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Note: This page contains sample records for the topic "high-power coherent terahertz" from the National Library of EnergyBeta (NLEBeta).
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We encourage you to perform a real-time search of NLEBeta
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1

Laser Seeding Yields High-Power Coherent Terahertz Radiation  

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

Power Coherent Terahertz Radiation Laser Seeding Yields High-Power Coherent Terahertz Radiation Print Wednesday, 25 April 2007 00:00 Researchers at Berkeley Lab have been exploring...

2

Laser Seeding Yields High-Power Coherent Terahertz Radiation  

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

Laser Seeding Yields High-Power Coherent Terahertz Radiation Print Researchers at Berkeley Lab have been exploring the ways coherent synchrotron radiation (CSR) is generated in...

3

Laser Seeding Yields High-Power Coherent Terahertz Radiation  

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

Laser Seeding Yields High-Power Coherent Terahertz Radiation Print Laser Seeding Yields High-Power Coherent Terahertz Radiation Print Researchers at Berkeley Lab have been exploring the ways coherent synchrotron radiation (CSR) is generated in electron storage rings when femtosecond lasers are used to carve out ultrafast x-ray pulses by femtoslicing (see "Tailored Terahertz Pulses from a Laser-Modulated Electron Beam"). In their most recent work, the researchers reported the first observation of seeding an instability of the electron beam by the laser, and they presented a physical model that shows how this occurs under the proper conditions. Such a mechanism makes it possible to control the instability onset and to exploit its gain for the generation of pulses of terahertz CSR of unprecedented power. Terahertz radiation with a wavelength from about 1 cm to about 100 microns between the microwave and the infrared would provide access to a large number of fundamental phenomena. To mention only some of them: excited electrons orbit, small molecules rotate, proteins vibrate, superconducting energy gaps resonate, and gaseous and solid-state plasmas oscillate at terahertz frequencies. But generating terahertz radiation is ordinarily a challenging task for any kind of source, including storage-ring-based synchrotron light sources. The new findings by the ALS group could represent a significant step toward satisfying the need for powerful terahertz sources.

4

Laser Seeding Yields High-Power Coherent Terahertz Radiation  

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

Laser Seeding Yields High-Power Coherent Terahertz Radiation Print Laser Seeding Yields High-Power Coherent Terahertz Radiation Print Researchers at Berkeley Lab have been exploring the ways coherent synchrotron radiation (CSR) is generated in electron storage rings when femtosecond lasers are used to carve out ultrafast x-ray pulses by femtoslicing (see "Tailored Terahertz Pulses from a Laser-Modulated Electron Beam"). In their most recent work, the researchers reported the first observation of seeding an instability of the electron beam by the laser, and they presented a physical model that shows how this occurs under the proper conditions. Such a mechanism makes it possible to control the instability onset and to exploit its gain for the generation of pulses of terahertz CSR of unprecedented power. Terahertz radiation with a wavelength from about 1 cm to about 100 microns between the microwave and the infrared would provide access to a large number of fundamental phenomena. To mention only some of them: excited electrons orbit, small molecules rotate, proteins vibrate, superconducting energy gaps resonate, and gaseous and solid-state plasmas oscillate at terahertz frequencies. But generating terahertz radiation is ordinarily a challenging task for any kind of source, including storage-ring-based synchrotron light sources. The new findings by the ALS group could represent a significant step toward satisfying the need for powerful terahertz sources.

5

Laser Seeding Yields High-Power Coherent Terahertz Radiation  

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

is generated in electron storage rings when femtosecond lasers are used to carve out ultrafast x-ray pulses by femtoslicing (see "Tailored Terahertz Pulses from a Laser-Modulated...

6

Production of high power femtosecond terahertz radiation  

SciTech Connect

The terahertz (THz) region of the electromagnetic spectrum is attracting interest for a broad range of applications ranging from diagnosing electron beams to biological imaging. Most sources of short pulse THz radiation utilize excitation of biased semiconductors or electro-optic crystals by high peak power lasers. For example, this was done by using an un-doped InAs wafer irradiated by a femtosecond free-electron laser (FEL) at the Thomas Jefferson National Accelerator Facility. Microwatt levels of THz radiation were detected when excited with FEL pulses at 1.06 mm wavelength and 10W average power. Recently substantially higher powers of femtosecond THz pulses produced by synchrotron emission were extracted from the electron beamline. Calculations and measurements confirm the production of coherent broadband THz radiation from relativistic electrons with an average power of nearly 20W, a world record in this wavelength range by a factor of 10,000. We describe the source, presenting theoretical calculations and their experimental verification. Potential applications of this exciting new source include driving new non-linear phenomena, performing pump-probe studies of dynamical properties of novel materials, and studying molecular vibrations and rotations, low frequency protein motions, phonons, superconductor band gaps, electronic scattering, collective electronic excitations (e.g., charge density waves), and spintronics.

Neil, George R.; Carr, G.L.; Gubeli III, Joseph F.; Jordan, K.; Martin, Michael C.; McKinney, Wayne R.; Shinn, Michelle; Tani, Masahiko; Williams, G.P.; Zhang, X.-C.

2003-07-11T23:59:59.000Z

7

Generation of high power single-cycle and multiple-cycle terahertz pulses  

E-Print Network (OSTI)

In this thesis, we present experimental methods and results of tabletop generation of high power single-cycle and frequency-tunable multiple-cycle terahertz (THz) pulses pumped with near-infrared ultrashort optical pulses ...

Chen, Zhao, S.M. Massachusetts Institute of Technology. Department of Chemistry

2013-01-01T23:59:59.000Z

8

Radiation from laser accelerated electron bunches: Coherent terahertz and femtosecond X-rays  

E-Print Network (OSTI)

of coherent transition radiation generated at a plasma-and G. Fubiani, “Terahertz radiation from laser acceleratedW. P. Leemans, “Synchrotron radiation from electron beams in

2004-01-01T23:59:59.000Z

9

IKNO, a user facility for coherent terahertz and UV synchrotron radiation  

E-Print Network (OSTI)

IKNO is a real multi-user facility that accommodates a largeIKNO, a user facility for coherent terahertz and UVis a proposal for a multi-user facility based on an electron

Sannibale, Fernando

2009-01-01T23:59:59.000Z

10

A MODEL FOR PRODUCING STABLE, BROADBAND TERAHERTZ COHERENT SYNCHROTRONRADIATION IN STORAGE RINGS  

SciTech Connect

We present a model for producing stable broadband coherent synchrotron radiation (CSR) in the terahertz frequency region in an electron storage ring. The model includes distortion of bunch shape from the synchrotron radiation (SR), enhancing higher frequency coherent emission and limits to stable emission due to a microbunching instability excited by the SR. We use this model to optimize the performance of a source for CSR emission.

Sannibale, Fernando; Byrd, John M.; Loftsdottir, Agusta; Martin, MichaelC.; Venturini, Marco

2003-06-13T23:59:59.000Z

11

High-power SRS lasers - coherent summators (the way it was)  

Science Conference Proceedings (OSTI)

The history of the research works performed under the guidance of H.G. Basov and aimed at developing high-energy lasers - coherent summators (CSs) - based on stimulated Raman scattering (SRS) in liquid nitrogen and liquid oxygen is reported. The work was performed jointly by researchers of FIAN [the Laboratory of Quantum Radiophysics (LQRP)] and VNIIEF. Many problems were solved as a result of these studies. Liquid nitrogen and oxygen were found to be optimal active media for high-power SRS lasers with high energy per pulse. A method for purifying these cryogenic liquids from micro- and nanoimpurities was developed, which made it possible to eliminate nonlinear loss of pump radiation and converted radiation in the active medium and ensure effective operation of SRS lasers - coherent summators (SRSL CSs) with high output energy. Cryogenic cells providing high optical homogeneity of liquid nitrogen and oxygen were developed, which ensured low (at a level of 0.1 mrad) divergence of converted radiation with high energy density. Raster focusing systems providing optimal concentration of pump radiation in the active medium were designed. These studies resulted in the development of high-power highenergy SRSL CSs with a low beam divergence, based on liquid nitrogen ({lambda}{sub S} = 1.89 {mu}m) and liquid oxygen ({lambda}{sub S} = 1.65 {mu}m), with pumping by explosively pumped iodine lasers (EPILs) ({lambda}{sub p} = 1.315 {mu}m). The characteristics of the SRSL CSs developed were record for that time (the end of 1960s and the beginning of 1970s): energy up to 2.5 kJ per 10-{mu}s pulse, beam divergence {approx}10{sup -4} rad, and beam energy density of several hundreds of J cm{sup -2}. (special issue devoted to the 90th anniversary of n.g. basov)

Grasiuk, Arkadii Z; Zubarev, I G; Efimkov, V F; Smirnov, V G [P N Lebedev Physical Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2012-12-31T23:59:59.000Z

12

Generation of coherent terahertz pulses in ruby at room temperature  

Science Conference Proceedings (OSTI)

We have shown that a coherently driven solid state medium can potentially produce strong controllable short pulses of THz radiation. The high efficiency of the technique is based on excitation of maximal THz coherence by applying resonant optical pulses to the medium. The excited coherence in the medium is connected to macroscopic polarization coupled to THz radiation. We have performed detailed simulations by solving the coupled density matrix and Maxwell equations. By using a simple V-type energy scheme for ruby, we have demonstrated that the energy of generated THz pulses ranges from hundreds of pico-Joules to nano-Joules at room temperature and micro-Joules at liquid helium temperature, with pulse durations from picoseconds to tens of nanoseconds. We have also suggested a coherent ruby source that lases on two optical wavelengths and simultaneously generates THz radiation. We discussed also possibilities of extension of the technique to different solid-state materials.

Kuznetsova, Elena; Rostovtsev, Yuri; Kalugin, Nikolai G.; Kolesov, Roman; Kocharovskaya, Olga [Institute for Quantum Studies and Department of Physics, Texas A and M University, College Station, Texas 77843 (United States); Scully, Marlan O. [Institute for Quantum Studies and Department of Physics, Texas A and M University, College Station, Texas 77843 (United States); Princeton Institute for Material Science and Department of Mechanical and Aerospace Engineering, Princeton University, New Jersey 08544 (United States)

2006-08-15T23:59:59.000Z

13

Tailored Terahertz Pulses from a Laser-Modulated Electron Beam  

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

Tailored Terahertz Pulses from a Laser-Modulated Electron Beam Print Researchers at the ALS have demonstrated a new method to generate tunable, coherent, broadband terahertz...

14

Coherent terahertz radiation from high-harmonic component of modulated free-electron beam in a tapered two-asymmetric grating structure  

SciTech Connect

Based on the mechanism of incoherent diffraction radiation excited by an electron bunch in a waveguide with periodic structure, this paper presents the concept of coherent terahertz (THz) radiation from the high-harmonic component of a modulated free-electron beam in a tapered two-asymmetric grating structure. The results show that in this mechanism 0.43 THz radiation can be generated with 10 A/cm{sup 2} current density, and the efficiency can reach 0.5%. Because of the low required current density and relative high efficiency, this concept shows the application potential for electron-beam-driven terahertz sources.

Zhang Yaxin; Zhou Yucong; Dong Liang; Liu Shenggang [Terahertz Science and Technology Research Center, University of Electronic Science and Technology of China, Chengdu 610054 (China)

2012-09-17T23:59:59.000Z

15

Terahertz quantum cascade lasers  

E-Print Network (OSTI)

The development of the terahertz frequency range has long been impeded by the relative dearth of compact, coherent radiation sources of reasonable power. This thesis details the development of quantum cascade lasers (QCLs) ...

Williams, Benjamin S. (Benjamin Stanford), 1974-

2003-01-01T23:59:59.000Z

16

Prospects for high power Linac Coherent Light Source (LCLS) development in the 1000{angstrom} {minus} 1{angstrom} wavelength range  

Science Conference Proceedings (OSTI)

Electron bunch requirements for single-pass saturation of a Free-Electron Laser (FEL) operating at full transverse coherence in the Self-Amplified Spontaneous Emission (SASE) mode include: (1) a high peak current, (2) a sufficiently low relative energy spread, and (3) a transverse emittance {var_epsilon}[r-m] satisfying the condition {var_epsilon} {le} {lambda}A/4{pi}, where {lambda}[m] is the output wavelength of the FEL. In the insertion device that induces the coherent amplification, the prepared electron bunch must be kept on a trajectory sufficiently collinear with the amplified photons without significant dilution of its transverse density. In this paper we discuss a Linac Coherent Light Source (LCLS) based on a high energy accelerator such as, e.g., the 3km S-band structure at the Stanford Linear Accelerator Center (SLAC), followed by a long high-precision undulator with superimposed quadrupole (FODO) focusing, to fulfill the given requirements for SASE operation in the 1000{Angstrom}--1{Angstrom} range. The electron source for the linac, an RF gun with a laser-excited photocathode featuring a normalized emittance in the 1--3 mm-mrad range, a longitudinal bunch duration of the order of 3 ps, and approximately 10{sup {minus}9} C/bunch, is a primary determinant of the required low transverse and longitudinal emittances. Acceleration of the injected bunch to energies in the 5--25 GeV range is used to reduce the relative longitudinal energy spread in the bunch, as well as to reduce the transverse emittance to values consistent with the cited wavelength regime. Two longitudinal compression stages are employed to increase the peak bunch current to the 2--5 kA levels required for sufficiently rapid saturation. The output radiation is delivered, via a grazing-incidence mirror bank, to optical instrumentation and a multi-user beam line system. Technological requirements for LCLS operation at 40{Angstrom}, 4.5{Angstrom}, and 1.5{Angstrom} are examined.

Tatchyn, R.; Bane, K.; Boyce, R. [and others

1994-03-01T23:59:59.000Z

17

Graphene Terahertz Plasmon Oscillators  

Science Conference Proceedings (OSTI)

In this paper we propose and discuss coherent terahertz sources based on charge density wave (plasmon) amplification in two-dimensional graphene. The coupling of the plasmons to interband electron-hole transitions in population inverted graphene layers ... Keywords: Carbon, Nanotechnology, Plasmons, Submillimeter Wave Oscillators, nanotechnology, plasmons, submillimeter-wave oscillators

F. Rana

2008-01-01T23:59:59.000Z

18

Observation of coherently enhanced tunable narrow-band terahertz transition radiation from a relativistic sub-picosecond electron bunch train  

SciTech Connect

We experimentally demonstrate the production of narrow-band ({delta}f/f{approx_equal}20% at f{approx_equal}0.5THz) transition radiation with tunable frequency over [0.37, 0.86] THz. The radiation is produced as a train of sub-picosecond relativistic electron bunches transits at the vacuum-aluminum interface of an aluminum converter screen. The bunch train is generated via a transverse-to-longitudinal phase space exchange technique. We also show a possible application of modulated beams to extend the dynamical range of a popular bunch length diagnostic technique based on the spectral analysis of coherent radiation.

Piot, P.; Maxwell, T. J. [Northern Illinois Center for Accelerator and Detector Development and Department of Physics, Northern Illinois University, DeKalb, Illinois 60115 (United States); Accelerator Physics Center, Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States); Sun, Y.-E [Accelerator Physics Center, Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States); Ruan, J.; Lumpkin, A. H.; Thurman-Keup, R. [Accelerator Division, Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States); Rihaoui, M. M. [Northern Illinois Center for Accelerator and Detector Development and Department of Physics, Northern Illinois University, DeKalb, Illinois 60115 (United States)

2011-06-27T23:59:59.000Z

19

Tailored Terahertz Pulses from a Laser-Modulated Electron Beam  

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

Tailored Terahertz Pulses from a Tailored Terahertz Pulses from a Laser-Modulated Electron Beam Tailored Terahertz Pulses from a Laser-Modulated Electron Beam Print Wednesday, 29 November 2006 00:00 Researchers at the ALS have demonstrated a new method to generate tunable, coherent, broadband terahertz radiation from a relativistic electron beam modulated by a femtosecond laser. Interaction of the ALS electron beam with a femtosecond laser pulse as they co-propagate through a wiggler modulates the electron energies within a short slice of the electron bunch with about the same duration as the laser pulse. This causes a dispersion of the electron trajectories, and the bunch develops a hole that emits short pulses of temporally and spatially coherent terahertz pulses synchronized to the laser. The technique allows tremendous flexibility in shaping the terahertz pulses by appropriate modulation of the laser pulse.

20

Coherent Synchrotron Radiation: Theory and Simulations.  

Science Conference Proceedings (OSTI)

The physics of coherent synchrotron radiation (CSR) emitted by ultra-relativistic electron bunches, known since the last century, has become increasingly important with the development of high peak current free electron lasers and shorter bunch lengths in storage rings. Coherent radiation can be described as a low frequency part of the familiar synchrotron radiation in bending magnets. As this part is independent of the electron energy, the fields of different electrons of a short bunch can be in phase and the total power of the radiation will be quadratic with the number of electrons. Naturally the frequency spectrum of the longitudinal electron distribution in a bunch is of the same importance as the overall electron bunch length. The interest in the utilization of high power radiation from the terahertz and far infrared region in the field of chemical, physical and biological processes has led synchrotron radiation facilities to pay more attention to the production of coherent radiation. Several laboratories have proposed the construction of a facility wholly dedicated to terahertz production using the coherent radiation in bending magnets initiated by the longitudinal instabilities in the ring. Existing synchrotron radiation facilities also consider such a possibility among their future plans. There is a beautiful introduction to CSR in the 'ICFA Beam Dynamics Newsletter' N 35 (Editor C. Biscari). In this paper we recall the basic properties of CSR from the theory and what new effects, we can get from the precise simulations of the coherent radiation using numerical solutions of Maxwell's equations. In particular, transverse variation of the particle energy loss in a bunch, discovered in these simulations, explains the slice emittance growth in bending magnets of the bunch compressors and transverse de-coherence in undulators. CSR may play same the role as the effect of quantum fluctuations of synchrotron radiation in damping rings. It can limit the minimum achievable emittance in the synchrotron light sources for short bunches.

Novokhatski, Alexander; /SLAC

2012-03-29T23:59:59.000Z

Note: This page contains sample records for the topic "high-power coherent terahertz" 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

Tailored Terahertz Pulses from a Laser-Modulated Electron Beam  

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

Tailored Terahertz Pulses from a Laser-Modulated Electron Beam Print Tailored Terahertz Pulses from a Laser-Modulated Electron Beam Print Researchers at the ALS have demonstrated a new method to generate tunable, coherent, broadband terahertz radiation from a relativistic electron beam modulated by a femtosecond laser. Interaction of the ALS electron beam with a femtosecond laser pulse as they co-propagate through a wiggler modulates the electron energies within a short slice of the electron bunch with about the same duration as the laser pulse. This causes a dispersion of the electron trajectories, and the bunch develops a hole that emits short pulses of temporally and spatially coherent terahertz pulses synchronized to the laser. The technique allows tremendous flexibility in shaping the terahertz pulses by appropriate modulation of the laser pulse.

22

Tailored Terahertz Pulses from a Laser-Modulated Electron Beam  

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

Tailored Terahertz Pulses from a Laser-Modulated Electron Beam Print Tailored Terahertz Pulses from a Laser-Modulated Electron Beam Print Researchers at the ALS have demonstrated a new method to generate tunable, coherent, broadband terahertz radiation from a relativistic electron beam modulated by a femtosecond laser. Interaction of the ALS electron beam with a femtosecond laser pulse as they co-propagate through a wiggler modulates the electron energies within a short slice of the electron bunch with about the same duration as the laser pulse. This causes a dispersion of the electron trajectories, and the bunch develops a hole that emits short pulses of temporally and spatially coherent terahertz pulses synchronized to the laser. The technique allows tremendous flexibility in shaping the terahertz pulses by appropriate modulation of the laser pulse.

23

Tailored Terahertz Pulses from a Laser-Modulated Electron Beam  

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

Tailored Terahertz Pulses from a Laser-Modulated Electron Beam Print Tailored Terahertz Pulses from a Laser-Modulated Electron Beam Print Researchers at the ALS have demonstrated a new method to generate tunable, coherent, broadband terahertz radiation from a relativistic electron beam modulated by a femtosecond laser. Interaction of the ALS electron beam with a femtosecond laser pulse as they co-propagate through a wiggler modulates the electron energies within a short slice of the electron bunch with about the same duration as the laser pulse. This causes a dispersion of the electron trajectories, and the bunch develops a hole that emits short pulses of temporally and spatially coherent terahertz pulses synchronized to the laser. The technique allows tremendous flexibility in shaping the terahertz pulses by appropriate modulation of the laser pulse.

24

Active Terahertz Metamaterial Devices  

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

Active Terahertz Metamaterial Devices Active Terahertz Metamaterial Devices Active Terahertz Metamaterial Devices Metamaterial structures are taught which provide for the modulation of terahertz frequency signals. Available for thumbnail of Feynman Center (505) 665-9090 Email Active Terahertz Metamaterial Devices Metamaterial structures are taught which provide for the modulation of terahertz frequency signals. Each element within an array of metamaterial (MM) elements comprises multiple loops and at least one gap. The MM elements may comprise resonators with conductive loops and insulated gaps, or the inverse in which insulated loops are present with conductive gaps; each providing useful transmissive control properties. The metamaterial elements are fabricated on a semiconducting substrate configured with a

25

High power microwave generator  

DOE Patents (OSTI)

A microwave generator efficiently converts the energy of an intense relativistic electron beam (REB) into a high-power microwave emission using the Smith-Purcell effect which is related to Cerenkov radiation. Feedback for efficient beam bunching and high gain is obtained by placing a cylindrical Smith-Purcell transmission grating on the axis of a toroidal resonator. High efficiency results from the use of a thin cold annular highly-magnetized REB that is closely coupled to the resonant structure.

Ekdahl, C.A.

1983-12-29T23:59:59.000Z

26

High power microwave generator  

DOE Patents (OSTI)

A microwave generator efficiently converts the energy of an intense relativistic electron beam (REB) into a high-power microwave emission using the Smith-Purcell effect which is related to Cerenkov radiation. Feedback for efficient beam bunching and high gain is obtained by placing a cylindrical Smith-Purcell transmission grating on the axis of a toroidal resonator. High efficiency results from the use of a thin cold annular highly-magnetized REB that is closely coupled to the resonant structure.

Ekdahl, Carl A. (Albuquerque, NM)

1986-01-01T23:59:59.000Z

27

Integrated heterodyne terahertz transceiver  

DOE Patents (OSTI)

A heterodyne terahertz transceiver comprises a quantum cascade laser that is integrated on-chip with a Schottky diode mixer. An antenna connected to the Schottky diode receives a terahertz signal. The quantum cascade laser couples terahertz local oscillator power to the Schottky diode to mix with the received terahertz signal to provide an intermediate frequency output signal. The fully integrated transceiver optimizes power efficiency, sensitivity, compactness, and reliability. The transceiver can be used in compact, fieldable systems covering a wide variety of deployable applications not possible with existing technology.

Lee, Mark (Albuquerque, NM); Wanke, Michael C. (Albuquerque, NM)

2009-06-23T23:59:59.000Z

28

Integrated heterodyne terahertz transceiver  

DOE Patents (OSTI)

A heterodyne terahertz transceiver comprises a quantum cascade laser that is integrated on-chip with a Schottky diode mixer. A terahertz signal can be received by an antenna connected to the mixer, an end facet or sidewall of the laser, or through a separate active section that can amplify the incident signal. The quantum cascade laser couples terahertz local oscillator power to the Schottky diode to mix with the received terahertz signal to provide an intermediate frequency output signal. The fully integrated transceiver optimizes power efficiency, sensitivity, compactness, and reliability. The transceiver can be used in compact, fieldable systems covering a wide variety of deployable applications not possible with existing technology.

Wanke, Michael C. (Albuquerque, NM); Lee, Mark (Albuquerque, NM); Nordquist, Christopher D. (Albuquerque, NM); Cich, Michael J. (Albuquerque, NM)

2012-09-25T23:59:59.000Z

29

Terahertz Quantum-Cascade Transmission-Line Metamaterials  

E-Print Network (OSTI)

Terahertz Transmission-Line Metamaterials . . . . . . .CRLH Transmission Lines . . . . . . . . . . . . . . . .Terahertz CRLH Transmission-Line Metamaterials . . . . . . .

Tavallaee, Amir Ali

2012-01-01T23:59:59.000Z

30

Terahertz radiation mixer  

DOE Patents (OSTI)

A terahertz radiation mixer comprises a heterodyned field-effect transistor (FET) having a high electron mobility heterostructure that provides a gatable two-dimensional electron gas in the channel region of the FET. The mixer can operate in either a broadband pinch-off mode or a narrowband resonant plasmon mode by changing a grating gate bias of the FET. The mixer can beat an RF signal frequency against a local oscillator frequency to generate an intermediate frequency difference signal in the microwave region. The mixer can have a low local oscillator power requirement and a large intermediate frequency bandwidth. The terahertz radiation mixer is particularly useful for terahertz applications requiring high resolution.

Wanke, Michael C. (Albuquerque, NM); Allen, S. James (Santa Barbara, CA); Lee, Mark (Albuquerque, NM)

2008-05-20T23:59:59.000Z

31

Direct Detector for Terahertz Radiation - Energy ...  

Patent 7,420,225: Direct detector for terahertz radiation A direct detector for terahertz radiation comprises a grating-gated field-effect transistor ...

32

Terahertz radiation from laser accelerated electron bunches  

E-Print Network (OSTI)

NUMBER 5 MAY 2004 Terahertz radiation from laser acceleratedand millimeter wave radiation from laser acceleratedNo. 5, May 2004 Terahertz radiation from laser accelerated

2004-01-01T23:59:59.000Z

33

High-Power Rf Load  

DOE Patents (OSTI)

A compact high-power RF load comprises a series of very low Q resonators, or chokes [16], in a circular waveguide [10]. The sequence of chokes absorb the RF power gradually in a short distance while keeping the bandwidth relatively wide. A polarizer [12] at the input end of the load is provided to convert incoming TE.sub.10 mode signals to circularly polarized TE.sub.11 mode signals. Because the load operates in the circularly polarized mode, the energy is uniformly and efficiently absorbed and the load is more compact than a rectangular load. Using these techniques, a load having a bandwidth of 500 MHz can be produced with an average power dissipation level of 1.5 kW at X-band, and a peak power dissipation of 100 MW. The load can be made from common lossy materials, such as stainless steel, and is less than 15 cm in length. These techniques can also produce loads for use as an alternative to ordinary waveguide loads in small and medium RF accelerators, in radar systems, and in other microwave applications. The design is easily scalable to other RF frequencies and adaptable to the use of other lossy materials.

Tantawi, Sami G. (San Mateo, CA); Vlieks, Arnold E. (Livermore, CA)

1998-09-01T23:59:59.000Z

34

Profile Terahertz facility.pmd  

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

Terahertz- and Millimeter-Wave Test Facility Terahertz- and Millimeter-Wave Test Facility B E N E F I T S Detect Terrorist-Related Contraband with Terahertz Technology * Spectral "fingerprints" uniquely identify materials * Can identify the factory where explosives and other chemicals were manufactured * Detects minute amounts of chemicals from a distance * Identifies materials in seconds Companies that develop or manufacture instruments to detect terrorist contraband can benefit by using a unique facility at the U.S. Department of Energy's Argonne National Laboratory. Called the Terahertz Test Facility, its sensitive, new instruments - developed at Argonne and available nowhere else in the world - can obtain spectral "fingerprints" that uniquely identify explosives, chemicals, and biological agents- and can even

35

The JLab high power ERL light source  

DOE Green Energy (OSTI)

A new THz/IR/UV photon source at Jefferson Lab is the first of a new generation of light sources based on an Energy-Recovered, (superconducting) Linac (ERL). The machine has a 160 MeV electron beam and an average current of 10 mA in 75 MHz repetition rate hundred femtosecond bunches. These electron bunches pass through a magnetic chicane and therefore emit synchrotron radiation. For wavelengths longer than the electron bunch the electrons radiate coherently a broadband THz {approx} half cycle pulse whose average brightness is > 5 orders of magnitude higher than synchrotron IR sources. Previous measurements showed 20 W of average power extracted[1]. The new facility offers simultaneous synchrotron light from the visible through the FIR along with broadband THz production of 100 fs pulses with >200 W of average power. The FELs also provide record-breaking laser power [2]: up to 10 kW of average power in the IR from 1 to 14 microns in 400 fs pulses at up to 74.85 MHz repetition rates and soon will produce similar pulses of 300-1000 nm light at up to 3 kW of average power from the UV FEL. These ultrashort pulses are ideal for maximizing the interaction with material surfaces. The optical beams are Gaussian with nearly perfect beam quality. See www.jlab.org/FEL for details of the operating characteristics; a wide variety of pulse train configurations are feasible from 10 microseconds long at high repetition rates to continuous operation. The THz and IR system has been commissioned. The UV system is to follow in 2005. The light is transported to user laboratories for basic and applied research. Additional lasers synchronized to the FEL are also available. Past activities have included production of carbon nanotubes, studies of vibrational relaxation of interstitial hydrogen in silicon, pulsed laser deposition and ablation, nitriding of metals, and energy flow in proteins. This paper will present the status of the system and discuss some of the discoveries we have made concerning the physics performance, design optimization, and operational limitations of such a first generation high power ERL light source.

G.R. Neil; C. Behre; S.V. Benson; M. Bevins; G. Biallas; J. Boyce; J. Coleman; L.A. Dillon-Townes; D. Douglas; H.F. Dylla; R. Evans; A. Grippo; D. Gruber; J. Gubeli; D. Hardy; C. Hernandez-Garcia; K. Jordan; M.J. Kelley; L. Merminga; J. Mammosser; W. Moore; N. Nishimori; E. Pozdeyev; J. Preble; R. Rimmer; Michelle D. Shinn; T. Siggins; C. Tennant; R. Walker; G.P. Williams and S. Zhang

2005-03-19T23:59:59.000Z

36

Terahertz Properties of Lithium Iron Phosphate Glasses  

Science Conference Proceedings (OSTI)

Presentation Title, Terahertz Properties of Lithium Iron Phosphate Glasses ... Field Assisted Viscous Flow and Crystallization in a Sodium Aluminosilicate Glass.

37

Loss Mechanisms and High Power Piezoelectric Components - TMS  

Science Conference Proceedings (OSTI)

Oct 15, 2006 ... Loss Mechanisms and High Power Piezoelectric Components ... we demonstrated high power multilayer piezoelectric transformers with Cu or ...

38

Active terahertz metamaterial devices  

DOE Patents (OSTI)

Metamaterial structures are taught which provide for the modulation of terahertz frequency signals. Each element within an array of metamaterial (MM) elements comprises multiple loops and at least one gap. The MM elements may comprise resonators with conductive loops and insulated gaps, or the inverse in which insulated loops are present with conductive gaps; each providing useful transmissive control properties. The metamaterial elements are fabricated on a semiconducting substrate configured with a means of enhancing or depleting electrons from near the gaps of the MM elements. An on to off transmissivity ratio of about 0.5 is achieved with this approach. Embodiments are described in which the MM elements incorporated within a Quantum Cascade Laser (QCL) to provide surface emitting (SE) properties.

Chen, Houtong (Los Alamos, NM); Padilla, Willie John (Newton, MA); Averitt, Richard Douglas (Newton, MA); O' Hara, John F. (Los Alamos, NM); Lee, Mark (Albuquerque, NM)

2010-11-02T23:59:59.000Z

39

New Wave: JILA Develops Efficient Source of Terahertz ...  

Science Conference Proceedings (OSTI)

... The system produces a peak terahertz field (20 volts per centimeter for an input power of 160 ... Contactless photoconductive terahertz generation. ...

2011-01-20T23:59:59.000Z

40

CHALLENGES FACING HIGH POWER PROTON ACCELERATORS  

Science Conference Proceedings (OSTI)

This presentation will provide an overview of the challenges of high power proton accelerators such as SNS, J-PARC, etc., and what we have learned from recent experiences. Beam loss mechanisms and methods to mitigate beam loss will also be discussed.

Plum, Michael A [ORNL

2013-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "high-power coherent terahertz" 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

Terahertz- and Millimeter-Wave Test Facility  

chemicals and nuclear materials • Locate and track chemical and radioactive plumes • Perform medical imaging Instruments at Argonne’s Terahertz Test

42

High Power RF Sources for Accelerators  

SciTech Connect

This presentation describes RF sources developed and under development at Calabazas Creek Research, Inc. for driving high power accelerators and colliders. The RF sources range from L-Band to W-Band and power levels from 10s of kilowatts CW to 200 MW pulsed. The configurations include standard klystrons, multiple beam klystrons, sheet beam devices, and gyroklystrons. The basic parameters are presented with a basic description of operation and applications.

Ives, Lawrence; Read, Michael; Neilson, Jeff; Borchard, Philipp; Mizuhara, Max [Calabazas Creek Research, Inc., 690 Port Drive, San Mateo, CA 94404 (United States); Lawson, Wesley [Insitute for Research in Applied Physics, University of Maryland, College Park, MD 20742 (United States)

2006-11-27T23:59:59.000Z

43

High-power accelerator technology and requirements  

SciTech Connect

Designs of high-power proton linear accelerators (linacs) for accelerator transmutation of waste (ATW) are being actively studied at Los Alamos National Laboratory and at several other laboratories worldwide. Beam parameters cover the 100- to 300-mA range in average current and 800 to 1600 MeV in energy. While ideas for such accelerators have been discussed for decades, the technology base has recently advanced to the point that the feasibility of machines in the ATW power class is now generally conceded. Factors contributing to this advance have been the following: experience gained with medium-power research accelerators, especially the LAMPF linac at Los Alamos; major improvements in the theory and technology of high-intensity high-brightness accelerators fostered by the SDIO Neutral Particle Beam program; and development of high-power continuous-wave (cw) radio-frequency (rf) generators for high-energy colliding-beam rings. The reference ATW accelerator concept described in this paper is based on room-temperature copper accelerating cavities. Advances in superconducting niobium cavity technology have opened the possibility of application to ATW-type linacs. Useful efficiency gains could be realized, especially for lower current systems, and there may be technical advantages as well. Technology issues that need to be addressed for superconducting rf linac designs include the development of high-power rf couplers, appropriate cavity designs, and superconducting focusing elements, as well as concerns about beam damage of niobium structures and dynamic rf control with high beam currents.

Lawrence, G.P. (Los Alamos National Lab., NM (United States))

1993-01-01T23:59:59.000Z

44

High Power UV LED Industrial Curing Systems  

Science Conference Proceedings (OSTI)

UV curing is a green technology that is largely underutilized because UV radiation sources like Hg Lamps are unreliable and difficult to use. High Power UV LEDs are now efficient enough to replace Hg Lamps, and offer significantly improved performance relative to Hg Lamps. In this study, a modular, scalable high power UV LED curing system was designed and tested, performing well in industrial coating evaluations. In order to achieve mechanical form factors similar to commercial Hg Lamp systems, a new patent pending design was employed enabling high irradiance at long working distances. While high power UV LEDs are currently only available at longer UVA wavelengths, rapid progress on UVC LEDs and the development of new formulations designed specifically for use with UV LED sources will converge to drive more rapid adoption of UV curing technology. An assessment of the environmental impact of replacing Hg Lamp systems with UV LED systems was performed. Since UV curing is used in only a small portion of the industrial printing, painting and coating markets, the ease of use of UV LED systems should increase the use of UV curing technology. Even a small penetration of the significant number of industrial applications still using oven curing and drying will lead to significant reductions in energy consumption and reductions in the emission of green house gases and solvent emissions.

Karlicek, Robert, F., Jr; Sargent, Robert

2012-05-14T23:59:59.000Z

45

CLIC RF High Power Production Testing Program  

SciTech Connect

The CLIC Power Extraction and Transfer Structure (PETS) is a passive microwave device in which bunches of the drive beam interact with the impedance of the periodically loaded waveguide and generate RF power for the main linac accelerating structure. The demands on the high power production ({approx} 150 MW) and the needs to transport the 100 A drive beam for about 1 km without losses, makes the PETS design rather unique and the operation very challenging. In the coming year, an intense PETS testing program will be implemented. The target is to demonstrate the full performance of the PETS operation. The testing program overview and test results available to date are presented.

Syratchev, I.; Riddone, G.; /CERN; Tantawi, S.G.; /SLAC

2011-11-02T23:59:59.000Z

46

High power, high frequency, vacuum flange  

DOE Patents (OSTI)

This invention is comprised of an improved waveguide flange is disclosed for high power operation that helps prevent arcs from being initiated at the junctions between waveguide sections. The flanges at the end of the waveguide sections have counterbores surrounding the waveguide tubes. When the sections are bolted together the counterbores form a groove that holds a fully annealed copper gasket. Each counterbore has a beveled step that is specially configured to insure the gasket forms a metal-to-metal vacuum seal without gaps or sharp edges. The resultant inner surface of the waveguide is smooth across the junctions between waveguide sections, and arcing is prevented.

Felker, B.; McDaniel, M.

1991-12-31T23:59:59.000Z

47

The Jefferson Lab High Power Light Source  

Science Conference Proceedings (OSTI)

Jefferson Lab has designed, built and operated two high average power free-electron lasers (FEL) using superconducting RF (SRF) technology and energy recovery techniques. Between 1999-2001 Jefferson Lab operated the IR Demo FEL. This device produced over 2 kW in the mid-infrared, in addition to producing world record average powers in the visible (50 W), ultraviolet (10 W) and terahertz range (50 W) for tunable, short-pulse (power demonstration of an accelerator configuration that is being exploited for a number of new accelerator-driven light source facilities that are currently under design or construction. The driver accelerator for the IR Demo FEL uses an Energy Recovered Linac (ERL) configuration that improves the energy efficiency and lowers both the capital and operating cost of such devices by recovering most of the power in the spent electron beam after optical power is extracted from the beam. The IR Demo FEL was de-commissioned in late 2001 for an upgraded FEL for extending the IR power to over 10 kW and the ultraviolet power to over 1 kW. The FEL Upgrade achieved 10 kW of average power in the mid-IR (6 microns) in July of 2004, and its IR operation currently is being extended down to 1 micron. In addition, we have demonstrated the capability of on/off cycling and recovering over a megawatt of electron beam power without diminishing machine performance. A complementary UV FEL will come on-line within the next year. This paper presents a summary of the FEL characteristics, user community accomplishments with the IR Demo, and planned user experiments.

James R. Boyce

2006-01-01T23:59:59.000Z

48

Resonant excitation of coherent Cerenkov radiation in dielectric lined waveguides  

Science Conference Proceedings (OSTI)

We report the observation of coherent Cerenkov radiation in the terahertz regime emitted by a relativistic electron pulse train passing through a dielectric lined cylindrical waveguide. We describe the beam manipulations and measurements involved in repetitive pulse train creation including comb collimation and nonlinear optics corrections. With this technique, modes beyond the fundamental are selectively excited by use of the appropriate frequency train. The spectral characterization of the structure shows preferential excitation of the fundamental and of a higher longitudinal mode.

Andonian, G.; Williams, O.; Wei, X.; Niknejadi, P.; Hemsing, E.; Rosenzweig, J. B. [Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, California 90095 (United States); Muggli, P. [University of Southern California, Los Angeles, California 90089 (United States); Babzien, M.; Fedurin, M.; Kusche, K.; Malone, R.; Yakimenko, V. [Accelerator Test Facility, Brookhaven National Laboratory, Upton, New York 11973 (United States)

2011-05-16T23:59:59.000Z

49

Design and High Power Testinng of ITER ECH and CD Transmission Line Components (A26505)  

E-Print Network (OSTI)

Proceedings Of 34th International Conference On Infrared, Millimeter, And Terahertz Waves, Busan, Korea (2009)34th International Conference on Infrared, Millimeter, and Terahertz Waves Busan, UA, 2009999617820

Olstad, R.A.

2009-07-13T23:59:59.000Z

50

High-Power Options for LANSCE  

SciTech Connect

The LANSCE linear accelerator at Los Alamos National Laboratory has a long history of successful beam operations at 800 kW. We have recently studied options for restoration of high-power operations including approaches for increasing the performance to multi-MW levels. In this paper we will discuss the results of this study including the present limitations of the existing accelerating structures at LANSCE, and the high-voltage and RF systems that drive them. Several options will be discussed and a preferred option will be presented that will enable the first in a new generation of scientific facilities for the materials community. The emphasis of this new facility is 'Matter-Radiation Interactions in Extremes' (MaRIE) which will be used to discover and design the advanced materials needed to meet 21st century national security and energy security challenges.

Garnett, Robert W. [Los Alamos National Laboratory

2011-01-01T23:59:59.000Z

51

Water Cooling of High Power Light Emitting Diode Henrik Srensen  

E-Print Network (OSTI)

Water Cooling of High Power Light Emitting Diode Henrik Sørensen Department of Energy Technology and product lifetime. The high power Light Emitting Diodes (LED) belongs to the group of electronics

Sørensen, Henrik

52

Room temperature terahertz polariton emitter  

SciTech Connect

Terahertz (THz) range electroluminescence from intersubband polariton states is observed in the ultra strong coupling regime, where the interaction energy between the collective excitation of a dense electron gas and a photonic mode is a significant portion of the uncoupled excitation energy. The polariton's increased emission efficiency along with a parabolic electron confinement potential allows operation up to room temperature in a nonresonant pumping scheme. This observation of room temperature electroluminescence of an intersubband device in the THz range is a promising proof of concept for more powerful THz sources.

Geiser, Markus; Scalari, Giacomo; Castellano, Fabrizio; Beck, Mattias; Faist, Jerome [Institute for Quantum Electronics, ETH Zurich, Wolfgang-Pauli-Strasse 16, 8093 Zurich (Switzerland)

2012-10-01T23:59:59.000Z

53

A terahertz plasmon cavity detector  

Science Conference Proceedings (OSTI)

Sensitivity of a plasmonic detector is enhanced by integrating a broadband log-periodic antenna with a two-dimensional plasma cavity that is defined by source, drain, and multiple gates of a GaAs/AlGaAs high electron mobility transistor. Both narrow-band terahertz detection and a rich harmonic spectrum are evident. With a bolometric sensor in the channel, we report responsivity, on resonance at 235-240 GHz and at 20 K, of up to 7 kV/W and a noise equivalent power of 5x10{sup -10} W/Hz{sup 1/2}.

Dyer, G. C.; Vinh, N. Q.; Allen, S. J. [Institute for Terahertz Science and Technology, UC Santa Barbara, Santa Barbara, California 93106 (United States); Aizin, G. R.; Mikalopas, J. [Kingsborough College, City University of New York, Brooklyn, New York 11235 (United States); Reno, J. L.; Shaner, E. A. [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States)

2010-11-08T23:59:59.000Z

54

Development of terahertz quantum-cascade lasers  

E-Print Network (OSTI)

The terahertz or the far-infrared frequency range of the electromagnetic spectrum ( ... ) has historically been technologically underdeveloped despite having many potential applications, primarily due to lack of suitable ...

Kumar, Sushil, Ph. D. Massachusetts Institute of Technology

2007-01-01T23:59:59.000Z

55

Retroactive Coherence  

E-Print Network (OSTI)

In gravitational microlensing, interference visibility is established when the spectral resolution of the observation is less than the reciprocal of the time delay difference. Using high resolutionspectroscopy fringes will be visible at large path differences, even when the source emission is incoherent. This is possible because coherence can be established after interference has already occurred. Results of a laboratory test are presented which demonstrate this retroactive establishment of coherence.

J. B. Peterson

2002-03-15T23:59:59.000Z

56

High-Power Plasma Switch for 11.4 GHz Microwave Pulse Compressor  

SciTech Connect

Results obtained in several experiments on active RF pulse compression at X-band using a magnicon as the high-power RF source are presented. In these experiments, microwave energy was stored in high-Q TE01 and TE02 modes of two parallel-fed resonators, and then discharged using switches activated with rapidly fired plasma discharge tubes. Designs and high-power tests of several versions of the compressor are described. In these experiments, coherent pulse superposition was demonstrated at a 5–9 MW level of incident power. The compressed pulses observed had powers of 50–70 MW and durations of 40–70 ns. Peak power gains were measured to be in the range of 7:1–11:1 with efficiency in the range of 50–63%.

Jay L. Hirshfield

2010-03-04T23:59:59.000Z

57

High power, high beam quality regenerative amplifier  

DOE Patents (OSTI)

A regenerative laser amplifier system generates high peak power and high energy per pulse output beams enabling generation of X-rays used in X-ray lithography for manufacturing integrated circuits. The laser amplifier includes a ring shaped optical path with a limited number of components including a polarizer, a passive 90 degree phase rotator, a plurality of mirrors, a relay telescope, and a gain medium, the components being placed close to the image plane of the relay telescope to reduce diffraction or phase perturbations in order to limit high peak intensity spiking. In the ring, the beam makes two passes through the gain medium for each transit of the optical path to increase the amplifier gain to loss ratio. A beam input into the ring makes two passes around the ring, is diverted into an SBS phase conjugator and proceeds out of the SBS phase conjugator back through the ring in an equal but opposite direction for two passes, further reducing phase perturbations. A master oscillator inputs the beam through an isolation cell (Faraday or Pockels) which transmits the beam into the ring without polarization rotation. The isolation cell rotates polarization only in beams proceeding out of the ring to direct the beams out of the amplifier. The diffraction limited quality of the input beam is preserved in the amplifier so that a high power output beam having nearly the same diffraction limited quality is produced.

