work numerically examines such regimes of strong damping, called quasitransient regimes, within the simplest model that takes into account the major effects. The simulations indicate that compression of powerful optical laser pulses in ionized low density solids indeed can be highly efficient.

Balakin, A. A.; Fraiman, G. M. [Institute of Applied Physics RAS, Nizhnii Novgorod 603950 (Russian Federation); Fisch, N. J. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540 (United States); Malkin, V. M. [Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540 (United States); Toroker, Z. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

2011-10-15T23:59:59.000Z

442

Application of the Relativistic Electron Beams Originating in the Discharges of Plasma Focus Type for the Combined Laser-Reb Plasma Heating  

Science Journals Connector (OSTI)

Experimental investigations of the recent years allow to treat the discharge of plasma-focus-type (DPF) as an inductive storage ... energy (concentrated in the magnetic field near focus) converts into the electro...

V. A. Gribkov

1976-01-01T23:59:59.000Z

443

Direct photo-etching of poly(methyl methacrylate) using focused extreme ultraviolet radiation from a table-top laser-induced plasma source  

SciTech Connect

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.

Barkusky, Frank; Peth, Christian; Bayer, Armin; Mann, Klaus [Laser-Laboratorium-Goettingen e.V., Hans-Adolf-Krebs-Weg 1, D-37077 Goettingen (Germany)

2007-06-15T23:59:59.000Z

444

Plasma density gradient injection of low absolute momentum spread electron bunches  

E-Print Network (OSTI)

t to the plasma density indicates the laser focus positionplasma exit. Scanning the jet position relative to the laser focus (

Geddes, C.G.R.

2008-01-01T23:59:59.000Z

445

1134 IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 36, NO. 4, AUGUST 2008 Soft X-Ray Laser Interferometry of Colliding  

E-Print Network (OSTI)

) accelerates plasma toward the axis of the cavity where plasma interactions can range from stagnation received November 30, 2007. This work was supported by the National Nuclear Security Administration under by a vacuum spatial filter, and it was shaped into a 310-m-wide 1.5-mm-FWHM-long line focus by a pair

Rocca, Jorge J.

446

Beat Heating of a Plasma  

Science Journals Connector (OSTI)

If two laser beams have a difference frequency nearly equal to the plasma frequency, nonlinear interaction resonantly excites longitudinal plasma oscillations. These then induce transitions to other transverse modes. Nonlinear damping of the longitudinal mode heats the plasma. The process is optimized by having parallel beams, equal laser intensities, and damping equal to the frequency mismatch.

Bruce I. Cohen; Allan N. Kaufman; Kenneth M. Watson

1972-08-28T23:59:59.000Z

447

Laser-Plasma Coupling with Ignition-Scale Targets: New Regimes and Frontiers on the National Ignition Facility  

Science Journals Connector (OSTI)

It is very exciting that the National Ignition Facility (NIF) is now operational and being used to irradiate ignition-scale hohlraums. As discussed in the last ... Summer School in Physics on the topic of laser-p...

William L. Kruer

2013-01-01T23:59:59.000Z

448

Direct photo-etching of poly(methyl methacrylate) using focused extreme ultraviolet radiation from a table-top laser-induced plasma source  

Science Journals Connector (OSTI)

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 EUVplasma source (pulse energy 3 ? mJ ? at ? ? = 13.5 ? nm plasma diameter ? 300 ? ? m ). By 10 demagnified imaging of the plasma a pulse energy density of ? 75 ? mJ ? cm 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 EUVirradiation. 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 ? ? m diameter which was employed for direct writing of surface structures in PMMA.

Frank Barkusky; Christian Peth; Armin Bayer; Klaus Mann

2007-01-01T23:59:59.000Z

449

Laser-driven fusion  

Science Journals Connector (OSTI)

The use of intense laser light to bring about thermonuclear reactions in a plasma is of considerable current interest. We present detailed analytical and computational studies which show the feasibility of laser-driven fusion. The required laser technology and the presently anticipated practical difficulties are discussed in outline.