Hackel, Lloyd A. (Livermore, CA); Dane, Clifford B. (Livermore, CA)

1993-01-01T23:59:59.000Z

58

High power, high beam quality regenerative amplifier  

DOE Patents (OSTI)

A regenerative laser amplifier system generates high peak power and high energy per pulse output beams enabling generation of X-rays used in X-ray lithography for manufacturing integrated circuits. The laser amplifier includes a ring shaped optical path with a limited number of components including a polarizer, a passive 90 degree phase rotator, a plurality of mirrors, a relay telescope, and a gain medium, the components being placed close to the image plane of the relay telescope to reduce diffraction or phase perturbations in order to limit high peak intensity spiking. In the ring, the beam makes two passes through the gain medium for each transit of the optical path to increase the amplifier gain to loss ratio. A beam input into the ring makes two passes around the ring, is diverted into an SBS phase conjugator and proceeds out of the SBS phase conjugator back through the ring in an equal but opposite direction for two passes, further reducing phase perturbations. A master oscillator inputs the beam through an isolation cell (Faraday or Pockels) which transmits the beam into the ring without polarization rotation. The isolation cell rotates polarization only in beams proceeding out of the ring to direct the beams out of the amplifier. The diffraction limited quality of the input beam is preserved in the amplifier so that a high power output beam having nearly the same diffraction limited quality is produced.

Hackel, L.A.; Dane, C.B.

1993-08-24T23:59:59.000Z

59

High power linear pulsed beam annealer  

DOE Patents (OSTI)

A high power pulsed electron beam is produced in a system comprised of an electron gun having a heated cathode, control grid, focus ring, and a curved drift tube. The drift tube is maintained at a high positive voltage with respect to the cathode to accelerate electrons passing through the focus ring and to thereby eliminate space charge. A coil surrounding the curved drift tube provides a magnetic field which maintains the electron beam focused about the axis of the tube and imparts motion on electrons in a spiral path for shallow penetration of the electrons into a target. The curvature of the tube is selected so there is no line of sight between the cathode and a target holder positioned within a second drift tube spaced coaxially from the curved tube. The second tube and the target holder are maintained at a reference voltage that decelerates the electrons. A second coil surrounding the second drift tube maintains the electron beam focused about the axis of the second drift tube and compresses the electron beam to the area of the target. The target holder can be adjusted to position the target where the cross section of the beam matches the area of the target.

Strathman, Michael D. (Concord, CA); Sadana, Devendra K. (Berkeley, CA); True, Richard B. (Sunnyvale, CA)

1983-01-01T23:59:59.000Z

60

Improved Collectors for High Power Gyrotrons  

Science Conference Proceedings (OSTI)

High power gyrotrons are used for electron cyclotron heating, current drive and parasitic mode suppression in tokamaks for fusion energy research. These devices are crucial for successful operation of many research programs around the world, including the ITER program currently being constructed in France. Recent gyrotron failures resulted from cyclic fatigue of the copper material used to fabricated the collectors. The techniques used to collect the spent beam power is common in many gyrotrons produced around the world. There is serious concern that these tubes may also be at risk from cyclic fatigue. This program addresses the cause of the collector failure. The Phase I program successfully demonstrated feasibility of a mode of operation that eliminates the cyclic operation that caused the failure. It also demonstrated that new material can provide increased lifetime under cyclic operation that could increase the lifetime by more than on order of magnitude. The Phase II program will complete that research and develop a collector that eliminates the fatigue failures. Such a design would find application around the world.

R. Lawrence Ives, Amarjit Singh, Michael Read, Philipp Borchard, Jeff Neilson

2009-05-20T23:59:59.000Z

Note: This page contains sample records for the topic "high-power coherent terahertz" 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

Resonant terahertz radiation from layered superconductors: mechanisms of damping and structure of dynamic states.  

SciTech Connect

Intrinsic Josephson-junction stacks realized in high-temperature superconductors may generate powerful electromagnetic radiation in terahertz frequency range. A major challenge is to synchronize phase oscillations in many junctions. A promising way of efficient synchronization is to excite an internal cavity mode, with the frequency set by the stack lateral size. We discuss several issues relevant for this mechanism: (i) damping of the resonance mode due to radiation into free space and into the base crystal, (ii) mechanisms of coupling to the internal mode, (iii) structures and stability of coherent states.

Koshelev, A. E.; Bulaevskii, L. N.; Materials Science Division; LANL

2009-01-01T23:59:59.000Z

62

High-power semiconductor separate-confinement double heterostructure lasers  

Science Conference Proceedings (OSTI)

The review is devoted to high-power semiconductor lasers. Historical reference is presented, physical and technological foundations are considered, and the concept of high-power semiconductor lasers is formulated. Fundamental and technological reasons limiting the optical power of a semiconductor laser are determined. The results of investigations of cw and pulsed high-power semiconductor lasers are presented. Main attention is paid to inspection of the results of experimental studies of single high-power semiconductor lasers. The review is mainly based on the data obtained in the laboratory of semiconductor luminescence and injection emitters at the A.F. Ioffe Physicotechnical Institute. (review)

Tarasov, I S [A.F. Ioffe Physical-Technical Institute, Russian Academy of Sciences, St. Petersburg (Russian Federation)

2010-10-15T23:59:59.000Z

63

High Power Performance Lithium Ion Battery - Energy Innovation Portal  

... “Optimization of Acetylene Black Conductive Additive and Polyvinylidene Fluoride Composition for high Power Rechargeable Lithium-Ion Cells,” The 211th ...

64

Available Technologies: High Power Performance Lithium Ion Battery  

Cell 1, which has the highest binder (PVDF) to acetylene black ratio, displays the most favorable discharge ASI. Lithium ion batteries with high power ...

65

Device Fabrication Method for High Power Density Capacitors  

Device Fabrication Method for High Power Density Capacitors Note: The technology described above is an early stage opportunity. Licensing rights to this intellectual ...

66

Diagnostics and steady-state high power operation  

Science Conference Proceedings (OSTI)

TORE SUPRA has now been upgraded to handle high power plasmas for very long duration. It came back into operation in 2001

Clément Laviron; and the Tore Supra Team

2003-01-01T23:59:59.000Z

67

Coherence and Linewidth Studies of a 4-nm High Power FEL  

E-Print Network (OSTI)

USA Abstract Recently the SSRL/SLAC and its collaboratorsavailable. Recently workers at SSRL/SLAC and collaborators

Fawley, W.M.

2008-01-01T23:59:59.000Z

68

Functionalized High Voltage Spinel Composite for High Power ...  

Science Conference Proceedings (OSTI)

Recently, spinel LiNi0.5Mn1.5O4 with high working voltage and long cycle life makes it become the one of most promising cathode for high power delivery.

69

High Power Superconducting Continuous Wave Linacs for Protons...  

Office of Science (SC) Website

(ANL) Developed in: Current Result of NP research: Spin-off of high power driver linac R&D for the FRIB project Application currently being supported by: DOE Office of Nuclear...

70

High Frequency High Power RF Generation using a Relativistic...  

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

FREQUENCY HIGH POWER RF GENERATION USING A RELATIVISTIC ELECTRON BEAM C. Jing , S. Antipov, P. Schoessow, and A. Kanareykin, Euclid Techlabs LLC, Solon, OH-44139 J.G. Power, M....

71

Quasi-optical mode converter for high power gyrotron  

Science Conference Proceedings (OSTI)

Gyrotrons are microwave / millimeter wave devices capable to deliver megawatt level continuous power at a frequency range up to 170GHz. The critical design issues for a high power gyrotrons are: (1) Magnetron injection Gun (2) Cavity with proper mode ...

B. K. Shukla; Dhiraj Bora

2011-02-01T23:59:59.000Z

72

Innovative fuel designs for high power density pressurized water reactor  

E-Print Network (OSTI)

One of the ways to lower the cost of nuclear energy is to increase the power density of the reactor core. Features of fuel design that enhance the potential for high power density are derived based on characteristics of ...

Feng, Dandong, Ph. D. Massachusetts Institute of Technology

2006-01-01T23:59:59.000Z

73

Design of annular fuel for high power density BWRs  

E-Print Network (OSTI)

Enabling high power density in the core of Boiling Water Reactors (BWRs) is economically profitable for existing or new reactors. In this work, we examine the potential for increasing the power density in BWR plants by ...

Morra, Paolo

2005-01-01T23:59:59.000Z

74

High Power Electrodynamics (HPE): Accelerator Operations and Technology,  

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

CONTACTS CONTACTS Group Leader Bruce Carlsten Deputy Group Leader Ellen Guenette Administrator Josephine (Jo) Torres High-Power Electrodynamics (HPE) The High-Power Electrodynamics (AOT-HPE) Group applies accelerator and beam technologies to national-security-directed energy missions. AOT-HPE has three programmatic thrusts: free-electron lasers (FELs), high-power microwaves (HPM), and compact radiography. To maintain a vigorous and robust technical base for addressing DOE and DoD needs, the group's project portfolio is balanced between exploratory research, infrastructure development, and programmatic deliverables for sponsors. Funding is roughly 25% from the Lab's Directed Research and Development Program, 65% from DoD, and 10% from DOE. Technology Focus Areas AOT-HPE is the Laboratory's main vehicle for applying accelerator-based technologies to directed-energy mission needs. The group recognizes that many directed-energy missions are enabled by compact high-brightness electron accelerators and mm-wave and THz technologies.

75

Ultra high vacuum broad band high power microwave window  

DOE Patents (OSTI)

An improved high vacuum microwave window has been developed that utilizes high density polyethylene coated on two sides with SiOx, SiNx, or a combination of the two. The resultant low dielectric and low loss tangent window creates a low outgassing, low permeation seal through which broad band, high power microwave energy may be passed. No matching device is necessary and the sealing technique is simple. The features of the window are broad band transmission, ultra-high vacuum compatibility with a simple sealing technique, low voltage standing wave ratio, high power transmission and low cost.

Nguyen-Tuong, Viet (Seaford, VA); Dylla, III, Henry Frederick (Yorktown, VA)

1997-01-01T23:59:59.000Z

76

Ultra high vacuum broad band high power microwave window  

DOE Patents (OSTI)

An improved high vacuum microwave window has been developed that utilizes high density polyethylene coated on two sides with SiOx, SiNx, or a combination of the two. The resultant low dielectric and low loss tangent window creates a low outgassing, low permeation seal through which broad band, high power microwave energy may be passed. No matching device is necessary and the sealing technique is simple. The features of the window are broad band transmission, ultra-high vacuum compatibility with a simple sealing technique, low voltage standing wave ratio, high power transmission and low cost. 5 figs.

Nguyen-Tuong, V.; Dylla, H.F. III

1997-11-04T23:59:59.000Z

77

Emission of coherent THz-radiation from superconductors.  

Science Conference Proceedings (OSTI)

Compact solid-state sources of terahertz (THz) radiation are being sought for sensing, imaging, and spectroscopy applications across the physical and biological sciences. We demonstrate that coherent continuous-wave THz radiation of sizable power can be extracted from intrinsic Josephson junctions in the layered high-temperature superconductor Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}. In analogy to a laser cavity, the excitation of an electromagnetic cavity resonance inside the sample generates a macroscopic coherent state in which a large number of junctions are synchronized to oscillate in phase. The emission power is found to increase as the square of the number of junctions reaching values of 0.5 microwatt at frequencies up to 0.85 THz, and persists up to 50 kelvin. These results should stimulate the development of superconducting compact sources of THz radiation.

Ozyuzer, L.; Koshelev, A. E.; Kurter, C.; Gopalsami, N.; Li, Q.; Tachiki, M.; Kadowaki, K.; Yamamoto, T.; Minami, H.; Yamaguchi, H.; Tachiki, T.; Gray, K. E.; Kwok, W.- K.; Welp, U.; Izmir Inst. Tech.; Illinois Inst. Tech.; Univ. Tokyo; Univ. Tsukuba; Nat. Defence Academy

2007-11-23T23:59:59.000Z

78

Using a Balun Transformer Combiner for High Power Microwave Experiments  

Science Conference Proceedings (OSTI)

A novel coaxial power combiner design has been duplicated that has distinct advantages over other combiner geometries that can handle high power. This design is being applied to combine four 3 kW power supplies to obtain a 10 kW, 5 MHz system for an ICRF antenna on HSX. In the past, Wilkinson type combiners have had limited application to high power systems because of the lack of non-inductive, high power, 100 Omega balance loads. With this new design, standard 50 Omega dummy loads can be used instead for the balance load. The cost is considerably lower than lumped element combiner designs which are dominated by capacitor costs. At such a relatively low frequency, a 3-dB quarter-wave coupled-line coupler becomes impractically long, and a conventional branch-line hybrid requires 35 Omega-line, which is commercially unavailable. The balun combiner uses less transmission line than a ring hybrid and has good bandwidth characteristics even away from its best line impedance. Theoretical calculations and modeling were performed for line impedances from 65 Omega to 75 Omega. Measurements from a low-power test device show excellent agreement with theory, and construction of the high power system is underway.

Kaufman, Michael C [ORNL; Pesavento, Philip V [ORNL

2011-01-01T23:59:59.000Z

79

Thin liquid lithium targets for high power density  

E-Print Network (OSTI)

Thin liquid lithium targets for high power density applications: heavy ion beam strippers and beta Hilton Malmö City #12;Outline Liquid Lithium Stripper idea for FRIB Brief theory of film stability Thickness measurement results Next Steps Beta-beams 2 #12;Liquid Lithium Stripper for FRIB: Advantages

McDonald, Kirk

80

Transmutation and energy-production with high power accelerators  

SciTech Connect

Accelerator-driven transmutation offers attractive new solutions to complex nuclear problems. This paper outlines the basics of the technology, summarizes the key application areas, and discusses designs of and performance issues for the high-power proton accelerators that are required.

Lawrence, G.P.

1995-07-01T23:59:59.000Z

Note: This page contains sample records for the topic "high-power coherent terahertz" 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

A high-power L-band RF window  

E-Print Network (OSTI)

June. 2001. [3] "700 MHz Window R&D at LBNL", R. Rimmer et.Testing of PEP-II RF Cavity Windows", M. Neubauer et. al. ,A HIGH-POWER L-BAND RF WINDOW* R.A. Rimmer † , G. Koehler,

2001-01-01T23:59:59.000Z

82

Low cost high power GaSB photovoltaic cells  

Science Conference Proceedings (OSTI)

High power density and high capacity factor are important attributes of a thermophotovoltaics (TPV) system and GaSb cells are enabling for TPV systems. A TPV cogeneration unit at an off grid site will compliment solar arrays producing heat and electricity on cloudy days with the solar arrays generating electricity on sunny days. Herein

Lewis M. Fraas; Han X. Huang; Shi-Zhong Ye; She Hui; James Avery; Russell Ballantyne

1997-01-01T23:59:59.000Z

83

Low cost high power GaSb thermophotovoltaic cells  

Science Conference Proceedings (OSTI)

High power density and high capacity factor are important attributes of a TPV system and GaSb cells are enabling for TPV systems. A TPV cogeneration unit at an off grid site will compliment solar arrays producing heat and electricity on cloudy days with the solar arrays generating electricity on sunny days. Herein

Lewis M. Fraas; Han X. Huang; Shi-Zhong Ye; James Avery; Russell Ballantyne

1997-01-01T23:59:59.000Z

84

High power light emitting diode based setup for photobleaching fluorescent impurities  

E-Print Network (OSTI)

High power light emitting diode based setup for photobleaching fluorescent impurities Tobias K be photobleached before final sample preparation. The instrument consists of high power light emitting diodes

Kaufman, Laura

85

High Power Microwave Switch Employing Electron Beam Triggering  

Science Conference Proceedings (OSTI)

A new type of switch for modulation of the Q-factor of a multi-mode storage resonator in a high-power active microwave pulse compressor is described. The operating principle of the switch is based on a sharp increase in the TE{sub 02{yields}}TE{sub 01} coupling coefficient, when an electron beam is injected into the switch cavity. The switch was tested at low power level in a compressor operated at X-band. A power gain of 19-20 in the compressed pulse with pulse duration of 40-50 ns was achieved. The proposed switch shows good prospects for use in high-power active pulse compressors.

Ivanov, O. A.; Vikharev, A. L. [Institute of Applied Physics RAS, Nizhny Novgorod, 603600 (Russian Federation); Omega-P, Inc., New Haven, Connecticut 06510 (United States); Isaev, V. A.; Lobaev, M. A. [Institute of Applied Physics RAS, Nizhny Novgorod, 603600 (Russian Federation); Hirshfield, J. L. [Omega-P, Inc., New Haven, Connecticut 06510 (United States); Department of Physics, Yale University, New Haven, Connecticut 06511 (United States)

2010-11-04T23:59:59.000Z

86

High Power Superconducting Continuous Wave Linacs for Protons and  

Office of Science (SC) Website

Power Superconducting Continuous Power Superconducting Continuous Wave Linacs for Protons and Heavy-Ions Nuclear Physics (NP) NP Home About Research Facilities Science Highlights Benefits of NP Spinoff Applications Spinoff Archives SBIR/STTR Applications of Nuclear Science and Technology Funding Opportunities Nuclear Science Advisory Committee (NSAC) News & Resources Contact Information Nuclear Physics U.S. Department of Energy SC-26/Germantown Building 1000 Independence Ave., SW Washington, DC 20585 P: (301) 903-3613 F: (301) 903-3833 E: sc.np@science.doe.gov More Information » Spinoff Archives High Power Superconducting Continuous Wave Linacs for Protons and Heavy-Ions Print Text Size: A A A RSS Feeds FeedbackShare Page Application/instrumentation: High Power Superconducting Continuous Wave Linacs for Protons and Heavy-Ions

87

Understanding High-Power Fiber-Optic Laser Beam Delivery  

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

High-Power Fiber-Optic Laser Beam Delivery High-Power Fiber-Optic Laser Beam Delivery The submitted manuscript has been authored by a contractor of the U.S. Government under contract No. W- 31-109-ENG-38. Accordingly, the U.S. Government retains a nonexclusive, royalty-free license to publish or reproduce the published form of this contribution, or allow others to do so, for U.S. Government purposes. Boyd V. Hunter and Keng H. Leong Argonne National Laboratory Technology Development Division Laser Applications Laboratory 9700 South Cass Avenue, Building 207 Argonne, Illinois 60439 Carl B. Miller, James F. Golden, Robert D. Glesias and Patrick J. Laverty U. S. Laser Corporation 825 Windham Court North P. O. Box 609 Wyckoff, New Jersey 07481 March 25, 1996 Manuscript to be submitted to Journal of Laser Applications

88

High-power regenerative Nd-phosphate glass amplifier  

Science Conference Proceedings (OSTI)

A compact high-power regenerative Nd-phosphate glass amplifier is described which incorporates spatial filtering and full image relay techniques. Output energies up to 1.2 J at a pulse duration of 140 +- 10 psec (FWHM) and 3 J at 900 +- 70 psec (FWHM) are achieved in a smooth nearly flattop beam intensity profile. Even with present-day technology, this system could be scaled into a terawatt regime.

Roschger, E.W.; Balmer, J.E.

1985-09-15T23:59:59.000Z

89

Towards Quantitative Simulations of High Power Proton Cyclotrons  

E-Print Network (OSTI)

PSI operates a cyclotron based high intensity proton accelerator routinely at an average beam power of 1.3MW. With this power the facility is at the worldwide forefront of high intensity proton accelerators. The beam current is practically limited by losses at extraction and the resulting activation of accelerator components. Further intensity upgrades and new projects aiming at an even higher average beam power, are only possible if the relative losses can be lowered in proportion, thus keeping absolute losses at a constant level. Maintaining beam losses at levels allowing hands-on maintenance is a primary challenge in any high power proton machine design and operation. In consequence, predicting beam halo at these levels is a great challenge and will be addressed in this paper. High power hadron driver have being used in many disciplines of science and, a growing interest in the cyclotron technology for high power hadron drivers are being observed very recently. This report will briefly introduce OPAL, a tool for precise beam dynamics simulations including 3D space charge. One of OPAL's flavors (OPAL-cycl) is dedicated to high power cyclotron modeling and is explained in greater detail. We then explain how to obtain initial conditions for our PSI Ring cyclotron which still delivers the world record in beam power of 1.3 MW continuous wave (cw). Several crucial steps are explained necessary to be able to predict tails at the level of 3\\sigma ... 4\\sigma in the PSI Ring cyclotron. We compare our results at the extraction with measurements, obtained with a 1.18 MW cw production beam. Based on measurement data, we develop a simple linear model to predict beam sizes of the extracted beam as a function of intensities and confirm the model with simulations.

Y. J. Bi; A. Adelmann; R. Dölling; M. Humbel; W. Joho; M. Seidel; T. J. Zhang

2010-12-03T23:59:59.000Z

90

Method and apparatus for tuning high power lasers  

DOE Patents (OSTI)

This invention relates to high power gas lasers that are adapted to be tuned to a desired lasing wavelength through the use of a gas cell to lower the gain at a natural lasing wavelength and "seeding" the laser with a beam from a low power laser which is lasing at the desired wavelength. This tuning is accomplished with no loss of power and produces a pulse with an altered pulse shape. It is potentially applicable to all gas lasers.

Hutchinson, Donald P. (Knoxville, TN); Vandersluis, Kenneth L. (Oak Ridge, TN)

1977-04-19T23:59:59.000Z

91

Active high-power RF switch and pulse compression system  

DOE Patents (OSTI)

A high-power RF switching device employs a semiconductor wafer positioned in the third port of a three-port RF device. A controllable source of directed energy, such as a suitable laser or electron beam, is aimed at the semiconductor material. When the source is turned on, the energy incident on the wafer induces an electron-hole plasma layer on the wafer, changing the wafer's dielectric constant, turning the third port into a termination for incident RF signals, and. causing all incident RF signals to be reflected from the surface of the wafer. The propagation constant of RF signals through port 3, therefore, can be changed by controlling the beam. By making the RF coupling to the third port as small as necessary, one can reduce the peak electric field on the unexcited silicon surface for any level of input power from port 1, thereby reducing risk of damaging the wafer by RF with high peak power. The switch is useful to the construction of an improved pulse compression system to boost the peak power of microwave tubes driving linear accelerators. In this application, the high-power RF switch is placed at the coupling iris between the charging waveguide and the resonant storage line of a pulse compression system. This optically controlled high power RF pulse compression system can handle hundreds of Megawatts of power at X-band.

Tantawi, Sami G. (San Mateo, CA); Ruth, Ronald D. (Woodside, CA); Zolotorev, Max (Mountain View, CA)

1998-01-01T23:59:59.000Z

92

Terahertz imaging and quantum cascade laser based devices  

E-Print Network (OSTI)

The terahertz (THz) frequency range (f=0.3-10 THz, [lambda]=30-1000 lam) is much less technologically developed that the adjacent microwave and infrared frequency ranges, but offers several advantages for imaging applications: ...

Lee, Alan Wei Min

2010-01-01T23:59:59.000Z

93

Characterization and analysis of highly diagonal Terahertz Quantum Cascade Lasers  

E-Print Network (OSTI)

The as yet unattained milestone of room-temperature operation is essential for establishing Terahertz Quantum Cascade Lasers (THz QCLs) as practical sources of THz radiation. Temperature performance is hypothesized to be ...

Chan, Chun Wang Ivan

2010-01-01T23:59:59.000Z

94

Development of tunable terahertz quantum cascade wire lasers  

E-Print Network (OSTI)

For a long time, terahertz (THz) radiation has been of great interest to scientific community because of its spectroscopic and imaging applications based on its unique properties, such as the capabilities to penetrate many ...

Qin, Qi, Ph. D. Massachusetts Institute of Technology

2012-01-01T23:59:59.000Z

95

High power variable couplers for ladder and spoke type resonators  

Science Conference Proceedings (OSTI)

Superconducting RF structures such as spoke resonators [1] have been developed which will accelerate very low velocity ions. This opens up the possibility for the use of these resonators in high power proton accelerators at energies as low as the output energies of typical RFQs. Most similar resonators have been used for the acceleration of ions requiring only low RF power input. In new applications such as for the Accelerator Transmutation of Nuclear Wastes (ATW) and Accelerator Production of Tritium (APT), higher RF power will be required because of the larger beam currents. This paper discusses some higher power variable coupler concepts that could be used with these structures.

Spalek, G. (George); Kuzminski, J. (Jozef)

2001-01-01T23:59:59.000Z

96

High-Power Microwave Switch Employing Electron Beam Triggering  

Science Conference Proceedings (OSTI)

A high-power active microwave pulse compressor is described that modulates the quality factor Q of the energy storage cavity by a new means involving mode conversion controlled by a triggered electron-beam discharge through a switch cavity. The electron beam is emitted from a diamond-coated molybdenum cathode. This report describes the principle of operation, the design of the switch, the configuration used for the test, and the experimental results. The pulse compressor produced output pulses with 140 - Ã?Â?165 MW peak power, power gain of 16 - 20, and pulse duration of 16 - 20 ns at a frequency of 11.43 GHz.

Jay L. Hirshfield

2012-09-19T23:59:59.000Z

97

Organic nonlinear crystals and high power frequency conversion  

SciTech Connect

We are searching for a new second- and third-harmonic generators among the salts of chiral organic acids and bases. We discuss the relevant properties of crystals from this group of compounds, including their nonlinear and phasematching characteristics, linear absorption, damage threshold and crystal growth. In addition, we summarize what is known concerning other nonlinear optical properties of these crystals, such as two-photon absorption, nonlinear refractive index, and stimulated Raman thresholds. A preliminary assessment is made of the potential of these materials for use in future high power, large aperture lasers such as those used for inertial confinement fusion experiments. 14 refs., 1 fig., 3 tabs.

Velsko, S.P.; Davis, L.; Wang, F.; Monaco, S.; Eimerl, D.

1987-12-01T23:59:59.000Z

98

High-power pulse modulator with ignitron discharger  

SciTech Connect

The high-power pulse modulator described here is used to produce spatial gaseous discharges and has an improved, controllable charging circuit, which permits a type ITR-4 ignitron discharger to be employed in a frequency mode as the basic commutator. The modulator is utilized in two modes: at a pulse repetition frequency of 50 Hz pulses are formed that have a duration of 25 usec and energies up to 3.5 kJ and at a frequency of 200 Hz, the pulses have a duration of -2 usec and energies up to 600 J. In all conditions the modulator operated stably with a wide range of load changes.

Anisimova, T.E.; Akkuratov, E.V.; Artemov, V.A.; Gromovenko, V.M.; Kalinin, V.P.; Nikonov, V.P.

1985-10-01T23:59:59.000Z

99

Visualization of patents and papers in terahertz technology: a comparative study  

Science Conference Proceedings (OSTI)

Terahertz technology is one of the most promising research areas in the 21st century. In this work, we intend to compare the research status quo on terahertz technology between 1990 and 2010 using knowledge domain visualization techniques. Our data consists ... Keywords: Aureka, CiteSpace, Patent, Scientometrics, Terahertz, Thomson innovation, Visualization

Guifeng Liu

2013-03-01T23:59:59.000Z

100

Application of High Powered Lasers to Perforated Completions  

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

Congress on Applications of Laser & Electro-Optics Congress on Applications of Laser & Electro-Optics October 13 - 16, 2003, Jacksonville, Florida Application of High Powered Lasers to Perforated Completions Zhiyue Xu, Claude B. Reed and Keng H. Leong Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 R. A. Parker Parker Geoscience Consulting, LLC, 6346 Secrest Street, Arvada, CO 80403 R. M. Graves, Petroleum Engineering Department, Colorado School of Mines, Golden, CO 80401 ABSTRACT As part of the process of drilling an oil or gas well, a steel production casing is often inserted to the bottom of the well and sealed with cement against the productive formation. Openings must be made through the steel casing wall and cement and into the rock formation to allow formation fluid to enter the well. Conventionally, a perforator is

Note: This page contains sample records for the topic "high-power coherent terahertz" 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

Computer Study of Isotope Production in High Power Accelerators  

E-Print Network (OSTI)

Methods for radionuclide production calculation in a high power proton accelerator have been developed and applied to study production of 22 isotopes by high-energy protons and neutrons. These methods are readily applicable to accelerator, and reactor, environments other than the particular model we considered and to the production of other radioactive and stable isotopes. We have also developed methods for evaluating cross sections from a wide variety of sources into a single cross section set and have produced an evaluated library covering about a third of all natural elements. These methods also are applicable to an expanded set of reactions. A 684 page detailed report on this study, with 37 tables and 264 color figures is available on the Web at http://t2.lanl.gov/publications/publications.html, or, if not accessible, in hard copy from the authors.

Van Riper, K A; Wilson, W B

1999-01-01T23:59:59.000Z

102

High power windows for WR650 waveguide couplers  

Science Conference Proceedings (OSTI)

Based on the robust, pre-stressed planar window concept successfully tested for PEP II and LEDA, a new design for planar ceramic windows to be used with WR650 waveguide fundamental power couplers at 1300 MHz or 1500 MHz has been developed. These windows should operate in pulsed or CW mode and sustain at least 100 kW average power levels. This paper describes an overview of the simulations performed to match the ceramics in WR650 waveguides, design details, as well as the RF measurements and performance assessed by RF power tests on several high power windows manufactured at JLAB. Funding Agency: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, and by The Office of Naval Research under contract to the Dept. of Energy.

Mircea Stirbet; Robert Rimmer; Thomas Elliott; Edward Daly; Katherine Wilson; Lynn Vogel; Haipeng Wang; Brian Carpenter; Karl Smith; Thomas Powers; Michael Drury; Robert Nichols; G. Davis

2007-06-01T23:59:59.000Z

103

High Power SiC Modules for HEVs and PHEVs  

DOE Green Energy (OSTI)

With efforts to reduce the cost, size, and thermal management systems for the power electronics drivetrain in hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs), wide band gap semiconductors including silicon carbide (SiC) have been identified as possibly being a partial solution. Research on SiC power electronics has shown their higher efficiency compared to Si power electronics due to significantly lower conduction and switching losses. This paper focuses on the development of a high power module based on SiC JFETs and Schottky diodes. Characterization of a single device, a module developed using the same device, and finally an inverter built using the modules is presented. When tested at moderate load levels compared to the inverter rating, an efficiency of 98.2% was achieved by the initial prototype.

Chinthavali, Madhu Sudhan [ORNL; Tolbert, Leon M [ORNL; Zhang, Hui [ORNL; Han, Jung H [ORNL; Barlow, Fred D. [University of Idaho; Ozpineci, Burak [ORNL

2010-01-01T23:59:59.000Z

104

Zero-switching-loss inverters for high-power applications  

SciTech Connect

The development of zero-switching-loss inverters has attracted much interest for industrial applications. The resonant dc link inverter (RDCLI) provides a simple and robust approach for realizing switching frequencies >20 kHz in multi-kilowatt systems but impresses substantial voltage stress (-- 2.5 supply voltage) across the devices. Two alternate topologies for realizing zero switching losses in high-power converters are proposed. The actively clamped resonant dc-link inverter (ACRLI) uses the concept of a lossless active clamp to restrict voltage stresses to only 1.3-1.5 supply voltage (V/sub s/) while maintaining a mode of operation similar to the RDCLI. For applications demanding substantially superior spectral performance, the resonant pole inverter (RPI), also called the quasi-resonant current mode inverter (QRCMI), is proposed as a viable topology. Detailed analysis, simulation, and experimental results are presented to verify operation principles of both power converters.

Divan, D.M.; Skibinski, G. (Wisconsin Univ., Madison, WI (USA). Dept. of Electrical and Computer Engineering)

1989-07-01T23:59:59.000Z

105

Computer Study of Isotope Production in High Power Accelerators  

E-Print Network (OSTI)

Methods for radionuclide production calculation in a high power proton accelerator have been developed and applied to study production of 22 isotopes by high-energy protons and neutrons. These methods are readily applicable to accelerator, and reactor, environments other than the particular model we considered and to the production of other radioactive and stable isotopes. We have also developed methods for evaluating cross sections from a wide variety of sources into a single cross section set and have produced an evaluated library covering about a third of all natural elements. These methods also are applicable to an expanded set of reactions. A 684 page detailed report on this study, with 37 tables and 264 color figures is available on the Web at http://t2.lanl.gov/publications/publications.html, or, if not accessible, in hard copy from the authors.

K. A. Van Riper; S. G. Mashnik; W. B. Wilson

1999-01-25T23:59:59.000Z

106

High power battery test methods for hybrid vehicle applications  

DOE Green Energy (OSTI)

Commonly used EV battery tests are not very suitable for testing hybrid vehicle batteries, which may be primarily intended to supply vehicle acceleration power. The capacity of hybrid vehicle batteries will be relatively small, they will typically operate over a restricted range of states-of-charge, and they may seldom if ever be fully recharged. Further, hybrid propulsion system designs will commonly impose a higher regeneration content than is typical for electric vehicles. New test methods have been developed for use in characterizing battery performance and life for hybrid vehicle use. The procedures described in this paper were developed from the requirements of the government-industry cooperative Partnership for A New Generation of Vehicles (PNGV) program; however, they are expected to have broad application to the testing of energy storage devices for hybrid vehicles. The most important performance measure for a high power battery is its pulse power capability as a function of state-of-charge for both discharge and regeneration pulses. It is also important to characterize cycle life, although the {open_quote}cycles{close_quote} involved are quite different from the conventional full-discharge, full-recharge cycle commonly used for EV batteries, This paper illustrates in detail several test profiles which have been selected for PNGV battery testing, along with some sample results and lessons learned to date from the use of these test profiles. The relationship between the PNGV energy storage requirements and these tests is described so that application of the test methods can be made to other hybrid vehicle performance requirements as well. The resulting test procedures can be used to characterize the pulse power capability of high power energy storage devices including batteries and ultracapacitors, as well as the life expectancy of such devices, for either power assist or dual mode hybrid propulsion system designs.

Hunt, G.L.; Haskins, H.; Heinrich, B.; Sutula, R.

1997-11-01T23:59:59.000Z

107

Coherence-Enhanced Lasing  

E-Print Network (OSTI)

Quantum coherence and interference effects in atomic and molecular physics has been extensively studied due to intriguing counterintuitive physics and potential important applications. In this paper we studied one such scenario of using quantum coherence to generate and enhanced gain in extreme ultra-violet(XUV)(@58.4nm in Helium) and infra-red(@794.76nm in Rubidium) regime of electromagnetic radiation. We show that using moderate external coherent drive, a substantial enhancement in the energy of the lasing pulse can be achieved under optimal conditions. The role of coherence is also discussed here.

Jha, Pankaj K

2013-01-01T23:59:59.000Z

108

The Development of low cost LiFePO4-based high power lithium...  

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

Development of low cost LiFePO4-based high power lithium-ion batteries Title The Development of low cost LiFePO4-based high power lithium-ion batteries Publication Type Journal...

109

Geophysical Applications of Partial Wavelet Coherence and Multiple Wavelet Coherence  

Science Conference Proceedings (OSTI)

In this paper, the application of partial wavelet coherence (PWC) and multiple wavelet coherence (MWC) to geophysics is demonstrated. PWC is a technique similar to partial correlation that helps identify the resulting wavelet coherence (WTC) ...

Eric K. W. Ng; Johnny C. L. Chan

2012-12-01T23:59:59.000Z

110

Argonne National Laboratory Terahertz- and Millimeter-Wave Test Facility  

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

PROFILE: PROFILE: Argonne Homeland Security Technologies APPLICATIONS A R G O N N E N A T I O N A L L A B O R A T O R Y Terahertz- and Millimeter-Wave Test Facility B E N E F I T S Detect Terrorist-Related Contraband with Terahertz Technology * Spectral "fingerprints" uniquely identify materials * Can identify the factory where explosives and other chemicals were manufactured * Detects minute amounts of chemicals from a distance * Identifies materials in seconds Companies that develop or manufacture instruments to detect terrorist contraband can benefit by using a unique facility at the U.S. Department of Energy's Argonne National Laboratory. Called the Terahertz Test Facility, its sensitive, new instruments - developed at Argonne and available nowhere else in the world - can obtain spectral "fingerprints" that uniquely

111

Generating Periodic Terahertz Structures in a Relativistic Electron Beam through Frequency Down-Conversion of Optical Lasers  

SciTech Connect

We report generation of density modulation at terahertz (THz) frequencies in a relativistic electron beam through laser modulation of the beam longitudinal phase space. We show that by modulating the energy distribution of the beam with two lasers, density modulation at the difference frequency of the two lasers can be generated after the beam passes through a chicane. In this experiment, density modulation around 10 THz was generated by down-converting the frequencies of an 800 nm laser and a 1550 nm laser. The central frequency of the density modulation can be tuned by varying the laser wavelengths, beam energy chirp, or momentum compaction of the chicane. This technique can be applied to accelerator-based light sources for generation of coherent THz radiation and marks a significant advance toward tunable narrow-band THz sources.

Dunning, Michael

2012-07-19T23:59:59.000Z

112

Advanced, High Power, Next Scale, Wave Energy Conversion Device  

SciTech Connect

The project conducted under DOE contract DE?EE0002649 is defined as the Advanced, High Power, Next Scale, Wave Energy Converter. The overall project is split into a seven?stage, gated development program. The work conducted under the DOE contract is OPT Stage Gate III work and a portion of Stage Gate IV work of the seven stage product development process. The project effort includes Full Concept Design & Prototype Assembly Testing building on our existing PowerBuoy? technology to deliver a device with much increased power delivery. Scaling?up from 150kW to 500kW power generating capacity required changes in the PowerBuoy design that addressed cost reduction and mass manufacturing by implementing a Design for Manufacturing (DFM) approach. The design changes also focused on reducing PowerBuoy Installation, Operation and Maintenance (IO&M) costs which are essential to reducing the overall cost of energy. In this design, changes to the core PowerBuoy technology were implemented to increase capability and reduce both CAPEX and OPEX costs. OPT conceptually envisaged moving from a floating structure to a seabed structure. The design change from a floating structure to seabed structure would provide the implementation of stroke? unlimited Power Take?Off (PTO) which has a potential to provide significant power delivery improvement and transform the wave energy industry if proven feasible.

Mekhiche, Mike [Principal Investigator] [Principal Investigator; Dufera, Hiz [Project Manager] [Project Manager; Montagna, Deb [Business Point of Contact] [Business Point of Contact

2012-10-29T23:59:59.000Z

113

Development of a high-power lithium-ion battery.  

DOE Green Energy (OSTI)

Safety is a key concern for a high-power energy storage system such as will be required in a hybrid vehicle. Present lithium-ion technology, which uses a carbon/graphite negative electrode, lacks inherent safety for two main reasons: (1) carbon/graphite intercalates lithium at near lithium potential, and (2) there is no end-of-charge indicator in the voltage profile that can signal the onset of catastrophic oxygen evolution from the cathode (LiCoO{sub 2}). Our approach to solving these safety/life problems is to replace the graphite/carbon negative electrode with an electrode that exhibits stronger two-phase behavior further away from lithium potential, such as Li{sub 4}Ti{sub 5}O{sub 12}. Cycle-life and pulse-power capability data are presented in accordance with the Partnership for a New Generation of Vehicles (PNGV) test procedures, as well as a full-scale design based on a spreadsheet model.

Jansen, A. N.

1998-09-02T23:59:59.000Z

114

Discharge Physics of High Power Impulse Magnetron Sputtering  

SciTech Connect

High power impulse magnetron sputtering (HIPIMS) is pulsed sputtering where the peak power exceeds the time-averaged power by typically two orders of magnitude. The peak power density, averaged over the target area, can reach or exceed 107 W/m2, leading to plasma conditions that make ionization of the sputtered atoms very likely. A brief review of HIPIMS operation is given in a tutorial manner, illustrated by some original data related to the self-sputtering of niobium in argon and krypton. Emphasis is put on the current-voltage-time relationships near the threshold of self-sputtering runaway. The great variety of current pulse shapes delivers clues on the very strong gas rarefaction, self-sputtering runaway conditions, and the stopping of runaway due to the evolution of atom ionization and ion return probabilities as the gas plasma is replaced by metal plasma. The discussions are completed by considering instabilities and the special case of ?gasless? self-sputtering.

Anders, Andre

2010-10-13T23:59:59.000Z

115

RF coupler for high-power CW FEL photoinjector  

SciTech Connect

A high-current emittance-compensated RF photoinjector is a key enabling technology for a high-power CW FEL. The design presently under way is a 100-mA 2.5-cell {pi}-mode, 700-MHz, normal conducting demonstration CW RF photoinjector. This photoinjector will be capable of accelerating 3 nC per bunch with an emittance at the wiggler less than 10 mm-mrad. The paper presents results for the RF coupling from ridged wave guides to hte photoinjector RF cavity. The LEDA and SNS couplers inspired this 'dog-bone' design. Electromagnetic modeling of the coupler-cavity system has been performed using both 2-D and 3-D frequency-domain calculations, and a novel time-domain approach with MicroWave Studio. These simulations were used to adjust the coupling coefficient and calculate the power-loss distribution on the coupling slot. The cooling of this slot is a rather challenging thermal management project.

Kurennoy, S. (Sergey); Young, L. M. (Lloyd M.)

2003-01-01T23:59:59.000Z

116

High power linear pulsed beam annealer. [Patent application  

DOE Patents (OSTI)

A high power pulsed electron beam system for annealing semiconductors is comprised of an electron gun having a heated cathode, control grid and focus ring for confining the pulsed beam of electrons to a predetermined area, and a curved drift tube. The drift tube and an annular Faraday shield between the focus ring and the drift tube are maintained at a high positive voltage with respect to the cathode to accelerate electrons passing through the focus ring, thereby eliminating space charge limitations on the emission of electrons from said gun. A coil surrounding the curved drift tube provides a magnetic field which maintains the electron beam focused about the axis of the tube. The magnetic field produced by the coil around the curved tube imparts motion to electrons in a spiral path for shallow penetration of the electrons into a target. It also produces a scalloped profile of the electron beam. A second drift tube spaced a predetermined distance from the curved tube is positioned with its axis aligned with the axis of the first drift tube. The second drift tube and the target holder are maintained at a reference voltage between the cathode voltage and the curved tube voltage to decelerate the electrons. A second coil surrounding the second drift tube, maintains the electron beam focused about the axis of the second drift tube. The magnetic field of the second coil comprises the electron beam to the area of the semiconductor on the target holder.

Strathman, M.D.; Sadana, D.K.; True, R.B.

1980-11-26T23:59:59.000Z

117

Performance and Technique of Coherent 2-?m Differential Absorption and Wind Lidar for Wind Measurement  

Science Conference Proceedings (OSTI)

A coherent 2-?m differential absorption and wind lidar (Co2DiaWiL) has been built with a high-power Q-switched Tm,Hm:YLF laser to measure CO2 concentration and radial wind speed. The performance of the Co2DiaWiL is described and analyzed, with a ...

Hironori Iwai; Shoken Ishii; Ryoko Oda; Kohei Mizutani; Shinya Sekizawa; Yasuhiro Murayama

2013-03-01T23:59:59.000Z

118

Optimization Studies for ISOL Type High-Powered Targets  

Science Conference Proceedings (OSTI)

The research studied one-step and two-step Isotope Separation on Line (ISOL) targets for future radioactive beam facilities with high driver-beam power through advanced computer simulations. As a target material uranium carbide in the form of foils was used because of increasing demand for actinide targets in rare-isotope beam facilities and because such material was under development in ISAC at TRIUMF when this project started. Simulations of effusion were performed for one-step and two step targets and the effects of target dimensions and foil matrix were studied. Diffusion simulations were limited by availability of diffusion parameters for UCx material at reduced density; however, the viability of the combined diffusion?effusion simulation methodology was demonstrated and could be used to extract physical parameters such as diffusion coefficients and effusion delay times from experimental isotope release curves. Dissipation of the heat from the isotope-producing targets is the limiting factor for high-power beam operation both for the direct and two-step targets. Detailed target models were used to simulate proton beam interactions with the targets to obtain the fission rates and power deposition distributions, which were then applied in the heat transfer calculations to study the performance of the targets. Results indicate that a direct target, with specification matching ISAC TRIUMF target, could operate in 500-MeV proton beam at beam powers up to ~40 kW, producing ~8 1013 fission/s with maximum temperature in UCx below 2200 C. Targets with larger radius allow higher beam powers and fission rates. For the target radius in the range 9-mm to 30-mm the achievable fission rate increases almost linearly with target radius, however, the effusion delay time also increases linearly with target radius.

Remec, Igor [Oak Ridge National Laboratory] [Oak Ridge National Laboratory; Ronningen, Reginald Martin [Michigan State University] [Michigan State University

2013-09-24T23:59:59.000Z

119

Development of high-power gyrotrons with gradually tapered cavity  

Science Conference Proceedings (OSTI)

In high power gyrotrons, the parasitic modes coupled with the operating mode cannot be avoided in the beam-wave interaction. These parasitic modes will decrease the efficiency of the gyrotrons. The purity of the operating mode affected by different tapers should be carefully studied. The steady-state self-consistent nonlinear theory for gyrotron with gradually tapered cavity is developed in this paper. A steady-state calculation code including 'cold cavity' and 'hot cavity' is designed. By comparison, a time-domain model analysis of gyrotron operation is also studied by particle-in-cell (PIC). It is found that the tapers of gyrotron have different influences on the modes coupling between the operating mode and the parasitic modes. During the study, an example of 94 GHz gyrotron with pure operating mode TE{sub 03} has been designed. The purity of the operating mode in the optimized cavity is up to -77 dB, and in output waveguide of the cavity is up to -76 dB. At the same time, the beam-wave interaction in the designed cavity has been simulated, too. An output power of 120 kW, corresponding to 41.6% efficiency and an oscillation frequency of 94.099 GHz have been achieved with a 50 kV, 6 A helical electron beam at a guiding magnetic field of 3.5485 T. The results show that the power in spurious modes of the optimized cavity may be kept far below than that of the traditional tapered cavity.

Lei Chaojun [Terahertz Science and Technology Research Center, University of Electronics Science and Technology of China, Chengdu 610054 (China); The Chinese People's Armed Police Force Academy, Langfang 065000 (China); Yu Sheng; Niu Xinjian; Liu Yinghui; Li Hongfu; Li Xiang [Terahertz Science and Technology Research Center, University of Electronics Science and Technology of China, Chengdu 610054 (China)

2012-12-15T23:59:59.000Z

120

Capacitive charging system for high power battery charging  

DOE Green Energy (OSTI)

This document describes a project to design, build, demonstrate, and document a Level 3 capacitive charging system, and it will be based on the existing PEZIC prototype capacitive coupler. The capacitive coupler will be designed to transfer power at a maximum of 600 kW, and it will transfer power by electric fields. The power electronics will transfer power at 100 kW. The coupler will be designed to function with future increases in the power electronics output power and increases in the amp/hours capacity of sealed batteries. Battery charging algorithms will be programmed into the control electronics. The finished product will be a programmable battery charging system capable of transferring 100 kW via a capacitive coupler. The coupler will have a low power loss of less than 25 watts when transferring 240 kW (400 amps). This system will increase the energy efficiency of high power battery charging, and it will enhance mobility by reducing coupler failures. The system will be completely documented. An important deliverable of this project is information. The information will be distributed to the Army`s TACOM-TARDEC`s Advanced Concept Group, and it will be distributed to commercial organizations by the Society of Automotive Engineers. The information will be valuable for product research, development, and specification. The capacitive charging system produced in this project will be of commercial value for future electric vehicles. The coupler will be designed to rapid charge batteries that have a capacity of several thousand amp/hours at hundreds of volts. The charging system built here will rapid charge batteries with several hundred amp/hours capacity, depending on the charging voltage.

NONE

1998-12-31T23:59:59.000Z

Note: This page contains sample records for the topic "high-power coherent terahertz" 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

A Framework to Simulate and Improve Terahertz Quantum Well  

E-Print Network (OSTI)

-practical temperatures. Combined with the complexity to realize terahertz emitters, it explains the difficulties of Applied Science in Electrical and Computer Engineering Waterloo, Ontario, Canada, 2013 © Simon Ferr´e 2013 Photodetector. Those devices working principle relies on a photocurrent created by the excitation of electrons

Anderson, Charles H.

122

IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. 46, NO. 3, MARCH 2011 583 High Power Terahertz and Millimeter-Wave Oscillator  

E-Print Network (OSTI)

CNS- 0448668 and by NSF CMS-0509018. REFERENCES [1] D. Corbus, I. Baring-Gould, S. Drouilhet, V.A. Corbus, S. Drouilhet, and R. Holz. Mod- eling, testing and economic analysis of a wind-electric battery

Afshari, Ehsan

123

Radiation from laser accelerated electron bunches: Coherent terahertz and femtosecond X-rays  

E-Print Network (OSTI)

by an intense ultrashort laser pulse,” Science, vol. 298,generated from intense laser-plasma interactions,” Appl.monochromatic x-rays in the laser synchrotron source

2004-01-01T23:59:59.000Z

124

IKNO, a user facility for coherent terahertz and UV synchrotron radiation  

E-Print Network (OSTI)

in existing 3rd generation light sources. Simultaneously toin modern 3rd generation light sources. 2. The IKNO storagea typical 3rd generation light source. The up to nine orders

Sannibale, Fernando

2009-01-01T23:59:59.000Z

125

High-power testing of PEP-II RF cavity windows  

SciTech Connect

We describe the high power testing of RF cavity windows for the PEP-II B factory. The window is designed for continuous operation at 476 MHz with up to 500 kW throughput and has been tested to full power using a modified PEP Klystron. The windows use an anti-multipactor coating on the vacuum side and the application and processing of this layer is discussed. The high power test configuration, RF processing history and high power performance are described.

Neubauer, M.; Allen, M.; Fant, K.; Hill, A.; Hoyt, M.; Judkins, J.; Schwarz, H. [Stanford Linear Accelerator Center, CA (United States); Rimmer, R.A. [Lawrence Berkeley National Lab., CA (United States)

1996-06-01T23:59:59.000Z

126

Low-Cost, High-Power Laser for Analytical and Other ...  

Search PNNL. PNNL Home; About; Research; Publications; Jobs; News; Contacts; Low-Cost, High-Power Laser for Analytical and Other Applications. ...

127

High-power LED driver with power-efficient LED-current-sensing technique.  

E-Print Network (OSTI)

??x, 73 leaves : ill. ; 30 cm HKUST Call Number: Thesis ECED 2007 LeungW To provide enough light output for various lighting applications, high-power… (more)

Leung, Wing Yan

2007-01-01T23:59:59.000Z

128

Theory of a laser-plasma method for detecting terahertz radiation  

SciTech Connect

A theory is developed for calculating the spectrum and the shape of a terahertz wave packet from the temporal profile of the energy of the second harmonic of the laser field generated during nonlinear interaction of laser and terahertz pulses in an optical-breakdown plasma. The spectral and temporal characteristics of the second-harmonic envelope and a terahertz pulse are shown to coincide only for short laser pulses. For long laser pulses, the second-harmonic spectral line shifts to the red and its temporal profile is determined by the time integral of the electric field of terahertz radiation.

Frolov, A. A., E-mail: frolov@ihed.ras.ru [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation); Borodin, A. V.; Esaulkov, M. N.; Kuritsyn, I. I.; Shkurinov, A. P. [Moscow State University (Russian Federation)

2012-06-15T23:59:59.000Z

129

Terahertz wave emission from intrinsic Josephson junctions in high-T{sub c} superconductors.  

SciTech Connect

Recently, we experimentally demonstrated that rectangular mesa structures of intrinsic Josephson junctions (IJJ) in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+d} (Bi2212) can be used as a compact solid-state generator of continuous, coherent and polarized terahertz (THz) radiation. In the present work, we will exhibit tall mesas (over 600 junctions) which were fabricated using UV lithography, e-beam lithography with photoresist and e-beam lithography with a Ti selective etching technique. We will present measurements of the c-axis resistance as a function of temperature and of current-voltage characteristics of THz emitting mesas with lateral sizes ranging from 30 x 300 to 100 x 300 {micro}m{sup 2}. Furthermore, we will discuss the dependence of the characteristics of the mesa structures on the oxygen doping level of the Bi2212 crystals. We will also experimentally show that the voltage-frequency relation of the ac Josephson effect has to match the cavity resonance for successful emission.

Ozyuzer, L.; Simsek, Y.; Koseoglu, H.; Turkoglu, F.; Kurter, C.; Welp, U.; Koshelev, A. E.; Gray, K. E.; Kwok, W. K.; Yamamoto, T.; Kadowaki, K.; Koval, Y.; Wang, H. B.; Muller, P.; Materials Science Division; Izmir Inst. of Tech.; Univ. of Erlangen-Nurnberg; Univ. of Tsukuba; National Inst. for Materials Science

2009-10-20T23:59:59.000Z

130

DESY, February 2001, TESLA Report 2001-04 Concept of the High Power e  

E-Print Network (OSTI)

DESY, February 2001, TESLA Report 2001-04 Concept of the High Power e± Beam Dumps for TESLA W. Bialowons, M. Maslov, M. Schmitz, V. Sytchev #12;1 Concept of the High Power e± Beam Dumps for TESLA W............................................................................................................... 19 #12;2 1 Introduction The TESLA accelerator is equipped with quite a number of extraction lines

131

High power light emitting diode based setup for photobleaching fluorescent impurities  

E-Print Network (OSTI)

High power light emitting diode based setup for photobleaching fluorescent impurities Tobias K be photobleached before final sample preparation. The instrument consists of high power light emitting diodes for simple photobleaching pur- poses, we designed a simple but efficient lighting system using light emitting

Kaufman, Laura

132

Coherent Inc | Open Energy Information  

Open Energy Info (EERE)

Coherent Inc Jump to: navigation, search Name Coherent Inc Place Santa Clara, California Zip 95054 Sector Solar Product US-based manufacturer of photonics-based equipments such as...

133

Coherent Radiation in an Undulator  

E-Print Network (OSTI)

solving the particle-radiation system in a self-consistentto clarify the coherent radiation mechanism. References 1.the Proceedings Coherent Radiation in an Undulator Y,H. Chin

Chin, Y.H.

2011-01-01T23:59:59.000Z

134

Constrainted Coherent States  

E-Print Network (OSTI)

Coherent states possess a regularized path integral and gives a natural relation between classical variables and quantum operators. Recent work by Klauder and Whiting has included extended variables, that can be thought of as gauge fields, into this formalism. In this paper, I consider the next step, and look at the roll of first class constraints.

M. C. Ashworth

1996-04-21T23:59:59.000Z

135

Scattering of terahertz radiation on a graphene-based nano-antenna  

E-Print Network (OSTI)

Scattering of terahertz radiation on a graphene-based nano-antenna Ignacio Llatser, , Christian, D6-008 08034 Barcelona, Spain Theoretical Nano-Photonics Group, Institute of High. Scattering of the terahertz radiation on a graphene-based nano-antenna is considered. Different

Cabellos-Aparicio, Albert

136

An exploration of the utilities of terahertz waves for the NDE of composites  

SciTech Connect

We report an investigation of terahertz waves for the nondestructive evaluation of composite materials and structures. The modalities of the terahertz radiation used were time domain spectroscopy (TDS) and continuous wave (CW). The composite materials and structures investigated include both non-conducting polymeric composites and carbon fiber composites. Terahertz signals in the TDS mode resembles that of ultrasound; however, unlike ultrasound, a terahertz pulse can detect a crack hidden behind a larger crack. This was demonstrated in thick GFRP laminates containing double saw slots. In carbon composites the penetration of terahertz waves is quite limited and the detection of flaws is strongly affected by the angle between the electric field vector of the terahertz waves and the intervening fiber directions. The structures tested in this study include both solid laminates and honeycomb sandwiches. The defects and anomalies investigated by terahertz waves were foreign material inclusions, simulated disbond and delamination, mechanical impact damage, heat damage, and water or hydraulic fluid ingression. The effectiveness and limitations of terahertz radiation for the NDE of composites are discussed.

Hsu, David K.; Im, Kwang-Hee; Chiou, Chien-Ping; Barnard, Daniel J. [Center for Nondestructive Evaluation, Iowa State University, Ames, Iowa 50011 (United States)

2011-06-23T23:59:59.000Z

137

Coherent Radiation in Insertion Devices  

E-Print Network (OSTI)

We calculate the coherent radiation in an undulator/wiggler with a vacuum chamber of arbitrary cross section. The backward radiation is a coherent and it has wavelengths about twice the period of the undulator/wiggler. Mostly of coherent radiation is going with the wavelengths approximately the bunch length at small angles however.

Mikhailichenko, A A

2011-01-01T23:59:59.000Z

138

Optical injection and terahertz detection of the macroscopic Berry curvature  

E-Print Network (OSTI)

We propose an experimental scheme to probe the Berry curvature of solids. Our method is sensitive to arbitrary regions of the Brillouin zone, and employs only basic optical and terahertz techniques to yield a background free signal. Using semiconductor quantum wells as a prototypical system, we discuss how to inject Berry curvature macroscopically, and probe it in a way that provides information about the underlying microscopic Berry curvature.

Kuljit S. Virk; J. E. Sipe

2011-08-19T23:59:59.000Z

139

Optical injection and terahertz detection of the macroscopic Berry curvature  

E-Print Network (OSTI)

We propose an experimental scheme to probe the Berry curvature of solids. Our method is sensitive to arbitrary regions of the Brillouin zone, and employs only basic optical and terahertz techniques to yield a background free signal. Using semiconductor quantum wells as a prototypical system, we discuss how to inject Berry curvature macroscopically, and probe it in a way that provides information about the underlying microscopic Berry curvature.

Virk, Kuljit S

2011-01-01T23:59:59.000Z

140

Tunable and collimated terahertz radiation generation by femtosecond laser pulses  

Science Conference Proceedings (OSTI)

A mechanism is proposed for the generation of tunable terahertz (THz) radiation under the application of two femtosecond laser pulses and an external magnetic field, where quick tunnel ionization is achieved that leads to higher plasma density evolution and large residual current for the efficient THz radiation generation. With the optimization of magnetic field, phase difference, and amplitudes of lasers' fields, a THz source can be obtained with tunable frequency and power along with a control on the direction of radiation emission.

Malik, Hitendra K.; Malik, Anil K.

2011-12-19T23:59:59.000Z

Note: This page contains sample records for the topic "high-power coherent terahertz" 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

Detection of nanosecond-scale, high power THz pulses with a field effect transistor  

Science Conference Proceedings (OSTI)

We demonstrate detection and resolution of high power, 34 ns free electron laser pulses using a rectifying field effect transistor. The detector remains linear up to an input power of 11 {+-} 0.5 W at a pulse energy of 20 {+-} 1 {mu}J at 240 GHz. We compare its performance to a protected Schottky diode, finding a shorter intrinsic time constant. The damage threshold is estimated to be a few 100 W. The detector is, therefore, well-suited for characterizing high power THz pulses. We further demonstrate that the same detector can be used to detect low power continuous-wave THz signals with a post detection limited noise floor of 3.1 {mu}W/{radical}(Hz). Such ultrafast, high power detectors are important tools for high power and high energy THz facilities such as free electron lasers.

Preu, S. [Physics Department and Institute for Terahertz Science and Technology, University of California, Santa Barbara, California 93106 (United States); Materials Department, University of California, Santa Barbara, California 93106 (United States); Chair for Applied Physics, University of Erlangen-Nuremberg, 91058 Erlangen (Germany); Lu, H.; Gossard, A. C. [Materials Department, University of California, Santa Barbara, California 93106 (United States); Sherwin, M. S. [Physics Department and Institute for Terahertz Science and Technology, University of California, Santa Barbara, California 93106 (United States)

2012-05-15T23:59:59.000Z

142

C-Band High Power RF Generation and Extraction Using a Dielectric...  

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

C-BAND HIGH POWER RF GENERATION AND EXTRACTION USING A DIELECTRIC LOADED WAVEGUIDE* F. Gao , M. Conde, W. Gai, R. Konecny, W. Liu, J. Power, Z. Yusof ANL, Argonne, IL 60439,...

143

High Power Testing of X-Band Dielectric-Loaded Accelerating Structures  

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

m-to-metal-to-dielectric in a region of high electric field that is expected to cause breakdown problems; and (2) high power density in the dielectric, since all the power passes...

144

NEUTRONIC AND THERMAL HYDRAULIC DESIGNS OF ANNULAR FUEL FOR HIGH POWER DENSITY BWRS  

E-Print Network (OSTI)

As a promising new fuel for high power density light water reactors, the feasibility of using annular fuel for BWR services is explored from both thermal hydraulic and neutronic points of view. Keeping the bundle size ...

Morra, P.

145

Report on High Power rf Testing of Quartz Based DLA Structure  

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

2 March, 2006 Report on High Power rf Testing of Quartz Based DLA Structure at NRL C. Jing, and R. Konecny Abstract: In this article, we report the experimental results of high...

146

Charged electret deposition for the manipulation of high power microwave flashover delay times  

Science Conference Proceedings (OSTI)

A quasi-permanent charged electret is embedded into the radiation window of a high power microwave system. It was experimentally observed that the additional electrostatic field introduced by the electret alters the delay times associated with the development of plasma at the window surface, resulting from high power microwave excitation. The magnitudes of both the statistical and formative delay times are investigated in detail for different pressures. Experimental observations are related to calculated discharge parameters using known E/p dependent properties.

Stephens, J.; Beeson, S.; Dickens, J.; Neuber, A. [Center for Pulsed Power and Power Electronics, Texas Tech University, Lubbock, Texas 79409 (United States)

2012-11-15T23:59:59.000Z

147

Reversible Mode Switching in Y coupled Terahertz Lasers  

E-Print Network (OSTI)

Electrically independent terahertz (THz) quantum cascade lasers (QCLs) are optically coupled in a Y configuration. Dual frequency, electronically switchable emission is achieved in one QCL using an aperiodic grating, designed using computer-generated hologram techniques, incorporated directly into the QCL waveguide by focussed ion beam milling. Multi-moded emission around 2.9 THz is inhibited, lasing instead occurring at switchable grating-selected frequencies of 2.88 and 2.92 THz. This photonic control and switching behaviour is selectively and reversibly transferred to the second, unmodified QCL via evanescent mode coupling, without the transfer of the inherent grating losses.

Marshall, Owen P; Khairuzzaman, Md; Beere, Harvey E; Ritchie, David A

2013-01-01T23:59:59.000Z

148

Transmission characteristics of circular metallic waveguides for terahertz radiation  

SciTech Connect

Transmission characteristics of oversized circular metallic waveguides excited by linearly polarised Gaussian laser beams in the terahertz range (4 - 28 THz) are studied theoretically and experimentally. Calculating the transmission characteristics, we have determined the conditions of applicability of the method of the eigenoscillations in the approximations of a real metal by an ideal metal or dielectric, depending on the transmitted radiation frequency. The existence of the transition region is established in the behaviour of the electrodynamic properties of metallic waveguides in the frequency range of 7.5 - 15 THz.

Volodenko, A V; Gurin, O V; Degtyarev, A V; Maslov, Vyacheslav A; Svich, V A; Senyuta, V S; Topkov, A N [V.N. Karazin Kharkov National University, Kharkov (Ukraine)

2011-09-30T23:59:59.000Z

149

Terahertz nano antenna enabled early transition in VO2  

E-Print Network (OSTI)

We study terahertz transmission through nano-patterned vanadium dioxide thin film. It is found that the patterning allows the lowering of the apparent transition temperature. For the case of the smallest width nano antennas, the transition temperature is lower by as many as ten degrees relative to the bare film, so that the nano patterned hysteresis curves completely separate themselves from their bare film counterparts. This early transition comes from the one order of magnitude enhanced effective dielectric constants by nano antennas. This phenomenon opens up the possibility of transition temperature engineering.

Jeong, Young-Gyun; Choi, Jae-Wook; Han, Sang-Hoon; Park, Hyeong-Ryeol; Park, Namkyoo; Kim, Bong-Jun; Kim, Hyun-Tak; Kim, Dai-Sik

2012-01-01T23:59:59.000Z

150

Desktop megawatt superradiant free-electron laser at terahertz frequencies  

SciTech Connect

I present a theoretical and simulation study of a desktop, megawatt (MW), terahertz (THz) superradiance free-electron laser (FEL) driven by a THz-pulse-train photoinjector. With nominal electron parameters from a THz-pulse-train photoinjector, this superradiant FEL is capable of generating more than 5 MW power at THz frequencies from a half-meter, single-pass undulator. Tapering the undulator to a length of 1.5 m can further increase the FEL output power to nearly 15 MW.

Huang, Y.-C. [Department of Electrical Engineering, National Tsinghua University, Hsinchu 30013, Taiwan (China)

2010-06-07T23:59:59.000Z

151

FY2001 Highlights Report for the Vehicle High-Power Energy Storage Program  

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

HIGH-POWER HIGH-POWER ENERGY STORAGE 2 0 0 1 A N N U A L P R O G R E S S R E P O R T U.S. Department of Energy Energy Efficiency and Renewable Energy Office of Transportation Technologies A C K N O W L E D G E M E N T We would like to express our sincere appreciation to Argonne National Laboratory and to Sentech, Inc., for their artistic and technical contributions in preparing and publishing this report. In addition, we would like to thank all our program participants for their contributions to the programs and all the authors who prepared the project abstracts that comprise this report. U.S. Department of Energy Office of Advanced Automotive Technologies 1000 Independence Ave., S.W. Washington, DC 20585-0121 FY 2001 Highlights Report for the Vehicle High-Power Energy Storage Program Energy Efficiency and Renewable Energy

152

High-Power Electrodes for Lithium-Ion Batteries | U.S. DOE Office of  

Office of Science (SC) Website

High-Power Electrodes for Lithium-Ion High-Power Electrodes for Lithium-Ion Batteries Energy Frontier Research Centers (EFRCs) EFRCs Home Centers Research Science Highlights Highlight Archives News & Events Publications Contact BES Home 04.27.12 High-Power Electrodes for Lithium-Ion Batteries Print Text Size: A A A RSS Feeds FeedbackShare Page Scientific Achievement For novel 3-D anodes made of sheets of carbon (graphene) and silicon nanoparticles, transport studies found much shorter lithium diffusion paths throughout the electrode and fast lithiation/delithiation of the nanoparticles. Significance and Impact This anode design holds a greater charge than conventional lithium-ion anodes and charges/discharges more rapidly while maintaining mechanical stability. Research Details Electrochemical studies: 83% of theoretical capacity (3200 mAh g-1)

153

Space reactor/Stirling cycle systems for high power Lunar applications  

DOE Green Energy (OSTI)

NASA`s Space Exploration Initiative (SEI) has proposed the use of high power nuclear power systems on the lunar surface as a necessary alternative to solar power. Because of the long lunar night ({approximately} 14 earth days) solar powered systems with the requisite energy storage in the form of regenerative fuel cells or batteries becomes prohibitively heavy at high power levels ({approximately} 100 kWe). At these high power levels nuclear power systems become an enabling technology for variety of missions. One way of producing power on the lunar surface is with an SP-100 class reactor coupled with Stirling power converters. In this study, analysis and characterization of the SP-100 class reactor coupled with Free Piston Stirling Power Conversion (FPSPC) system will be performed. Comparison of results with previous studies of other systems, particularly Brayton and Thermionic, are made.

Schmitz, P.D. [Sverdrup Technology, Inc., Brook Park, OH (United States). Lewis Research Center Group; Mason, L.S. [National Aeronautics and Space Administration, Cleveland, OH (United States). Lewis Research Center

1994-09-01T23:59:59.000Z

154

High power X-ray welding of metal-matrix composites  

DOE Patents (OSTI)

A method for joining metal-matrix composites (MMCs) by using high power x-rays as a volumetric heat source is provided. The method involves directing an x-ray to the weld line between two adjacent MMCs materials to create an irradiated region or melt zone. The x-rays have a power density greater than about 10{sup 4} watts/cm{sup 2} and provide the volumetric heat required to join the MMC materials. Importantly, the reinforcing material of the metal-matrix composites remains uniformly distributed in the melt zone, and the strength of the MMCs are not diminished. In an alternate embodiment, high power x-rays are used to provide the volumetric heat required to weld metal elements, including metal elements comprised of metal alloys. In an alternate embodiment, high power x-rays are used to provide the volumetric heat required to weld metal elements, including metal elements comprised of metal alloys.

Rosenberg, Richard A.; Goeppner, George A.; Noonan, John R.; Farrell, William J.; Ma, Qing

1997-12-01T23:59:59.000Z

155

High power x-ray welding of metal-matrix composites  

DOE Patents (OSTI)

A method for joining metal-matrix composites (MMCs) by using high power x-rays as a volumetric heat source is provided. The method involves directing an x-ray to the weld line between two adjacent MMCs materials to create an irradiated region or melt zone. The x-rays have a power density greater than about 10.sup.4 watts/cm.sup.2 and provide the volumetric heat required to join the MMC materials. Importantly, the reinforcing material of the metal-matrix composites remains uniformly distributed in the melt zone, and the strength of the MMCs are not diminished. In an alternate embodiment, high power x-rays are used to provide the volumetric heat required to weld metal elements, including metal elements comprised of metal alloys. In an alternate embodiment, high power x-rays are used to provide the volumetric heat required to weld metal elements, including metal elements comprised of metal alloys.

Rosenberg, Richard A. (Naperville, IL); Goeppner, George A. (Orland Park, IL); Noonan, John R. (Naperville, IL); Farrell, William J. (Flossmoor, IL); Ma, Qing (Westmont, IL)

1999-01-01T23:59:59.000Z

156

Nonlinear terahertz spectroscopy of electronic and vibrational responses in condensed matter systems  

E-Print Network (OSTI)

In this work, I describe experiments utilizing high-field terahertz (THz) pulses to initiate nonlinear responses in several classes of materials. We have developed several methods for interrogating the nonlinear THz response ...

Hwang, Harold Young

2012-01-01T23:59:59.000Z

157

Interdigitated Antennas for Broadband Terahertz Generation Mitch Connolly,1,2  

E-Print Network (OSTI)

Japan Program, Rice University, Houston, Texas, U.S.A. 2 Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology, Okinawa, Japan The terahertz (THz) feild has become a hot topic for many

158

In-Plane Focusing of Terahertz Surface Waves on a Gradient Index Metamaterial Film  

E-Print Network (OSTI)

We designed and implemented a gradient index metasurface for the in-plane focusing of confined terahertz surface waves. We measured the spatial propagation of the surface waves by two-dimensional mapping of the complex electric field using a terahertz near-field spectroscope. The surface waves were focused to a diameter of 500 \\micro m after a focal length of approx. 2 mm. In the focus, we measured a field amplitude enhancement of a factor of 3.

Volk, Martin F; Neu, Jens; Beigang, René; Rahm, Marco

2013-01-01T23:59:59.000Z

159

Electro-optic crystal mosaics for the generation of terahertz radiation  

DOE Patents (OSTI)

Apparatus for the generation of high energy terahertz radiation is presented and comprises laser means effective to produce subpicosecond optical pulses and a mosaic comprising a plurality of planar electro-optic crystals fastened together edge to edge in the form of a grid. The electro-optic crystals are in optical communication with the subpicosecond optical pulses, and behave as a single large electro-optic crystal, producing high energy terahertz radiation by way of optical rectification. 5 figs.

Carrig, T.J.; Taylor, A.J.; Stewart, K.R.

1996-08-06T23:59:59.000Z

160

Coherent Orthogonal Polynomials  

E-Print Network (OSTI)

We discuss as a fundamental characteristic of orthogonal polynomials like the existence of a Lie algebra behind them, can be added to their other relevant aspects. At the basis of the complete framework for orthogonal polynomials we put thus --in addition to differential equations, recurrence relations, Hilbert spaces and square integrable functions-- Lie algebra theory. We start here from the square integrable functions on the open connected subset of the real line whose bases are related to orthogonal polynomials. All these one-dimensional continuous spaces allow, besides the standard uncountable basis ${|x>}$, for an alternative countable basis ${|n>}$. The matrix elements that relate these two bases are essentially the orthogonal polynomials: Hermite polynomials for the line and Laguerre and Legendre polynomials for the half-line and the line interval, respectively. Differential recurrence relations of orthogonal polynomials allow us to realize that they determine a unitary representation of a non-compact Lie algebra, whose second order Casimir ${\\cal C}$ gives rise to the second order differential equation that defines the corresponding family of orthogonal polynomials. Thus, the Weyl-Heisenberg algebra $h(1)$ with ${\\cal C}=0$ for Hermite polynomials and $su(1,1)$ with ${\\cal C}=-1/4$ for Laguerre and Legendre polynomials are obtained. Starting from the orthogonal polynomials the Lie algebra is extended both to the whole space of the ${\\cal L}^2$ functions and to the corresponding Universal Enveloping Algebra and transformation group. Generalized coherent states from each vector in the space ${\\cal L}^2$ and, in particular, generalized coherent polynomials are thus obtained.

E Celeghini; Mariano A del Olmo

2012-05-29T23:59:59.000Z

Note: This page contains sample records for the topic "high-power coherent terahertz" 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

Diagnostic Characterization of High-Power Lithium-Ion Batteries For Use in Hybrid Electric Vehicles  

E-Print Network (OSTI)

Diagnostic Characterization of High-Power Lithium-Ion Batteries For Use in Hybrid Electric Vehicles Lithium-ion batteries are a fast-growing technology that is attractive for use in portable electronics of lithium-ion batteries for hybrid electric vehicle (HEV) applications. The ATD Program is a joint effort

162

Diagnostic Characterization of High Power Lithium-Ion Batteries for Use in Hybrid Electric Vehicles  

E-Print Network (OSTI)

Diagnostic Characterization of High Power Lithium-Ion Batteries for Use in Hybrid Electric Vehicles. Manuscript submitted May 15, 2000; revised manuscript received January 15, 2001. Lithium-ion batteries effort by the U.S. Department of Energy to aid the development of lithium-ion batteries for hybrid

163

Synthesis of hybrid nanowire arrays and their application as high power supercapacitor electrodesw  

E-Print Network (OSTI)

Synthesis of hybrid nanowire arrays and their application as high power supercapacitor electrodesw- plies.2­7 For such applications, it is extremely important to develop supercapacitors with higher power and they have been used as electrodes for supercapacitors.11­14 In spite of having ideal properties, CNT based

Ajayan, Pulickel M.

164

Highly Conductive and Porous Activated Reduced Graphene Oxide Films for High-Power Supercapacitors  

E-Print Network (OSTI)

Highly Conductive and Porous Activated Reduced Graphene Oxide Films for High-Power Supercapacitors for a free-standing carbon film reported to date. A two-electrode supercapacitor using these carbon films. KEYWORDS: Graphene, flexible film, chemical activation, supercapacitors Free-standing thin film materials

165

Electrical characterization and modelling of round spiral supercapacitors for high power applications  

E-Print Network (OSTI)

Electrical characterization and modelling of round spiral supercapacitors for high power of supercapacitors under railway and electrical traction constraints. Electrical model parameters according of supercapacitors and give precious information on its state of health. These kinds of studies need a powerful

Paris-Sud XI, Université de

166

Research on Control System of High Power DFIG Wind Power System  

Science Conference Proceedings (OSTI)

Compared with constant speed constant frequency wind turbine, variable speed constant frequency wind turbine has many advantages: higher efficiency of wind energy converting to electric power, absorbing gust energy, smoothly cutting into the network ... Keywords: wind power, DFIG, high power, LQR, variable speed constant frequency, constant power control

Li Jianlin; Xu Honghua

2008-12-01T23:59:59.000Z

167

The Design and Implementation of a High-power Mobile Substation  

Science Conference Proceedings (OSTI)

This paper presents a scheme design and implementation of a high-power mobile substation, which used to convert local standard AC to the requirement of electrical equipment. In this system, a three-phase AC generator is driven by a DC motor, the motor ... Keywords: AC, frequency, motor, generator, feedback, efficiency, PID

Yongtai Chen; Tuyaun Qin; Jing Tang; Li Cai

2012-05-01T23:59:59.000Z

168

High power breakdown testing of a photonic band-gap accelerator structure with elliptical rods  

E-Print Network (OSTI)

An improved single-cell photonic band-gap (PBG) structure with an inner row of elliptical rods (PBG-E) was tested with high power at a 60 Hz repetition rate at X-band (11.424 GHz), achieving a gradient of 128??MV/m at a ...

Munroe, Brian James

169

Nano-structured anode material for high-power battery system in electric vehicles.  

SciTech Connect

A new MSNP-LTO anode is developed to enable a high-power battery system that provides three times more power than any existing battery system. It shows excellent cycle life and low-temperature performance, and exhibits unmatched safety characteristics.

Amine, K.; Belharouak, I.; Chen, Z.; Taison, T.; Yumoto, H.; Ota, N.; Myung, S.-T.; Sun, Y.-K. (Chemical Sciences and Engineering Division); (Enerdel Lithium Power Systems); (Iwate Univ.); (Hanyang Univ.)

2010-07-27T23:59:59.000Z

170

A CONTINUOUS HIGH POWER BEAM DUMP OF THE HOT-DOG-COOKER TYPE  

SciTech Connect

A beam dump with partially rotating water-cooled tube arrays is proposed and studied for the dump of continuous high power density unneutralized ion beams out of the neutral beam injectors. Analyses were made of both steady and transient heat transfer characteristics.

Yoshikawa, Kiyoshi

1980-03-01T23:59:59.000Z

171

Applications of high power millimeter waves in the DIII-D fusion program  

SciTech Connect

First operation of a new generation of MW level, 110 GHz generator (gyrotron) on the DIII-D fusion experimental device has been achieved. The desire for high power, cw millimeter (mm) wave sources to support fusion research and development is just now beginning to be realized. Plasma heating and current drive with directed mm waves rely on the strong absorption achieved when the wave frequency matches the natural ``cyclotron`` frequency of electrons in a magnetic field, or its harmonics. Recent progress in fusion experiments highlights the need for control of the interior details of the hot plasma, and nun wave systems are ideally suited for this role. A brief status of fusion research is given, and the importance of mm waves in the future directions for fusion research is described. The vacuum transmission components necessary for transmitting, monitoring, and launching high power 1 10 GHz waves into a plasma have been developed at General Atomics (GA) and will be described. High power mm waves have a number of attractive technological features for fusion applications compared with other candidate plasma heating and current drive technologies. Millimeter waves can be transmitted with high power density over large distances with low losses by utilizing corrugated waveguides, so the generators can be sited remotely, facilitating maintenance and saving valuable space near the fusion device.

Freeman, R.L.

1996-08-01T23:59:59.000Z

172

Transient Quantum Coherent Response to a Partially Coherent Radiation Field  

E-Print Network (OSTI)

The response of an arbitrary closed quantum system to a partially coherent electric field is investigated, with a focus on the transient coherences in the system. As a model we examine, both perturbatively and numerically, the coherences induced in a three level $V$ system. Both rapid turn-on and pulsed turn-on effects are investigated. The effect of a long and incoherent pulse is also considered, demonstrating that during the pulse the system shows a coherent response which reduces after the pulse is over. Both the pulsed scenario and the thermally broadened CW case approach a mixed state in the long time limit, with rates dictated by the adjacent level spacings and the coherence time of the light, and via a mechanism that is distinctly difference from traditional decoherence. These two excitation scenarios are also explored for a minimal "toy" model of the electronic levels in pigment protein complex PC645 by both a collisionally broadened CW laser and by a noisy pulse, where unexpectedly long transient coherence times are observed and explained. The significance of environmentally induced decoherence is noted.

Z. S. Sadeq; Paul Brumer

2013-12-10T23:59:59.000Z

173

Quantum-Bayesian Coherence  

E-Print Network (OSTI)

In a quantum-Bayesian take on quantum mechanics, the Born Rule cannot be interpreted as a rule for setting measurement-outcome probabilities from an objective quantum state. But if not, what is the role of the rule? In this paper, we argue that it should be seen as an empirical addition to Bayesian reasoning itself. Particularly, we show how to view the Born Rule as a normative rule in addition to usual Dutch-book coherence. It is a rule that takes into account how one should assign probabilities to the consequences of various intended measurements on a physical system, but explicitly in terms of prior probabilities for and conditional probabilities consequent upon the imagined outcomes of a special counterfactual reference measurement. This interpretation is seen particularly clearly by representing quantum states in terms of probabilities for the outcomes of a fixed, fiducial symmetric informationally complete (SIC) measurement. We further explore the extent to which the general form of the new normative rule implies the full state-space structure of quantum mechanics. It seems to get quite far.

Christopher A. Fuchs; Ruediger Schack

2009-06-11T23:59:59.000Z

174

Technology survey and performance scaling for the design of high power nuclear electric power and propulsion systems.  

E-Print Network (OSTI)

??High power nuclear electric propulsion systems have the capability to enable many next-generation space exploration applications. To date, use of electric primary propulsion in flight… (more)

White, Daniel B., Jr

2011-01-01T23:59:59.000Z

175

Coherent control of neutron interferometry  

E-Print Network (OSTI)

In this thesis, several novel techniques are proposed and demonstrated for measuring the coherent properties of materials and testing aspects of quantum information processing using a single crystal neutron interferometer. ...

Pushin, Dmitry A

2007-01-01T23:59:59.000Z

176

Covariant Closed String Coherent States  

Science Conference Proceedings (OSTI)

We give the first construction of covariant coherent closed string states, which may be identified with fundamental cosmic strings. We outline the requirements for a string state to describe a cosmic string, and provide an explicit and simple map that relates three different descriptions: classical strings, light cone gauge quantum states, and covariant vertex operators. The resulting coherent state vertex operators have a classical interpretation and are in one-to-one correspondence with arbitrary classical closed string loops.

Hindmarsh, Mark; Skliros, Dimitri [Department of Physics and Astronomy, University of Sussex, Brighton, East Sussex BN1 9QH (United Kingdom)

2011-02-25T23:59:59.000Z

177

Current-induced terahertz oscillations in plasmonic crystal  

SciTech Connect

We discuss a possible mechanism of the current instability in multi-gated structures with periodic modulation of the electron density in the device channel. In such structures, the plasma wave velocity is periodically modulated as well, and the stationary electric current may become unstable with respect to generation of the plasma oscillations. In the simplest model of periodically alternating stripes of the electron density with plasma wave velocities s{sub a} and s{sub b}, respectively (s{sub a} < s{sub b}), the instability occurs when the electron drift velocity approaches s{sub a}. For typical parameters, the plasma oscillation frequency can be tuned to be in the terahertz range of frequencies.

Kachorovskii, V. Yu. [Center for Integrated Electronics, Rensselaer Polytechnic Institute, 110, 8th Street, Troy, New York 12180 (United States); A. F. Ioffe Physical-Technical Institute, 26 Polytechnicheskaya Street, St. Petersburg 194021 (Russian Federation); Shur, M. S. [Center for Integrated Electronics, Rensselaer Polytechnic Institute, 110, 8th Street, Troy, New York 12180 (United States)

2012-06-04T23:59:59.000Z

178

Terahertz Radiation from a Pipe with Small Corrugations  

SciTech Connect

We have studied through analytical and numerical methods the use of a relativistic electron bunch to drive a metallic beam pipe with small corrugations for the purpose of generating terahertz radiation. For the case of a pipe with dimensions that do not change along its length, we have shown that - with reasonable parameters - one can generate a narrow-band radiation pulse with frequency {approx}1 THz, and total energy of a few milli-Joules. The pulse length tends to be on the order of tens of picoseconds. We have also shown that, if the pipe radius is tapered along its length, the generated pulse will end up with a frequency chirp; if the pulse is then made to pass through a compressor, its final length can be reduced to a few picoseconds and its peak power increased to 1 GW. We have also shown that wall losses tend to be significant and need to be included in the structure design.

Bane, K.L.F.; Stupakov, G.; /SLAC

2012-01-26T23:59:59.000Z

179

Design of an electron gun for terahertz radiation source  

E-Print Network (OSTI)

With the aim to obtain short-pulse bunches with high peak current for a terahertz radiation source, an EC-ITC (External-Cathode Independently Tunable Cells) RF gun was employed. As the external injecting electron source of the ITC RF gun, a gridded DC gun plays a key role, the performance of which determines the beam quality in the injector and transport line. In order to make the beam well compressed in the ITC RF gun, the energy of the electrons acquired from the gridded DC gun should be 15 KeV at most. A proper structure of the gridded gun is shown to overcome the strong space- charge force on the cathode, which is able to generate 6 {\\mu}s beam with 4.5A current successfully.

Li, Ji; Hu, Tongning; Chen, Qushan; Feng, Guangyao; Shang, Lei; Li, Chenglong

2013-01-01T23:59:59.000Z

180

PPPL delivers a plasma source that will enable high-power beam pulses in a  

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

delivers a plasma source that will enable high-power beam pulses in a delivers a plasma source that will enable high-power beam pulses in a new Berkeley Lab accelerator March 19, 2012 Tweet Widget Facebook Like Google Plus One Erik Gilson with a copper-clad module and chamber for testing the units. (Photo by Elle Starkman, PPPL Office of Communications) Erik Gilson with a copper-clad module and chamber for testing the units. Gallery: Interior views of a plasma-source module. (Photo by Elle Starkman, PPPL Office of Communications) Interior views of a plasma-source module. Technician aligns plasma source with NDCX-II accelerator in background. (Photo by Elle Starkman, PPPL Office of Communications) Technician aligns plasma source with NDCX-II accelerator in background. Plainsboro, New Jersey - Scientists at the U.S. Department of Energy's

Note: This page contains sample records for the topic "high-power coherent terahertz" 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

Durability of Low Pt Fuel Cells Operating at High Power Density  

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

SPIRE Program Kickoff SPIRE Program Kickoff Topic 3A. Cell Degradation Studies / Degradation Studies Durability of Low Pt Fuel Cells Operating at High Power Density US DOE Fuel Cell Projects Kickoff Meeting DOE Award: DE-EE0000469 October 1 st , 2009 Program Objectives The objective of this program is to study and identify strategies to assure durability of fuel cells designed to meet DOE cost targets. Technical Barriers Barrier Approach Strategy A. Durability Reinforced, Stabilized Membrane MEA Partner Durability-Enhanced Electrodes Electrocatalyst/MEA Partner Optimized Operating Conditions Parametric model & experimental studies B. Cost Low Pt Loadings (0.2 mg/cm 2 ) Electrocatalyst/MEA Partner High Power Density (>1.0W/cm 2 ) Open Flowfield Stack Metallic Stack Architecture Incumbent Derivative

182

Thermal And Mechanical Analysis of High-power Light-emitting Diodes with Ceramic Packages  

E-Print Network (OSTI)

In this paper we present the thermal and mechanical analysis of high-power light-emitting diodes (LEDs) with ceramic packages. Transient thermal measurements and thermo-mechanical simulation were performed to study the thermal and mechanical characteristics of ceramic packages. Thermal resistance from the junction to the ambient was decreased from 76.1 oC/W to 45.3 oC/W by replacing plastic mould to ceramic mould for LED packages. Higher level of thermo-mechanical stresses in the chip were found for LEDs with ceramic packages despite of less mismatching coefficients of thermal expansion comparing with plastic packages. The results suggest that the thermal performance of LEDs can be improved by using ceramic packages, but the mounting process of the high power LEDs with ceramic packages is critically important and should be in charge of delaminating interface layers in the packages.

J. Hu; L. Yang; M. -W. Shin

2008-01-07T23:59:59.000Z

183

AN ASSESSMENT OF FLYWHEEL HIGH POWER ENERGY STORAGE TECHNOLOGY FOR HYBRID VEHICLES  

Science Conference Proceedings (OSTI)

An assessment has been conducted for the DOE Vehicle Technologies Program to determine the state of the art of advanced flywheel high power energy storage systems to meet hybrid vehicle needs for high power energy storage and energy/power management. Flywheel systems can be implemented with either an electrical or a mechanical powertrain. The assessment elaborates upon flywheel rotor design issues of stress, materials and aspect ratio. Twelve organizations that produce flywheel systems submitted specifications for flywheel energy storage systems to meet minimum energy and power requirements for both light-duty and heavy-duty hybrid applications of interest to DOE. The most extensive experience operating flywheel high power energy storage systems in heavy-duty and light-duty hybrid vehicles is in Europe. Recent advances in Europe in a number of vehicle racing venues and also in road car advanced evaluations are discussed. As a frame of reference, nominal weight and specific power for non-energy storage components of Toyota hybrid electric vehicles are summarized. The most effective utilization of flywheels is in providing high power while providing just enough energy storage to accomplish the power assist mission effectively. Flywheels are shown to meet or exceed the USABC power related goals (discharge power, regenerative power, specific power, power density, weight and volume) for HEV and EV batteries and ultracapacitors. The greatest technical challenge facing the developer of vehicular flywheel systems remains the issue of safety and containment. Flywheel safety issues must be addressed during the design and testing phases to ensure that production flywheel systems can be operated with adequately low risk.