Keith A. Brueckner and Siebe Jorna

1974-04-01T23:59:59.000Z

450

A domain decomposition method for pseudo-spectral electromagnetic simulations of plasmas  

SciTech Connect

Pseudo-spectral electromagnetic solvers (i.e. representing the fields in Fourier space) have extraordinary precision. In particular, Haber et al. presented in 1973 a pseudo-spectral solver that integrates analytically the solution over a finite time step, under the usual assumption that the source is constant over that time step. Yet, pseudo-spectral solvers have not been widely used, due in part to the difficulty for efficient parallelization owing to global communications associated with global FFTs on the entire computational domains. A method for the parallelization of electromagnetic pseudo-spectral solvers is proposed and tested on single electromagnetic pulses, and on Particle-In-Cell simulations of the wakefield formation in a laser plasma accelerator. The method takes advantage of the properties of the Discrete Fourier Transform, the linearity of Maxwells equations and the finite speed of light for limiting the communications of data within guard regions between neighboring computational domains. Although this requires a small approximation, test results show that no significant error is made on the test cases that have been presented. The proposed method opens the way to solvers combining the favorable parallel scaling of standard finite-difference methods with the accuracy advantages of pseudo-spectral methods.

Vay, Jean-Luc, E-mail: jlvay@lbl.gov [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)] [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Haber, Irving; Godfrey, Brendan B. [University of Maryland, College Park, MD 20742 (United States)] [University of Maryland, College Park, MD 20742 (United States)

2013-06-15T23:59:59.000Z

451

Beam-Dynamics Studies and Advanced Accelerator Research at CTF-3 Compact Final Focus, Laser Compton Scattering, Plasmas, etc.  

E-Print Network (OSTI)

Preliminary investigations are summarized on the possible use of the CTF3 facility for extended beam-dynamics studies and advanced accelerator R&D, which would exploit its unique properties and beam availability. The key element of these considerations is the possible addition of a test beam-delivery system comprising a compact final focus and advanced collimation concepts, scaled from 3 TeV down to low energy and having a short total length. Operational experience, verification of critical questions (octupole tail folding, beam halo transport, etc.), diagnostics (e.g., rf BPMs) and stabilization could all be explored in such a facility, which would benefit not only the CLIC study, but all linear collider projects. Another interesting application would be the study of plasma-beam interaction, which may include plasma focusing, plasma acceleration, ion-channel radiation, and plasma wigglers.

Assmann, R W; Burkhardt, H; Corsini, R; Faus-Golfe, A; Gronberg, J; Redaelli, S; Schulte, Daniel; Velasco, M; Zimmermann, Frank

2002-01-01T23:59:59.000Z

452

Experiments and multiscale simulations of laser propagation through  

E-Print Network (OSTI)

LETTERS Experiments and multiscale simulations of laser propagation through ignition-scale plasmas- energy, ignition-size laser beam through fusion-size plasmas on the National Ignition Facility (NIF and astrophysical phenomena. The laser­plasma interactions in these ignition hohlraums are complex because the laser

Loss, Daniel

453

Optimization of extreme ultraviolet photons emission and collection in mass-limited laser produced plasmas for lithography application  

E-Print Network (OSTI)

Optimization of extreme ultraviolet photons emission and collection in mass-limited laser produced in DPP or with pre-pulsing in LPP provide wide area for optimization in regards to conversion efficiency and collection as well as calculating photons source location and size. We optimized several parameters of dual

Harilal, S. S.

454

Development of an on-line isotope dilution laser ablation inductively coupled plasma mass spectrometry (LAICP-MS) method for determination of boron in silicon wafers  

Science Journals Connector (OSTI)

A method has been developed based on an on-line isotope dilution technique couple with laser ablation/inductively coupled plasma mass spectrometry (LAICP-MS), for the determination of boron in p-type silicon wafers. The laser-ablated sample aerosol was mixed on-line with an enriched boron aerosol supplied continuously using a conventional nebulization system. Upon mixing the two aerosol streams, the isotope ratio of boron changed rapidly and was then recorded by the ICP-MS system for subsequent quantification based on the isotope dilution principle. As an on-line solid analysis method, this system accurately quantifies boron concentrations in silicon wafers without the need for an internal or external solid reference standard material. Using this on-line isotope dilution technique, the limit of detection for boron in silicon wafers is 2.8נ1015atomscm?3. The analytical results obtained using this on-line methodology agree well with those obtained using wet chemical digestion methods for the analysis of p-type silicon wafers containing boron concentrations ranging from 1.0נ1016 to 9.6נ1018atomscm?3.

Chao-Kai Yang; Po-Hsiang Chi; Yong-Chine Lin; Yuh-Chang Sun; Mo-Hsiung Yang

2010-01-01T23:59:59.000Z

455

Formation and direct writing of color centers in LiF using a laser-induced extreme ultraviolet plasma in combination with a Schwarzschild objective  

SciTech Connect

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.