Hansen, James Gerald [ORNL

2012-02-01T23:59:59.000Z

184

Time-dependent polarization states of high power, ultrashort laser pulses during atmospheric propagation  

E-Print Network (OSTI)

We investigate, through simulation, the evolution of polarization states during atmospheric propagation of high power, ultrashort laser pulses. A delayed rotational response model handling arbitrary, transverse polarization couples both the amplitude and phase of the polarization states. We find that, while circularly and linearly polarized pulses maintain their polarization, elliptically polarized pulses become depolarized due to energy equilibration between left and right circularly polarized states. The depolarization can be detrimental to remote radiation generation schemes and obscures time-integrated polarization measurements.

Palastro, J P

2013-01-01T23:59:59.000Z

185

Photoionization of optically trapped ultracold atoms with a high-power light-emitting diode  

SciTech Connect

Photoionization of laser-cooled atoms using short pulses of a high-power light-emitting diode (LED) is demonstrated. Light pulses as short as 30 ns have been realized with the simple LED driver circuit. We measure the ionization cross section of {sup 85}Rb atoms in the first excited state, and show how this technique can be used for calibrating efficiencies of ion detector assemblies.

Goetz, Simone; Hoeltkemeier, Bastian; Amthor, Thomas; Weidemueller, Matthias [Physikalisches Institut, Universitaet Heidelberg, Im Neuenheimer Feld 226, 69120 Heidelberg (Germany)

2013-04-15T23:59:59.000Z

186

High power pulsed plasma MHD experiments. Annual report 1 Jan 81-30 Sep 82  

SciTech Connect

Results of high power pulsed plasma MHD experiments are reported. An explosively driven plasma source is used to drive a Faraday mode MHD generator with an externally applied B-field of several tesla. The highest power achieved was 6 gigawatts in a 140 kJ electrical pulse delivered to a resistive load. The experimentally observed scaling relationships of power with applied B-field and electrode area are also presented.

Baum, D.W.; Gill, S.P.; Shimmin, W.L.; Watson, J.D.

1982-09-30T23:59:59.000Z

187

Temperature-Dependent Battery Models for High-Power Lithium-Ion Batteries  

DOE Green Energy (OSTI)

In this study, two battery models for a high-power lithium ion (Li-Ion) cell were compared for their use in hybrid electric vehicle simulations in support of the U.S. Department of Energy's Hybrid Electric Vehicle Program. Saft America developed the high-power Li-Ion cells as part of the U.S. Advanced Battery Consortium/U.S. Partnership for a New Generation of Vehicles programs. Based on test data, the National Renewable Energy Laboratory (NREL) developed a resistive equivalent circuit battery model for comparison with a 2-capacitance battery model from Saft. The Advanced Vehicle Simulator (ADVISOR) was used to compare the predictions of the two models over two different power cycles. The two models were also compared to and validated with experimental data for a US06 driving cycle. The experimental voltages on the US06 power cycle fell between the NREL resistive model and Saft capacitance model predictions. Generally, the predictions of the two models were reasonably close to th e experimental results; the capacitance model showed slightly better performance. Both battery models of high-power Li-Ion cells could be used in ADVISOR with confidence as accurate battery behavior is maintained during vehicle simulations.

Johnson, V.H.; Pesaran, A.A. (National Renewable Energy Laboratory); Sack, T. (Saft America)

2001-01-10T23:59:59.000Z

188

Active high-power RF pulse compression using optically switched resonant delay lines  

DOE Green Energy (OSTI)

The authors present the design and a proof of principle experimental results of an optically controlled high power rf pulse compression system. The design should, in principle, handle few hundreds of Megawatts of power at X-band. The system is based on the switched resonant delay line theory. It employs resonant delay lines as a means of storing rf energy. The coupling to the lines is optimized for maximum energy storage during the charging phase. To discharge the lines, a high power microwave switch increases the coupling to the lines just before the start of the output pulse. The high power microwave switch, required for this system, is realized using optical excitation of an electron-hole plasma layer on the surface of a pure silicon wafer. The switch is designed to operate in the TE{sub 01} mode in a circular waveguide to avoid the edge effects present at the interface between the silicon wafer and the supporting waveguide; thus, enhancing its power handling capability.

Tantawi, S.G.; Ruth, R.D.; Vlieks, A.E. [Stanford Univ., CA (US). Stanford Linear Accelerator Center; Zolotorev, M. [Lawrence Berkeley National Lab., CA (US)

1996-11-01T23:59:59.000Z

189

Coherent infrared imaging camera (CIRIC)  

SciTech Connect

New developments in 2-D, wide-bandwidth HgCdTe (MCT) and GaAs quantum-well infrared photodetectors (QWIP) coupled with Monolithic Microwave Integrated Circuit (MMIC) technology are now making focal plane array coherent infrared (IR) cameras viable. Unlike conventional IR cameras which provide only thermal data about a scene or target, a coherent camera based on optical heterodyne interferometry will also provide spectral and range information. Each pixel of the camera, consisting of a single photo-sensitive heterodyne mixer followed by an intermediate frequency amplifier and illuminated by a separate local oscillator beam, constitutes a complete optical heterodyne receiver. Applications of coherent IR cameras are numerous and include target surveillance, range detection, chemical plume evolution, monitoring stack plume emissions, and wind shear detection.

Hutchinson, D.P.; Simpson, M.L.; Bennett, C.A.; Richards, R.K.; Emery, M.S.; Crutcher, R.I.; Sitter, D.N. Jr.; Wachter, E.A.; Huston, M.A.

1995-07-01T23:59:59.000Z

190

Screening report on cell materials for high-power Li-Ion HEV batteries.  

DOE Green Energy (OSTI)

The Battery Technology Department at Argonne National Laboratory is a major participant in the U.S. Department of Energy's Advanced Technology Development (ATD) program. This multi-national laboratory program is dedicated to improving lithium-ion batteries for high-power HEV and FCEV applications. As part of the FreedomCAR Partnership, this program is addressing the three key barriers for high-power lithium-ion batteries: calendar life, abuse tolerance, and cost. All three of these barriers can be addressed by the choice of materials used in the cell chemistry. To date, the ATD program has developed two high-power cell chemistries, denoted our Gen 1 and Gen 2 cell chemistries. The selection of materials for use in the Gen 2 cell chemistry was based largely on reducing material cost and extending cell calendar life, relative to our Gen 1 cell chemistry. Table 1 provides a list of the materials used in our Gen 2 cell chemistry and their projected costs, when produced in large-scale quantities. In evaluating advanced materials, we have focused our efforts on materials that are lower cost than those listed in Table 1, while simultaneously offering enhanced chemical, structural, and thermal stability. Therefore, we have focused on natural graphite anode materials (having round-edge particle morphologies), cathode materials that contain more Mn and less Co and Ni (which can be produced via low-cost processes), lower cost electrode binders and/or binders that possess superior bonding properties at lower concentrations, and lower cost salts and solvents (with superior thermal and oxidation/reduction stability) for use in the electrolyte. The purpose of this report is to document the results of screening tests that were performed on a large number of advanced low-cost materials. These materials were screened for their potential to impact positively on the calendar life, safety, and/or cost of high-power lithium-ion cell chemistries, relative to our Gen 2 cell chemistry. As part of this effort, we developed and employed a set of standard test protocols to evaluate all of the materials. After brief descriptions of the screening test methodologies and equipment, relevant data on each material are summarized in the body of this report. We have evaluated five categories of materials, and the report is organized accordingly. Results will be presented on advanced carbons for anodes, improved cathode materials, new salts and solvent systems, alternative binders, and novel separators.

Liu, J.; Kahaian, A.; Belharouak, I.; Kang, S.; Oliver, S.; Henriksen, S.; Amine, K.

2003-04-24T23:59:59.000Z

191

High power tests of dressed supconducting 1.3 GHz RF cavities  

SciTech Connect

A single-cavity test cryostat is used to conduct pulsed high power RF tests of superconducting 1.3 GHz RF cavities at 2 K. The cavities under test are welded inside individual helium vessels and are outfitted ('dressed') with a fundamental power coupler, higher-order mode couplers, magnetic shielding, a blade tuner, and piezoelectric tuners. The cavity performance is evaluated in terms of accelerating gradient, unloaded quality factor, and field emission, and the functionality of the auxiliary components is verified. Test results from the first set of dressed cavities are presented here.

Hocker, A.; Harms, E.R.; Lunin, A.; Sukhanov, A.; /Fermilab

2011-03-01T23:59:59.000Z

192

Surface treated natural graphite as anode material for high-power Li-ion battery applications.  

Science Conference Proceedings (OSTI)

High power application of Li-ion battery in hybrid electrical vehicles requires low cost and safe cell materials. Among the various carbon anode materials used in lithium ion batteries, natural graphite shows the most promise with advantages in performance and cost. However, natural graphite is not compatible with propylene carbonate (PC)-based electrolytes, which have a lower melting point and improved safety characteristics. The problem with it is that the molecules of propylene carbonate intercalate with Li+ into graphite, and that frequently leads to the exfoliation of the graphite matrix.

Liu, J.; Vissers, D. R.; Amine, K.; Barsukov, I. V.; Henry, F.; Doniger, J.; Chemical Engineering; Superior Graphite Co.

2006-01-01T23:59:59.000Z

193

High Power, High Voltage FETs in Linear Applications: A User's Perspective  

SciTech Connect

The specifications of the current crop of highpower, high-voltage field-effect transistors (FETs) can lure a designer into employing them in high-voltage DC equipment. Devices with extremely low on-resistance and very high power ratings are available from several manufacturers. However, our experience shows that high-voltage, linear operation of these devices at near-continuous duty can present difficult reliability challenges at stress levels well-below their published specifications. This paper chronicles the design evolution of a 600 volt, 8 ampere shunt regulator for use with megawatt-class radio transmitters, and presents a final design that has met its reliability criteria.

N. Greenough, E. Fredd, S. DePasquale

2009-09-21T23:59:59.000Z

194

Measurement and modeling of mirror distortion in a high power FEL  

Science Conference Proceedings (OSTI)

Mirror heating in a high power FEL can alter the optical mode and affect the gain of the laser. This can lead to a large reduction of the laser power from ideal values. Measurements of the power and mode size in the Jefferson Lab IR Demo laser have shown clear evidence of mirror distortion at high average power leading (up to 17 kW incident on the mirrors and over 40 W absorbed per mirror). The measurements and comparisons with modeling will be presented. Both steady state and transient analyses and measurements are considered.

Benson, S.; Neil, G.; Michelle D. Shinn

2000-01-01T23:59:59.000Z

195

Coherent scattering from a free gas  

E-Print Network (OSTI)

We investigate decoherence in atom interferometry due to scattering from a background gas and show that the supposition that residual coherence is due to near-forward scattering is incorrect. In fact, the coherent part is ...

Sanders, Scott N.

196

Modeling coherence in ESOL learner texts  

Science Conference Proceedings (OSTI)

To date, few attempts have been made to develop new methods and validate existing ones for automatic evaluation of discourse coherence in the noisy domain of learner texts. We present the first systematic analysis of several methods for assessing coherence ...

Helen Yannakoudakis; Ted Briscoe

2012-06-01T23:59:59.000Z

197

Failure modes in high-power lithium-ion batteries for use inhybrid electric vehicles  

DOE Green Energy (OSTI)

The Advanced Technology Development (ATD) Program seeks to aid the development of high-power lithium-ion batteries for hybrid electric vehicles. Nine 18650-size ATD baseline cells were tested under a variety of conditions. The cells consisted of a carbon anode, LiNi{sub 0.8}Co{sub 0.2}O{sub 2} cathode and DEC-EC-LiPF{sub 6} electrolyte, and they were engineered for high-power applications. Selected instrumental techniques such as synchrotron IR microscopy, Raman spectroscopy, scanning electron microscopy, atomic force microscopy, gas chromatography, etc. were used to characterize the anode, cathode, current collectors and electrolyte from these cells. The goal was to identify detrimental processes which lead to battery failure under a high-current cycling regime as well as during storage at elevated temperatures. The diagnostic results suggest that the following factors contribute to the cell power loss: (a) SEI deterioration and non-uniformity on the anode, (b) morphology changes, increase of impedance and phase separation on the cathode, (c) pitting corrosion on the cathode Al current collector, and (d) decomposition of the LiPF{sub 6} salt in the electrolyte at elevated temperature.

Kostecki, R.; Zhang, X.; Ross Jr., P.N.; Kong, F.; Sloop, S.; Kerr, J.B.; Striebel, K.; Cairns, E.; McLarnon, F.

2001-06-22T23:59:59.000Z

198

Design and testing of high power, repetitively pulsed solid-state closing switches  

DOE Green Energy (OSTI)

Repetitively pulsed closing switches are often required in high-power physics experiments. Traditionally, ignitrons have been used for these applications. There are reasons why ignitrons have undesirable features, such as the high trigger current which causes electromagnetic interference, the arc instability and environmental concern with the mercury used in the switches. With the development of ever increasing power rating of solid-state switches, in particular thyristors, the designer has the tools to replace ignitrons with solid-state devices. Using as an example a recently designed and tested 10 kV, 80 kA high-power switch, the design philosophy for repetitively pulsed switches is developed. The parameters which impose the greatest challenge on the device, such as di/dt, temperature rise and reverse blocking voltage are investigated with respect to their capability when operating in the pulsed mode. Starting with the available device data sheet information and published results of the dependency of the number of life cycles as a function of the device temperature, it is shown how the overload capability of a device for short term pulsed applications can be exploited. The detailed design of a 2 Hz, 10{sup 8} cycle, 12.5 kV, 80 kA, 3 ms switch, with a short circuit capability of 250 kA, is presented. The paper concludes with a short summary about device limits in voltage, current amplitude and pulse length ratings for repetitively pulsed switches using available thyristors.

Boenig, H.J. [Los Alamos National Lab., NM (United States); Schwartzenberg, J.W.; Willinger, L.J.; Piccone, D.E. [Silicon Power Corp., Malvern, PA (United States); Lopez, D.A.; Smolleck, H.A. [New Mexico State Univ., Las Cruces, NM (United States). Dept. of Electrical and Computer Engineering

1997-04-01T23:59:59.000Z

199

COLLECTIVE EVIDENCE FOR INVERSE COMPTON EMISSION FROM EXTERNAL PHOTONS IN HIGH-POWER BLAZARS  

Science Conference Proceedings (OSTI)

We present the first collective evidence that Fermi-detected jets of high kinetic power (L{sub kin}) are dominated by inverse Compton emission from upscattered external photons. Using a sample with a broad range in orientation angle, including radio galaxies and blazars, we find that very high power sources (L{sub kin} > 10{sup 45.5} erg s{sup -1}) show a significant increase in the ratio of inverse Compton to synchrotron power (Compton dominance) with decreasing orientation angle, as measured by the radio core dominance and confirmed by the distribution of superluminal speeds. This increase is consistent with beaming expectations for external Compton (EC) emission, but not for synchrotron self-Compton (SSC) emission. For the lowest power jets (L{sub kin} < 10{sup 43.5} erg s{sup -1}), no trend between Compton and radio core dominance is found, consistent with SSC. Importantly, the EC trend is not seen for moderately high power flat spectrum radio quasars with strong external photon fields. Coupled with the evidence that jet power is linked to the jet speed, this finding suggests that external photon fields become the dominant source of seed photons in the jet comoving frame only for the faster and therefore more powerful jets.

Meyer, Eileen T.; Fossati, Giovanni [Department of Physics and Astronomy, Rice University, Houston, TX 77005 (United States); Georganopoulos, Markos [Department of Physics, Joint Center for Astrophysics, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 (United States); Lister, Matthew L. [Department of Physics, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907 (United States)

2012-06-10T23:59:59.000Z

200

High power millimeter wave experiment of ITER relevant electron cyclotron heating and current drive system  

Science Conference Proceedings (OSTI)

High power, long pulse millimeter (mm) wave experiments of the RF test stand (RFTS) of Japan Atomic Energy Agency (JAEA) were performed. The system consists of a 1 MW/170 GHz gyrotron, a long and short distance transmission line (TL), and an equatorial launcher (EL) mock-up. The RFTS has an ITER-relevant configuration, i.e., consisted by a 1 MW-170 GHz gyrotron, a mm wave TL, and an EL mock-up. The TL is composed of a matching optics unit, evacuated circular corrugated waveguides, 6-miter bends, an in-line waveguide switch, and an isolation valve. The EL-mock-up is fabricated according to the current design of the ITER launcher. The Gaussian-like beam radiation with the steering capability of 20 deg. - 40 deg. from the EL mock-up was also successfully proved. The high power, long pulse power transmission test was conducted with the metallic load replaced by the EL mock-up, and the transmission of 1 MW/800 s and 0.5 MW/1000 s was successfully demonstrated with no arcing and no damages. The transmission efficiency of the TL was 96%. The results prove the feasibility of the ITER electron cyclotron heating and current drive system.

Takahashi, K.; Kajiwara, K.; Oda, Y.; Kasugai, A.; Kobayashi, N.; Sakamoto, K. [Japan Atomic Energy Agency, 801-1 Mukoyama, Naka, Ibaraki 311-0193 (Japan); Doane, J.; Olstad, R. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States); Henderson, M. [ITER Organization, CS90 046, 13067 St. Paul lez Durance Cedex (France)

2011-06-15T23:59:59.000Z

Note: This page contains sample records for the topic "high-power coherent terahertz" 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

High power RF test of an 805 MHz RF cavity for a muon cooling channel  

SciTech Connect

We present recent high power RF test results on an 805 MHz cavity for a muon cooling experiment at Lab G in Fermilab. In order to achieve high accelerating gradient for large transverse emittance muon beams, the cavity design has adopted a pillbox like shape with 16 cm diameter beam iris covered by thin Be windows, which are demountable to allow for RF tests of different windows. The cavity body is made from copper with stiff stainless steel rings brazed to the cavity body for window attachments. View ports and RF probes are available for visual inspections of the surface of windows and cavity and measurement of the field gradient. Maximum of three thermo-couples can be attached to the windows for monitoring the temperature gradient on the windows caused by RF heating. The cavity was measured to have Q{sub 0} of about 15,000 with copper windows and coupling constant of 1.3 before final assembling. A 12 MW peak power klystron is available at Lab G in Fermilab for the high power test. The cavity and coupler designs were performed using the MAFIA code in the frequency and the time domain. Numerical simulation results and cold test measurements on the cavity and coupler will be presented for comparisons.

Li, Derun; Corlett, J.; MacGill, R.; Rimmer, R.; Wallig, J.; Zisman, M.; Moretti, A.; Qian, Z.; Wu, V.; Summers, D.; Norem, J.

2002-05-30T23:59:59.000Z

202

FERROELECTRIC SWITCH FOR A HIGH-POWER Ka-BAND ACTIVE PULSE COMPRESSOR  

Science Conference Proceedings (OSTI)

Results are presented for design of a high-power microwave switch for operation at 34.3 GHz, intended for use in an active RF pulse compressor. The active element in the switch is a ring of ferroelectric material, whose dielectric constant can be rapidly changed by application of a high-voltage pulse. As envisioned, two of these switches would be built into a pair of delay lines, as in SLED-II at SLAC, so as to allow 30-MW ?s-length Ka-band pulses to be compressed in time by a factor-of-9 and multiplied in amplitude to generate 200 MW peak power pulses. Such high-power pulses could be used for testing and evaluation of high-gradient mm-wave accelerator structures, for example. Evaluation of the switch design was carried out with an X-band (11.43 GHz) prototype, built to incorporate all the features required for the Ka-band version.

Hirshfield, Jay L. [Omega-P, Inc.

2013-12-18T23:59:59.000Z

203

High-power, Ultralow-noise Semiconductor External Cavity Lasers Based on Low-confinement Optical Waveguide Gain Media  

E-Print Network (OSTI)

For the past several years, we have been developing a new class of high-power, low-noise semiconductor optical gain medium based on the slab-coupled optical waveguide (SCOW) concept. The key characteristics of the SCOW ...

Juodawlkis, Paul W.

204

Technology survey and performance scaling for the design of high power nuclear electric power and propulsion systems  

E-Print Network (OSTI)

High power nuclear electric propulsion systems have the capability to enable many next-generation space exploration applications. To date, use of electric primary propulsion in flight systems has been limited to low-power, ...

White, Daniel B., Jr

2011-01-01T23:59:59.000Z

205

Controlling terahertz waves with meta-materials and photonic bandgap structures  

SciTech Connect

We will describe research conducted at Los Alamos National Laboratory towards developing components for controlling terahertz waves. We employ meta-materials and, particularly, meta-films, as very compact absorbers for controlling quasioptical beams. We believe that dielectric photonic bandgap structures could replace ordinary metal waveguide devices at THz, since metal structures become extremely lossy in this frequency range.

Shchegolkov, Dmitry [Los Alamos National Laboratory; Azad, Abul [Los Alamos National Laboratory; O' Hara, John F [Los Alamos National Laboratory; Moody, Nathan A [Los Alamos National Laboratory; Simakov, Evgenya I [Los Alamos National Laboratory

2010-12-07T23:59:59.000Z

206

Coded excitation of broadband terahertz using optical rectification in poled lithium niobate  

E-Print Network (OSTI)

Coded excitation of broadband terahertz using optical rectification in poled lithium niobate T optical rectification of femtosecond laser pulses in poled lithium niobate patterned with a 53-bit binary forms can be generated by optical rectification in poled lithium niobate PLN . A femtosecond laser pulse

Buma, Takashi

207

Analysis and design of terahertz microstrip antenna on photonic bandgap material  

Science Conference Proceedings (OSTI)

In this paper, a dielectric slab with periodic implantation of the air gaps has been analyzed. An effective dielectric permittivity of the 1-D photonic bandgap substrate material (PBG material) with host material as Polytetrafluoroethylene (PTFE) has ... Keywords: Directivity, Electromagnetic band gap, Metamaterial, Microstrip patch antenna, Radiation efficiency, Terahertz spectrum

Kumud Ranjan Jha; G. Singh

2012-12-01T23:59:59.000Z

208

Ultrafast shift and injection currents observed in wurtzite semiconductors via emitted terahertz radiation  

E-Print Network (OSTI)

and injection currents have been generated in bulk GaAs and strained GaAs quantum wells QWs , respectivelyUltrafast shift and injection currents observed in wurtzite semiconductors via emitted terahertz; published online 18 November 2005 Shift and injection currents are generated in the wurtzite semiconductors

Van Driel, Henry M.

209

Modeling of large aperture third harmonic frequency conversion of high power Nd:glass laser systems  

SciTech Connect

To provide high-energy, high-power beams at short wavelengths for inertial-confinement-fusion experiments, we routinely convert the 1.053-{mu}m output of the Nova, Nd:phosphate-glass, laser system to its third-harmonic wavelength. We describe performance and conversion efficiency modeling of the 3 {times} 3 arrays potassium-dihydrogen-phosphate crystal plates used for type II/type II phase-matched harmonic conversion of Nova 0.74-m diameter beams, and an alternate type I/type II phase-matching configuration that improves the third-harmonic conversion efficiency. These arrays provide energy conversion of up to 65% and intensity conversion to 70%. 19 refs., 11 figs.

Henesian, M.A.; Wegner, P.J.; Speck, D.R.; Bibeau, C.; Ehrlich, R.B.; Laumann, C.W.; Lawson, J.K.; Weiland, T.L.

1991-03-13T23:59:59.000Z

210

Uniform irradiation of adjustable target spots in high-power laser driver  

Science Conference Proceedings (OSTI)

For smoothing and shaping the on-target laser patterns flexibly in high-power laser drivers, a scheme has been developed that includes a zoom lens array and two-dimensional smoothing by spectral dispersion (SSD). The size of the target pattern can be controlled handily by adjusting the focal length of the zoom lens array, while the profile of the pattern can be shaped by fine tuning the distance between the target and the focal plane of the principal focusing lens. High-frequency stripes inside the pattern caused by beamlet interference are wiped off by spectral dispersion. Detailed simulations indicate that SSD works somewhat differently for spots of different sizes. For small spots, SSD mainly smooths the intensity modulation of low-to-middle spatial frequency, while for large spots, SSD sweeps the fine speckle structure to reduce nonuniformity of middle-to-high frequency. Spatial spectra of the target patterns are given and their uniformity is evaluated.

Jiang Xiujuan; Li Jinghui; Li Huagang; Li Yang; Lin Zunqi

2011-09-20T23:59:59.000Z

211

A high-power spatial filter for Thomson scattering stray light reduction  

Science Conference Proceedings (OSTI)

The Thomson scattering diagnostic on the High Beta Tokamak-Extended Pulse (HBT-EP) is routinely used to measure electron temperature and density during plasma discharges. Avalanche photodiodes in a five-channel interference filter polychromator measure scattered light from a 6 ns, 800 mJ, 1064 nm Nd:YAG laser pulse. A low cost, high-power spatial filter was designed, tested, and added to the laser beamline in order to reduce stray laser light to levels which are acceptable for accurate Rayleigh calibration. A detailed analysis of the spatial filter design and performance is given. The spatial filter can be easily implemented in an existing Thomson scattering system without the need to disturb the vacuum chamber or significantly change the beamline. Although apertures in the spatial filter suffer substantial damage from the focused beam, with proper design they can last long enough to permit absolute calibration.

Levesque, J. P.; Litzner, K. D.; Mauel, M. E.; Maurer, D. A.; Navratil, G. A.; Pedersen, T. S. [Department of Applied Physics and Applied Mathematics, Columbia University, 500 W. 120th Street, New York, New York 10027 (United States)

2011-03-15T23:59:59.000Z

212

High-Power Solid-State Lasers from a Laser Glass Perspective  

Science Conference Proceedings (OSTI)

Advances in laser glass compositions and manufacturing have enabled a new class of high-energy/high-power (HEHP), petawatt (PW) and high-average-power (HAP) laser systems that are being used for fusion energy ignition demonstration, fundamental physics research and materials processing, respectively. The requirements for these three laser systems are different necessitating different glasses or groups of glasses. The manufacturing technology is now mature for melting, annealing, fabricating and finishing of laser glasses for all three applications. The laser glass properties of major importance for HEHP, PW and HAP applications are briefly reviewed and the compositions and properties of the most widely used commercial laser glasses summarized. Proposed advances in these three laser systems will require new glasses and new melting methods which are briefly discussed. The challenges presented by these laser systems will likely dominate the field of laser glass development over the next several decades.

Campbell, J H; Hayden, J S; Marker, A J

2010-12-17T23:59:59.000Z

213

High-Power Laser Pulse Recirculation for Inverse Compton Scattering-Produced Gamma-Rays  

Science Conference Proceedings (OSTI)

Inverse Compton scattering of high-power laser pulses on relativistic electron bunches represents an attractive method for high-brightness, quasi-monoenergetic {gamma}-ray production. The efficiency of {gamma}-ray generation via inverse Compton scattering is severely constrained by the small Thomson scattering cross section. Furthermore, repetition rates of high-energy short-pulse lasers are poorly matched with those available from electron accelerators, resulting in low repetition rates for generated {gamma}-rays. Laser recirculation has been proposed as a method to address those limitations, but has been limited to only small pulse energies and peak powers. Here we propose and experimentally demonstrate an alternative method for laser pulse recirculation that is uniquely capable of recirculating short pulses with energies exceeding 1 J. Inverse Compton scattering of recirculated Joule-level laser pulses has a potential to produce unprecedented peak and average {gamma}-ray brightness in the next generation of sources.

Jovanovic, I; Shverdin, M; Gibson, D; Brown, C

2007-04-17T23:59:59.000Z

214

Interfacial electron and phonon scattering processes in high-powered nanoscale applications.  

SciTech Connect

The overarching goal of this Truman LDRD project was to explore mechanisms of thermal transport at interfaces of nanomaterials, specifically linking the thermal conductivity and thermal boundary conductance to the structures and geometries of interfaces and boundaries. Deposition, fabrication, and post possessing procedures of nanocomposites and devices can give rise to interatomic mixing around interfaces of materials leading to stresses and imperfections that could affect heat transfer. An understanding of the physics of energy carrier scattering processes and their response to interfacial disorder will elucidate the potentials of applying these novel materials to next-generation high powered nanodevices and energy conversion applications. An additional goal of this project was to use the knowledge gained from linking interfacial structure to thermal transport in order to develop avenues to control, or 'tune' the thermal transport in nanosystems.

Hopkins, Patrick E.

2011-10-01T23:59:59.000Z

215

LEDA - A HIGH-POWER TEST BED OF INNOVATION AND OPPORTUNITY  

Science Conference Proceedings (OSTI)

The low-energy demonstration accelerator (LEDA) is an operational 6.7-MeV. 100-mA proton accelerator consisting of an injector, radio-frequency quadrupole (RFQ), and all associated integration equipment. In order to achieve this unprecedented level of performance (670-kW of beam power) from an RFQ, a number of design innovations were required. They will highlight a number of those more significant technical advances, including those in the proton injector, the RFQ configuration, the RF klystrons, the beam stop, and the challenges of beam measurements. In addition to identifying the importance of these innovations to LEDA performance, they will summarize the plans for further testing, and the possibilities for addition of more accelerating structures, including the planned use of very-low-beta super-conducting structures. LEDA's current and upgradable configuration is appropriate for several future high-power accelerators, including those for the transmutation of radioactive waste.

J. SCHNEIDER; R. SHEFFIELD

2000-08-01T23:59:59.000Z

216

Precision Neutrino Oscillation Measurements using Simultaneous High-Power, Low-Energy Project-X Beams  

E-Print Network (OSTI)

The first phase of the long-baseline neutrino experiment, LBNE10, will use a broadband, high-energy neutrino beam with a 10-kt liquid argon TPC at 1300 km to study neutrino oscillation. In this paper, we describe potential upgrades to LBNE10 that use Project X to produce high-intensity, low-energy neutrino beams. Simultaneous, high-power operation of 8- and 60-GeV beams with a 200-kt water Cerenkov detector would provide sensitivity to nu_mu to nu_e oscillations at the second oscillation maximum. We find that with ten years of data, it would be possible to measure sin2(2theta_13) with precision comparable to that expected from reactor antineutrino disappearance and to measure the value of the CP phase, delta_CP, with an uncertainty of (5-10) degrees. This document is submitted for inclusion in Snowmass 2013.

M. Bishai; M. Diwan; S. Kettell; J. Stewart; R. Tschirhart; B. Viren; L. Whitehead; E. Worcester

2013-07-02T23:59:59.000Z

217

Measurement of beam energy spectrum and impurity content in high-power neutral beam injectors  

DOE Green Energy (OSTI)

The energy spectrum and impurity content of a high-power neutral beam are measured by implanting the beam into high-purity silicon crystals. The depth distribution of the beam particles is then measured by secondary ion mass spectrometry (SIMS); the penetration depth is a function of the incident particle energy. This is one of the few measurement techniques that can determine neutral beam energy components directly. From the results, percentages of atomic and molecular ions in the source plasma can be inferred. Use of deuterium as the source gas provides insight into the role of residual hydrogen in the ion source and accelerating grids and in the SIMS analysis. The principal impurities are carbon and oxygen. Preliminary data indicate that carbon can originate from both methane and carbon monoxide, while oxygen can come from molecular oxygen, carbon monoxide, and water. Results are given and future plans are discussed.

Langley, R.A.; Ryan, P.M.; Tsai, C.C.; Menon, M.M.; Botnick, E.M.; Magee, C.W.

1985-05-01T23:59:59.000Z

218

Method of Fabrication of High Power Density Solid Oxide Fuel Cells  

DOE Patents (OSTI)

A method for producing ultra-high power density solid oxide fuel cells (SOFCs). The method involves the formation of a multilayer structure cells wherein a buffer layer of doped-ceria is deposited intermediate a zirconia electrolyte and a cobalt iron based electrode using a colloidal spray deposition (CSD) technique. For example, a cobalt iron based cathode composed of (La,Sr)(Co,Fe)O(LSCF) may be deposited on a zirconia electrolyte via a buffer layer of doped-ceria deposited by the CSD technique. The thus formed SOFC have a power density of 1400 mW/cm.sup.2 at 600.degree. C. and 900 mW/cm.sup.2 at 700.degree. C. which constitutes a 2-3 times increased in power density over conventionally produced SOFCs.

Pham, Ai Quoc (San Jose, CA); Glass, Robert S. (Livermore, CA)

2008-09-09T23:59:59.000Z

219

Application of high powered lasers to drilling and completing deep walls.  

SciTech Connect

High powered laser rock drilling was studied as a revolutionary method for drilling and completing deep gas and oil wells. The objectives of this 2002 to 2003 fiscal year research were to study the concept that large diameter holes can be created by multiple overlapping small beam spots, to determine the ability of lasers to drill rock submerged to some depth in water, to demonstrate the possibilities of lasers for perforating application, and to determine the wavelength effects on rock removal. Laser technology applied to well drilling and completion operations is attractive because it has the potential to reduce drilling time, create a ceramic lining that may eliminate the need for steel casing, provide additional monitor-on-drilling laser sensors and improve well performance through improved perforation. The results from this research will help engineering design on a laser-based well drilling system.

Reed, C. B.; Xu, Z.; Parker, R. A.; Gahan, B. C.; Batarseh, S.; Graves, R. M.; Figueroa, H.; Deeg, W.

2003-07-30T23:59:59.000Z

220

FY2000 Highlights Report for the Vehicle High-Power Energy Storage Program  

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

Energy Energy Office of Advanced Automotive Technologies 1000 Independence Avenue, S.W. Washington, DC 20585-0121 FY 2000 Highlights Report for the Vehicle High-Power Energy Storage Program Energy Efficiency and Renewable Energy Office of Transportation Technologies Office of Advanced Automotive Technologies Energy Management Team Raymond A. Sutula Energy Management Team Leader November 2000 This document highlights work sponsored by agencies of the U.S. Government. Neither the U.S. Government nor any agency, thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe

Note: This page contains sample records for the topic "high-power coherent terahertz" 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

High-power microwave LDMOS transistors for wireless data transmission technologies (Review)  

Science Conference Proceedings (OSTI)

The fields of the application, structure, fabrication, and packaging technology of high-power microwave LDMOS transistors and the main advantages of these devices were analyzed. Basic physical parameters and some technology factors were matched for optimum device operation. Solid-state microwave electronics has been actively developed for the last 10-15 years. Simultaneously with improvement of old devices, new devices and structures are actively being adopted and developed and new semiconductor materials are being commercialized. Microwave LDMOS technology is in demand in such fields as avionics, civil and military radars, repeaters, base stations of cellular communication systems, television and broadcasting transmitters, and transceivers for high-speed wireless computer networks (promising Wi-Fi and Wi-Max standards).

Kuznetsov, E. V., E-mail: E.Kouzntsov@tcen.ru; Shemyakin, A. V. [Moscow Institute of Electronic Technology, SMC Technological Center (Russian Federation)

2010-12-15T23:59:59.000Z

222

An innovative demonstration of high power density in a compact MHD (magnetohydrodynamic) generator  

DOE Green Energy (OSTI)

The present program was conducted by the University of Tennessee Space Institute (UTSI). It was by its nature a high risk experimental program to demonstrate the feasibility of high power density operation in a laboratory scale combustion driven MHD generator. Maximization of specific energy was not a consideration for the present program, but the results have implications in this regard by virtue of high energy fuel used. The power density is the ratio of the electrical energy output to the internal volume of the generator channel. The MHD process is a volumetric process and the power density is therefore a direct measure of the compactness of the system. Specific energy, is the ratio of the electrical energy output to consumable energy used for its production. The two parameters are conceptually interrelated. To achieve high power density and implied commensurate low system volume and weight, it was necessary to use an energetic fuel. The high energy fuel of choice was a mixture of powdered aluminum and carbon seeded with potassium carbonate and burned with gaseous oxygen. The solid fuel was burned in a hybrid combustion scheme wherein the fuel was cast within a cylindrical combustor in analogy with a solid propellant rocket motor. Experimental data is limited to gross channel output current and voltage, magnetic field strength, fuel and oxidizer flow rates, flow train external temperatures and combustor pressure. Similarly, while instantaneous oxidizer flow rates were measured, only average fuel consumption based on pre and post test component weights and dimensions was possible. 4 refs., 60 figs., 9 tabs.

Schmidt, H.J.; Lineberry, J.T.; Chapman, J.N.

1990-06-01T23:59:59.000Z

223

Coherent Communications, Imaging and Targeting  

SciTech Connect

Laboratory and field demonstration results obtained as part of the DARPA-sponsored Coherent Communications, Imaging and Targeting (CCIT) program are reviewed. The CCIT concept uses a Phase Conjugation Engine based on a quadrature receiver array, a hologram processor and a spatial light modulator (SLM) for high-speed, digital beam control. Progress on the enabling MEMS SLM, being developed by a consortium consisting of LLNL, academic institutions and small businesses, is presented.

Stappaerts, E; Baker, K; Gavel, D; Wilks, S; Olivier, S; Brase, J; Olivier, S; Brase, J

2003-10-03T23:59:59.000Z

224

Does coherence enhance transport in photosynthesis?  

E-Print Network (OSTI)

Recent observations of coherence in photosynthetic complexes have led to the question of whether quantum effects can occur in vivo, not under femtosecond laser pulses but in incoherent sunlight and at steady state, and, if so, whether the coherence explains the high exciton transfer efficiency. We distinguish several types of coherence and show that although some photosynthetic pathways are partially coherent processes, photosynthesis in nature proceeds through stationary states. This distinction allows us to rule out several mechanisms of transport enhancement in sunlight. In particular, although they are crucial for understanding exciton transport, neither wavelike motion nor microscopic coherence, on their own, enhance the efficiency. By contrast, two partially coherent mechanisms---ENAQT and supertransfer---can enhance transport even in sunlight and thus constitute motifs for the optimisation of artificial sunlight harvesting. Finally, we clarify the importance of ultrafast spectroscopy in understanding i...

Kassal, Ivan; Rahimi-Keshari, Saleh

2012-01-01T23:59:59.000Z

225

Does coherence enhance transport in photosynthesis?  

E-Print Network (OSTI)

Recent observations of coherence in photosynthetic complexes have led to the question of whether quantum effects can occur in vivo, not under femtosecond laser pulses but in incoherent sunlight and at steady state, and, if so, whether the coherence explains the high exciton transfer efficiency. We distinguish several types of coherence and show that although some photosynthetic pathways are partially coherent processes, photosynthesis in nature proceeds through stationary states. This distinction allows us to rule out several mechanisms of transport enhancement in sunlight. In particular, although they are crucial for understanding exciton transport, neither wavelike motion nor microscopic coherence, on their own, enhance the efficiency. By contrast, two partially coherent mechanisms---ENAQT and supertransfer---can enhance transport even in sunlight and thus constitute motifs for the optimisation of artificial sunlight harvesting. Finally, we clarify the importance of ultrafast spectroscopy in understanding incoherent processes.

Ivan Kassal; Joel Yuen-Zhou; Saleh Rahimi-Keshari

2012-10-18T23:59:59.000Z

226

Coherence delay augmented laser beam homogenizer  

SciTech Connect

The geometrical restrictions on a laser beam homogenizer are relaxed by ug a coherence delay line to separate a coherent input beam into several components each having a path length difference equal to a multiple of the coherence length with respect to the other components. The components recombine incoherently at the output of the homogenizer, and the resultant beam has a more uniform spatial intensity suitable for microlithography and laser pantogography. Also disclosed is a variable aperture homogenizer, and a liquid filled homogenizer.

Rasmussen, Paul (Livermore, CA); Bernhardt, Anthony (Berkeley, CA)

1993-01-01T23:59:59.000Z

227

Interferometric SAR coherence classification utility assessment  

SciTech Connect

The classification utility of a dual-antenna interferometric synthetic aperture radar (IFSAR) is explored by comparison of maximum likelihood classification results for synthetic aperture radar (SAR) intensity images and IPSAR intensity and coherence images. The addition of IFSAR coherence improves the overall classification accuracy for classes of trees, water, and fields. A threshold intensity-coherence classifier is also compared to the intensity-only classification results.

Yocky, D.A.

1998-03-01T23:59:59.000Z

228

Multiple quantum coherence in HYSCORE spectra  

Science Conference Proceedings (OSTI)

The implementation of matched pulses in two-dimensional electron spin echo envelope modulation experiments results in a drastic increase in intensity of peaks representing nuclear multiple quantum coherence. For a spin system consisting of one electron spin S= 1 2 and two nuclei with spin I= 1 2 the nuclear coherence created by the sequence (?/2)???(?/2) is calculated. The transfer amplitudes between different kinds of nuclear coherences of a microwave ? pulse are given. A new matched HYSCORE pulse sequence

Lorenz Liesum; Arthur Schweiger

2001-01-01T23:59:59.000Z

229

Coherent instabilities in random lasers  

SciTech Connect

A numerical study is presented of random lasers as a function of the pumping rate above the threshold for lasing. Depending on the leakiness of the system resonances, which is typically larger in random lasers compared to conventional lasers, we observe that the stationary lasing regime becomes unstable above a second threshold. Coherent instabilities are observed as self pulsation at a single frequency of the output intensity, population inversion, as well as the atomic polarization. We find these Rabi oscillations have the same frequency everywhere in the random laser despite the fact that the field intensity strongly depends on the spatial location.

Andreasen, Jonathan; Sebbah, Patrick; Vanneste, Christian [Laboratoire de Physique de la Matiere Condensee, CNRS UMR 6622, Universite de Nice-Sophia Antipolis, Parc Valrose, F-06108, Nice Cedex 02 (France)

2011-08-15T23:59:59.000Z

230

Coherent Control of Quantum Matter  

Science Conference Proceedings (OSTI)

This talk addresses some recent work aimed at controlling the low-lying electrodynamics of quantum solids using strong field transients. The excitation of selected vibrational resonances to manipulate the many-body physics of one dimensional Mott Hubbard Insulators and to perturb competing orders in High-Tc superconductors is also covered. Finally, the speaker shows how the electrodynamics of layered superconductors can be driven through the orderparameter phase gradient, demonstrating ultrafast transistor action in a layered superconductor. Advances in the use of coherent optics, from tabletop sources to THz and x-ray free-electron lasers are also discussed.

Cavalleri, Andrea [Max Planck Institute

2011-10-05T23:59:59.000Z

231

Development and extended operation of a high power radiation loaded heat pipe  

SciTech Connect

A high temperature, high power molybdenum-lithium heat pipe has been fabricated and tested at 1500 K for 1700 hours with radiant heat rejection. Power throughput during the test was approximately 14 kW, corresponding to an axial flux density of 11 kW/cm/sup 2/ for the 1.59 cm diameter heat pipe. Radial flux density was 70 W/cm/sup 2/ over an evaporator length of 40.0 cm. Condenser length was approximately 150 cm with radiant heat rejection from the condenser to a coaxial water cooled radiation calorimeter. A plasma sprayed, high emissivity coating was used on the condenser surface to increase the radiant heat rejection during the tests. The heat pipe was operated for 514 hours at steady state conditions before being damaged during a planned shutdown for test equipment maintenance. The damage was repaired and the initial 1000 hour test period completed without further incident. After physical examination of the heat pipe at 1000 hours the test was resumed and the heat pipe operated at the same conditions for an additional 700 hours before conclusion of this test phase.

Merrigan, M.A.; Keddy, E.S.; Runyan, J.R.; Martinez, H.E.

1984-06-01T23:59:59.000Z

232

Boron-rich plasma by high power impulse magnetron sputtering of lanthanum hexaboride  

Science Conference Proceedings (OSTI)

Boron-rich plasmas have been obtained using a LaB{sub 6} target in a high power impulse sputtering (HiPIMS) system. The presence of {sup 10}B{sup +}, {sup 11}B{sup +}, Ar{sup 2+}, Ar{sup +}, La{sup 2+}, and La{sup +} and traces of La{sup 3+}, {sup 12}C{sup +}, {sup 14}N{sup +}, and {sup 16}O{sup +} have been detected using an integrated mass and energy spectrometer. Peak currents as low as 20 A were sufficient to obtain plasma dominated by {sup 11}B{sup +} from a 5 cm planar magnetron. The ion energy distribution function for boron exhibits an energetic tail extending over several 10 eV, while argon shows a pronounced peak at low energy (some eV). This is in agreement with models that consider sputtering (B, La) and gas supply (from background and 'recycling'). Strong voltage oscillations develop at high current, greatly affecting power dissipation and plasma properties.

Oks, Efim M. [State University of Control Systems and Radioelectronics, Tomsk (Russian Federation); Anders, Andre [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2012-10-15T23:59:59.000Z

233

New high power 200 MHz RF system for the LANSCE drift tube linac  

SciTech Connect

The Los Alamos Neutron Science Center (LANSCE) linac provides an 800 MeV direct H{sup +} proton beam, and injects H{sup {minus}} to the upgraded proton storage ring for charge accumulation for the Short Pulse Spallation Source. Accelerating these interlaced beams requires high average power from the 201.25 MHz drift tube linac (DTL) RF system. Three power amplifiers have operated at up to three Megawatts with 12% duty factor. The total number of electron power tubes in the RF amplifiers and their modulators has been reduced from fifty-two to twenty-four. The plant continues to utilize the original design of a tetrode driving a super power triode. Further increases in the linac duty factor are limited, in part, by the maximum dissipation ratings of the triodes. A description of the system modifications proposed to overcome these limitations includes new power amplifiers using low-level RF modulation for tank field control. The first high power Diacrode{reg_sign} is being delivered and a new amplifier cavity is being designed. With only eight power tubes, the new system will deliver both peak power and high duty factor, with lower mains power and cooling requirements. The remaining components needed for the new RF system will be discussed.

Lyles, J.; Friedrichs, C.; Lynch, M.

1998-12-31T23:59:59.000Z

234

Battery-level material cost model facilitates high-power li-ion battery cost reductions.  

SciTech Connect

Under the FreedomCAR Partnership, Argonne National Laboratory (ANL) is working to identify and develop advanced anode, cathode, and electrolyte components that can significantly reduce the cost of the cell chemistry, while simultaneously enhancing the calendar life and inherent safety of high-power Li-Ion batteries. Material cost savings are quantified and tracked via the use of a cell and battery design model that establishes the quantity of each material needed in batteries designed to meet the requirements of hybrid electric vehicles (HEVs). In order to quantify the material costs, relative to the FreedomCAR battery cost goals, ANL uses (1) laboratory cell performance data, (2) its battery design model and (3) battery manufacturing process yields to create battery-level material cost models. Using these models and industry-supplied material cost information, ANL assigns battery-level material costs for different cell chemistries. These costs can then be compared to the battery cost goals to determine the probability of meeting the goals with these cell chemistries. The most recent freedomCAR cost goals for 25-kW and 40-kW power-assist HEV batteries are $500 and $800, respectively, which is $20/kW in both cases. In 2001, ANL developed a high-power cell chemistry that was incorporated into high-power 18650 cells for use in extensive accelerated aging and thermal abuse characterization studies. This cell chemistry serves as a baseline for this material cost study. It incorporates a LiNi0.8Co0.15Al0.05O2 cathode, a synthetic graphite anode, and a LiPF6 in EC:EMC electrolyte. Based on volume production cost estimates for these materials-as well as those for binders/solvents, cathode conductive additives, separator, and current collectors--the total cell winding material cost for a 25-kW power-assist HEV battery is estimated to be $399 (based on a 48- cell battery design, each cell having a capacity of 15.4 Ah). This corresponds to {approx}$16/kW. Our goal is to reduce the cell winding material cost to <$10/kW, in order to allow >$10/kW for the cell and battery manufacturing costs, as well as profit for the industrial manufacturer. The material cost information is obtained directly from the industrial material suppliers, based on supplying the material quantities necessary to support an introductory market of 100,000 HEV batteries/year. Using its battery design model, ANL provides the material suppliers with estimates of the material quantities needed to meet this market, for both 25-kW and 40-kW power-assist HEV batteries. Also, ANL has funded a few volume-production material cost analyses, with industrial material suppliers, to obtain needed cost information. In a related project, ANL evaluates and develops low-cost advanced materials for use in high-power Li-Ion HEV batteries. [This work is the subject of one or more separate papers at this conference.] Cell chemistries are developed from the most promising low-cost materials. The performance characteristics of test cells that employ these cell chemistries are used as input to the cost model. Batteries, employing these cell chemistries, are designed to meet the FreedomCAR power, energy, weight, and volume requirements. The cost model then provides a battery-level material cost and material cost breakdown for each battery design. Two of these advanced cell chemistries show promise for significantly reducing the battery-level material costs (see Table 1), as well as enhancing calendar life and inherent safety. It is projected that these two advanced cell chemistries (A and B) could reduce the battery-level material costs by an estimated 24% and 43%, respectively. An additional cost advantage is realized with advanced chemistry B, due to the high rate capability of the 3-dimensional LiMn{sub 2}O{sub 4} spinel cathode. This means that a greater percentage of the total Ah capacity of the cell is usable and cells with reduced Ah capacity can be used. This allows for a reduction in the quantity of the anode, electrolyte, separator, and current collector materials needed f

Henriksen, G.; Chemical Engineering

2003-01-01T23:59:59.000Z

235

Gas breakdown driven by L band short-pulse high-power microwave  

SciTech Connect

High power microwave (HPM) driven gas breakdown is a major factor in limiting the radiation and transmission of HPM. A method that HPM driven gas breakdown could be obtained by changing the aperture of horn antenna is studied in this paper. Changing the effective aperture of horn antenna can adjust the electric field in near field zone, leading to gas breakdown. With this method, measurements of air and SF{sub 6} breakdowns are carried out on a magnetically insulated transmission-line oscillators, which is capable of generating HPM with pulse duration of 30 ns, and frequency of 1.74 GHz. The typical breakdown waveforms of air and SF{sub 6} are presented. Besides, the breakdown field strengths of the two gases are derived at different pressures. It is found that the effects of air and SF{sub 6} breakdown on the transmission of HPM are different: air breakdown mainly shortens the pulse width of HPM while SF{sub 6} breakdown mainly reduces the peak output power of HPM. The electric field threshold of SF{sub 6} is about 2.4 times larger than that of air. These differences suggest that gas properties have a great effect on the transmission characteristic of HPM in gases.

Yang Yiming; Yuan Chengwei; Qian Baoliang [College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

2012-12-15T23:59:59.000Z

236

HIGH POWER TEST OF RF SEPARATOR FOR 12 GEV UPGRADE OF CEBAF AT JLAB  

Science Conference Proceedings (OSTI)

CEBAF at JLab is in the process of an energy upgrade from 6 GeV to 12 GeV. The existing setup of the RF separator cavities in the 5th pass will not be adequate to extract the highest energy (11 GeV) beam to any two existing halls (A, B or C) while simultaneously delivering to the new hall D in the case of the proposed 12 GeV upgrade of the machine. To restore this capability, we are exploring the possibility of extension of existing normal conducting 499 MHz TEM-type rf separator cavities. Detailed numerical studies suggest that six 2-cell normal conducting structures meet the requirements; each 2-cell structure will require up to 4 kW RF input power in contrast with the current nominal operating power of 1.0 to 2.0 kW. A high power test of 4 kW confirms that the cavity meet the requirement.

S. Ahmed, M. Wissmann, J. Mammosser, C. Hovater, M. Spata, G. Krafft, J. Delayen

2012-07-01T23:59:59.000Z

237

Energy confinement experiments on Doublet III with high power neutral beam heating  

DOE Green Energy (OSTI)

Energy confinement experiments with up to 8 MW of both hydrogen and deuterium neutral beam power were performed in deuterium plasmas with limiter and expanded boundary divertor configurations. The results of NBI-dominated experiments indicated that total stored energy W/sub T/ and energy confinement time tau/sub E/ had little or no variation with electron density anti n/sub e/ and toroidal field B/sub T/ and scaled linearly with plasma current I/sub p/. Previous studies in limiter discharges indicated a weak dependence on plasma elongation kappa. The confinement time dependence on elongation was not determined for divertor discharges, but assuming a dependence similar to that for limiter discharges both limiter and divertor data were consistent with W/sub T/ and tau/sub E/ proportional to I/sub p/..sqrt..kappa. The variation of plasma stored energy with neutral beam power was consistent with a linear relationship. The linear equation describing this relationship had a non-zero intercept which illustrated the fact that energy confinement time deteriorated with neutral beam power. The energy confinement time appears to be approaching an asymptotic value at high power, consistent with a linear functional form for stored energy. However, a power law functional form for stored energy and energy confinement time can not be ruled out.

DeBoo, J.C.; Groebner, R.J.

1985-05-01T23:59:59.000Z

238

RF Couplers for Normal-Conducting Photoinjector of High-Power CW FEL  

E-Print Network (OSTI)

A high-current emittance-compensated RF photoinjector is a key enabling technology for a high-power CW FEL. A preliminary design of a normal-conducting, 2.5-cell pi-mode, 700-MHz CW RF photoinjector that will be built for demonstration purposes, is completed. This photoinjector will be capable of accelerating a 100-mA electron beam (3 nC per bunch at 35 MHz bunch repetition rate) to 2.7 MeV while providing an emittance below 7 mm-mrad at the wiggler. More than 1 MW of RF power will be fed into the photoinjector cavity through two ridge-loaded tapered waveguides. The waveguides are coupled to the cavity by "dog-bone" irises cut in a thick wall. Due to CW operation of the photoinjector, the cooling of the coupler irises is a rather challenging thermal management project. This paper presents results of a detailed electromagnetic modeling of the coupler-cavity system, which has been performed to select the coupler design that minimizes the iris heating due to RF power loss in its walls.

Kurennoy, Sergey; Wood, Richard L; Schultheiss, T J; Rathke, John; Young, Lloyd

2004-01-01T23:59:59.000Z

239

Radiation effects at a high power accelerator and applications to advanced energy sources  

Science Conference Proceedings (OSTI)

Many materials are exposed to atom-displacing radiation at high-power accelerators such as the Los Alamos Meson Physics Facility (LAMPF). Beam current densities in the 800-MeV proton beam vary from 12.5 mA cm{sup {minus}2} (8 {times} 10{sup 16} p/cm{sup 2}s) on graphite targets to 20-{mu}A cm{sup {minus}2} (1.3 {times} 10{sup 14} p/cm{sup 2}s) on metal-alloy windows. High-level radiation damage results from these particle fluxes. As a consequence of secondary-particle generation in targets and windows and low-level beam losses that lead to particle interactions with structural material, various components are exposed to low-level proton fluxes, gamma radiation, and neutron fluxes of 10{sup 6}--10{sup 10} n/cm{sup 2}s. These include vacuum seals and vacuum chambers of stainless steel and aluminum alloys, solid-state devices for control, diagnostic, and data acquisition electronics, closed-loop cooling-water systems, and insulators. Properties of these materials are degraded by the radiation exposure. Studies of LAMPF and other accelerators, however, have produced solutions to materials problems, allowing the machines to operate for acceptable times without failure. Nevertheless, additional improvements are being investigated in order to further improve operational reliability and safety. 25 refs., 3 figs., 3 tabs.

Sommer, W.F.; Garner, F.A.; Brown, R.D.; Wechsler, M.S. (Los Alamos National Lab., NM (USA); Battelle Pacific Northwest Lab., Richland, WA (USA); Los Alamos National Lab., NM (USA); Iowa State Univ. of Science and Technology, Ames, IA (USA))

1989-01-01T23:59:59.000Z

240

RF Distribution System for High Power Test of the SNS Cryomodule  

Science Conference Proceedings (OSTI)

A four-way waveguide RF power distribution system for testing the Spallation Neutron Source (SNS) multi-cavity cryomodule to investigate the collective behavior has been developed. A single klystron operating at 805MHz for 1.3 msec at 60Hz powers the 4-way waveguide splitter to deliver up to 400 kW to individual cavities. Each cavity is fed through a combination of waveguide splitters and vector modulators (VM) to provide independent magnitude and phase controls. The waveguide vector modulator consists of two quadrature hybrids and two motorized waveguide phase shifters. The phase shifters and the assembled waveguide vector modulators were individually tested and characterized for low power and high RF power in the SNS RF test facility. Precise calibrations of magnitude and phase were performed to generate the look up tables (LUTs) to provide operational references during the cryomodule test. An I-Q demodulator module was developed and utilized to measure relative phases in pulsed high RF power operation. PLC units were developed for mechanical control of the phase shifters. Initial low/high power measurements were made using LabVIEW. An operation algorithm has been implemented into EPICS control for the cryomodule test stand.

Lee, Sung-Woo [ORNL; Kang, Yoon W [ORNL; Broyles, Michael R [ORNL; Crofford, Mark T [ORNL; Geng, Xiaosong [ORNL; Kim, Sang-Ho [ORNL; Phibbs, Curtis L [ORNL; Strong, William Herb [ORNL; Peglow, Robert C [ORNL; Vassioutchenko, Alexandre V [ORNL

2012-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "high-power coherent terahertz" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
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to obtain the most current and comprehensive results.


241

RF couplers for normal-conducting photoinjector of high-power CW FEL  

SciTech Connect

A high-current emittance-compensated RF photoinjector is a key enabling technology for a high-power CW FEL. A preliminary design of a normal-conducting, 2.5-cell pi-mode, 700-MHz CW RF photoinjector that will be built for demonstration purposes, is completed. This photoinjector will be capable of accelerating a 100-mA electron beam (3 nC per bunch at 35 MHz bunch repetition rate) to 2.7 MeV while providing an emittance below 7 mm-mrad at the wiggler. More than 1 MW of RF power will be fed into the photoinjector cavity through two ridge-loaded tapered waveguides. The waveguides are coupled to the cavity by 'dog-bone' irises cut in a thick wall. Due to CW operation of the photoinjector, the cooling of the coupler irises is a rather challenging thermal management project. This paper presents results of a detailed electromagnetic modeling of the coupler-cavity system, which has been performed to select the coupler design that minimizes the iris heating due to RF power loss in its walls.

Kurennoy, S. (Sergey)

2004-01-01T23:59:59.000Z

242

High power operation of the university of Maryland coaxial gyroklystron experiment  

SciTech Connect

We report the experimental studies of high power amplification in a coaxial three-cavity X-band gyroklystron. A single-anode magnetron injection gun (MIG) is used to produce a 520 A beam of 470 keV electrons with an average ratio of perpendicular-to-parallel velocity of about one. The voltage flat top is nearly 2 {mu}s. All cavities are designed to operate in the TE{sub 011} coaxial mode near 8.6 GHz. The input cavity is driven by a 150 kW, 3 {mu}s coaxial magnetron through a single slot in the radial wall. Peak powers of 75{endash}85 MW are measured with a conversion efficiency of nearly 32{percent} and a large signal gain of about 30 dB. This performance is in good agreement with simulations and represents approximately a tri-fold increase in the peak power capability of pulsed X-band gyroklystrons. We also report on the design of a three cavity second harmonic gyroklystron which is expected to produce 100 MW at 17.14 GHz. We close with a general discussion of scaling our designs to higher frequencies. {copyright} {ital 1999 American Institute of Physics.}

Lawson, W.; Arjona, M.; Castle, M.; Hogan, B.; Granatstein, V.; Reiser, M. [Institute for Plasma Research and Electrical Engineering Department, University of Maryland, College Park, Maryland 20742 (United States)

1999-07-01T23:59:59.000Z

243

High power operation of the university of Maryland coaxial gyroklystron experiment  

SciTech Connect

We report the experimental studies of high power amplification in a coaxial three-cavity X-band gyroklystron. A single-anode magnetron injection gun (MIG) is used to produce a 520 A beam of 470 keV electrons with an average ratio of perpendicular-to-parallel velocity of about one. The voltage flat top is nearly 2 {mu}s. All cavities are designed to operate in the TE{sub 011} coaxial mode near 8.6 GHz. The input cavity is driven by a 150 kW, 3 {mu}s coaxial magnetron through a single slot in the radial wall. Peak powers of 75-85 MW are measured with a conversion efficiency of nearly 32% and a large signal gain of about 30 dB. This performance is in good agreement with simulations and represents approximately a tri-fold increase in the peak power capability of pulsed X-band gyroklystrons. We also report on the design of a three cavity second harmonic gyroklystron which is expected to produce 100 MW at 17.14 GHz. We close with a general discussion of scaling our designs to higher frequencies.

Lawson, W.; Arjona, M.; Castle, M.; Hogan, B.; Granatstein, V.; Reiser, M. [Institute for Plasma Research and Electrical Engineering Department, University of Maryland, College Park, Maryland 20742 (United States)

1999-07-12T23:59:59.000Z

244

Aluminum-doped lithium nickel cobalt oxide electrodes for high-power lithium-ion batteries.  

DOE Green Energy (OSTI)

Non-doped and aluminum-doped LiNi{sub 0.8}Co{sub 0.2}O{sub 2} cathodes from three industrial developers coupled with graphite anodes were made into lithium-ion cells for high-power applications. The powder morphology of the active cathode materials was examined by a scanning electron microscope. The electrochemical performance of these cells was investigated by hybrid pulse power characterization (HPPC) testing, accelerated aging, and AC impedance measurement of symmetric cells. Although all of the fresh cells are found to meet and exceed the power requirements set by PNGV, the power capability of those cells with non-doped LiNi {sub 0.8}Co{sub 0.2}O{sub 2} cathodes fades rapidly due to the rise of the cell impedance. Al-doping is found very effective to suppress the cell impedance rise by stabilizing the charge-transfer impedance on the cathode side. The stabilization mechanism may be related to the low average oxidation state of nickel ions in the cathode. The powder morphology also plays a secondary role in determining the impedance stabilization.

Chen, C. H.; Liu, J.; Stoll, M. E.; Henriksen, G.; Vissers, D. R.; Amine, K.; Chemical Engineering; Univ. of Science and Technology of China

2004-04-05T23:59:59.000Z

245

Reflective Coherent Spatial Light Modulator (RCSLM)  

Reflective Coherent Spatial Light Modulator (RCSLM) Note: The technology described above is an early stage opportunity. Licensing rights to this intellectual property may

246

Emission of terahertz waves from stacks of intrinsic Josephson junctions.  

SciTech Connect

By patterning mesoscopic crystals of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} (BSCCO) into electromagnetic resonators the oscillations of a large number of intrinsic Josephson junctions can be synchronized into a macroscopic coherent state accompanied by the emission of strong continuous wave THz-radiation. The temperature dependence of the emission is governed by the interplay of self-heating in the resonator and by re-trapping of intrinsic Josephson junctions which can yield a strongly non-monotonic temperature dependence of the emission power. Furthermore, proper shaping of the resonators yields THz-sources with voltage-tunable emission frequencies.

Gray, K. E.; Koshelev, A. E.; Kurter, C.; Kadowaki, K.; Yamamoto, T.; Minami, H.; Yamaguchi, H.; Tachiki, M.; Kwok, W.-K.; Welp, U.; Materials Science Division; Izmir Inst. of Tech.; Univ. Tsukuba; Univ. Tokyo

2009-06-01T23:59:59.000Z

247

Terahertz radiation source based on self-wake beam bunching  

SciTech Connect

A table top device for producing high power T-ray beams is described. A rectangular electron beam that can be produced out of a photoinjector via stacking of the laser pulse, and running off-crest of the photoinjector rf is sent through a dielectric loaded waveguide. Due to the beam's self-wake its energy becomes modulated. In the chicane beamline following the dielectric energy-bunching section this energy modulation is converted to a density modulation-a bunch train. The density modulated beam can be sent through a power extraction section, like a dielectric loaded accelerating structure, or simply can intercept a foil target, producing THz radiation of various bandwidths and power levels.

Antipov, Sergey; Jing Chunguang; Schoessow, Paul; Kanareykin, Alexei; Jiang Bo; Yakimenko, Vitaly; Zholents, Alexander; Gai Wei [Euclid Techlabs LLC, Solon OH 44139 (United States); Shanghai Institute of Applied Physics, Shanghai (China); Brookhaven National Laboratory, Upton NY, 11973 (United States); Argonne National Laboratory, Argonne IL, 60439 (United States)

2012-12-21T23:59:59.000Z

248

Optical coherence domain reflectometry guidewire  

DOE Patents (OSTI)

A guidewire with optical sensing capabilities is based on a multiplexed optical coherence domain reflectometer (OCDR), which allows it to sense location, thickness, and structure of the arterial walls or other intra-cavity regions as it travels through the body during minimally invasive medical procedures. This information will be used both to direct the guidewire through the body by detecting vascular junctions and to evaluate the nearby tissue. The guidewire contains multiple optical fibers which couple light from the proximal to distal end. Light from the fibers at the distal end of the guidewire is directed onto interior cavity walls via small diameter optics such as gradient index lenses and mirrored corner cubes. Both forward viewing and side viewing fibers can be included. The light reflected or scattered from the cavity walls is then collected by the fibers, which are multiplexed at the proximal end to the sample arm of an optical low coherence reflectometer. The guidewire can also be used in nonmedical applications.

Colston, Billy W. (Livermore, CA); Everett, Matthew (Pleasanton, CA); Da Silva, Luiz B. (Danville, CA); Matthews, Dennis (Moss Beach, CA)

2001-01-01T23:59:59.000Z

249

Towards loss compensated and lasing terahertz metamaterials based on optically pumped graphene  

E-Print Network (OSTI)

It is evidenced by numerical calculations that optically pumped graphene is suitable for compensating inherent loss in terahertz (THz) metamaterials. In a first step, the complex conductivity of graphene under optical pumping is calculated and the proper conditions for terahertz amplification in single layer graphene are determined. It is shown that amplification in graphene occurs for temperatures up to room temperature and for moderate pump intensities when pumped at a telecommunication wavelength $\\lambda=1.5~\\mathrm{\\mu m}$. Furthermore, the amplification properties of graphene are evaluated and discussed at a temperature as low as $T=77~\\mathrm{K}$ and a pump intensity $I=300~\\mathrm{mW/mm^2}$ to investigate the coupling between graphene and a plasmonic split ring resonator (SRR) metamaterial. The contributions of ohmic and dielectric loss mechanisms are studied by full wave simulations. As a result, it is found that the loss of a split-ring resonator metamaterial can be compensated by optically stimulat...

Weis, Peter; Rahm, Marco

2013-01-01T23:59:59.000Z

250

Materials cost evaluation report for high-power Li-ion batteries.  

SciTech Connect

The U.S. Department of Energy (DOE) is the lead federal agency in the partnership between the U.S. automobile industry and the federal government to develop fuel cell electric vehicles (FCEVs) and hybrid electric vehicles (HEVs) as part of the FreedomCAR Partnership. DOE's FreedomCAR and Vehicle Technologies Office sponsors the Advanced Technology Development (ATD) Program--involving 5 of its national laboratories--to assist the industrial developers of high-power lithium-ion batteries to overcome the barriers of cost, calendar life, and abuse tolerance so that this technology can be rendered practical for use in HEV and FCEV applications under the FreedomCAR Partnership. In the area of cost reduction, Argonne National Laboratory (ANL) is working to identify and develop advanced anode, cathode, and electrolyte components that can significantly reduce the cost of the cell chemistry, while simultaneously extending the calendar life and enhancing the inherent safety of this electrochemical system. The material cost savings are quantified and tracked via the use of a cell and battery design model that establishes the quantity of each material needed in the production of batteries that are designed to meet the requirements of a minimum-power-assist HEV battery or a maximum-power-assist HEV battery for the FreedomCAR Partnership. Similar models will be developed for FEV batteries when the requirements for those batteries are finalized. In order to quantify the material costs relative to the FreedomCAR battery cost goals, ANL uses (1) laboratory cell performance data, (2) its battery design model and (3) battery manufacturing process yields to create battery-level material cost models. Using these models and industry-supplied material cost information, ANL assigns battery-level material costs for different cell chemistries. These costs can then be compared with the battery cost goals to determine the probability of meeting the goals with these cell chemistries. As can be seen from the results of this materials cost study, a cell chemistry based on the use of a LiMn{sub 2}O{sub 4} cathode material is lowest-cost and meets our battery-level material cost goal of <$250 for a 25-kW minimum-power-assist HEV battery. A major contributing factor is the high-rate capability of this material, which allows one to design a lower-capacity cell to meet the battery-level power and energy requirements. This reduces the quantities of the other materials needed to produce a 25-kW minimum-power-assist HEV battery. The same is true for the 40-kW maximum-power-assist HEV battery. Additionally, the LiMn{sub 2}O{sub 4} cathode is much more thermally and chemically stable than the LiNi{sub 0.8}Co{sub 0.2}O{sub 2} type cathode, which should enhance inherent safety and extend calendar life (if the LiMn{sub 2}O{sub 4} cathode can be stabilized against dissolution via HF attack). Therefore, we recommend that the FreedomCAR Partnership focus its research and development efforts on developing this type of low-cost high-power lithium-ion cell chemistry. Details supporting this recommendation are provided in the body of this report.

Henriksen, G. L.; Amine, K.; Liu, J.

2003-01-10T23:59:59.000Z

251

Materials cost evaluation report for high-power Li-ion batteries.  

Science Conference Proceedings (OSTI)

The U.S. Department of Energy (DOE) is the lead federal agency in the partnership between the U.S. automobile industry and the federal government to develop fuel cell electric vehicles (FCEVs) and hybrid electric vehicles (HEVs) as part of the FreedomCAR Partnership. DOE's FreedomCAR and Vehicle Technologies Office sponsors the Advanced Technology Development (ATD) Program--involving 5 of its national laboratories--to assist the industrial developers of high-power lithium-ion batteries to overcome the barriers of cost, calendar life, and abuse tolerance so that this technology can be rendered practical for use in HEV and FCEV applications under the FreedomCAR Partnership. In the area of cost reduction, Argonne National Laboratory (ANL) is working to identify and develop advanced anode, cathode, and electrolyte components that can significantly reduce the cost of the cell chemistry, while simultaneously extending the calendar life and enhancing the inherent safety of this electrochemical system. The material cost savings are quantified and tracked via the use of a cell and battery design model that establishes the quantity of each material needed in the production of batteries that are designed to meet the requirements of a minimum-power-assist HEV battery or a maximum-power-assist HEV battery for the FreedomCAR Partnership. Similar models will be developed for FEV batteries when the requirements for those batteries are finalized. In order to quantify the material costs relative to the FreedomCAR battery cost goals, ANL uses (1) laboratory cell performance data, (2) its battery design model and (3) battery manufacturing process yields to create battery-level material cost models. Using these models and industry-supplied material cost information, ANL assigns battery-level material costs for different cell chemistries. These costs can then be compared with the battery cost goals to determine the probability of meeting the goals with these cell chemistries. As can be seen from the results of this materials cost study, a cell chemistry based on the use of a LiMn{sub 2}O{sub 4} cathode material is lowest-cost and meets our battery-level material cost goal of battery. A major contributing factor is the high-rate capability of this material, which allows one to design a lower-capacity cell to meet the battery-level power and energy requirements. This reduces the quantities of the other materials needed to produce a 25-kW minimum-power-assist HEV battery. The same is true for the 40-kW maximum-power-assist HEV battery. Additionally, the LiMn{sub 2}O{sub 4} cathode is much more thermally and chemically stable than the LiNi{sub 0.8}Co{sub 0.2}O{sub 2} type cathode, which should enhance inherent safety and extend calendar life (if the LiMn{sub 2}O{sub 4} cathode can be stabilized against dissolution via HF attack). Therefore, we recommend that the FreedomCAR Partnership focus its research and development efforts on developing this type of low-cost high-power lithium-ion cell chemistry. Details supporting this recommendation are provided in the body of this report.

Henriksen, G. L.; Amine, K.; Liu, J.

2003-01-10T23:59:59.000Z

252

High-power laser and arc welding of thorium-doped iridium alloys  

SciTech Connect

The arc and laser weldabilities of two Ir-0.3% W alloys containing 60 and 200 wt ppM Th have been investigated. The Ir-.03% W alloy containing 200 wt ppM Th is severely prone to hot cracking during gas tungsten-arc welding. Weld metal cracking results from the combined effects of heat-affected zone liquation cracking and solidification cracking. Scanning electron microscopic analysis of the fractured surface revealed patches of low-melting eutectic. The cracking is influenced to a great extent by the fusion zone microstructure and thorium content. The alloy has been welded with a continuous-wave high-power CO/sub 2/ laser system with beam power ranging from 5 to 10 kW and welding speeds of 8 to 25 mm/s. Successful laser welds without hot cracking have been obtained in this particular alloy. This is attributable to the highly concentrated heat source available in the laser beam and the refinement in fusion zone microstructure obtained during laser welding. Efforts to refine the fusion zone structure during gas tungsten-arc welding of Ir-0.3 % W alloy containing 60 wt ppM Th were partially successful. Here transverse arc oscillation during gas tungsten-arc welding refines the fusion zone structure to a certain extent. However, microstructural analysis of this alloy's laser welds indicates further refinement in the fusion zone microstructure than in that from the gas tungsten-arc process using arc oscillations. The fusion zone structure of the laser weld is a strong function of welding speed.

David, S.A.; Liu, C.T.

1980-05-01T23:59:59.000Z

253

High-power liquid-lithium jet target for neutron production  

E-Print Network (OSTI)

A compact Liquid-Lithium Target (LiLiT) was built and tested with a high-power electron gun at Soreq Nuclear Research Center. The lithium target, to be bombarded by the high-intensity proton beam of the Soreq Applied Research Accelerator Facility (SARAF), will constitute an intense source of neutrons produced by the 7Li(p,n)7Be reaction for nuclear astrophysics research and as a pilot setup for accelerator-based Boron Neutron Capture Therapy (BNCT). The liquid-lithium jet target acts both as neutron-producing target and beam dump by removing the beam thermal power (>5 kW, >1 MW/cm3) with fast transport. The target was designed based on a thermal model, accompanied by a detailed calculation of the 7Li(p,n) neutron yield, energy distribution and angular distribution. Liquid lithium is circulated through the target loop at ~200oC and generates a stable 1.5 mm-thick film flowing at a velocity up to 7 m/s onto a concave supporting wall. Electron beam irradiation demonstrated that the liquid-lithium target can dissipate electron power areal densities of > 4 kW/cm2 and volume power density of ~ 2 MW/cm3 at a lithium flow of ~4 m/s while maintaining stable temperature and vacuum conditions. The LiLiT setup is presently in online commissioning stage for high-intensity proton beam irradiation (1.91- 2.5 MeV, 1-2 mA) at SARAF.

S. Halfon; A. Arenshtam; D. Kijel; M. Paul; D. Berkovits; I. Eliyahu; G. Feinberg; M. Friedman; N. Hazenshprung; I. Mardor; A. Nagler; G. Shimel; M. Tessler; I. Silverman

2013-11-13T23:59:59.000Z

254

High-power laser and arc welding of thorium-doped iridium alloys  

DOE Green Energy (OSTI)

The arc and laser weldabilities of two Ir-0.3% W alloys containing 60 and 200 wt ppM Th have been investigated. The Ir-.03% W alloy containing 200 wt ppM Th is severely prone to hot cracking during gas tungsten-arc welding. Weld metal cracking results from the combined effects of heat-affected zone liquation cracking and solidification cracking. Scanning electron microscopic analysis of the fractured surface revealed patches of low-melting eutectic. The cracking is influenced to a great extent by the fusion zone microstructure and thorium content. The alloy has been welded with a continuous-wave high-power CO/sub 2/ laser system with beam power ranging from 5 to 10 kW and welding speeds of 8 to 25 mm/s. Successful laser welds without hot cracking have been obtained in this particular alloy. This is attributable to the highly concentrated heat source available in the laser beam and the refinement in fusion zone microstructure obtained during laser welding. Efforts to refine the fusion zone structure during gas tungsten-arc welding of Ir-0.3 % W alloy containing 60 wt ppM Th were partially successful. Here transverse arc oscillation during gas tungsten-arc welding refines the fusion zone structure to a certain extent. However, microstructural analysis of this alloy's laser welds indicates further refinement in the fusion zone microstructure than in that from the gas tungsten-arc process using arc oscillations. The fusion zone structure of the laser weld is a strong function of welding speed.

David, S.A.; Liu, C.T.

1980-05-01T23:59:59.000Z

255

Study of second harmonic generation by high power laser beam in magneto plasma  

SciTech Connect

This paper examines the problem of nonlinear generation of second harmonic of a high power laser pulse propagating in magnetized plasma. The propagation of strong laser beam is proposed in the direction perpendicular to a relatively weak static magnetic field. The laser pulse is taken to be linearly polarized, with the orientation of its electric field that corresponds to an ordinary electromagnetic wave. Besides the standard ponderomotive nonlinearity, the appropriate wave equation also contains the nonlinearity that arises from the relativistic electron jitter velocities. During its propagation, the laser beam gets filamented on account of relativistic and pondermotive nonlinearities present in the plasma. The generated plasma wave gets coupled into the filamentary structures of the pump beam. Due to the expected presence of the beam filamentation, the work has been carried out by considering modified paraxial approximation (i.e., beyond the standard paraxial approximation of a very broad beam). It is found that the power of the plasma wave is significantly affected by the magnetic field strength in the presence of both relativistic and pondermotive nonlinearities. It is investigated that the second harmonic generation is also considerably modified by altering the strength of magnetic field. To see the effect of static magnetic field on the harmonic generation, a key parameter, i.e., the ratio of the cyclotron frequency {omega}{sub c}=eB{sub 0}/mc over the laser frequency {omega}{sub 0} has been used, where c is the velocity of light, m and e are the mass and charge of the electron and B{sub 0} is the externally applied magnetic field.

Sharma, Prerana [Ujjain Engineering College, Ujjain, Madhya Pradesh 465010 (India); Sharma, R. P. [Centre for Energy Studies, Indian Institute of Technology, New Delhi 110016 (India)

2012-12-15T23:59:59.000Z

256

A high power beam-on-target test of liquid lithium target for RIA.  

Science Conference Proceedings (OSTI)

Experiments were conducted to demonstrate the stable operation of a windowless liquid lithium target under extreme thermal loads that are equivalent to uranium beams from the proposed Rare Isotope Accelerator (RIA) driver linac. The engineering and safety issues accompanying liquid lithium systems are first discussed. The liquid metal technology knowledge base generated primarily for fast reactors, and liquid metal cooled fusion reactors, was applied to the development of these systems in a nuclear physics laboratory setting. The use of a high energy electron beam for simulating a high power uranium beam produced by the RIA driver linac is also described. Calculations were performed to obtain energy deposition profiles produced by electron beams at up to a few MeV to compare with expected uranium beam energy deposition profiles. It was concluded that an experimental simulation using a 1-MeV electron beam would be a valuable tool to assess beam-jet interaction. In the experiments, the cross section of the windowless liquid lithium target was 5 mm x 10 mm, which is a 1/3rd scale prototype target, and the velocity of the liquid lithium was varied up to 6 m/s. Thermal loads up to 20 kW within a beam spot diameter of 1mm were applied on the windowless liquid lithium target by the 1-MeV electron beam. The calculations showed that the maximum power density and total power deposited within the target, from the electron beam, was equivalent to that of a 200-kW, 400-MeV/u uranium beam. It was demonstrated that the windowless liquid lithium target flowing at velocities as low as 1.8 m/s stably operated under beam powers up to 20 kW without disruption or excessive vaporization.

Nolen, J.; Reed, C.; Novick, V.; Specht, J.; Plotkin, P.; Momozaki,Y.; Gomes, I.

2005-08-29T23:59:59.000Z

257

Mechanism of terahertz photoconductivity in semimetallic HgTe/CdHgTe quantum wells  

Science Conference Proceedings (OSTI)

Terahertz photoconductivity in magnetic fields in semimetallic HgTe/CdHgTe quantum wells has been studied. The main contribution to photoconductivity comes from a signal that appears as a result of electron-gas heating. It is shown that, with the cyclotron resonance conditions satisfied, the photoconductivity signal is composed of cyclotron-resonance and bolometric components. However, in this case too, the bolometric contribution predominates.

Vasilyev, Yu. B., E-mail: yu.vasilyev@mail.ioffe.ru [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation); Mikhailov, N. N. [Russian Academy of Sciences, Rzhanov Institute of Semiconductor Physics, Siberian Branch (Russian Federation); Gouider, F. [Institut fuer Angewandte Physik (Germany); Vasilyeva, G. Yu. [St. Petersburg State Polytechnic University (Russian Federation); Nachtwei, G. [Institut fuer Angewandte Physik (Germany)

2012-05-15T23:59:59.000Z

258

High energy terahertz pulses from organic crystals: DAST and DSTMS pumped at Ti:sapphire wavelength  

E-Print Network (OSTI)

High energy terahertz pulses are produced by optical rectification (OR) in organic crystals DAST and DSTMS by a Ti:sapphire amplifier system centered at 0.8 microns. The simple scheme provides broadband spectra between 1 and 5 THz, when pumped by collimated 60 fs near-infrared pump pulse and it is scalable in energy. Fluence-dependent conversion efficiency and damage threshold are reported as well as optimized OR at visible wavelength.

Monoszlai, B; Jazbinsek, M; Hauri, C P

2013-01-01T23:59:59.000Z

259

Analysis and design of terahertz antennas based on plasmonic resonant graphene sheets  

SciTech Connect

Resonant graphene antennas used as true interfaces between terahertz (THz) space waves and a source/detector are presented. It is shown that in addition to the high miniaturization related to the plasmonic nature of the resonance, graphene-based THz antenna favorably compare with typical metal implementations in terms of return loss and radiation efficiency. Graphene antennas will contribute to the development of miniature, efficient, and potentially transparent all-graphene THz transceivers for emerging communication and sensing application.

Tamagnone, M. [Adaptive MicroNano Wave Systems, LEMA/Nanolab, Ecole Polytechnique Federale de Lausanne (EPFL), 1015 Lausanne (Switzerland); Laboratory of Electromagnetics and Acoustics (LEMA), Ecole Polytechnique Federale de Lausanne (EPFL), 1015 Lausanne (Switzerland); Gomez-Diaz, J. S.; Perruisseau-Carrier, J. [Adaptive MicroNano Wave Systems, LEMA/Nanolab, Ecole Polytechnique Federale de Lausanne (EPFL), 1015 Lausanne (Switzerland); Mosig, J. R. [Laboratory of Electromagnetics and Acoustics (LEMA), Ecole Polytechnique Federale de Lausanne (EPFL), 1015 Lausanne (Switzerland)

2012-12-01T23:59:59.000Z

260

HIGH-POWER PRECISION CURRENT SUPPLY IST2-1000M FOR ELEMENTS OF MAGNETIC SYSTEMS OF ACCELERATORS AND  

E-Print Network (OSTI)

BF), a detached supply transformer and power switch. Power box PB comprises the following: - a threeHIGH-POWER PRECISION CURRENT SUPPLY IST2-1000M FOR ELEMENTS OF MAGNETIC SYSTEMS OF ACCELERATORS. These supplies are intended to power magnetic systems of accelerators, requiring high stability and low ripples

Kozak, Victor R.

Note: This page contains sample records for the topic "high-power coherent terahertz" from the National Library of EnergyBeta (NLEBeta).
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261

Analysis and Design of a High Power Density Axial Flux Permanent Magnet Linear Synchronous Machine Used for Stirling System  

Science Conference Proceedings (OSTI)

a high power density axial flux permanent magnet linear synchronous machine and the stirling system will be introduced. This machine is a tubular axial flux permanent magnet machine. It comprises two parts: stator and mover. With the 2D finite-element ... Keywords: permanent magnet, stirling engine, linear motor

Ping Zheng; Xuhui Gan; Lin Li

2010-09-01T23:59:59.000Z

262

Development of high power green light emitting diode dies in piezoelectric GaInN/GaN  

E-Print Network (OSTI)

Development of high power green light emitting diode dies in piezoelectric GaInN/GaN Christian in green light emitting diodes is one of the big challenges towards all-solid- state lighting. The prime,3], and commercialization [4,5] of high brightness light emitting diodes LEDs has led to a 1.82 Billion-$/year world market

Detchprohm, Theeradetch

263

Multisegmented Au-MnO2/Carbon Nanotube Hybrid Coaxial Arrays for High-Power Supercapacitor Applications  

E-Print Network (OSTI)

Multisegmented Au-MnO2/Carbon Nanotube Hybrid Coaxial Arrays for High-Power SupercapacitorVised Manuscript ReceiVed: NoVember 4, 2009 The present work reports on synthesis and supercapacitor applications hybrid coaxial arrays are efficient electrodes for supercapacitor applications. Au-segmented MnO2/CNT

Ajayan, Pulickel M.

264

A coherence model based on syntactic patterns  

Science Conference Proceedings (OSTI)

We introduce a model of coherence which captures the intentional discourse structure in text. Our work is based on the hypothesis that syntax provides a proxy for the communicative goal of a sentence and therefore the sequence of sentences in a coherent ...

Annie Louis; Ani Nenkova

2012-07-01T23:59:59.000Z

265

A NEW CROWBAR SYSTEM FOR THE PROTECTION OF HIGH POWER GRIDDED TUBES AND MICROWAVE DEVICES  

SciTech Connect

As part of the electron cyclotron heating (ECH) facility upgrade at the DIII-D National Fusion Facility, two 8.4 MW modulator/regulator power systems were designed and constructed (Ref. 1). Each power system uses a high power tetrode to modulate and regulate the cathode voltage for two 1 MW-class 110 GHz gyrotrons (Ref. 2). A critical element in the power system is the fault energy divertor, or crowbar switch, that protects the tetrode and the gyrotrons in the event of an arc fault. Traditionally, mercury filled ignitron switches are used for this application, but it was desired to eliminate hazardous materials and improve overall switching performance. The new crowbar switch system was required to meet the following requirements: Operating voltage: -105 kVdc; Peak current (750 ms e-fold): 1.6 kA; Follow-on current: <1 kA (25 ms); Charge transfer per shot: <15 Cb; and Turn-on time: <1 {micro}s. The switch that was chosen for the new design is a low pressure deuterium filled device, called a metal-arc thyratron, manufactured by Marconi Applied Technologies (Ref. 3). In addition to the new crowbar switch assembly, improved fault signal processing circuitry was developed. This new circuitry uses fiber-optics for signal and trigger transmission and a complex programmable logic device for high speed signal and logic processing. Two generations of metal-arc thyratrons have been commissioned in the two ECH power systems constructed at DIII-D. In the first, the crowbar system performed extremely well, meeting all of the operating requirements and demonstrating its ability to protect a 36 gauge copper wire from fusing (energy let-through <10 J). However, after accumulating over 500 shots, the metal-arc thyratrons lost their ability to reliably hold-off voltage. This problem was solved by Marconi with a design modification of the thyratron electrodes. The second generation tubes were installed in the second ECH power system. The crowbar system was fully commissioned and all of the performance requirements were satisfactorily achieved. The design of the crowbar switch and the fault signal processing system and their performance will be presented in this paper.

S.G.E. PRONKO; T.E.HARRIS

2001-04-01T23:59:59.000Z

266

Interface microstructure engineering by high power impulse magnetron sputtering for the enhancement of adhesion  

SciTech Connect

An excellent adhesion of hard coatings to steel substrates is paramount in practically all application areas. Conventional methods utilize Ar glow etching or cathodic arc discharge pretreatments that have the disadvantage of producing weak interfaces or adding droplets, respectively. One tool for interface engineering is high power impulse magnetron sputtering (HIPIMS). HIPIMS is based on conventional sputtering with extremely high peak power densities reaching 3 kW cm{sup -2} at current densities of >2 A cm{sup -2}. HIPIMS of Cr and Nb was used to prepare interfaces on 304 stainless steel and M2 high speed steel (HSS). During the pretreatment, the substrates were biased to U{sub bias}=-600 V and U{sub bias}=-1000 V in the environment of a HIPIMS of Cr and Nb plasma. The bombarding flux density reached peak values of 300 mA cm{sup -2} and consisted of highly ionized metal plasma containing a high proportion of Cr{sup 1+} and Nb{sup 1+}. Pretreatments were also carried out with Ar glow discharge and filtered cathodic arc as comparison. The adhesion was evaluated for coatings consisting of a 0.3 {mu}m thick CrN base layer and a 4 {mu}m thick nanolayer stack of CrN/NbN with a period of 3.4 nm, hardness of HK{sub 0.025}=3100, and residual stress of -1.8 GPa. For HIPIMS of Cr pretreatment, the adhesion values on M2 HSS reached scratch test critical load values of L{sub C}=70 N, thus comparing well to L{sub C}=51 N for interfaces pretreated by arc discharge plasmas and to L{sub C}=25 N for Ar etching. Cross sectional transmission electron microscopy studies revealed a clean interface and large areas of epitaxial growth in the case of HIPIMS pretreatment. The HIPIMS pretreatment promoted strong registry between the orientation of the coating and polycrystalline substrate grains due to the incorporation of metal ions and the preservation of crystallinity of the substrate. Evidence and conditions for the formation of cube-on-cube epitaxy and axiotaxy on steel and {gamma}-TiAl substrates are presented.