Barkusky, Frank; Peth, Christian; Mann, Klaus; Feigl, Torsten; Kaiser, Norbert [Laser-Laboratorium Goettingen e.V., Hans-Adolf-Krebs-Weg 1, D-37077 Goettingen (Germany); Fraunhofer-Institut fuer Angewandte Optik und Feinmechanik, Albert-Einstein-Strasse 7, D-07745 Jena (Germany)

2005-10-15T23:59:59.000Z

456

Formation and direct writing of color centers in LiF using a laser-induced extreme ultraviolet plasma in combination with a Schwarzschild objective  

Science Journals Connector (OSTI)

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 EUVsource. 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 EUVsource (pulse energy 3 mJ at 13.5 nm and plasma diameter approximately 300 ? m ) energy densities of 73 mJ ? cm 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 EUVradiation was investigated. F 2 F 3 and F 3 + 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 ? m diameter was generated which accomplishes direct writing of color centers with micrometer resolution.

Frank Barkusky; Christian Peth; Klaus Mann; Torsten Feigl; Norbert Kaiser

2005-01-01T23:59:59.000Z

457

P. Muggli, ATF Users Meeting 07/05/07 Multi-bunch Plasma Wakefield  

NLE Websites -- All DOE Office Websites (Extended Search)

Yakimenko Brookhaven National Laboratory, Upton, Long Island, NY Wayne D. Kimura, STI Optronics, Inc., Bellevue, WA Presented by Patric Muggli, USC Work supported by US DoE 2 P....

458

EXPERIMENTAL RESULTS OF A PLASMA WAKEFIELD ACCELERATOR USING MULTIPLE ELECTRON BUNCHES  

E-Print Network (OSTI)

. Yakimenko, BNL, Upton, NY, USA W. D. Kimura STI Optronics, Inc., Bellevue, WA, USA Abstract We present some

Brookhaven National Laboratory

459

SciTech Connect: Beam Matching to a Plasma Wakefield Accelerator...  

Office of Scientific and Technical Information (OSTI)

the E-164X PWFA experiments at SLAC. Authors: Marsh, K.A.; Clayton, C.E.; Huang, C.; Johnson, D.K.; Joshi, C.; Lu, W.; Mori, W.B.; Zhou, M.; UCLA; Barnes, C.D.; Decker, F.J.;...

460

Visual Exploration of Turbulent Combustion and Laser-Wakefield Accelerator Simulations  

E-Print Network (OSTI)

hydrogen flames under different levels of turbulence ­ Lean combustion reduces emissions Important-dependent, difficult to characterize) · Scientific Goal: ­ Understanding the temporal evolution of burning cells Simulations 4 Feature Tracking in Combustion Simulations · Isotherm represents "flame surface" · Fuel

Note: This page contains sample records for the topic "laser plasma wakefield" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


461

Three regimes of relativistic beam - plasma interaction  

SciTech Connect

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.

Muggli, P.; Allen, B.; Fang, Y.; Yakimenko, V.; Babzien, M.; Kusche, K.; Fedurin, M.; Vieira, J.; Martins, J.; Silva, L. [Max Planck Institute for Physics, 80805 Munich (Germany) and University of Southern California, Los Angeles, CA 90089 (United States); University of Southern California, Los Angeles, CA 90089 (United States); Brookhaven National Laboratory, Upton, NY 11973 (United States); GoLP/Instituto de Plasmas e Fusao Nuclear - Laboratorio Associado Instituto Superior Tecnico (IST), Technical University of Lisbon, Lisboa (Portugal)

2012-12-21T23:59:59.000Z

462

Positron Beam Propagation in a Meter Long Plasma Channel  

SciTech Connect

Recent experiments and simulations have shown that positron beams propagating in plasmas can be focused and also create wakes with large accelerating gradients. For similar parameters, the wakes driven by positron beams are somewhat smaller compared to the case of an electron beam. Simulations have shown that the wake amplitude can be increased if the positron beam is propagated in a hollow plasma channel (Ref. 1). This paper, compares experimentally, the propagation and beam dynamics of a positron beam in a meter scale homogeneous plasma, to a positron beam hollow channel plasma. The results show that positron beams in hollow channels are less prone to distortions and deflections. Hollow channels were observed to guide the positron beam onto the channel axis. Beam energy loss was also observed implying the formation of a large wake amplitude. The experiments were carried out as part of the E-162 plasma wakefield experiments at SLAC.