Ehiasarian, A. P.; Wen, J. G.; Petrov, I. [Materials and Engineering Research Institute, Sheffield Hallam University, Howard Street, Sheffield S1 1WB (United Kingdom); Frederick Seitz Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801 and Materials Science Department, University of Illinois, Urbana, Illinois 61801 (United States)

2007-03-01T23:59:59.000Z

267

HIGH-POWER TURBODRILL AND DRILL BIT FOR DRILLING WITH COILED TUBING  

SciTech Connect

Commercial introduction of Microhole Technology to the gas and oil drilling industry requires an effective downhole drive mechanism which operates efficiently at relatively high RPM and low bit weight for delivering efficient power to the special high RPM drill bit for ensuring both high penetration rate and long bit life. This project entails developing and testing a more efficient 2-7/8 in. diameter Turbodrill and a novel 4-1/8 in. diameter drill bit for drilling with coiled tubing. The high-power Turbodrill were developed to deliver efficient power, and the more durable drill bit employed high-temperature cutters that can more effectively drill hard and abrasive rock. This project teams Schlumberger Smith Neyrfor and Smith Bits, and NASA AMES Research Center with Technology International, Inc (TII), to deliver a downhole, hydraulically-driven power unit, matched with a custom drill bit designed to drill 4-1/8 in. boreholes with a purpose-built coiled tubing rig. The U.S. Department of Energy National Energy Technology Laboratory has funded Technology International Inc. Houston, Texas to develop a higher power Turbodrill and drill bit for use in drilling with a coiled tubing unit. This project entails developing and testing an effective downhole drive mechanism and a novel drill bit for drilling 'microholes' with coiled tubing. The new higher power Turbodrill is shorter, delivers power more efficiently, operates at relatively high revolutions per minute, and requires low weight on bit. The more durable thermally stable diamond drill bit employs high-temperature TSP (thermally stable) diamond cutters that can more effectively drill hard and abrasive rock. Expectations are that widespread adoption of microhole technology could spawn a wave of 'infill development' drilling of wells spaced between existing wells, which could tap potentially billions of barrels of bypassed oil at shallow depths in mature producing areas. At the same time, microhole coiled tube drilling offers the opportunity to dramatically cut producers' exploration risk to a level comparable to that of drilling development wells. Together, such efforts hold great promise for economically recovering a sizeable portion of the estimated remaining shallow (less than 5,000 feet subsurface) oil resource in the United States. The DOE estimates this U.S. targeted shallow resource at 218 billion barrels. Furthermore, the smaller 'footprint' of the lightweight rigs utilized for microhole drilling and the accompanying reduced drilling waste disposal volumes offer the bonus of added environmental benefits. DOE analysis shows that microhole technology has the potential to cut exploratory drilling costs by at least a third and to slash development drilling costs in half.

Robert Radtke; David Glowka; Man Mohan Rai; David Conroy; Tim Beaton; Rocky Seale; Joseph Hanna; Smith Neyrfor; Homer Robertson

2008-03-31T23:59:59.000Z

268

Composite Cathode for High-Power Density Solid Oxide Fuel Cells  

DOE Green Energy (OSTI)

Reduction of solid oxide fuel cell (SOFC) operating temperature will play a key role in reducing the stack cost by allowing the use of low-cost metallic interconnects and new approaches to sealing, while making applications such as transportation more feasible. Reported results for anode-supported SOFCs show that cathode polarization resistance is the primary barrier to achieving high power densities at operating temperatures of 700 C and lower. This project aims to identify and develop composite cathodes that could reduce SOFC operating temperatures below 700 C. This effort focuses on study and use of (La,Sr)(Co,Fe)O{sub 3} (LSCF) based composite cathodes, which have arguably the best potential to substantially improve on the currently-used, (La,Sr)MnO{sub 3}-Yttria-stabilized Zirconia. During this Phase I, it was successfully demonstrated that high performances can be achieved with LSCF/Gadolinium-Doped Ceria composite cathodes on Ni-based anode supported cells operating at 700 C or lower. We studied electrochemical reactions at LSCF/Yttria-stabilized Zirconia (YSZ) interfaces, and observed chemical reactions between LSCF and YSZ. By using ceria electrolytes or YSZ electrolytes with ceria diffusion barrier layers, the chemical reactions between LSCF and electrolytes were prevented under cathode firing conditions necessary for the optimal adhesion of the cathodes. The protection provided by ceria layer is expected to be adequate for stable long-term cathode performances, but more testing is needed to verify this. Using ceria-based barrier layers, high performance Ni-YSZ anode supported cells have been demonstrated with maximum power densities of 0.8W/cm2 at 700 C and 1.6W/cm{sup 2} at 800 C. Ni-SDC anode supported cells with SDC electrolytes yielded >1W/cm{sup 2} at 600 C. We speculate that the power output of Ni-YSZ anode supported cell at 700 C and lower, was limited by the quality of the Ceria and Ceria YSZ interface. Improvements in the low-temperature performances are expected based on further development of barrier layer fabrication processes and optimization of cathode microstructure.

Ilwon Kim; Scott Barnett; Yi Jiang; Manoj Pillai; Nikkia McDonald; Dan Gostovic; Zhongryang Zhan; Jiang Liu

2004-01-31T23:59:59.000Z

269

Investigations of silica alcogel aging using coherent light  

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

Investigations of silica alcogel aging using coherent light Title Investigations of silica alcogel aging using coherent light Publication Type Journal Article Year of Publication...

270

A GAP package for computation with coherent configurations  

Science Conference Proceedings (OSTI)

We present a GAP package for computing with Schurian coherent configurations and their representations. Keywords: GAP, GRAPE, association scheme, centralizer ring, coherent configuration, permutation group, sage, semidefinite programming

Dmitrii V. Pasechnik; Keshav Kini

2010-09-01T23:59:59.000Z

271

High-power Waveguide Dampers for the Short-Pulse X-Ray Project at the Advanced Photon Source  

Science Conference Proceedings (OSTI)

High-power waveguide dampers have been designed and prototyped for the Short-Pulse X-ray (SPX) cavities at the Advanced Photon Source. The cavities will operate at 2.815 GHz and utilize the TM110 dipole mode. As a result, higher-order (HOM) and lower-order mode (LOM) in-vacuum dampers have been designed to satisfy the demanding broadband damping requirements in the APS storage ring. The SPX single-cell cavity consists of two WR284 waveguides for damping the HOMs and one WR284 waveguide for primarily damping the LOM where up to 2kW will be dissipated in the damping material. The damper designs and high-power experimental results will be discussed in this paper.

Waldschmidt, G J; Liu, J; Middendorf, M E; Nassiri, A; Smith, T L; Wu, G; Henry, J; Mammosser, J D; Rimmer, R A

2012-07-01T23:59:59.000Z

272

Excitation of terahertz radiation by an electron beam in a dielectric lined waveguide with rippled dielectric surface  

SciTech Connect

A relativistic electron beam propagating through a dielectric lined waveguide, with ripple on the dielectric surface, excites a free electron laser type instability where ripple acts as a wiggler. The spatial modulation of permittivity in the ripple region couples a terahertz radiation mode to a driven mode of lower phase velocity, where the beam is in Cerenkov resonance with the slow mode. Both the modes grow at the expanse of beam energy. The terahertz frequency increases as the beam velocity increases. The growth rate of the instability goes as one third power of beam density.

Tripathi, Deepak; Uma, R. [Center for Energy Studies, Indian Institute of Technology Delhi, New Delhi 110016 (India); Tripathi, V. K. [Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016 (India)

2012-09-15T23:59:59.000Z

273

The development of low cost LiFePO4-based high power lithium-ion batteries  

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

development of low cost LiFePO4-based high power lithium-ion batteries development of low cost LiFePO4-based high power lithium-ion batteries Title The development of low cost LiFePO4-based high power lithium-ion batteries Publication Type Journal Article Year of Publication 2005 Authors Striebel, Kathryn A., Joongpyo Shim, Azucena Sierra, Hui Yang, Xiangyun Song, Robert Kostecki, and Kathryn N. McCarthy Journal Journal of Power Sources Volume 146 Pagination 33-38 Keywords libob, lifepo4, lithium-ion, post-test, raman spectroscopy Abstract Pouch type LiFePO4-natural graphite lithium-ion cells were cycled at constant current with periodic pulse-power testing in several different configurations. Components were analyzed after cycling with electrochemical, Raman and TEM techniques to determine capacity fade mechanisms. The cells with carbon-coated current collectors in the cathode and LiBOB-salt electrolyte showed the best performance stability. In many cases, iron species were detected on the anodes removed from cells with both TEM and Raman spectroscopy. The LiFePO4 electrodes showed unchanged capacity suggesting that the iron is migrating in small quantities and is acting as a catalyst to destabilize the anode SEI in these cells.

274

High Power Testing Results of the X-band Mixed-mode RF Windows for Linear Colliders  

SciTech Connect

In this paper, we summarize the high power testing results of the X-band mixed-mode RF windows at KEK and SLAC for linear colliders. The main feature of these windows is that the combination of modes on the surface of the ceramic significantly decreases the electric and magnetic fields in the junction between the ceramic and the metal. So far two types of high power windows (with the diameter of 53 mm and 64 mm) have been fabricated. A high power model of the smaller type window was fabricated and tested in a resonant ring at KEK. A maximum circulating power of 81 MW with 300 ns duration or 66 MW with 700 ns duration was achieved. Light emission was observed for a power level of over 10 MW. Later, both windows were shipped to SLAC for even higher power testing using combined power from two klystrons. The first window (53 mm diameter) achieved a transmitted power of 80 MW with 1.5 microsec duration at 30 Hz repetition. It was not destroyed during the testing. The testing of the second window was carried out next to the small type and achieved 62 MW with 1.5 microsec duration with 10 Hz repetition. The final results of both windows are presented in this report.

Loewen, Roderick J

2000-10-26T23:59:59.000Z

275

Improved long-term electrical stability of pulsed high-power diodes using dense carbon fiber velvet cathodes  

Science Conference Proceedings (OSTI)

The influence of fibrous velvet cathodes on the electrical stability of a planar high-power diode powered by a {approx}230 kV, {approx}110 ns pulse has been investigated. The current density was on the order of {approx}123 A/cm{sup 2}. A combination of time-resolved electrical and optical diagnostics has been employed to study the basic phenomenology of the temporal and spatial evolution of the diode plasmas. Additionally, an impedance model was used to extract information about this plasma from voltage and current profiles. The results from the two diagnostics were compared. By comparison with commercial polymer velvet cathode, the dense carbon fiber velvet cathode showed superior long-term electrical stability as judged by the change in cathode turn-on field, ignition delays, diode impedance, and surface plasma characteristics during the voltage flattop, a promising result for applications where reliable operation at high power is required. Finally, it was shown that the interaction of the electron beam with the stainless steel anode did not lead to the formation of anode plasma. These results may be of interest to the high power microwave systems with cold cathodes.

Yang Jie; Shu Ting; Wang Hui [College of Opto-Electric Science and Engineering, National University of Defense Technology, Hunan 410073 (China)

2012-07-15T23:59:59.000Z

276

Coherent Synoptic Disturbances in the Australian Monsoon  

Science Conference Proceedings (OSTI)

Coherent synoptic-scale weather systems within the Australian monsoon are identified and tracked in the isentropic potential vorticity (PV) field from the ECMWF Interim Reanalysis (ERA-Interim) dataset during the Southern Hemisphere summer. The ...

Gareth J. Berry; Michael J. Reeder; Christian Jakob

2012-12-01T23:59:59.000Z

277

Disentangling chat with local coherence models  

Science Conference Proceedings (OSTI)

We evaluate several popular models of local discourse coherence for domain and task generality by applying them to chat disentanglement. Using experiments on synthetic multiparty conversations, we show that most models transfer well from text to dialogue. ...

Micha Elsner; Eugene Charniak

2011-06-01T23:59:59.000Z

278

A Coherent Strategy for Qauntum Gravity  

E-Print Network (OSTI)

Affine quantum gravity, which differs notably from either string theory or loop quantum gravity, is briefly reviewed. Emphasis in this article is placed on the use of affine coherent states in this program.

John R. Klauder

2004-11-10T23:59:59.000Z

279

Managing coherence via put/get windows  

DOE Patents (OSTI)

A method and apparatus for managing coherence between two processors of a two processor node of a multi-processor computer system. Generally the present invention relates to a software algorithm that simplifies and significantly speeds the management of cache coherence in a message passing parallel computer, and to hardware apparatus that assists this cache coherence algorithm. The software algorithm uses the opening and closing of put/get windows to coordinate the activated required to achieve cache coherence. The hardware apparatus may be an extension to the hardware address decode, that creates, in the physical memory address space of the node, an area of virtual memory that (a) does not actually exist, and (b) is therefore able to respond instantly to read and write requests from the processing elements.

Blumrich, Matthias A. (Ridgefield, CT); Chen, Dong (Croton on Hudson, NY); Coteus, Paul W. (Yorktown Heights, NY); Gara, Alan G. (Mount Kisco, NY); Giampapa, Mark E. (Irvington, NY); Heidelberger, Philip (Cortlandt Manor, NY); Hoenicke, Dirk (Ossining, NY); Ohmacht, Martin (Yorktown Heights, NY)

2011-01-11T23:59:59.000Z

280

Managing coherence via put/get windows  

DOE Patents (OSTI)

A method and apparatus for managing coherence between two processors of a two processor node of a multi-processor computer system. Generally the present invention relates to a software algorithm that simplifies and significantly speeds the management of cache coherence in a message passing parallel computer, and to hardware apparatus that assists this cache coherence algorithm. The software algorithm uses the opening and closing of put/get windows to coordinate the activated required to achieve cache coherence. The hardware apparatus may be an extension to the hardware address decode, that creates, in the physical memory address space of the node, an area of virtual memory that (a) does not actually exist, and (b) is therefore able to respond instantly to read and write requests from the processing elements.

Blumrich, Matthias A. (Ridgefield, CT); Chen, Dong (Croton on Hudson, NY); Coteus, Paul W. (Yorktown Heights, NY); Gara, Alan G. (Mount Kisco, NY); Giampapa, Mark E. (Irvington, NY); Heidelberger, Philip (Cortlandt Manor, NY); Hoenicke, Dirk (Ossining, NY); Ohmacht, Martin (Yorktown Heights, NY)

2012-02-21T23:59:59.000Z

Note: This page contains sample records for the topic "high-power coherent terahertz" 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

Source of coherent short wavelength radiation  

DOE Patents (OSTI)

An apparatus for producing coherent radiation ranging from X-rays to the far ultraviolet (i.e., 1 Kev to 10 eV) utilizing the Compton scattering effect. A photon beam from a laser is scattered on a high energy electron bunch from a pulse power linac. The short wavelength radiation produced by such scattering has sufficient intensity and spatial coherence for use in high resolution applications such as microscopy.

Villa, Francesco (Alameda, CA)

1990-01-01T23:59:59.000Z

282

A toy model for Macroscopic Quantum Coherence  

E-Print Network (OSTI)

The present article deals with Macroscopic Quantum Coherence resorting only to basic quantum mechanics. A square double well is used to illustrate the Leggett-Caldeira oscillations. The effect of thermal-radiation on two-level systems is discussed to some extent. The concept of decoherence is introduced at an elementary level. Handles are deduced for the energy, temperature and time scales involved in Macroscopic Quantum Coherence.

R. Muñoz-Vega; José-Job J. Flores-Godoy; G. Fernández-Anaya; Encarnación Salinas-Hernández

2012-10-29T23:59:59.000Z

283

Insertion of coherence requests for debugging a multiprocessor  

DOE Patents (OSTI)

A method and system are disclosed to insert coherence events in a multiprocessor computer system, and to present those coherence events to the processors of the multiprocessor computer system for analysis and debugging purposes. The coherence events are inserted in the computer system by adding one or more special insert registers. By writing into the insert registers, coherence events are inserted in the multiprocessor system as if they were generated by the normal coherence protocol. Once these coherence events are processed, the processing of coherence events can continue in the normal operation mode.

Blumrich, Matthias A. (Ridgefield, CT); Salapura, Valentina (Chappaqua, NY)

2010-02-23T23:59:59.000Z

284

Enhancing the energy of terahertz radiation from plasma produced by intense femtosecond laser pulses  

SciTech Connect

Terahertz (THz) radiation from atomic clusters illuminated by intense femtosecond laser pulses is investigated. By studying the angular distribution, polarization properties and energy dependence of THz waves, we aim to obtain a proper understanding of the mechanism of THz generation. The properties of THz waves measured in this study differ from those predicted by previously proposed mechanisms. To interpret these properties qualitatively, we propose that the radiation is generated by time-varying quadrupoles, which are produced by the ponderomotive force of the laser pulse.

Jahangiri, Fazel [Advanced Research Center for Beam Science, ICR, Kyoto University, Kyoto (Japan) [Advanced Research Center for Beam Science, ICR, Kyoto University, Kyoto (Japan); Laser and Plasma Research Institute, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Hashida, Masaki; Tokita, Shigeki; Sakabe, Shuji [Advanced Research Center for Beam Science, ICR, Kyoto University, Kyoto (Japan) [Advanced Research Center for Beam Science, ICR, Kyoto University, Kyoto (Japan); Department of Physics, GSS, Kyoto University, Kyoto (Japan); Nagashima, Takeshi; Hangyo, Masanori [Department of Physics, GSS, Kyoto University, Kyoto (Japan) [Department of Physics, GSS, Kyoto University, Kyoto (Japan); Institute of Laser Engineering, Osaka University, Osaka (Japan)

2013-05-13T23:59:59.000Z

285

Dependence of terahertz power from laser-produced plasma on laser intensity  

SciTech Connect

Power of terahertz radiation from plasma which is generated from air irradiated by coupled ({omega}, 2{omega}) femtosecond laser pulses is analyzed for high laser intensities, for which non-linear plasma effects on the pulse propagation become essential, with multidimensional particle-in-cell simulations including the self-consistent plasma kinetics. The growth rate of THz power becomes slower as the laser intensity increases. A reason of such a lowering of efficiency in THz emission is found to be ionization of air by the laser pulse, which results in poor focusing of laser pulses.

Shin, J.-H.; Zhidkov, A.; Jin, Z.; Hosokai, T.; Kodama, R. [Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita, Osaka 565-0871 (Japan); Photon Pioneers Center, Osaka University, 2-1, Yamadaoka, Suita, Osaka 565-0871 (Japan); Japan Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka (Japan)

2012-07-11T23:59:59.000Z

286

Heating and cooling of a two-dimensional electron gas by terahertz radiation  

Science Conference Proceedings (OSTI)

The absorption of terahertz radiation by free charge carriers in n-type semiconductor quantum wells accompanied by the interaction of electrons with acoustic and optical phonons is studied. It is shown that intrasubband optical transitions can cause both heating and cooling of the electron gas. The cooling of charge carriers occurs in a certain temperature and radiation frequency region where light is most efficiently absorbed due to intrasubband transitions with emission of optical phonons. In GaAs quantum wells, the optical cooling of electrons occurs most efficiently at liquid nitrogen temperatures, while cooling is possible even at room temperature in GaN heterostructures.

Budkin, G. V.; Tarasenko, S. A., E-mail: tarasenko@coherent.ioffe.ru [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)

2011-04-15T23:59:59.000Z

287

Terahertz Time-Domain Spectroscopy Study of Silica Aerogels and Adsorbed Molecular Jiangquan Zhang and D. Grischkowsky*  

E-Print Network (OSTI)

Terahertz Time-Domain Spectroscopy Study of Silica Aerogels and Adsorbed Molecular Vapors Jiangquan time-domain spectroscopy (THz-TDS) study of hydrophobic and hydrophilic silica aerogels, and the adsorption of several molecular vapors in the hydrophilic silica aerogel. The hydrophobic and hydrophilic

Oklahoma State University

288

Coherent structures and aeolian saltation  

E-Print Network (OSTI)

Aeolian sand transport models, widely employed by coastal scientists and managers, assume temporal and spatial homogeneity within the saltation field. This research questions that assumption by demonstrating that the saltation field is event-driven, therefore indicating that the saltation field is not temporally steady. The findings from this research may explain a portion of the conclusions from previous studies that indicated inequalities between model-estimated and field-measured aeolian sand transport. The relationship between unsteadiness in a turbulent wind field and pulses in a sand transport field was investigated on a beach near Shoalhaven Heads, New South Wales, Australia. Microphone-based saltation sensors, “miniphones,” and thermal anemometers (both instruments constructed exclusively for this field experiment) were co-located (0.02 m separation on center) and deployed between 0.01 and 0.0225 m above the bed, and sampled at 6000 Hz. Average grain size at the field site was 0.30 mm. Five runs totaling 2050 seconds of wind and saltation data were analyzed. The continuous wavelet transform, using the Morlet wavelet base, was the principle method for analyzing the wind and saltation records. The cross continuous wavelet transform was used to analyze the wind and saltation time series concurrently. Wind, saltation, and cross events were discerned by selecting wavelet power coefficients between wavelet scales of 0.4 and 3.0 seconds and with coefficients exceeding the 95% confidence interval. Average event spacing was 6.10, 6.50, and 6.73 seconds for the wind, saltation, and cross events, respectively. The average event spacing measured in this research was compared to the empirical-based model presented by Rao, Narashimha, and Narayanan (1971). The correspondence between the model and this research strongly suggests that bursting-type coherent structures were present. The durations of average wind, saltation, and cross events were 1.87, 2.10, and 1.73 seconds, respectively. Integral time scales, calculated using normalized auto correlation and power spectral density analysis, were approximately two seconds for the wind and saltation systems. The temporal coincidence of the integral time scale estimations and the event durations for the wind and saltation system strongly suggests that wind events are driving sand transport events.

Ellis, Jean Taylor

2006-12-01T23:59:59.000Z

289

Power Beamed Photon Sails: New Capabilities Resulting From Recent Maturation Of Key Solar Sail And High Power Laser Technologies  

SciTech Connect

This paper revisits some content in the First International Symposium on Beamed Energy Propulsion in 2002 related to the concept of propellantless in-space propulsion utilizing an external high energy laser to provide momentum to an ultralightweight (gossamer) spacecraft. The design and construction of the NanoSail-D solar sail demonstration spacecraft has demonstrated in space flight hardware the concept of small, very light--yet capable--spacecraft. The results of the Joint High Power Solid State Laser (JHPSSL) have also increased the effectiveness and reduced the cost of an entry level laser source. This paper identifies the impact from improved system parameters on current mission applications.

Montgomery, Edward E. IV [United States Army Space and Missile Defense Command, Huntsville, Alabama (United States)

2010-05-06T23:59:59.000Z

290

The development of low cost LiFePO4-based high power lithium-ion batteries  

DOE Green Energy (OSTI)

The cycling performance of low-cost LiFePO4-based high-power lithium-ion cells was investigated and the components were analyzed after cycling to determine capacity fade mechanisms. Pouch type LiFePO4/natural graphite cells were assembled and evaluated by constant C/2 cycling, pulse-power and impedance measurements. From post-test electrochemical analysis after cycling, active materials, LiFePO4 and natural graphite, showed no degradation structurally or electrochemically. The main reasons for the capacity fade of cell were lithium inventory loss by side reaction and possible lithium deposition on the anode.

Shim, Joongpyo; Sierra, Azucena; Striebel, Kathryn A.

2003-11-25T23:59:59.000Z

291

Analysis and experimental results of a single-stage high-power-factor electronic ballast based on flyback converter  

SciTech Connect

A new single-stage high-power-factor electronic ballast based on a flyback converter is presented in this paper. The ballast is able to supply a fluorescent lamp assuring a high-input power factor for the utility line. Other features are lamp power regulation against line voltage variations and low lamp current crest factor, both assuring long lamp life. The ballast is analyzed at steady-state operation, and design equations and characteristics are obtained. Also, a procedure for the ballast design is presented. Finally, simulation and experimental results from a laboratory prototype are shown.

Calleja, A.J.; Alonso, J.M.; Lopez, E.; Ribas, J.; Martinez, J.A.; Rico-Secades, M.

1999-11-01T23:59:59.000Z

292

Ultrafast terahertz probes of transient conducting and insulating phases in an electron-hole gas  

DOE Green Energy (OSTI)

Many-body systems in nature exhibit complexity and self-organization arising from seemingly simple laws. The long-range Coulomb interaction between electrical charges generates a plethora of bound states in matter, ranging from the hydrogen atom to complex biochemical structures. Semiconductors form an ideal laboratory for studying many-body interactions of quasi-particles among themselves and with lattice vibrations and light. Oppositely charged electron and hole quasi-particles can coexist in an ionized but correlated plasma, or form bound hydrogen-like pairs called excitons which strongly affect physical properties. The pathways between such states however remain elusive in near-visible optical experiments that detect a subset of excitons with vanishing center-of-mass momenta. In contrast, transitions between internal exciton levels which occur in the far-infrared at terahertz (10 s) frequencies are in dependent of this restriction suggesting their use as a novel pro be of pair dynamics. Here, we employ an ultrafast terahertz probe to directly investigate the dynamical interplay of optically-generated excitons and unbound electron-hole pairs in GaAs quantum wells. Our observations witness an unexpected quasi-instantaneous excitonic enhancement, reveal formation of insulating excitons on a hundred picosecond timescale and manifest conditions under which excitonic populations prevail.

Kaindl, Robert A.; Carnahan, Marc A.; Hagele, Daniel; Lovenich, Reinhold; Chemla, Daniel S.

2003-04-10T23:59:59.000Z

293

The Linac Coherent Light Source is  

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

Coherent Light Source is Coherent Light Source is a revolution in x-ray science. Just as the invention of x-ray machines a century ago astonishingly revealed the inside of our bodies and began new sciences, the world's first x-ray laser will open up unprecedented opportunities. Pioneering experiments will advance our understand ing of everything from the hidden physics inside planets, to how proteins function as the engines of life, to building nanotechnology devices for the backbone of future industry and technology. The applications are legion: medicine, electronics, biology, solid-state physics, nanotechnology, energy production, industry and fields that do not yet exist. Linac Coherent Light Source New Tools Create New Science The LCLS is dramatically different from any x-ray

294

VUV absorption spectroscopy measurements of the role of fast neutral atoms in high-power gap breakdown  

DOE Green Energy (OSTI)

The maximum power achieved in a wide variety of high-power devices, including electron and ion diodes, z pinches, and microwave generators, is presently limited by anode-cathode gap breakdown. A frequently-discussed hypothesis for this effect is ionization of fast neutral atoms injected throughout the anode-cathode gap during the power pulse. The authors describe a newly-developed diagnostic tool that provides the first direct test of this hypothesis. Time-resolved vacuum-ultraviolet absorption spectroscopy is used to directly probe fast neutral atoms with 1 mm spatial resolution in the 10 mm anode-cathode gap of the SABRE 5 MV, 1 TW applied-B ion diode. Absorption spectra collected during Ar RF glow discharges and with CO{sub 2} gas fills confirm the reliability of the diagnostic technique. Throughout the 50--100 ns ion diode pulses no measurable neutral absorption is seen, setting upper limits of 0.12--1.5 x 10{sup 14} cm{sup {minus}3} for ground state fast neutral atom densities of H, C, N, O, F. The absence of molecular absorption bands also sets upper limits of 0.16--1.2 x 10{sup 15} cm{sup {minus}3} for common simple molecules. These limits are low enough to rule out ionization throughout the gap as a breakdown mechanism. This technique can now be applied to quantify the role of neutral atoms in other high-power devices.

FILUK,A.B.; BAILEY,JAMES E.; CUNEO,MICHAEL E.; LAKE,PATRICK WAYNE; NASH,THOMAS J.; NOACK,DONALD D.; MARON,Y.

2000-03-20T23:59:59.000Z

295

Fundamental Studies and Development of III-N Visible LEDs for High-Power Solid-State Lighting Applications  

SciTech Connect

The goal of this program is to understand in a fundamental way the impact of strain, defects, polarization, and Stokes loss in relation to unique device structures upon the internal quantum efficiency (IQE) and efficiency droop (ED) of III-nitride (III-N) light-emitting diodes (LEDs) and to employ this understanding in the design and growth of high-efficiency LEDs capable of highly-reliable, high-current, high-power operation. This knowledge will be the basis for our advanced device epitaxial designs that lead to improved device performance. The primary approach we will employ is to exploit new scientific and engineering knowledge generated through the application of a set of unique advanced growth and characterization tools to develop new concepts in strain-, polarization-, and carrier dynamics-engineered and low-defect materials and device designs having reduced dislocations and improved carrier collection followed by efficient photon generation. We studied the effects of crystalline defect, polarizations, hole transport, electron-spillover, electron blocking layer, underlying layer below the multiplequantum- well active region, and developed high-efficiency and efficiency-droop-mitigated blue LEDs with a new LED epitaxial structures. We believe new LEDs developed in this program will make a breakthrough in the development of high-efficiency high-power visible III-N LEDs from violet to green spectral region.

Dupuis, Russell

2012-02-29T23:59:59.000Z

296

Analysis of the mode composition of an X-band overmoded O-type Cerenkov high-power microwave oscillator  

SciTech Connect

Overmoded slow wave structures (SWSs) with large diameter are utilized in O-type Cerenkov high-power microwave (HPM) sources for their high power capacity. However, multi-modes may be output simultaneously in the overmoded O-type Cerenkov HPM sources. In order to achieve high mode purity, the mode composition of the output power should be analyzed quantitatively when the structure of this type of device is being optimized. Two accurate numerical methods of making quantitative analysis of the mode composition in particle-in-cell model are introduced in this paper. And then, the mode composition of an X-band O-type Cerenkov oscillator with overmoded SWSs (D/{lambda} Almost-Equal-To 2.7) is analyzed. The analysis indicates that appropriate selection of the parameters of overmoded SWSs and electron beam is important, as mentioned in previous reports, for realizing mode selection in beam-wave interaction. Besides, designing of the mode conversion effect, which is rarely discussed, can also affect the mode purity of output power. After adjustment of the dimensions of the tapered waveguide, which converts the combination of 'surface wave' and 'volume wave' to the 'volume wave' in the output waveguide, the percentage of total output microwave power carried by the TM{sub 01} mode is higher than 95% in the X-band overmoded Cerenkov oscillator at the diode voltage ranging from 570 kV to 750 kV.

Zhang Dian; Zhang Jun; Zhong Huihuang; Jin Zhenxing [College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

2012-10-15T23:59:59.000Z

297

Microscopy and spectroscopy of lithium nickel oxide based particles used in high-power lithium-ion cells.  

DOE Green Energy (OSTI)

Structural and electronic investigations were conducted on lithium nickel oxide-based particles used in positive electrodes of 18650-type high-power Li-ion cells. K-edge X-ray absorption spectroscopy (XAS) revealed trivalent Ni and Co ions in the bulk LiNi{sub 0.8}Co{sub 0.2}O{sub 2} powder used to prepare the high power electrode laminates. Using oxygen K-edge XAS, high resolution electron microscopy, nanoprobe diffraction, and electron energy-loss spectroscopy, we identified a <5 nm thick modified layer on the surface of the oxide particles, which results from the loss of Ni and Li ordering in the layered R{bar 3}m structure. This structural change was accompanied by oxygen loss and a lowering of the Ni- and Co-oxidation states in the surface layer. Growth of this surface layer may contribute to the impedance rise observed during accelerated aging of these Li-ion cells.

Abraham, D. P.; Twesten, R. D.; Balasubramanian, M.; Kropf, A. J.; Fischer, D.; McBreen, J.; Petrov, I.; Amine, K.; Chemical Engineering; Univ. of Illinois; BNL; NIST

2003-11-01T23:59:59.000Z

298

Coherent optical control of electronic excitations in functionalized semiconductor nanostructures  

Science Conference Proceedings (OSTI)

The feasibility of creating and manipulating coherent quantum states on surfaces offunctionalized semiconductor nanostructures is computationally investigated. Quantumdynamics simulations of electron-hole transfer between catechol molecules adsorbed ... Keywords: adsorbates, coherent control, semiconductors, wave-packet dynamics

L. G. C. Rego; S. G. Abuabara; V. S. Batista

2005-07-01T23:59:59.000Z

299

Some Additional Coherence Data in the Inertial Subrange  

Science Conference Proceedings (OSTI)

Some coherence measurements, taken at the Näsudden wind energy test site, for small separation distances at a height of 65–77 m, are analyzed in terms of a theoretical coherence model for isotropic turbulence, and for Davenport similarity.

Ann-Sofi Smedman

1987-12-01T23:59:59.000Z

300

Quasi Light Fields: A Model of Coherent Image Formation  

E-Print Network (OSTI)

We develop a model of coherent image formation that strikes a balance between the simplicity of the light field and the comprehensive predictive power of Maxwell's equations, by extending the light field to coherent radiation.

Accardi, Anthony J.

Note: This page contains sample records for the topic "high-power coherent terahertz" 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

Direct Atmospheric Forcing of Geostrophic Eddies. Part II: Coherence Maps  

Science Conference Proceedings (OSTI)

The theory of stochastic atmospheric forcing of quasigeostrophic eddies is applied to calculate coherence maps, that is, the coherence between the oceanic response at one location and the atmospheric forcing at another location as a function of ...

Angelika Lippert; Peter Müller

1995-01-01T23:59:59.000Z

302

Coherence Maps for Wind-Forced Quasigeostrophic Flows  

Science Conference Proceedings (OSTI)

Coherence maps are a useful tool to study the oceanic response to atmospheric forcing. For a specific frequency band these maps display the coherence between the oceanic current (or pressure) at a single mooring location and the atmospheric ...

Peter Müller

1997-09-01T23:59:59.000Z

303

Agent communication pragmatics: the cognitive coherence approach  

Science Conference Proceedings (OSTI)

Different approaches have investigated the syntax and semantics of agent communication languages. However, these approaches have not indicated how agents should dynamically use communications. Instead of filling this pragmatics gap, most approaches have ... Keywords: Agent communication language, Cognitive coherence, Dialogue games, Multi-agents systems, Pragmatics, Social commitments

Philippe Pasquier; Brahim Chaib-Draa

2005-12-01T23:59:59.000Z

304

Delta Coherence Protocols: The Home Update Protocol  

SciTech Connect

We describe a new class of directory coherence protocols called delta coherence protocols that use network guarantees to support a new and highly concurrent approach to maintain a consistent shared memory. Delta coherence protocols are more concurrent than other coherence protocols in that they allow processes to pipeline memory accesses without violating sequential consistency; support multiple concurrent readers and writers to the same cache block; and allow processes to access multiple shared variables atomically without invalidating the copies held by other processes or otherwise obtaining exclusive access to the referenced variables. Delta protocols include both update and invalidate protocols. In this paper we describe the simplest, most basic delta protocol, an update protocol called the home update protocol. Delta protocols are based on isotach network guarantees. An isotach network maintains a logical time system that allows each process to predict and control the logical time at which its messages are received. Processes use isotach guarantees to control the logical time at which their requests on shared memory appear to be executed. We prove the home update protocol is correct using logical time to reason about the order in which requests are executed.

Williams, C.; Reynolds, P.F.; de Supinoki, B.

2000-07-21T23:59:59.000Z

305

Coherent multilayer crystals and method of making  

SciTech Connect

A new material consisting of a multilayer crystalline structure which is coherent perpendicular to the layers and where each layer is composed of a single crystalline element. The individual layers may vary from 2.ANG. to 100.ANG. or more in thickness.

Schuller, Ivan K. (Woodridge, IL); Falco, Charles M. (Tucson, AZ)

1984-01-01T23:59:59.000Z

306

Method of making coherent multilayer crystals  

DOE Patents (OSTI)

A new material consisting of a coherent multilayer crystal of two or more elements where each layer is composed of a single element. Each layer may vary in thickness from about 2 .ANG. to 2500 .ANG.. The multilayer crystals are prepared by sputter deposition under conditions which slow the sputtered atoms to near substrate temperatures before they contact the substrate.

Schuller, Ivan K. (Woodridge, IL); Falco, Charles M. (Woodridge, IL)

1984-01-01T23:59:59.000Z

307

Deriving Efficient Cache Coherence Protocols Through Refinement  

Science Conference Proceedings (OSTI)

We address the problem of developing efficient cache coherence protocols for use in distributed systems implementing distributed shared memory (DSM) using message passing. A serious drawback of traditional approaches to this problem is that the users ... Keywords: DSM protocols, communication protocols, refinement

Ratan Nalumasu; Ganesh Gopalakrishnan

2002-01-01T23:59:59.000Z

308

Coherent Radiation Effects in the LCLS Undulator  

Science Conference Proceedings (OSTI)

For X-ray Free-Electron Lasers such as LCLS and TESLA FEL, a change in the electron energy while amplifying the FEL radiation can shift the resonance condition out of the bandwidth of the FEL. The largest sources of energy loss is the emission of incoherent undulator radiation. Because the loss per electron depends only on the undulator parameters and the beam energy, which are fixed for a given resonant wavelength, the average energy loss can be compensated for by a fixed taper of the undulator. Coherent radiation has a strong enhancement proportional to the number of electrons in the bunch for frequencies comparable to or longer than the bunch dimension. If the emitted coherent energy becomes comparable to that of the incoherent emission, it has to be included in the taper as well. However, the coherent loss depends on the bunch charge and the applied compression scheme and a change of these parameters would require a change of the taper. This imposes a limitation on the practical operation of Free-Electron Lasers, where the taper can only be adjusted manually. In this presentation we analyze the coherent emission of undulator radiation and transition undulator radiation for LCLS, and estimate whether the resulting energy losses are significant for the operation of LCLS.

Reiche, S.; /UCLA; Huang, Z.; /SLAC

2010-12-14T23:59:59.000Z

309

Coherent multilayer crystals and method of making  

DOE Patents (OSTI)

A new material is described consisting of a coherent multilayer crystal of two or more elements where each layer is composed of a single element. Each layer may vary in thickness from about 2 A to 2500 A. The multilayer crystals are prepared by sputter deposition under conditions which slow the sputtered atoms to near substrate temperatures before they contact the substrate.

Schuller, I.K.; Falco, C.M.

1980-10-30T23:59:59.000Z

310

Brief paper: Structural archetypes for coherency  

Science Conference Proceedings (OSTI)

The power system model is divided into a study system (SS) and an external group (EG). Three structural archetypes for coherency (SAC) are defined. Each SAC is a set of structural conditions on the power system which when satisfied cause the EG to remain ... Keywords: Power systems, dynamic equivalents, modal analysis, singular perturbation

John F. Dorsey; Robert A. Schlueter

1984-05-01T23:59:59.000Z

311

Isolating quantum coherence with pathway-selective coherent multi-dimensional spectroscopy  

E-Print Network (OSTI)

Coherent coupling between spatially separated systems has long been explored as a necessary requirement for quantum information and cryptography. Recent discoveries suggest such phenomena appear in a much wider range of processes, including light-harvesting in photosynthesis. These discoveries have been facilitated by developments in coherent multi-dimensional spectroscopy (CMDS) that allow interactions between different electronic states to be identified in crowded spectra. For complex systems, however, spectral broadening and multiple overlapping peaks limit the ability to separate, identify and properly analyse all contributions. Here we demonstrate how pathway-selective CMDS can overcome these limitations to reveal, isolate and allow detailed analysis of weak coherent coupling between spatially separated excitons localised to different semiconductor quantum wells. Selective excitation of the coherence pathways, by spectrally shaping the laser pulses, provides access to previously hidden details and enable...

Tollerud, Jonathan O; Davis, Jeffrey A

2013-01-01T23:59:59.000Z

312

SU(N) Coherent States and Irreducible Schwinger Bosons  

E-Print Network (OSTI)

We exploit the SU(N) irreducible Schwinger boson to construct SU(N) coherent states. This construction of SU(N) coherent state is analogous to the construction of the simplest Heisenberg-Weyl coherent states. The coherent states belonging to irreducible representations of SU(N) are labeled by the eigenvalues of the $(N-1)$ SU(N) Casimir operators and are characterized by $(N-1)$ complex orthonormal vectors describing the SU(N) group manifold.

Manu Mathur; Indrakshi Raychowdhury

2010-07-09T23:59:59.000Z

313

Thresholdless coherent light scattering from subband polaritons in a strongly coupled microcavity  

E-Print Network (OSTI)

We study a “strongly coupled” (SC) polariton system formed between the atomlike intersubband transitions in a semiconductor nanostructure and the terahertz optical modes that are localized at the edges of a gold aperture. ...

Williams, Benjamin S.

314

2012 ARPA-E Energy Innovation Summit: Profiling Foro Energy: High Power Lasers - Long Distances (Performer Video)  

SciTech Connect

The third annual ARPA-E Energy Innovation Summit was held in Washington D.C. in February, 2012. The event brought together key players from across the energy ecosystem - researchers, entrepreneurs, investors, corporate executives, and government officials - to share ideas for developing and deploying the next generation of energy technologies. A few videos were selected for showing during the Summit to attendees. These 'performer videos' highlight innovative research that is ongoing and related to the main topics of the Summit's sessions. Featured in this video from Foro Energy are Joel Moxley, Founder and CEO, Mark Zediker, Founder and CTO, and Paul Deutch, President and COO. Steven Chu, Secretary of Energy, also appears briefly in this video to praise the accomplishment of a high powered laser that can transmit that power long distances for faster and more powerful drilling of geothermal, oil, and gas wells.

None Available

2012-02-28T23:59:59.000Z

315

Numerical investigation of the physical model of a high-power electromagnetic wave in a magnetically insulated transmission line  

SciTech Connect

An efficient numerical code for simulating the propagation of a high-power electromagnetic pulse in a vacuum transmission line is required to study the physical phenomena occurring in such a line, to analyze the operation of present-day megavolt generators at an {approx}10-TW power level, and to design such new devices. The main physical theoretical principles are presented, and the stability of flows in the near-threshold region at the boundary of the regime of magnetic self-insulation is investigated based on one-dimensional telegraph equations with electron losses. Numerical (difference) methods-specifically, a method of characteristics and a finite-difference scheme-are described and their properties and effectiveness are compared by analyzing the high-frequency modes.

Samokhin, A. A. [Troitsk Institute for Innovation and Fusion Research (Russian Federation)

2010-02-15T23:59:59.000Z

316

Means and method for characterizing high power, ultra short laser pulses in a real time, on line manner  

DOE Patents (OSTI)

An ultra short (<10 ps), high power laser pulse is temporally characterized by a system that uses a physical measurement of a wavefront that has been altered in a known manner. The system includes a first reflection switch to remove a portion of a pulse from a beam of pulses, then includes a second reflection switch, operating in a mode that is opposite to the first reflection switch, to slice off a portion of that removed portion. The sliced portion is then directed to a measuring device for physical measurement. The two reflection switches are arranged with respect to each other and with respect to the beam of ultra short pulses such that physical measurement of the sliced portion is related to the temporal measurement of the ultra short pulse by a geometric or trigonometric relationship. The reflection switches are operated by a control pulse that is directed to impinge on each of the reflection switches at a 90.degree. angle of incidence.

Veligdan, James T. (Manorville, NY)

1994-01-01T23:59:59.000Z

317

WAYPOINT: scaling coherence to thousand-core architectures  

Science Conference Proceedings (OSTI)

In this paper, we evaluate a set of coherence architectures in the context of a 1024-core chip multiprocessor (CMP) tailored to throughput-oriented parallel workloads. Based on our analysis, we develop and evaluate two techniques for scaling coherence ... Keywords: accelerator architecture, cache coherence, probe filtering

John H. Kelm; Matthew R. Johnson; Steven S. Lumettta; Sanjay J. Patel

2010-09-01T23:59:59.000Z

318

Particle Production of Coherently Oscillating Nonclassical Inflaton in FRW Universe  

E-Print Network (OSTI)

We study particle production of coherently oscillating inflaton in the semiclassical theory of gravity by representing inflaton in coherent and squeezed state formalisms. A comparative study of the inflaton in classical gravity with coherent state inflaton in semiclassical gravity is also presented.

K. K. Venkataratnam; P. K. Suresh

2004-02-18T23:59:59.000Z

319

Statistical evaluation of coherence estimated from optimally beamformed signals  

Science Conference Proceedings (OSTI)

In this paper we investigate a situation where we want to perform a coherence analysis of two signal sources, one of which is measured directly, and the other is measured through a sensor array affected by noise. To extract the latter signal, we suggest ... Keywords: Beamforming, Cortico-muscular coherence, Magnitude squared coherence, Statistical distribution

Radoslav Bortel, Pavel Sovka

2013-09-01T23:59:59.000Z

320

Coherent State Distinguishability in Continuous Variable Quantum Cryptography  

E-Print Network (OSTI)

We use the probability of error as a measure of distinguishability between two pure and two mixed symmetric coherent states in the context of continuous variable quantum cryptography. We show that the two mixed symmetric coherent states (in which the various components have the same real part) never give an eavesdropper more information than two pure coherent states.

Christian Weedbrook; Mile Gu; Andrew M. Lance; Thomas Symul; Ping Koy Lam; Timothy C. Ralph

2007-03-15T23:59:59.000Z

Note: This page contains sample records for the topic "high-power coherent terahertz" from the National Library of EnergyBeta (NLEBeta).
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to obtain the most current and comprehensive results.


321

The Development of the Electrically Controlled High Power RF Switch and Its Application to Active RF Pulse Compression Systems  

SciTech Connect

In the past decades, there has been increasing interest in pulsed high power RF sources for building high-gradient high-energy particle accelerators. Passive RF pulse compression systems have been used in many applications to match the available RF sources to the loads requiring higher RF power but a shorter pulse. Theoretically, an active RF pulse compression system has the advantage of higher efficiency and compactness over the passive system. However, the key component for such a system an element capable of switching hundreds of megawatts of RF power in a short time compared to the compressed pulse width is still an open problem. In this dissertation, we present a switch module composed of an active window based on the bulk effects in semiconductor, a circular waveguide three-port network and a movable short plane, with the capability to adjust the S-parameters before and after switching. The RF properties of the switch module were analyzed. We give the scaling laws of the multiple-element switch systems, which allow the expansion of the system to a higher power level. We present a novel overmoded design for the circular waveguide three-port network and the associated circular-to-rectangular mode-converter. We also detail the design and synthesis process of this novel mode-converter. We demonstrate an electrically controlled ultra-fast high power X-band RF active window built with PIN diodes on high resistivity silicon. The window is capable of handling multi-megawatt RF power and can switch in 2-300ns with a 1000A current driver. A low power active pulse compression experiment was carried out with the switch module and a 375ns resonant delay line, obtaining 8 times compression gain with a compression ratio of 20.

Guo, Jiquan; /SLAC

2009-03-20T23:59:59.000Z

322

Controlling and Streaking Nanotip Photoemission by Enhanced Single-cycle Terahertz Pulses  

E-Print Network (OSTI)

The active control of matter by strong electromagnetic fields is of growing importance, with applications all across the optical spectrum from the extreme-ultraviolet to the far-infrared. In recent years, phase-stable terahertz (THz) fields have shown tremendous potential in the observation and manipulation of elementary excitations in complex systems. The combination of concepts from attosecond science with advanced THz technology facilitates novel spectroscopic schemes, such as THz streaking. In general, driving charges at lower frequency enhances interaction energies and can promote drastically different dynamics. For example, mid-infrared excitation induces field-driven sub-cycle electron dynamics in nanostructure nearfields. Such frequency scalings will also impact nanostructure-based streaking, which has been theoretically proposed. Here, we experimentally demonstrate extensive control over nanostructure photoelectron emission using single-cycle THz transients. The locally enhanced THz near-field at a n...

Wimmer, L; Solli, D R; Yalunin, S V; Echternkamp, K; Ropers, C

2013-01-01T23:59:59.000Z

323

Intense terahertz emission from molecular beam epitaxy-grown GaAs/GaSb(001)  

SciTech Connect

Intense terahertz (THz) electromagnetic wave emission was observed in undoped GaAs thin films deposited on (100) n-GaSb substrates via molecular beam epitaxy. GaAs/n-GaSb heterostructures were found to be viable THz sources having signal amplitude 75% that of bulk p-InAs. The GaAs films were grown by interruption method during the growth initiation and using various metamorphic buffer layers. Reciprocal space maps revealed that the GaAs epilayers are tensile relaxed. Defects at the i-GaAs/n-GaSb interface were confirmed by scanning electron microscope images. Band calculations were performed to infer the depletion region and electric field at the i-GaAs/n-GaSb and the air-GaAs interfaces. However, the resulting band calculations were found to be insufficient to explain the THz emission. The enhanced THz emission is currently attributed to a piezoelectric field induced by incoherent strain and defects.

Sadia, Cyril P.; Laganapan, Aleena Maria; Agatha Tumanguil, Mae; Estacio, Elmer; Somintac, Armando; Salvador, Arnel [National Institute of Physics, University of the Philippines Diliman, Quezon City 1101 (Philippines); Que, Christopher T. [Physics Department, De La Salle University, 2401 Taft Avenue, Manila 1004 (Philippines); Yamamoto, Kohji; Tani, Masahiko [Research Center for Development of Far-Infrared Region, University of Fukui, Fukui 910-8507 (Japan)

2012-12-15T23:59:59.000Z

324

Using Quantum Coherence to Enhance Gain in Atomic Physics  

E-Print Network (OSTI)

Quantum coherence and interference effects in atomic and molecular physics has been extensively studied due to intriguing counterintuitive physics and potential important applications. Here we present one such application of using quantum coherence to generate and enhance gain in extreme ultra-violet(XUV)(@58.4nm in Helium) and infra-red(@794.76nm in Rubidium) regime of electromagnetic radiation. We show that using moderate external coherent drive, a substantial enhancement in the energy of the lasing pulse can be achieved under optimal conditions. We also discuss the role of coherence. The present paper is intended to be pedagogical on this subject of coherence-enhanced lasing.

Pankaj K. Jha

2013-01-28T23:59:59.000Z

325

Linac Coherent Light SourCe  

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

Linac Linac Coherent Light SourCe after the Stanford Linear Accelerator Center (now the SLAC National Accelerator Laboratory) developed its two- mile-long linear accelerator (linac), it received approval from the Department of Energy to construct the Linac Coherent Light Source (LCLS), the first free electron laser (FEL) facility that would be able to produce x-rays short and bright enough that individual molecules could be imaged in their natural states. 40 years Genesis of the idea In 1992, Dr. Claudio Pellegrini, a professor at UCLA, first developed a proposal for a facility that would eventually become LCLS. The idea generated interest within the scientific community, and a design study report conducted by SLAC in the late 1990s led to the first

326

Studies of eRHIC coherent instabilities  

Science Conference Proceedings (OSTI)

In the presence of an effective coherent electron cooling, the rms ion bunch length in eRHIC will be kept at 8.3 cm for 250 GeV protons, which is much shorter than the current RHIC 45 cm rms bunch length. Together with the increased bunch intensity and total bunch number, coherent instabilities could be a potential limitation for achieving desired machine performance. In this study, we use the tracking code TRANFT to find thresholds and growth rates for single bunch and coupled bunch instabilities with linear chromaticity and amplitude dependent tune shift taken into account. Based on the simulation results, requirements of machine parameters such as rf voltage, linear chromaticity, and tune dependence of betatron amplitude are specified to suppress these instabilities.

Wang G.; Blaskiewicz, M.

2012-05-20T23:59:59.000Z

327

Coherent spin control by electromagnetic vacuum fluctuations  

SciTech Connect

In coherent control, electromagnetic vacuum fluctuations usually cause coherence loss through irreversible spontaneous emission. However, since the dissipation via emission is essentially due to correlation of the fluctuations, when emission ends in a superposition of multiple final states, correlation between different pathways may build up if the 'which way' information is not fully resolved (i.e., the emission spectrum is broader than the transition energy range). Such correlation can be exploited for spin-flip control in a {Lambda}-type three-level system, which manifests itself as an all-optical spin echo in nonlinear optics with two orders of optical fields saved as compared with stimulated Raman processes. This finding represents a class of optical nonlinearity induced by electromagnetic vacuum fluctuations.

Wang Jing [Department of Physics, Chinese University of Hong Kong, Shatin, N.T. (Hong Kong); Department of Physics, Tsinghua University, Beijing 100084 (China); Liu Renbao [Department of Physics, Chinese University of Hong Kong, Shatin, N.T. (Hong Kong); Zhu Bangfen [Department of Physics, Tsinghua University, Beijing 100084 (China); Institute of Advanced Study, Tsinghua University, Beijing 100084 (China); Sham, L. J. [Department of Physics, University of California-San Diego, La Jolla, California 92093-0319 (United States); Steel, D. G. [H. M. Randall Laboratory of Physics, University of Michigan, Ann Arbor, Michigan 48109 (United States)

2011-05-15T23:59:59.000Z

328

Method and apparatus for coherent burst ranging  

DOE Patents (OSTI)

A high resolution ranging method is described utilizing a novel modulated waveform, hereafter referred to as coherent burst modulation. In the coherent burst method, high frequency modulation of an acoustic or electromagnetic transmitter, such as a laser, is performed at a modulation frequency. This modulation frequency is transmitted quasi-continuously in the form of interrupted bursts of radiation. Energy from the transmitter is directed onto a target, interacts with the target, and the returning energy is collected. The encoded burst pattern contained in the collected return signal is detected coherently by a receiver that is tuned so as to be principally sensitive to the modulation frequency. The receiver signal is processed to determine target range using both time-of-flight of the burst envelope and phase shift of the high frequency modulation. This approach effectively decouples the maximum unambiguous range and range resolution relationship of earlier methods, thereby allowing high precision ranging to be conducted at arbitrarily long distances using at least one burst of encoded energy. The use of a receiver tuned to the high frequency modulation contained within the coherent burst vastly improves both sensitivity in the detection of the target return signal and rejection of background interferences, such as ambient acoustic or electromagnetic noise. Simultaneous transmission at several energies (or wavelengths) is possible by encoding each energy with a separate modulation frequency or pattern; electronic demodulation at the receiver allows the return pattern for each energy to be monitored independently. Radial velocity of a target can also be determined by monitoring change in phase shift of the return signal as a function of time. 12 figs.

Wachter, E.A.; Fisher, W.G.

1998-04-28T23:59:59.000Z

329

Method and apparatus for coherent burst ranging  

DOE Patents (OSTI)

A high resolution ranging method is described utilizing a novel modulated waveform, hereafter referred to as coherent burst modulation. In the coherent burst method, high frequency modulation of an acoustic or electromagnetic transmitter, such as a laser, is performed at a modulation frequency. This modulation frequency is transmitted quasi-continuously in the form of interrupted bursts of radiation. Energy from the transmitter is directed onto a target, interacts with the target, and the returning energy is collected. The encoded burst pattern contained in the collected return signal is detected coherently by a receiver that is tuned so as to be principally sensitive to the modulation frequency. The receiver signal is processed to determine target range using both time-of-flight of the burst envelope and phase shift of the high frequency modulation. This approach effectively decouples the maximum unambiguous range and range resolution relationship of earlier methods, thereby allowing high precision ranging to be conducted at arbitrarily long distances using at least one burst of encoded energy. The use of a receiver tuned to the high frequency modulation contained within the coherent burst vastly improves both sensitivity in the detection of the target return signal and rejection of background interferences, such as ambient acoustic or electromagnetic noise. Simultaneous transmission at several energies (or wavelengths) is possible by encoding each energy with a separate modulation frequency or pattern; electronic demodulation at the receiver allows the return pattern for each energy to be monitored independently. Radial velocity of a target can also be determined by monitoring change in phase shift of the return signal as a function of time.

Wachter, Eric A. (138 Bay Path Dr., Oak Ridge, TN 37830); Fisher, Walter G. (8514 Carl Valentine, Knoxville, TN 37931)

1998-01-01T23:59:59.000Z

330

COHERENT LASER VISION SYSTEM (CLVS) OPTION PHASE  

Science Conference Proceedings (OSTI)

The purpose of this research project was to develop a prototype fiber-optic based Coherent Laser Vision System (CLVS) suitable for DOE's EM Robotic program. The system provides three-dimensional (3D) vision for monitoring situations in which it is necessary to update the dimensional spatial data on the order of once per second. The system has total immunity to ambient lighting conditions.

Robert Clark

1999-11-18T23:59:59.000Z

331

Coherence delay augmented laser beam homogenizer  

DOE Patents (OSTI)

It is an object of the present invention to provide an apparatus that can reduce the apparent coherence length of a laser beam so the beam can be used with an inexpensive homogenizer to produce an output beam with a uniform spatial intensity across its entire cross section. It is a further object of the invention to provide an improved homogenizer with a variable aperture size that is simple and easily made. It is still an additional object of the invention to provide an improved liquid filled homogenizer utilizing total internal reflection for improved efficiency. These, and other objects of the invention are realized by using a ``coherence delay line,`` according to the present invention, in series between a laser and a homogenizer. The coherence delay line is an optical ``line`` that comprises two mirrors, one partially reflecting, and one totally reflecting, arranged so that light incident from the laser first strikes the partially reflecting mirror. A portion of the beam passes through, and a portion is reflected back to the totally reflecting mirror.

Rasmussen, P.; Bernhardt, A.

1991-12-31T23:59:59.000Z

332

Design and 3D simulation of a two-cavity wide-gap relativistic klystron amplifier with high power injection  

Science Conference Proceedings (OSTI)

By using an electromagnetic particle-in-cell (PIC) code, an S-band two-cavity wide-gap klystron amplifier (WKA) loaded with washers/rods structure is designed and investigated for high power injection application. Influences of the washers/rods structure on the high frequency characteristics and the basic operation of the amplifier are presented. Generally, the rod structure has great impacts on the space-charge potential depression and the resonant frequency of the cavities. Nevertheless, if only the resonant frequency is tuned to the desired operation frequency, effects of the rod size on the basic operation of the amplifier are expected to be very weak. The 3-dimension (3-D) PIC simulation results show an output power of 0.98 GW corresponding to an efficiency of 33% for the WKA, with a 594 keV, 5 kA electron beam guided by an external magnetic field of 1.5 Tesla. Moreover, if a conductive plane is placed near the output gap, such as the electron collector, the beam potential energy can be further released, and the RF power can be increased to about 1.07 GW with the conversion efficiency of about 36%.

Bai Xianchen; Yang Jianhua; Zhang Jiande [College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

2012-08-15T23:59:59.000Z

333

High power testing of the 402.5 MHZ and 805 MHZ RF windows for the spallation neutron source accelerator  

SciTech Connect

Hisorically, Radio Frequency (RF) windows have been a common point of failure in input power couplers; therefore, reliable RF windows are critical to the success of the Spallation Neutron Source (SNS) project. The normal conducting part of the SNS accelerator requires six RF windows at 402.5 MHz and eight RF windows at 805 MHz[l]. Each RF window will transmit up to 180 kW of average power and 2.5 MW peak power at 60 Hz with 1.2 millisecond pulses. The RF windows, designed and manufactured by Thales, were tested at the full average power for 4 hours to ensure no problems with the high average power and then tested to an effective forward power level of 10 MW by testing at 2.5 MW forward power into a short and varying the phase of the standing wave. The sliding short was moved from 0 to 180 degrees to ensure no arcing or breakdown problems occur in any part of the window. This paper discusses the results of the high power testing of both the 402.5 MHz and the 805 MHz RF windows. Problems encountered during testing and the solutions for these problems are discussed.

Cummings, K. A. (Karen Ann); De Baca, J. M. (John M.); Harrison, J. S. (John S.); Rodriguez, M. B. (Manuelita B.); Torrez, P. A. (Phillip A.); Warner, D. K. (David K.)

2003-01-01T23:59:59.000Z

334

Characterization of the Li(Si)/CoS(2) couple for a high-voltage, high-power thermal battery  

DOE Green Energy (OSTI)

In order to determined the capabilities of a thermal battery with high-voltage and high-power requirements, a detailed characterization of the candidate LiSi/LiCl-LiBr-LiF/CoS{sub 2} electrochemical couple was conducted. The rate capability of this system was investigated using 0.75 inch-dia. and 1.25 inch-dia. single and multiple cells under isothermal conditions, where the cells were regularly pulsed at increasingly higher currents. Limitations of the electronic loads and power supplies necessitated using batteries to obtain the desired maximum current densities possible for this system. Both 1.25 inch-dia. and 3 inch-dia. stacks were used with the number of cells ranging from 5 to 20. Initial tests involved 1.25 inch-dia. cells, where current densities in excess of 15 A/cm{sup 2} (>200 W/cm{sup 2}) were attained with 20-cell batteries during 1-s pulses. In subsequent follow-up tests with 3 inch-dia., 10-cell batteries, ten 400-A 1-s pulses were delivered over an operating period often minutes. These tests formed the foundation for subsequent full-sized battery tests with 125 cells with this chemistry.

GUIDOTTI,RONALD A.; REINHARDT,FREDERICK W.

2000-02-01T23:59:59.000Z

335

Physics of Plasma-Based Ion Implantation&Deposition (PBIID)and High Power Impulse Magnetron Sputtering (HIPIMS): A Comparison  

SciTech Connect

The emerging technology of High Power Impulse MagnetronSputtering (HIPIMS) has much in common with the more establishedtechnology of Plasma Based Ion Implantation&Deposition (PBIID):both use pulsed plasmas, the pulsed sheath periodically evolves andcollapses, the plasma-sheath system interacts with the pulse-drivingpower supply, the plasma parameters are affected by the power dissipated,surface atoms are sputtered and secondary electrons are emitted, etc.Therefore, both fields of science and technology could learn from eachother, which has not been fully explored. On the other hand, there aresignificant differences, too. Most importantly, the operation of HIPIMSheavilyrelies on the presence of a strong magnetic field, confiningelectrons and causing their ExB drift, which is closed for typicalmagnetron configurations. Second, at the high peak power levels used forHIPIMS, 1 kW/cm2 or greater averaged over the target area, the sputteredmaterial greatly affects plasma generation. For PBIID, in contrast,plasma generation and ion processing of the surface (ion implantation,etching, and deposition) are considered rela-tively independentprocesses. Third, secondary electron emission is generally considered anuisance for PBIID, especially at high voltages, whereas it is a criticalingredient to the operation of HIPIMS. Fourth, the voltages in PBIID areoften higher than in HIPIMS. For the first three reasons listed above,modelling of PBIID seems to be easier and could give some guidance forfuture HIPIMS models, which, clearly, will be more involved.

Anders, Andre

2007-08-28T23:59:59.000Z

336

Hazard Analysis for the High Power Accelerator Production of Tritium (APT) Experiments at the Los Alamos Neutron Scattering Center (LANSCE).  

SciTech Connect

The Accelerator Production of Tritium (APT) Target/Blanket and Materials Engineering Demonstration and Development (ED and D) Project has undertaken a major program of high-power materials irradiation at the Los Alamos Neutron Science Center (LANSCE) Accelerator. Five experiments have been installed in the Target A-6 area, immediately before the Isotope Production facility and the LANSCE bearnstop, where they will take a 1.0-mAmp-proton beam for up to 10 months. This operation is classed as a Nuclear Category (cat)-3 activity, since enough radionuclides buildup in the path of tie beam to exceed cat-3 threshold quantities. In the process of analyzing this buildup, it was realized that a loss of coolant accident (LOCA) could result in oxidation and subsequent vaporization of certain tungsten elements contained in our experiments. If this process occurs in the presence of steam, breakup of the water molecule would also provide a potentially explosive source of hydrogen, causing maximum release of radioactive aerosols to the surrounding environment. This process can occur in a matter of seconds. Such a release would result in potentially unacceptable dose to the public at the LANSCE site boundary, 800 meters from the A-6 area.

Waters, L.S.

1999-06-08T23:59:59.000Z

337

Diagnostic evaluation of power fade phenomena and calendar lifereduction in high-power lithium-ion batteries  

DOE Green Energy (OSTI)

High-power Li-ion cells with graphite anodes and LiNi{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2} cathodes that were cycled and stored at elevated temperatures showed a significant impedance rise and capacity fade, which were associated primarily with the LiNi{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2} cathode. A combination of electrochemical, physical, and chemical diagnostic techniques, including Raman, SEM, and current-sensing AFM, was used to characterize the cathodes from these cells in order to produce a clear picture of the mechanism for cell degradation. Systematic Raman mapping of 50 x 80 {mu}m areas at 0.9 {mu}m spatial resolution produced semi-quantitative composition maps of cathode surfaces. Raman microscopy surface composition maps and SEM images of cathodes from tested cells revealed that cell cycling or storage at elevated temperatures led to significant changes in the LiNi{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2}/elemental-carbon surface concentration ratio. The loss of conductive carbon correlated with the power and capacity fade of the tested cathodes and the loss of surface electronic conductivity.

Kostecki, Robert; McLarnon, Frank

2004-05-01T23:59:59.000Z

338

Means and method for characterizing high power, ultra short laser pulses in a real time, on line manner  

DOE Patents (OSTI)

An ultra short (<10 ps), high power laser pulse is temporally characterized by a system that uses a physical measurement of a wavefront that has been altered in a known manner. The system includes a first reflection switch to remove a portion of a pulse from a beam of pulses, then includes a second reflection switch, operating in a mode that is opposite to the first reflection switch, to slice off a portion of that removed portion. The sliced portion is then directed to a measuring device for physical measurement. The two reflection switches are arranged with respect to each other and with respect to the beam of ultra short pulses such that physical measurement of the sliced portion is related to the temporal measurement of the ultra short pulse by a geometric or trigonometric relationship. The reflection switches are operated by a control pulse that is directed to impinge on each of the reflection switches at a 90[degree] angle of incidence. 8 figures.

Veligdan, J.T.

1994-03-08T23:59:59.000Z

339

OECD-International Platform on Policy Coherence for Development | Open  

Open Energy Info (EERE)

International Platform on Policy Coherence for Development International Platform on Policy Coherence for Development Jump to: navigation, search Tool Summary Name: OECD-International Platform on Policy Coherence for Development Agency/Company /Organization: Organisation for Economic Co-Operation and Development (OECD) Focus Area: Economic Development Topics: Co-benefits assessment Resource Type: Guide/manual, Lessons learned/best practices, Technical report User Interface: Website Website: community.oecd.org/community/pcd Cost: Free Language: English OECD-International Platform on Policy Coherence for Development Screenshot References: OECD-International Platform on Policy Coherence for Development[1] "The "International Platform on Policy Coherence for Development"" is intended as an interactive tool to be built up over time. It contains four

340

Experimental demonstration of a Hadamard gate for coherent state qubits  

SciTech Connect

We discuss and make an experimental test of a probabilistic Hadamard gate for coherent state qubits. The scheme is based on linear optical components, nonclassical resources, and the joint projective action of a photon counter and a homodyne detector. We experimentally characterize the gate for the coherent states of the computational basis by full tomographic reconstruction of the transformed output states. Based on the parameters of the experiment, we simulate the fidelity for all coherent state qubits on the Bloch sphere.

Tipsmark, Anders; Laghaout, Amine; Andersen, Ulrik L. [Department of Physics, Technical University of Denmark, Fysikvej, DK-2800 Kgs. Lyngby (Denmark); Dong, Ruifang [Quantum Frequency Standards Division, National Time Service Center (NTSC), Chinese Academy of Sciences, 710600 Lintong, Shaanxi (China); Department of Physics, Technical University of Denmark, Fysikvej, DK-2800 Kgs. Lyngby (Denmark); Marek, Petr [Department of Optics, Palacky University, 17. listopadu 12, CZ-77146 Olomouc (Czech Republic); Jezek, Miroslav [Department of Optics, Palacky University, 17. listopadu 12, CZ-77146 Olomouc (Czech Republic); Department of Physics, Technical University of Denmark, Fysikvej, DK-2800 Kgs. Lyngby (Denmark)

2011-11-15T23:59:59.000Z

Note: This page contains sample records for the topic "high-power coherent terahertz" 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

SLAC Linac Coherent Light Source User Site  

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

Welcome to the LCLS User Resources Site Welcome to the LCLS User Resources Site User Portal | Agreements | Data Collection & Analysis | Logistics | Policies | Proposals | Safety | Schedules | Shipping The Linac Coherent Light Source (LCLS) encourages scientists from diverse fields to submit proposals for experiments that utilize the LCLS's unique capabilities. Interested scientists are encouraged to learn more about the latest developments by contacting LCLS staff scientists and by reviewing the instrument descriptions. Step-By-Step Instructions to Working at LCLS Review LCLS Policies Review Machine FAQ & Parameters Register and Submit Proposals Confirm User Agreement Reserve Accommodations Complete Safety Training Request Computer Account Establish User Account Ship Samples/Equipment Review Check-in Procedures

342

Status of the Linac Coherent Light Source  

Science Conference Proceedings (OSTI)

The Linac Coherent Light Source (LCLS) is a free electron laser facility in construction at Stanford Linear Accelerator Center. It is designed to operate in the wavelength range 0.15-1.5 nanometers. At the time of this conference, civil construction of new tunnels and buildings is complete, the necessary modifications to the SLAC linac are complete, and the undulator system and x-ray optics/diagnostics are being installed. The electron gun, 135 MeV injector linac and 250 MeV bunch compressor were commissioned in 2007. Accelerator commissioning activities are presently devoted to the achievement of performance goals for the completed 14 GeV linac.

Galayda, John N.; /SLAC

2011-11-04T23:59:59.000Z

343

Performance Evaluation of a Multi-Port DC-DC Current Source Converter for High Power Applications  

E-Print Network (OSTI)

With the ever-growing developments of sustainable energy sources such as fuel cells, photovoltaics, and other distributed generation, the need for a reliable power conversion system that interfaces these sources is in great demand. In order to provide the highest degree of flexibility in a truly distributed network, it is desired to not only interface multiple sources, but to also interface multiple loads. Modern multi-port converters use high frequency transformers to deliver the different power levels, which add to the size and complexity of the system. The different topological variations of the proposed multi-port dc-dc converter have the potential to solve these problems. This thesis proposes a unique dc-dc current source converter for multi-port power conversion. The presented work will explain the proposed multi-port dc-dc converter's operating characteristics, control algorithms, design and a proof of application. The converter will be evaluated to determine its functionality and applicability. Also, it will be shown that our converter has advantages over modern multi-port converters in its ease of scalability from kW to MW, low cost, high power density and adaption to countless combinations of multiple sources. Finally we will present modeling and simulation of the proposed converter using the PSIM software. This research will show that this new converter topology is unstable without feedback control. If the operating point is moved, one of the source ports of the multiport converter becomes unstable and dies off supplying very little or no power to the load while the remaining source port supplies all of the power the load demands. In order to prevent this and add stability to the converter a simple yet unique control method was implemented. This control method allowed for the load power demanded to be shared between the two sources as well as regulate the load voltage about its desired value.

Yancey, Billy Ferrall

2010-05-01T23:59:59.000Z

344

The Coherent X-ray Imaging (CXI) Instrument at the Linac Coherent Light Source (LCLS)  

Science Conference Proceedings (OSTI)

The Linac Coherent Light Source (LCLS) has become the first ever operational hard X-ray Free Electron Laser in 2009. It will operate as a user facility capable of delivering unique research opportunities in multiple fields of science. The LCLS and the LCLS Ultrafast Science Instruments (LUSI) construction projects are developing instruments designed to make full use of the capabilities afforded by the LCLS beam. One such instrument is being designed to utilize the LCLS coherent beam to image with high resolution any sub-micron object. This instrument is called the Coherent X-ray Imaging (CXI) instrument. This instrument will provide a flexible optical system capable of tailoring key beam parameters for the users. A suite of shot-to-shot diagnostics will also be provided to characterize the beam on every pulse. The provided instrumentation will include multi-purpose sample environments, sample delivery and a custom detector capable of collecting 2D data at 120 Hz. In this article, the LCLS will be briefly introduced along with the technique of Coherent X-ray Diffractive Imaging (CXDI). A few examples of scientific opportunities using the CXI instrument will be described. Finally, the conceptual layout of the instrument will be presented along with a description of the key requirements for the overall system and specific devices required.

Boutet, Sebastien

2011-08-16T23:59:59.000Z

345

Photon-added Coherent States in Parametric Down-conversion  

E-Print Network (OSTI)

Photon-added coherent states have been realized in optical parametric down-conversion by Zavatta {\\em et al} [Science 306 (2004) 660-662]. In this report, it is established that the states generated in the process are {\\em ideal} photon-added coherent states. It is shown that the scheme can generate higher order photon-added coherent states. A comparative study of the down-conversion process and atom-cavity interaction in generating the photon-added coherent states is presented.

S. Sivakumar

2011-01-20T23:59:59.000Z

346

Coherent Anti-Stokes Raman Spectroscopy (CARS) - Available ...  

Search PNNL. PNNL Home; About; Research; Publications; Jobs; News; Contacts; Coherent Anti-Stokes Raman Spectroscopy (CARS) Battelle Number(s): 11982. ...

347

Photon-added coherent states for exactly solvable Hamiltonians  

E-Print Network (OSTI)

Photon-added Gazeau-Klauder and Klauder-Perelomov coherent states are investigated. Application to P\\"oschl-Teller potentials is given.

M. Daoud

2004-09-18T23:59:59.000Z

348

Science and Instrumentation for the Linac Coherent Light Source...  

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

Science and Instrumentation for the Linac Coherent Light Source WB00852.GIF (317 bytes) Where: SLAC Panofsky Auditorium When: Friday, October 15, 1999 (1:30 pm) Saturday,...

349

Resonator for Coherent Addition of Semiconductor Laser Arrays ...  

Resonator for Coherent Addition of Semiconductor Laser Arrays and Applications for a Solar Pumped Laser Array Oak Ridge National Laboratory. Contact ...

350

Optimization of Real Asset Portfolio using a Coherent Risk Measure  

E-Print Network (OSTI)

Nov 19, 2008 ... Optimization of Real Asset Portfolio using a Coherent Risk Measure: ... initial techniques evolved to the use of enterprise portfolio management, ...

351

A Broader Perspective about Organization and Coherence in Biological Systems  

E-Print Network (OSTI)

The implications of large-scale coherence in biological systems and possible links to quantum theory are only beginning to be explored. Whether quantum-like coherent phenomena are relevant, or even possible at all, at the high temperatures of biological systems remains unsettled. Here, we present a broader perspective on biological organization and how quantum-like dynamics and coherence might shape the very fabric from which complex biological systems are organized. Regardless of its exact nature, a unique form of coherence seems apparent at multiple scales in biology and its better characterization may have broad consequences for the understanding of living organisms as complex systems.

Martin Robert

2012-12-03T23:59:59.000Z

352

Minimally invasive diagnostic imaging using high resolution Optical Coherence Tomography  

E-Print Network (OSTI)

Advances in medical imaging have given researchers unprecedented capabilities to visualize, characterize and understand biological systems. Optical Coherence Tomography (OCT) is a high speed, high resolution imaging technique ...

Herz, Paul Richard, 1972-

2004-01-01T23:59:59.000Z

353

Security improvement of using modified coherent state for quantum cryptography  

E-Print Network (OSTI)

Weak coherent states as a photon source for quantum cryptography have limit in secure data rate and transmission distance because of the presence of multi-photon events and loss in transmission line. Two-photon events in a coherent state can be taken out by a two-photon interference scheme. We investigate the security issue of utilizing this modified coherent state in quantum cryptography. A 4 dB improvement in secure data rate or a nearly two-fold increase in transmission distance over the coherent state are found. With a recently proposed and improved encoding strategy, further improvement is possible.

Y. J. Lu; Luobei Zhu; Z. Y. Ou

2005-01-30T23:59:59.000Z

354

Conference 5739, SPIE International Symposium Integrated Optoelectronic Devices, 22-27 Jan 2005, San Jose, CA Development of high power green light emitting diode dies in  

E-Print Network (OSTI)

, San Jose, CA Development of high power green light emitting diode dies in piezoelectric Ga in green light emitting diodes is one of the big challenges towards all-solid- state lighting. The prime,3], and commercialization [4,5] of high brightness light emitting diodes LEDs has led to a 1.82 Billion-$/year world market

Wetzel, Christian M.

355

Efficient quantum computing using coherent photon conversion  

E-Print Network (OSTI)

Single photons provide excellent quantum information carriers, but current schemes for preparing, processing and measuring them are inefficient. For example, down-conversion provides heralded, but randomly timed single photons, while linear-optics gates are inherently probabilistic. Here, we introduce a deterministic scheme for photonic quantum information. Our single, versatile process---coherent photon conversion---provides a full suite of photonic quantum processing tools, from creating high-quality heralded single- and multiphoton states free of higher-order imperfections to implementing deterministic multiqubit entanglement gates and high-efficiency detection. It fulfils all requirements for a scalable photonic quantum computing architecture. Using photonic crystal fibres, we experimentally demonstrate a four-colour nonlinear process usable for coherent photon conversion and show that current technology provides a feasible path towards deterministic operation. Our scheme, based on interacting bosonic fields, is not restricted to optical systems, but could also be implemented in optomechanical, electromechanical and superconducting systems which exhibit extremely strong intrinsic nonlinearities.

N. K. Langford; S. Ramelow; R. Prevedel; W. J. Munro; G. J. Milburn; A. Zeilinger

2011-06-10T23:59:59.000Z

356

Catheter guided by optical coherence domain reflectometry  

DOE Patents (OSTI)

A guidance and viewing system based on multiplexed optical coherence domain reflectometry is incorporated into a catheter, endoscope, or other medical device to measure the location, thickness, and structure of the arterial walls or other intra-cavity regions at discrete points on the medical device during minimally invasive medical procedures. The information will be used both to guide the device through the body and to evaluate the tissue through which the device is being passed. Multiple optical fibers are situated along the circumference of the device. Light from the distal end of each fiber is directed onto the interior cavity walls via small diameter optics (such as gradient index lenses and mirrored corner cubes). Both forward viewing and side viewing fibers can be included. The light reflected or scattered from the cavity walls is then collected by the fibers and multiplexed at the proximal end to the sample arm of an optical low coherence reflectometer. The system may also be implemented in a nonmedical inspection device.

Everett, Matthew (Pleasanton, CA); Colston, Billy W. (Livermore, CA); Da Silva, Luiz B. (Danville, CA); Matthews, Dennis (Moss Beach, CA)

2002-01-01T23:59:59.000Z

357

Quantum process tomography with coherent states  

E-Print Network (OSTI)

We develop an enhanced technique for characterizing quantum optical processes based on probing unknown quantum processes only with coherent states. Our method substantially improves the original proposal [M. Lobino et al., Science 322, 563 (2008)], which uses a filtered Glauber-Sudarshan decomposition to determine the effect of the process on an arbitrary state. We introduce a new relation between the action of a general quantum process on coherent state inputs and its action on an arbitrary quantum state. This relation eliminates the need to invoke the Glauber-Sudarshan representation for states; hence it dramatically simplifies the task of process identification and removes a potential source of error. The new relation also enables straightforward extensions of the method to multi-mode and non-trace-preserving processes. We illustrate our formalism with several examples, in which we derive analytic representations of several fundamental quantum optical processes in the Fock basis. In particular, we introduce photon-number cutoff as a reasonable physical resource limitation and address resource vs accuracy trade-off in practical applications. We show that the accuracy of process estimation scales inversely with the square root of photon-number cutoff.

Saleh Rahimi-Keshari; Artur Scherer; Ady Mann; Ali T. Rezakhani; A. I. Lvovsky; Barry C. Sanders

2010-09-17T23:59:59.000Z

358

Tunability of the terahertz space-charge modulation in a vacuum microdiode  

SciTech Connect

Under certain conditions, space-charge limited emission in vacuum microdiodes manifests as clearly defined bunches of charge with a regular size and interval. The frequency corresponding to this interval is in the terahertz range. In this computational study, it is demonstrated that, for a range of parameters, conducive to generating THz frequency oscillations, the frequency is dependant only on the cold cathode electric field and on the emitter area. For a planar micro-diode of given dimension, the modulation frequency can be easily tuned simply by varying the applied potential. Simulations of the microdiode are done for 84 different combinations of emitter area, applied voltage, and gap spacing, using a molecular dynamics based code with exact Coulomb interaction between all electrons in the vacuum gap, which is of the order 100. It is found, for a fixed emitter area, that the frequency of the pulse train is solely dependant on the vacuum electric field in the diode, described by a simple power law. It is also found that, for a fixed value of the electric field, the frequency increases with diminishing size of the emitting spot on the cathode. Some observations are made on the spectral quality, and how it is affected by the gap spacing in the diode and the initial velocity of the electrons.

Jonsson, P.; Ilkov, Marjan; Manolescu, A.; Valfells, A. [School of Science and Engineering, Reykjavik University, 101 Reykjavik (Iceland); Pedersen, A. [Science Institute, University of Iceland, 101 Reykjavik (Iceland)

2013-02-15T23:59:59.000Z

359

Graphene-based nano-antennas for electromagnetic nanocommunications in the terahertz band  

E-Print Network (OSTI)

Abstract—Nanotechnology is enabling the development of devices in a scale ranging from one to a few hundred nanometers. Coordination and information sharing among these nano-devices will lead towards the development of future nanonetworks, boosting the range of applications of nanotechnology in the biomedical, environmental and military fields. Despite the major progress in nano-device design and fabrication, it is still not clear how these atomically precise machines will communicate. Recently, the advancements in graphene-based electronics have opened the door to electromagnetic communications in the nanoscale. In this paper, a new quantum mechanical framework is used to analyze the properties of Carbon Nanotubes (CNTs) as nano-dipole antennas. For this, first the transmission line properties of CNTs are obtained using the tight-binding model as functions of the CNT length, diameter, and edge geometry. Then, relevant antenna parameters such as the fundamental resonant frequency and the input impedance are calculated and compared to those of a nano-patch antenna based on a Graphene Nanoribbon (GNR) with similar dimensions. The results show that for a maximum antenna size in the order of several hundred nanometers (the expected maximum size for a nano-device), both a nano-dipole and a nano-patch antenna will be able to radiate electromagnetic waves in the terahertz band (0.1-10.0 THz). I.

Josep Miquel Jornet; Ian F. Akyildiz

2010-01-01T23:59:59.000Z

360

Nexus between directionality of terahertz waves and structural parameters in groove patterned InAs  

SciTech Connect

We performed terahertz (THz) time-domain spectroscopy in various geometries, for characterizing the directivity of THz waves emitted from groove patterned InAs structures. We first identified two transient transport processes as underlying THz emission mechanisms in InAs epilayers with different thicknesses. Carrier drift around the surface depletion region was predominant for the THz wave generation in the thin sample group (10-70 nm), whereas electronic diffusion overrode the drift currents in the thick sample group (370-900 nm) as revealed by the amplitude change and phase reversal. Through a combination of electron-beam lithography and inductively coupled plasma etching in 1 {mu}m-thick InAs epilayers, we could further periodically fabricate either asymmetric V-groove patterns or symmetric parabolic apertures. The THz amplitude was enhanced, particularly along the line-of-sight transmissive direction when the periodic groove patterns act as microscale reflective mirrors separated by a scale of the diffusion length.

Yim, Jong-Hyuk; Min, Kyunggu; Jeong, Hoonil; Jho, Young-Dahl [School of Information and Communications, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Lee, Eun-Hye; Song, Jin-Dong [Center for Opto-Electronics Convergence Systems, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of)

2013-04-07T23:59:59.000Z

Note: This page contains sample records for the topic "high-power coherent terahertz" 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

Harmonic mode competition in a terahertz gyrotron backward-wave oscillator  

Science Conference Proceedings (OSTI)

Electron cyclotron maser interactions at terahertz (THz) frequencies require a high-order-mode structure to reduce the wall loss to a tolerable level. To generate THz radiation, it is also essential to employ cyclotron harmonic resonances to reduce the required magnetic field strength to a value within the capability of the superconducting magnets. However, much weaker harmonic interactions in a high-order-mode structure lead to serious mode competition problems. The current paper addresses harmonic mode competition in the gyrotron backward wave oscillator (gyro-BWO). We begin with a comparative study of the mode formation and oscillation thresholds in the gyro-BWO and gyromonotron. Differences in linear features result in far fewer 'windows' for harmonic operation of the gyro-BWO. Nonlinear consequences of these differences are examined in particle simulations of the multimode competition processes in the gyro-BWO, which shed light on the competition criteria between modes of different as well as the same cyclotron harmonic numbers. The viability of a harmonic gyro-BWO is assessed on the basis of the results obtained.

Kao, S. H.; Chiu, C. C.; Chang, P. C.; Wu, K. L.; Chu, K. R. [Department of Physics, National Taiwan University, Taipei 106, Taiwan (China)

2012-10-15T23:59:59.000Z

362

Cache coherence tradeoffs in shared-memory MPSoCs  

Science Conference Proceedings (OSTI)

Shared memory is a common interprocessor communication paradigm for single-chip multiprocessor platforms. Snoop-based cache coherence is a very successful technique that provides a clean shared-memory programming abstraction in general-purpose chip multiprocessors, ... Keywords: Cache coherence, low power, multiprocessor, system-on-chip

Mirko Loghi; Massimo Poncino; Luca Benini

2006-05-01T23:59:59.000Z

363

Fast approximation of matrix coherence and statistical leverage  

Science Conference Proceedings (OSTI)

The statistical leverage scores of a matrix A are the squared row-norms of the matrix containing its (top) left singular vectors and the coherence is the largest leverage score. These quantities are of interest in recently-popular problems such as matrix ... Keywords: matrix coherence, randomized algorithm, statistical leverage

Petros Drineas; Malik Magdon-Ismail; Michael W. Mahoney; David P. Woodruff

2012-01-01T23:59:59.000Z

364

Terahertz quantum cascade lasers with thin resonant-phonon depopulation active regions and surface-plasmon waveguides  

E-Print Network (OSTI)

We report three-well, resonant-phonon depopulation terahertz quantum cascade lasers with semi-insulating surface-plasmon waveguides and reduced active region (AR) thicknesses. Devices with thicknesses of 10, 7.5, 6, and 5 {\\mu}m are compared in terms of threshold current density, maximum operating temperature, output power and AR temperature. Thinner ARs are technologically less demanding for epitaxial growth and result in reduced electrical heating of devices. However, it is found that 7.5-{\\mu}m-thick devices give the lowest electrical power densities at threshold, as they represent the optimal trade-off between low electrical resistance and low threshold gain.

Salih, M; Valavanis, A; Khanna, S P; Li, L H; Cunningham, J E; Davies, A G; Linfield, E H

2013-01-01T23:59:59.000Z

365

Terahertz quantum cascade lasers with thin resonant-phonon depopulation active regions and surface-plasmon waveguides  

E-Print Network (OSTI)

We report three-well, resonant-phonon depopulation terahertz quantum cascade lasers with semi-insulating surface-plasmon waveguides and reduced active region (AR) thicknesses. Devices with thicknesses of 10, 7.5, 6, and 5 {\\mu}m are compared in terms of threshold current density, maximum operating temperature, output power and AR temperature. Thinner ARs are technologically less demanding for epitaxial growth and result in reduced electrical heating of devices. However, it is found that 7.5-{\\mu}m-thick devices give the lowest electrical power densities at threshold, as they represent the optimal trade-off between low electrical resistance and low threshold gain.

M. Salih; P. Dean; A. Valavanis; S. P. Khanna; L. H. Li; J. E. Cunningham; A. G. Davies; E. H. Linfield

2013-03-13T23:59:59.000Z

366

Tematea: Issue Based Modules for Coherent Implementation of Biodiversity  

Open Energy Info (EERE)

Tematea: Issue Based Modules for Coherent Implementation of Biodiversity Tematea: Issue Based Modules for Coherent Implementation of Biodiversity Conventions Jump to: navigation, search Tool Summary LAUNCH TOOL Name: Tematea: Issue Based Modules for Coherent Implementation of Biodiversity Conventions Agency/Company /Organization: United Nations Environment Programme, International Union for Conservation of Nature Sector: Land Topics: Implementation, Co-benefits assessment, - Environmental and Biodiversity Resource Type: Guide/manual, Training materials, Lessons learned/best practices Website: www.tematea.org Tematea: Issue Based Modules for Coherent Implementation of Biodiversity Conventions Screenshot References: Tematea[1] Summary "The TEMATEA Project on Issue-Based Modules supports a better and more coherent national implementation of biodiversity-related conventions

367

Polaron Coherence Condensation in Layered Colossal Resistive Manganites  

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

Polaron Coherence Condensation Polaron Coherence Condensation in Layered Colossal Resistive Manganites Polaron Coherence Condensation in Layered Colossal Resistive Manganites Print Wednesday, 30 July 2008 00:00 Novel quantum phenomena, such as high-temperature superconductivity (HTSC) and colossal magnetoresistance (CMR), arise in certain materials where the interactions between electrons are very strong, but the mechanism driving their appearance remains a major puzzle. Now, angle-resolved photoemission findings from an international team led by researchers from Stanford University and the ALS provide the first direct spectroscopic evidence that the transition from insulator to metal in CMR manganese oxides (manganites) results from coherent "polaron condensation." The new findings also suggest that coherence-driven transitions are a generic controlling factor for novel quantum phenomena in doped transition-metal oxides.

368

Linac Coherent Light Source Overview | Department of Energy  

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

Linac Coherent Light Source Overview Linac Coherent Light Source Overview Linac Coherent Light Source Overview Addthis Description Take an animated tour of the Linac Coherent Light Source (LCLS). Follow the laser pulse from the injector gun all the way through to the Far Experimental Hall. Duration 5:50 Topic Physics Credit Energy Department Video MR. : The SLAC National Accelerator Laboratory is located in the heart of California's beautiful San Francisco Bay Area. Operated by Stanford University for the U.S. Department of Energy, SLAC has been home to the world's longest particle accelerator for nearly 50 years. In 2009 SLAC ushered in a new era in its long history of physics research with a new kind of laser called the Linac Coherent Light Source, or LCLS. The LCLS is the first laser in the world to produce hard X-rays, which can

369

Dynamic Coherence in Excitonic Molecular Complexes under Various Excitation Conditions  

E-Print Network (OSTI)

In this paper, we investigate the relevance of dynamic electronic coherence under conditions natural to light-harvesting systems. We formulate the results of a quantum mechanical treatment of a weak light-matter interaction in terms of experimental observable, such as the incident light spectrum and the absorption spectrum of the material, and we derive the description of the incoherent F\\"orster type energy transfer fully from the wave function formalism. We demonstrate that excitation of a coherent superposition of electronic eigenstates of natural light-harvesting complexes by sunlight or by excitation transfer from a neighboring antenna is unlikely and that dynamical coherence therefore cannot play any significant role in natural photosynthesis, regardless of their life time. Dynamical coherence as a transient phenomenon must be strictly distinguished from the effect of excited state delocalization (also termed quantum coherence in the literature) which is established by interaction between the pigments a...