Marsh, K.A.; Blue, B.E.; Clayton, C.E.; Joshi, C.; Mori, W.B.; /UCLA; Decker, F.-J.; Hogan, M.J.; Iverson, R.; O'Connell, C.; Raimondi, P.; Siemann, Robert H.; Walz, D.; /SLAC; Katsouleas, T.C.; Muggli, P.; /Southern California U.

2008-03-17T23:59:59.000Z

463

Plasma jets and plasma bullets  

Science Journals Connector (OSTI)

Plasma plumes, or plasma jets, belong to a large family of gas discharges whereby the discharge plasma is extended beyond the plasma generation region into the surrounding ambience, either by a field (e.g. electromagnetic, convective gas flow, or shock wave) or a gradient of a directionless physical quantity (e.g. particle density, pressure, or temperature). This physical extension of a plasma plume gives rise to a strong interaction with its surrounding environment, and the interaction alters the properties of both the plasma and the environment, often in a nonlinear and dynamic fashion. The plasma is therefore not confined by defined physical walls, thus extending opportunities for material treatment applications as well as bringing in new challenges in science and technology associated with complex open-boundary problems. Some of the most common examples may be found in dense plasmas with very high dissipation of externally supplied energy (e.g. in electrical, optical or thermal forms) and often in or close to thermal equilibrium. For these dense plasmas, their characteristics are determined predominantly by strong physical forces of different fields, such as electrical, magnetic, thermal, shock wave, and their nonlinear interactions [1]. Common to these dense plasma plumes are significant macroscopic plasma movement and considerable decomposition of solid materials (e.g. vaporization). Their applications are numerous and include detection of elemental traces, synthesis of high-temperature materials and welding, laser--plasma interactions, and relativistic jets in particle accelerators and in space [2][4]. Scientific challenges in the understanding of plasma jets are exciting and multidisciplinary, involving interweaving transitions of all four states of matter, and their technological applications are wide-ranging and growing rapidly. Using the Web of Science database, a search for journal papers on non-fusion plasma jets reveals that a long initial phase up to 1990 with only 31 papers per year on average, and a total of some 1300 papers, precedes a considerable growth of some 3550% in research activity every five years, over the last 20 years or so. As shown in the table, the annual dissemination of the field is more than 1600 papers and the total number of papers is in excess of 20000. This upwards trajectory is typical of a strong and growing subject area in physical science, with considerable capacity in both fundamental science and applications. PeriodNumber of papersPapers per annum 19481990130031 199119952279456 199620003447689 200120054571914 2006201066401328 2011 1658 In many of the dense plasma jets discussed above, strong physical forces generated by the plasma are often desired and this favours plasma generation at elevated gas pressure, including atmospheric pressure, which favours a high level of gas ionization. Historically it has been challenging to reduce and control the strong physical forces in high-pressure plasmas for applications where these are unwanted, for example, surface modification of polymeric sheets [5]. Indeed, there is a real need for a vast range of material processing applications at temperatures below 100oC (or below 400 K) and this favours atmospheric-pressure plasma jets sustained far from thermal equilibrium with the dissipated electrical energy largely used not in heat generation but in unleashing non-equilibrium chemical reactions. The long-standing difficulty of effectively controlling the level of gas ionization at atmospheric pressure was overcome by the technological breakthrough of achieving atmospheric-pressure glow discharges in the late 1980s [6]. A related challenge stemming from high collisionality of atmospheric-pressure plasmas (v >> ?0) means that large-area plasmas sustained between parallel-plate electrodes are very susceptible to strong plasma instabilities when molecular gases are introduced for processing applications. This led to an effective technological solution in the early to late 1990s of confining atmospheric plasmas in a small v

M G Kong; B N Ganguly; R F Hicks

2012-01-01T23:59:59.000Z

464

High-power radio frequency pulse generation and extration based on wakefield excited by an intense charged particle beam in dielectric-loaded waveguides.  

SciTech Connect

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 train with a bunch spacing of 769ps and bunch charges of 50nC each, 90.4MW and 8.68MW of extracted power levels are expected to be reached at 20.8GHz and 35.1GHz, respectively. In order to improve efficiency in HOM power extraction, a novel technique has been proposed to suppress unintended modes.

Gao, F.; High Energy Physics; Illinois Inst. of Tech

2009-07-24T23:59:59.000Z

465

Laser Roadshow  

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outreach Laser Roadshow The NIF Laser Roadshow includes a number of interactive laser demonstratio