Chenu, Aurélia; Mancal, Tomáš

2013-01-01T23:59:59.000Z

370

VORPAL Simulations Relevant to Coherent Electron Cooling  

SciTech Connect

Coherent electron cooling (CEC)* combines the best features of electron cooling and stochastic cooling, via free-electron laser technology**, to offer the possibility of cooling high-energy hadron beams with order-of-magnitude shorter cooling times. Many technical difficulties must be resolved via full-scale 3D simulations, before the CEC concept can be validated experimentally. VORPAL is the ideal code for simulating the â modulatorâ and â kickerâ regions, where the electron and hadron beams will co-propagate as in a conventional electron cooling section. Unlike previous VORPAL simulations*** of electron cooling physics, where dynamical friction on the ions was the key metric, it is the details of the electron density wake driven by each ion in the modulator section that must be understood, followed by strong amplification in the FEL. We present some initial simulation results. In particular, we compare the semi-analytic binary collision model with electrostatic particle-in-cell (PIC).

Bell, G.I.; Bruhwiler, D.L.; Sobol, A.V.; Ben-Zvi, Ilan; Litvinenko, Vladimir; Derbenev, Yaroslav

2008-07-01T23:59:59.000Z

371

VORPAL simulations relevant to coherent electron cooling  

Science Conference Proceedings (OSTI)

Coherent electron cooling (CEC) [1] combines the best features of electron cooling and stochastic cooling, via free-electron laser technology [2], to offer the possibility of cooling high-energy hadron beams with order-of-magnitude shorter cooling times. Many technical difficulties must be resolved via full-scale 3D simulations, before the CEC concept can be validated experimentally. VORPAL is the ideal code for simulating the modulator and kicker regions, where the electron and hadron beams will co-propagate as in a conventional electron cooling section. Unlike previous VORPAL simulations [3] of electron cooling physics, where dynamical friction on the ions was the key metric, it is the details of the electron density wake driven by each ion in the modulator section that must be understood, followed by strong amplification in the FEL. We present some initial simulation results.

Bell,G.; Bruhwiler, D.; Sobol, A.; Ben-Zvi, I.; Litvinenko, V.; Derbenev, Y.

2008-06-23T23:59:59.000Z

372

Birefringence insensitive optical coherence domain reflectometry system  

DOE Patents (OSTI)

A birefringence insensitive fiber optic optical coherence domain reflectometry (OCDR) system is provided containing non-polarization maintaining (non-PM) fiber in the sample arm and the reference arm without suffering from signal degradation caused by birefringence. The use of non-PM fiber significantly reduces the cost of the OCDR system and provides a disposable or multiplexed section of the sample arm. The dispersion in the reference arm and sample arm of the OCDR system are matched to achieve high resolution imaging. This system is useful in medical applications or for non-medical in situ probes. The disposable section of non-PM fiber in the sample arm can be conveniently replaced when contaminated by a sample or a patient.

Everett, Matthew J. (Livermore, CA); Davis, Joseph G. (Lafayette, CA)

2002-01-01T23:59:59.000Z

373

Low-Cost Superconducting Wire for Wind Generators: High Performance, Low Cost Superconducting Wires and Coils for High Power Wind Generators  

SciTech Connect

REACT Project: The University of Houston will develop a low-cost, high-current superconducting wire that could be used in high-power wind generators. Superconducting wire currently transports 600 times more electric current than a similarly sized copper wire, but is significantly more expensive. The University of Houston’s innovation is based on engineering nanoscale defects in the superconducting film. This could quadruple the current relative to today’s superconducting wires, supporting the same amount of current using 25% of the material. This would make wind generators lighter, more powerful and more efficient. The design could result in a several-fold reduction in wire costs and enable their commercial viability of high-power wind generators for use in offshore applications.

None

2012-01-01T23:59:59.000Z

374

Post-processing of polymer foam tissue scaffolds with high power ultrasound: a route to increased pore interconnectivity, pore size and fluid transport  

E-Print Network (OSTI)

We expose thick polymer foam tissue scaffolds to high power ultrasound and study its effect on the openness of the pore architecture and fluid transport through the scaffold. Our analysis is supported by measurements of fluid uptake during insonification and imaging of the scaffold microstructure via x-ray computed tomography, scanning electron microscopy and acoustic microscopy. The ultrasonic treatment is found to increase the mean pore size by over 10%. More striking is the improvement in fluid uptake: for scaffolds with only 40% water uptake via standard immersion techniques, we can routinely achieve full saturation of the scaffold over approximately one hour of exposure. These desirable modifications occur with no loss of scaffold integrity and negligible mass loss, and are optimized when the ultrasound treatment is coupled to a pre-wetting stage with ethanol. Our findings suggest that high power ultrasound is a highly targetted and efficient means to promote pore interconnectivity and fluid transport in...

Watson, N J; Reinwald, Y; White, L J; Ghaemmaghami, A M; Morgan, S P; Rose, F R A J; Povey, M J W; Parker, N G

2013-01-01T23:59:59.000Z

375

Post-processing of polymer foam tissue scaffolds with high power ultrasound: a route to increased pore interconnectivity, pore size and fluid transport  

E-Print Network (OSTI)

We expose thick polymer foam tissue scaffolds to high power ultrasound and study its effect on the openness of the pore architecture and fluid transport through the scaffold. Our analysis is supported by measurements of fluid uptake during insonification and imaging of the scaffold microstructure via x-ray computed tomography, scanning electron microscopy and acoustic microscopy. The ultrasonic treatment is found to increase the mean pore size by over 10%. More striking is the improvement in fluid uptake: for scaffolds with only 40% water uptake via standard immersion techniques, we can routinely achieve full saturation of the scaffold over approximately one hour of exposure. These desirable modifications occur with no loss of scaffold integrity and negligible mass loss, and are optimized when the ultrasound treatment is coupled to a pre-wetting stage with ethanol. Our findings suggest that high power ultrasound is a highly targetted and efficient means to promote pore interconnectivity and fluid transport in thick foam tissue scaffolds.

N J Watson; R K Johal; Y Reinwald; L J White; A M Ghaemmaghami; S P Morgan; F R A J Rose; M J W Povey; N G Parker

2013-02-18T23:59:59.000Z

376

Swept source optical coherence microscopy for pathological assessment of cancerous tissues  

E-Print Network (OSTI)

Optical coherence microscopy (OCM) combines optical coherence tomography (OCT) with confocal microscopy and enables depth resolved visualization of biological specimens with cellular resolution. OCM offers a suitable ...

Ahsen, Osman Oguz

2013-01-01T23:59:59.000Z

377

Excitation of guided ELF-VLF waves through modification of the F{sub 2} ionospheric layer by high-power radio waves  

SciTech Connect

The possibility of controlled excitation of ELF-VLF electromagnetic waves through modification of the F{sub 2} ionospheric layer by high-power high-frequency emission is demonstrated in a natural experiment by using the Sura midlatitude heating facility. The excited low-frequency waves can be used to explore the near-Earth space and stimulate the excitation of a magnetospheric maser.

Markov, G. A.; Belov, A. S.; Komrakov, G. P. [Lobachevsky State University (Russian Federation); Parrot, M. [Environmental Physics and Chemistry Laboratory (France)

2012-03-15T23:59:59.000Z

378

Coherent state of a weakly interacting ultracold Fermi gas  

E-Print Network (OSTI)

We examine the weakly interacting atoms in an ultracold Fermi gas leading to a state of macroscopic coherence, from a theoretical perspective. It has been shown that this state can be described as a fermionic coherent state. These coherent states are the eigenstates of fermionic annihilation operators, the eigenvalues being anti-commuting numbers or Grassmann numbers. By exploiting the simple rules of Grassmann algebra and a close kinship between relations evaluated for more familiar bosonic fields and those for fermionic fields, we derive the thermodynamic limit, the spontaneous symmetry breaking and the quasi-particle spectrum of the fermionic system.

Arnab Ghosh; Sudarson Sekhar Sinha; Deb Shankar Ray

2013-01-17T23:59:59.000Z

379

Some features of photolithography image formation in partially coherent light  

SciTech Connect

The coherent-noise level in projection images of an opaque-screen sharp edge, formed in the model scheme of photolithography system at different degrees of spatial coherence of screen-illuminating light is studied experimentally. The spatial coherence of laser radiation was reduced by applying a specially developed device, used as a separate functional unit in the system model. The smoothing of the spatial fluctuations of radiation intensity caused by the random spatial inhomogeneity of the initial beam intensity in the obtained images is shown to be highly efficient. (imaging and image processing. holography)

Kitsak, M A [Cooperative Association for Internet Data Analysis, University of California, San Diego (United States); Kitsak, A I [Department of Laser Physics and Spectroscopy, Belarusian State University, Minsk (Belarus)

2010-12-09T23:59:59.000Z

380

Generation of coherent structures after cosmic inflation  

Science Conference Proceedings (OSTI)

We investigate the nonlinear dynamics of hybrid inflation models, which are characterized by two real scalar fields interacting quadratically. We start by solving numerically the coupled Klein-Gordon equations in static Minkowski spacetime, searching for possible coherent structures. We find long-lived, localized configurations, which we identify as a new kind of oscillon. We demonstrate that these two-field oscillons allow for ''excited'' states with much longer lifetimes than those found in previous studies of single-field oscillons. We then solve the coupled field equations in an expanding Friedmann-Robertson-Walker spacetime, finding that as the field responsible for inflating the Universe rolls down to oscillate about its minimum, it triggers the formation of long-lived two-field oscillons, which can contribute up to 20% of the total energy density of the Universe. We show that these oscillons emerge for a wide range of parameters consistent with WMAP 7-year data. These objects contain total energy of about 25x10{sup 20} GeV, localized in a region of approximate radius 6x10{sup -26} cm. We argue that these structures could have played a key role during the reheating of the Universe.

Gleiser, Marcelo; Stamatopoulos, Nikitas [Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755 (United States); Graham, Noah [Department of Physics, Middlebury College, Middlebury, Vermont 05753 (United States)

2011-05-01T23:59:59.000Z

Note: This page contains sample records for the topic "high-power coherent terahertz" 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

Polaron Coherence Condensation in Layered Colossal Resistive Manganites  

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

Polaron Coherence Condensation in Layered Colossal Resistive Manganites Print Polaron Coherence Condensation in Layered Colossal Resistive Manganites Print Novel quantum phenomena, such as high-temperature superconductivity (HTSC) and colossal magnetoresistance (CMR), arise in certain materials where the interactions between electrons are very strong, but the mechanism driving their appearance remains a major puzzle. Now, angle-resolved photoemission findings from an international team led by researchers from Stanford University and the ALS provide the first direct spectroscopic evidence that the transition from insulator to metal in CMR manganese oxides (manganites) results from coherent "polaron condensation." The new findings also suggest that coherence-driven transitions are a generic controlling factor for novel quantum phenomena in doped transition-metal oxides.

382

Spatial Coherence of Tropical Rainfall at the Regional Scale  

Science Conference Proceedings (OSTI)

This study examines the spatial coherence characteristics of daily station observations of rainfall in five tropical regions during the principal rainfall season(s): the Brazilian Nordeste, Senegal, Kenya, northwestern India, and northern ...

Vincent Moron; Andrew W. Robertson; M. Neil Ward; Pierre Camberlin

2007-11-01T23:59:59.000Z

383

An 11-cm Coherent Polarimetric Radar for Meteorological Research  

Science Conference Proceedings (OSTI)

The Geophysics Directorate of the U.S. Air Force developed a unique 11-cm (S-band) coherent polarimetric radar. The radar can transmit signals of alternating orthogonal polarizations, with either circular or linear basis, and receive signals of ...

James I. Metcalf; Alexander W. Bishop; Richard C. Chanley; Timothy C. Hiett; Pio J. Petrocchi

1993-06-01T23:59:59.000Z

384

Argumentation and Persuasion in the Cognitive Coherence Theory  

Science Conference Proceedings (OSTI)

This paper presents a coherentist approach to argumentation that extends previous proposals on cognitive coherence based agent communication pragmatics (inspired from social psychology) and propose (1) an alternative view on argumentation that is (2) ...

Philippe Pasquier; Iyad Rahwan; Frank Dignum; Liz Sonenberg

2006-05-01T23:59:59.000Z

385

Effects of Wind Turbulence on Coherent Doppler Lidar Performance  

Science Conference Proceedings (OSTI)

The effects of wind turbulence on pulsed coherent Doppler lidar performance are investigated theoretically and with computer simulations. The performance of velocity estimators is determined for the case of a single realization of a wind field ...

Rod Frehlich

1997-02-01T23:59:59.000Z

386

Polaron Coherence Condensation in Layered Colossal Resistive Manganites  

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

Polaron Coherence Condensation in Layered Colossal Resistive Manganites Print Polaron Coherence Condensation in Layered Colossal Resistive Manganites Print Novel quantum phenomena, such as high-temperature superconductivity (HTSC) and colossal magnetoresistance (CMR), arise in certain materials where the interactions between electrons are very strong, but the mechanism driving their appearance remains a major puzzle. Now, angle-resolved photoemission findings from an international team led by researchers from Stanford University and the ALS provide the first direct spectroscopic evidence that the transition from insulator to metal in CMR manganese oxides (manganites) results from coherent "polaron condensation." The new findings also suggest that coherence-driven transitions are a generic controlling factor for novel quantum phenomena in doped transition-metal oxides.

387

Magnetism studies using resonant, coherent, x-ray scattering...  

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

10:00am SLAC, Bldg. 137, Room 226 Keoki Seu Seminar: With the advent of free electron lasers there has been interest in using coherent x-rays to probe condensed matter systems....

388

Modeling Pulse-to-Pulse Coherent Doppler Sonar  

Science Conference Proceedings (OSTI)

Coherent Doppler sonar provides a powerful tool for probing boundary layer flows under field and laboratory conditions. However, velocity profiling applications of this technique are complicated by characteristic velocity and range ambiguities. ...

L. Zedel

2008-10-01T23:59:59.000Z

389

Scalable directoryless shared memory coherence using execution migration  

E-Print Network (OSTI)

We introduce the concept of deadlock-free migration-based coherent shared memory to the NUCA family of architectures. Migration-based architectures move threads among cores to guarantee sequential semantics in large ...

Lis, Mieszko

2010-11-22T23:59:59.000Z

390

The minimum-uncertainty coherent states for Landau levels  

Science Conference Proceedings (OSTI)

The Glauber minimum-uncertainty coherent states with two variables for Landau levels, based on the representation of Weyl-Heisenberg algebra by two different modes, have been studied about four decades ago. Here, we introduce new two-variable coherent states with minimum uncertainty relationship for Landau levels in three different methods: the infinite unitary representation of su(1, 1) is realized in two different methods, first, by consecutive levels with the same energy gaps and also with the same value for z-angular momentum quantum number, then, by shifting z-angular momentum mode number by two units while the energy level remaining the same. Besides, for su(2), whether by lowest Landau levels or Landau levels with lowest z-angular momentum, just one finite unitary representation is introduced. Having constructed the generalized Klauder-Perelomov coherent states, for any of the three representations, we obtain their Glauber coherency by displacement operator of Weyl-Heisenberg algebra.

Dehghani, A. [Physics Department, Payame Noor University, P. O. Box 19395-4697 Tehran (Iran, Islamic Republic of); Fakhri, H. [Department of Theoretical Physics and Astrophysics, Faculty of Physics, University of Tabriz, P. O. Box 51666-16471 Tabriz (Iran, Islamic Republic of); Mojaveri, B. [Department of Physics, Azarbaijan Shahid Madani University, P. O. Box 51745-406 Tabriz (Iran, Islamic Republic of)

2012-12-15T23:59:59.000Z

391

The mediating role of coherence in curriculum implementation  

Science Conference Proceedings (OSTI)

Implementation of inquiry-based curriculum materials has been a challenge in science education. Recent research points to the importance of coherence in professional development as a means to improving implementation. Policy researchers have defined ...

William Penuel; Barry J. Fishman; Lawrence P. Gallagher; Christine Korbak; Bladimir Lopez-Prado

2008-06-01T23:59:59.000Z

392

Optimizing directory-based cache coherence on the RAW architecture  

E-Print Network (OSTI)

Caches help reduce the effect of long-latency memory requests, by providing a high speed data-path to local memory. However, in multi-processor systems utilizing shared memory, cache coherence protocols are necessary to ...

Ramaswamy, Satish

2005-01-01T23:59:59.000Z

393

Coherent combination of slab-coupled optical waveguide lasers  

E-Print Network (OSTI)

A long-standing challenge for semiconductor lasers is scaling the optical power and brightness of many diode lasers by coherent beam combination. Because single-mode semiconductor lasers have limited power available from ...

Dorsch, Friedhelm

394

Spatial Coherence and Seasonal Predictability of Monsoon Onset over Indonesia  

Science Conference Proceedings (OSTI)

The seasonal potential predictability of monsoon onset during the August–December season over Indonesia is studied through analysis of the spatial coherence of daily station rainfall and gridded pentad precipitation data from 1979 to 2005. The ...

Vincent Moron; Andrew W. Robertson; Rizaldi Boer

2009-02-01T23:59:59.000Z

395

Spatial Coherence and Predictability of Indonesian Wet Season Rainfall  

Science Conference Proceedings (OSTI)

Rainfall from 63 stations across Indonesia is examined for the period 1950–98 to determine the spatial coherence of wet season anomalies. An example of almost unrelated anomalies at two neighboring stations is presented. Principal component ...

Malcolm Haylock; John McBride

2001-09-01T23:59:59.000Z

396

Asymptotic Properties of an Autocorrelation Coefficient for Coherent Doppler Sonar  

Science Conference Proceedings (OSTI)

A new formula is derived for the asymptotic form of the magnitude of an autocorrelation coefficient for coherent Doppler sonar. The autocorrelation magnitude is shown to be a biased estimator in the limit of infinite ensemble length. Numerical ...

Jeremy Dillon; Len Zedel; Alex E. Hay

2011-07-01T23:59:59.000Z

397

Estimating Spatial Velocity Statistics with Coherent Doppler Lidar  

Science Conference Proceedings (OSTI)

The spatial statistics of a simulated turbulent velocity field are estimated using radial velocity estimates from simulated coherent Doppler lidar data. The structure functions from the radial velocity estimates are processed to estimate the ...

Rod Frehlich; Larry Cornman

2002-03-01T23:59:59.000Z

398

Observation of Coherence in the Photosystem II Reaction Center  

E-Print Network (OSTI)

Photosynthesis powers life on our planet. The basic photosynthetic architecture comprises antenna complexes to harvest solar energy and reaction centers to convert the energy into a stable charge separated state. In oxygenic photosynthesis, the initial charge separation event occurs in the photosystem II reaction center; the only known natural enzyme that uses solar energy to split water. Energy transfer and charge separation in photosynthesis are rapid and have high quantum efficiencies. Recently, nonlinear spectroscopic experiments have suggested that electronic coherence may play a role in energy transfer efficiency in antenna complexes. Here we report the observation of coherence in the photosystem II reaction center by two dimensional electronic spectroscopy. The frequencies of the observed coherences match exciton difference frequencies and/or known vibrational modes of the photosystem II reaction center. These observations raise questions about the possible role of electronic and/or vibrational coherence in the fundamental charge separation process in oxygenic photosynthesis.

Franklin D. Fuller; Jie Pan; S. Seckin Senlik; Daniel E. Wilcox; Jennifer P. Ogilvie

2013-10-03T23:59:59.000Z

399

Studying coherence in ultra-cold atomic gases  

E-Print Network (OSTI)

This thesis will discuss the study of coherence properties of ultra-cold atomic gases. The atomic systems investigated include a thermal cloud of atoms, a Bose-Einstein condensate and a fermion pair condensate. In each ...

Miller, Daniel E. (Daniel Edward)

2007-01-01T23:59:59.000Z

400

Quasi light fields: Extending the light field to coherent radiation  

E-Print Network (OSTI)

Imaging technologies such as dynamic viewpoint generation are engineered for incoherent radiation using the traditional light field, and for coherent radiation using electromagnetic field theory. We present a model of ...

Accardi, Anthony J.

Note: This page contains sample records for the topic "high-power coherent terahertz" 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.


401

Accumulation of different visual feature descriptors in a coherent framework  

Science Conference Proceedings (OSTI)

We present a temporal accumulation scheme which disambiguates different kinds of visual 3D descriptors within one coherent framework. The accumulation consists of a twofold process: First, by means of a Bayesian filtering outliers become eliminated and ...

Jeppe Barsøe Jessen; Florian Pilz; Dirk Kraft; Nicolas Pugeault; Norbert Krüger

2011-05-01T23:59:59.000Z

402

Spatial Coherence of Monthly Precipitation in the United States  

Science Conference Proceedings (OSTI)

Factor analysis and an orthogonal rotation to the varimax criterion are used to identify the synoptic-scale regions of the United States over which monthly precipitation amounts show the greatest spatial coherence. The regions are consistent with ...

John E. Walsh; Michael B. Richman; David W. Allen

1982-04-01T23:59:59.000Z

403

Coherent multi-photon interference and compensation of polarization dispersion  

E-Print Network (OSTI)

This thesis will explore strategies for coherent manipulation of multi-photon packets. Correlated multi-photon states can arise in nonlinear optical devices. A nonlinear quantum interferometer which includes these states ...

Fini, John Michael

2001-01-01T23:59:59.000Z

404

SLAC National Accelerator Laboratory - Linac Coherent Light Source...  

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

LCLS - Linac Coherent Light Source Banner image of LCLS undulator hall. LCLS, the world's first hard X-ray free-electron laser, pushes science to new extremes with ultrabright,...

405

Direct Observations of Coherent Backscatter of Radar Waves in Precipitation  

Science Conference Proceedings (OSTI)

In previous work, it was argued that a source of radar coherent scatter occurs in the direction perpendicular to the direction of wave propagation because of the presence of grids of enhanced particle concentrations with spatial periodicities in ...

A. R. Jameson; A. B. Kostinski

2010-09-01T23:59:59.000Z

406

Exploiting temporal coherence in real-time rendering  

Science Conference Proceedings (OSTI)

Temporal coherence (TC), the correlation of contents between adjacent rendered frames, exists across a wide range of scenes and motion types in practical real-time rendering. By taking advantage of TC, we can save redundant computation and improve ...

Daniel Scherzer; Lei Yang; Oliver Mattausch

2010-12-01T23:59:59.000Z

407

Teapot: language support for writing memory coherence protocols  

Science Conference Proceedings (OSTI)

Recent shared-memory parallel computer systems offer the exciting possibility of customizing memory coherence protocols to fit an application's semantics and sharing patterns. Custom protocols have been used to achieve message-passing performance---while ...

Satish Chandra; Brad Richards; James R. Larus

1996-05-01T23:59:59.000Z

408

Comparison of 2- and 10-µm Coherent Doppler Lidar Performance  

Science Conference Proceedings (OSTI)

The performance of 2- and 10-µm coherent Doppler lidar is presented in terms of the statistical distribution of the maximum-likelihood velocity estimator from simulations for fixed range resolution and fixed velocity search space as a function of ...

Rod Frehlich

1995-04-01T23:59:59.000Z

409

Partially Coherent Backscatter in Radar Observations of Precipitation  

Science Conference Proceedings (OSTI)

Classical radar theory only considers incoherent backscatter from precipitation. Can precipitation generate coherent scatter as well? Until now, the accepted answer has been no, because hydrometeors are distributed sparsely in space (relative to ...

A. R. Jameson; A. B. Kostinski

2010-06-01T23:59:59.000Z

410

Processing and Interpretation of Coherent Dual-Polarized Radar Measurements  

Science Conference Proceedings (OSTI)

Dual-polarized coherent radar measurements are used to estimate the differential propagation phase or DP between horizontal and vertical polarization states. The slope of DP is an estimate of the specific differential phase KDP. This process is ...

J. Hubbert; V. Chandrasekar; V. N. Bringi; P. Meischner

1993-04-01T23:59:59.000Z

411

Polaron Coherence Condensation in Layered Colossal Resistive Manganites  

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

Polaron Coherence Condensation in Layered Colossal Resistive Manganites Print Polaron Coherence Condensation in Layered Colossal Resistive Manganites Print Novel quantum phenomena, such as high-temperature superconductivity (HTSC) and colossal magnetoresistance (CMR), arise in certain materials where the interactions between electrons are very strong, but the mechanism driving their appearance remains a major puzzle. Now, angle-resolved photoemission findings from an international team led by researchers from Stanford University and the ALS provide the first direct spectroscopic evidence that the transition from insulator to metal in CMR manganese oxides (manganites) results from coherent "polaron condensation." The new findings also suggest that coherence-driven transitions are a generic controlling factor for novel quantum phenomena in doped transition-metal oxides.

412

Lagrangian Coherent Structures near a Subtropical Jet Stream  

Science Conference Proceedings (OSTI)

Direct Lyapunov exponents and stability results are used to extract and distinguish Lagrangian coherent structures (LCS) from a three-dimensional atmospheric dataset generated from the Weather Research and Forecasting (WRF) model. The numerical ...

Wenbo Tang; Manikandan Mathur; George Haller; Douglas C. Hahn; Frank H. Ruggiero

2010-07-01T23:59:59.000Z

413

Large-Amplitude Coherent Anomalies in Baroclinic Zonal Flows  

Science Conference Proceedings (OSTI)

In a previous paper the authors developed an asymptotic time-dependent theory for coherent structures on a marginally stable baroclinic flow. It was shown that solitary waves, as well as other more general disturbances of sufficient amplitude, ...

Karl R. Helfrich; Joseph Pedlosky

1995-05-01T23:59:59.000Z

414

Macroscopic coherence between quantum condensates formed at different times  

E-Print Network (OSTI)

We demonstrate macroscopic coherence between quantum condensates generated at different times, separated by more than the particle dephasing time. This is possible due to the dressed light-matter nature of exciton-polaritons, which can be injected resonantly by optical excitation at well-defined momenta. We show that the build-up of coherence between condensates depends on the interaction between the particles, particle density, as well as temperature despite the non-equilibrium nature of the condensate, whereas the mass of the particles plays no role in the condensation of resonantly injected polaritons. This experiment also makes it possible for us to measure directly the large nonlinear phase shift resulting from the polariton-polariton interaction energy. Our results provide direct evidence for coherence between different condensates and demonstrate a new approach for probing their ultrafast dynamics, opening new directions in the study of matter coherence as well as in practical applications such as quantum information and ultrafast logic.

Alex Hayat; Christoph Lange; Lee A. Rozema; Rockson Chang; Shreyas Potnis; Henry M. van Driel; Aephraim M. Steinberg; Mark Steger; David W. Snoke; Loren N. Pfeiffer; Kenneth W. West

2013-09-30T23:59:59.000Z

415

Coherent energy manipulation in single-neutron interferometry  

E-Print Network (OSTI)

We have observed the stationary interference oscillations of a triple-entangled neutron state in an interferometric experiment. Time-dependent interaction with two radio-frequency (rf) fields enables coherent manipulation of an energy degree of freedom in a single neutron. The system is characterized by a multiply entangled state governed by a Jaynes-Cummings Hamiltonian. The experimental results confirm coherence of the manipulation as well as the validity of the description.

S. Sponar; J. Klepp; R. Loidl; S. Filipp; G. Badurek; Y. Hasegawa; H. Rauch

2008-03-25T23:59:59.000Z

416

Short-pulse limits in optical instrumentation design for the SLAC Linac Cohereent Light Source (LCLS)  

E-Print Network (OSTI)

Short-pulse limits in optical instrumentation design for the SLAC Linac Cohereent Light Source (LCLS)

Tatchyn, R

1999-01-01T23:59:59.000Z

417

Applications of Ultrafast Terahertz Pulses for Intra-ExcitonicSpectroscopy of Quasi-2D Electron-Hole Gases  

Science Conference Proceedings (OSTI)

Excitons are of fundamental interest and of importance foropto-electronic applications of bulk and nano-structured semiconductors.This paper discusses the utilization of ultrafast terahertz (THz) pulsesfor the study of characteristic low-energy excitations of photoexcitedquasi 2D electron-hole (e-h) gases. Optical-pump THz-probe spectroscopyat 250-kHz repetition rate is employed to detect characteristic THzsignatures of excitons and unbound e-h pairs in GaAs quantum wells.Exciton and free-carrier densities are extracted from the data using atwo-component model. We report the detailed THz response and pairdensities for different photoexcitation energies resonant to heavy-holeexcitons, light-hole excitons, or the continuum of unbound pairs. Suchexperiments can provide quantitative insights into wavelength, time, andtemperature dependence of the low-energy response and composition ofoptically excited e-h gases in low-dimensionalsemiconductors.

Kaindl, Robert A.; Carnahan, Marc A.; Hagele, Daniel; Chemla, D.S.

2006-09-02T23:59:59.000Z

418

Measurement-based Coherency Identification and Aggregation for Power Systems  

SciTech Connect

In power system model reduction, a high reduction ratio is often desired to handle much more complex power systems. The bottleneck of traditional methods lies in: ? Coherency identification methods are conservative. Some coherency generators are not detected when system topology or operating points change, because coherency identification depends on system topology or operating points. ?There are some solitary generators in external systems. These generators do not belong to any coherency group. However, sometimes these solitary generators have little impact on tie-line power flow, and it might be possible to ignore their dynamics in model reduction. But because they do not belong to any coherency group, existing reduction methods cannot handle them well. In order to overcome the first problem, a measurement-based online coherency identification method is presented in this paper. By analyzing post-fault trajectories measured by Phasor Measurement Units (PMUs), coherency generators are identified through principal component analysis. The method can track time-varying system topology and operating points. In order to address the second problem, this paper introduces sensitivity analysis into traditional reduction methods. The sensitivity of tie-line power flow against injected active power of external system generators is derived. Those generators having loose connection with tie-line power are identified through the sensitivity analysis, and their dynamics are ignored by replacing them with negative impedances. We test if the sensitivity, based on static power flow, provides good guidance to reduce the dynamic model. Case studies show that the proposed method can handle well these solitary generators and the reduction ratio can be enhanced through this method. Future work will include generalization of the sensitivity method.

Wang, Shaobu; Lu, Shuai; Lin, Guang; Zhou, Ning

2012-07-26T23:59:59.000Z

419

X-ray photoelectron spectroscopy of negative electrodes from high-power lithium-ion cells showing various levels of power fade  

DOE Green Energy (OSTI)

High-power lithium-ion cells for transportation applications are being developed and studied at Argonne National Laboratory. The current generation of cells containing LiNi{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2}-based cathodes, graphite-based anodes, and LiPF6-based electrolytes show loss of capacity and power during accelerated testing at elevated temperatures. Negative electrode samples harvested from some cells that showed varying degrees of power and capacity fade were examined by X-ray photoelectron spectroscopy (XPS). The samples exhibited a surface film on the graphite, which was thicker on samples from cells that showed higher fade. Furthermore, solvent-based compounds were dominant on samples from low power fade cells, whereas LiPF{sub 6}-based products were dominant on samples from high power fade cells. The effect of sample rinsing and air exposure is discussed. Mechanisms are proposed to explain the formation of compounds suggested by the XPS data.

Herstedt, Marie; Abraham, Daniel P.; Kerr, John B.

2004-02-28T23:59:59.000Z

420

Technical Report: Final project report for Terahertz Spectroscopy of Complex Matter  

SciTech Connect

This project designed characterization techniques for thin films of complex matter and other materials in the terahertz spectral region extending from approximately 100 GHz to 4000 GHz (4 THz) midway between radio waves and light. THz has traditionally been a difficult region of the spectrum in which to conduct spectroscopic measurements. The “THz gap” arises from the nature of the sources and detectors used in spectroscopy both at the optical (high frequency) side and electronic (low frequency) side of the gap. To deal with the extremely rapid oscillations of the electric field in this frequency region this research project adapted techniques from both the electronics and optics technologies by fabricating microscopic antennas and driving them with short optical pulses. This research technique creates nearly single cycle pulses with extremely broad spectral bandwidth that are able to cover the THz spectral range with a single measurement. The technique of THz time domain spectroscopy (THz-TDS) has seen increasing use and acceptance in laboratories over the past fifteen years. However significant technical challenges remain in order to allow THz-TDS to be applied to measurement of solid materials, particularly thin films and complex matter. This project focused on the development and adaptation of time domain THz measurement techniques to investigate the electronic properties of complex matter in the terahertz frequency region from 25 GHz to beyond 5 THz (<1 inv. cm to >165 inv. cm). This project pursued multiple tracks in adapting THz Time Domain Spectroscopy (THz-TDS) to measurement of complex matter. The first, and most important, is development of a reliable methods to characterize the complex dielectric constant of thin films with high accuracy when the wavelength of the THz radiation is much longer than the thickness of the film. We have pursued several techniques for measurement of thin films. The most promising of these are waveguide spectroscopy and THz interferometry. Since THz spectroscopy measures the changes of the transmitted spectra, any noise on the THz signal contributes to measurement errors. The dynamic range—defined as the RMS noise of the THz detector compared to the peak THz signal—of THz spectroscopy using photoconductive antennas is extremely high, typically over 10,000. However the precision with which spectroscopic data can be measured is limited by the noise on the laser source which is typically 0.1% to 1%. For low values of the sample absorbance and for values of optical thickness less than approximately 0.01, the change in transmission approaches the measurement accuracy. The sample refractive index can be measured with better accuracy since the index causes a temporal shift of the THz pulse by an amount time shift of nd/c where n is the refractive index, d the sample thickness, and c the speed of light. Time shifts of tens of femtoseconds can generally be resolved so that index-thickness values of nd > ten microns can be accurately measured. Waveguide spectroscopy is a way to increase the path length in thin film by several orders of magnitude, and thus have a large interaction length even when the film is much less than a wavelength in thickness. Film thicknesses of 10’s of nm have been measured. THz interferometry cancels out many of the noise sources of THz spectroscopy and can thus result in measurements of films of several hundred nm in thickness and is additionally suitable for optical pump, THz probe spectroscopic techniques. A large amount of additional work was performed in support of the main project direction or to explore promising alternative avenues for research. This report discussed work on the the confinement of low density species for measurement of nanogram or picogram quantities of material. Whispering gallery mode resonators to achieve long path lengths were also investigated as were imaging techniques for sub-wavelength imaging of thin films. The report concludes with a report on investigations of fundamental issues in THz beam propagation and coupli

R. A. Cheville; D. R. Grischkowsky

2007-02-08T23:59:59.000Z

Note: This page contains sample records for the topic "high-power coherent terahertz" 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

Technical Report: Final project report for Terahertz Spectroscopy of Complex Matter  

Science Conference Proceedings (OSTI)

This project designed characterization techniques for thin films of complex matter and other materials in the terahertz spectral region extending from approximately 100 GHz to 4000 GHz (4 THz) midway between radio waves and light. THz has traditionally been a difficult region of the spectrum in which to conduct spectroscopic measurements. The “THz gap” arises from the nature of the sources and detectors used in spectroscopy both at the optical (high frequency) side and electronic (low frequency) side of the gap. To deal with the extremely rapid oscillations of the electric field in this frequency region this research project adapted techniques from both the electronics and optics technologies by fabricating microscopic antennas and driving them with short optical pulses. This research technique creates nearly single cycle pulses with extremely broad spectral bandwidth that are able to cover the THz spectral range with a single measurement. The technique of THz time domain spectroscopy (THz-TDS) has seen increasing use and acceptance in laboratories over the past fifteen years. However significant technical challenges remain in order to allow THz-TDS to be applied to measurement of solid materials, particularly thin films and complex matter. This project focused on the development and adaptation of time domain THz measurement techniques to investigate the electronic properties of complex matter in the terahertz frequency region from 25 GHz to beyond 5 THz (165 inv. cm). This project pursued multiple tracks in adapting THz Time Domain Spectroscopy (THz-TDS) to measurement of complex matter. The first, and most important, is development of a reliable methods to characterize the complex dielectric constant of thin films with high accuracy when the wavelength of the THz radiation is much longer than the thickness of the film. We have pursued several techniques for measurement of thin films. The most promising of these are waveguide spectroscopy and THz interferometry. Since THz spectroscopy measures the changes of the transmitted spectra, any noise on the THz signal contributes to measurement errors. The dynamic range—defined as the RMS noise of the THz detector compared to the peak THz signal—of THz spectroscopy using photoconductive antennas is extremely high, typically over 10,000. However the precision with which spectroscopic data can be measured is limited by the noise on the laser source which is typically 0.1% to 1%. For low values of the sample absorbance and for values of optical thickness less than approximately 0.01, the change in transmission approaches the measurement accuracy. The sample refractive index can be measured with better accuracy since the index causes a temporal shift of the THz pulse by an amount time shift of nd/c where n is the refractive index, d the sample thickness, and c the speed of light. Time shifts of tens of femtoseconds can generally be resolved so that index-thickness values of nd > ten microns can be accurately measured. Waveguide spectroscopy is a way to increase the path length in thin film by several orders of magnitude, and thus have a large interaction length even when the film is much less than a wavelength in thickness. Film thicknesses of 10’s of nm have been measured. THz interferometry cancels out many of the noise sources of THz spectroscopy and can thus result in measurements of films of several hundred nm in thickness and is additionally suitable for optical pump, THz probe spectroscopic techniques. A large amount of additional work was performed in support of the main project direction or to explore promising alternative avenues for research. This report discussed work on the the confinement of low density species for measurement of nanogram or picogram quantities of material. Whispering gallery mode resonators to achieve long path lengths were also investigated as were imaging techniques for sub-wavelength imaging of thin films. The report concludes with a report on investigations of fundamental issues in THz beam propagation and coupli

R. A. Cheville; D. R. Grischkowsky

2007-02-08T23:59:59.000Z

422

Atomic Frequency standards Based on Pulsed Coherent Light Storage  

E-Print Network (OSTI)

We propose a new scheme of microwave frequency standards based on pulsed coherent optical information storage. Unlike the usual frequency reference where the Ramsey fringe is printed on the population of a certain state, we print the Ramsey fringe on the coherence. Then the coherence is detected in the form of a retrieval light. The central line of the Ramsey fringe can be used as a frequency reference in an absorption-cell-based atomic frequency standard. This scheme is free of light shifts as the interrogating process is separated from the optical pumping processes, and the cavity pulling effect is negligible due to the low Q requirement. Encoding the Ramsey interference into the retrieval light pulse has the merit of high signal to noise ratio and the estimated frequency stability of shot noise limit is about $2\\times10^{-14}$ in 1 second, this scheme is promising for building small, compact and stable atomic frequency standards.

Yan, Bo; Wang, Yuzhu

2008-01-01T23:59:59.000Z

423

Transverse Coherence of the LCLS X-Ray Beam  

Science Conference Proceedings (OSTI)

Self-amplifying spontaneous radiation free-electron lasers, such as the LCLS or the European X-FEL, rely on the incoherent, spontaneous radiation as the seed for the amplifying process. Though this method overcomes the need for an external seed source one drawback is the incoherence of the effective seed signal. The FEL process allows for a natural growth of the coherence because the radiation phase information is spread out within the bunch due to slippage and diffraction of the radiation field. However, at short wavelengths this spreading is not sufficient to achieve complete coherence. In this presentation we report on the results of numerical simulations of the LCLS X-ray FEL. From the obtained radiation field distribution the coherence properties are extracted to help to characterize the FEL as a light source.

Not Available

2010-12-01T23:59:59.000Z

424

Method and apparatus for coherent imaging of infrared energy  

DOE Patents (OSTI)

A coherent camera system performs ranging, spectroscopy, and thermal imaging. Local oscillator radiation is combined with target scene radiation to enable heterodyne detection by the coherent camera`s two-dimensional photodetector array. Versatility enables deployment of the system in either a passive mode (where no laser energy is actively transmitted toward the target scene) or an active mode (where a transmitting laser is used to actively illuminate the target scene). The two-dimensional photodetector array eliminates the need to mechanically scan the detector. Each element of the photodetector array produces an intermediate frequency signal that is amplified, filtered, and rectified by the coherent camera`s integrated circuitry. By spectroscopic examination of the frequency components of each pixel of the detector array, a high-resolution, three-dimensional or holographic image of the target scene is produced for applications such as air pollution studies, atmospheric disturbance monitoring, and military weapons targeting. 8 figs.

Hutchinson, D.P.

1998-05-12T23:59:59.000Z

425

Observation of Coherence in the Photosystem II Reaction Center  

E-Print Network (OSTI)

Photosynthesis powers life on our planet. The basic photosynthetic architecture comprises antenna complexes to harvest solar energy and reaction centers to convert the energy into a stable charge separated state. In oxygenic photosynthesis, the initial charge separation event occurs in the photosystem II reaction center; the only known natural enzyme that uses solar energy to split water. Energy transfer and charge separation in photosynthesis are rapid and have high quantum efficiencies. Recently, nonlinear spectroscopic experiments have suggested that electronic coherence may play a role in energy transfer efficiency in antenna complexes. Here we report the observation of coherence in the photosystem II reaction center by two dimensional electronic spectroscopy. The frequencies of the observed coherences match exciton difference frequencies and/or known vibrational modes of the photosystem II reaction center. These observations raise questions about the possible role of electronic and/or vibrational coheren...

Fuller, Franklin D; Senlik, S Seckin; Wilcox, Daniel E; Ogilvie, Jennifer P

2013-01-01T23:59:59.000Z

426

Targeted coherent search for gravitational waves from compact binary coalescences  

SciTech Connect

We introduce a method for conducting a targeted, coherent search for compact binary coalescences. The search is tailored to be used as a follow-up to electromagnetic transients such as gamma-ray bursts. We derive the coherent search statistic for Gaussian detector noise and discuss the benefits of a coherent, multidetector search over coincidence methods. To mitigate the effects of nonstationary data, we introduce a number of signal consistency tests, including the null signal-to-noise ratio, amplitude consistency, and several {chi}{sup 2} tests. We demonstrate the search performance on Gaussian noise and on data from LIGO's fourth science run and verify that the signal consistency tests are capable of removing the majority of noise transients, giving the search an efficiency comparable to that achieved in Gaussian noise.

Harry, I. W.; Fairhurst, S. [School of Physics and Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff, CF24 3AA (United Kingdom)

2011-04-15T23:59:59.000Z

427

Direct three-dimensional coherently scattered x-ray microtomography  

Science Conference Proceedings (OSTI)

Purpose: It has been shown that coherently scattered x rays can be used to discriminate and identify specific components in a mixture of low atomic weight materials. The authors demonstrated a new method of doing coherently scattered x-ray tomography with a thin sheet of x ray. Methods: A collimated x-ray fan-beam, a parallel polycapillary collimator, and a phantom consisting of several biocompatible materials of low attenuation-based contrast were used to investigate the feasibility of the method. Because of the particular experimental setup, only the phantom translation perpendicular to the x-ray beam is needed and, thus, there is no need of Radon-type tomographic reconstruction, except for the correction of the attenuation to the primary and scattered x rays, which was performed by using a conventional attenuation-based tomographic image data set. The coherent scatter image contrast changes with momentum transfer among component materials in the specimen were investigated with multiple x-ray sources with narrow bandwidth spectra generated with anode and filter combinations of Cu/Ni (8 keV), Mo/Zr (18 keV), and Ag/Pd (22 keV) and at multiple scatter angles by orienting the detector and polycapillary collimator at different angles to the illuminating x ray. Results: The contrast among different materials changes with the x-ray source energy and the angle at which the image was measured. The coherent scatter profiles obtained from the coherent scatter images are consistent with the published results. Conclusions: This method can be used to directly generate the three-dimensional coherent scatter images of small animal, biopsies, or other small objects with low atomic weight biological or similar synthetic materials with low attenuation contrast. With equipment optimized, submillimeter spatial resolution may be achieved.

Cui Congwu; Jorgensen, Steven M.; Eaker, Diane R.; Ritman, Erik L. [Department of Medical Physics, CancerCare Manitoba, 675 McDermot Avenue, Winnipeg, Manitoba R3E 0V9 (Canada); Department of Physiology and Biomedical Engineering, Mayo Clinic, 200 First Street Southwest, Alfred Building 2-409, Rochester, Minnesota 55905 (United States)

2010-12-15T23:59:59.000Z

428

Generating polarization controllable FELs at Dalian coherent light source  

E-Print Network (OSTI)

The property of the FEL polarization is of great importance to the user community. FEL pulses with ultra-high intensity and flexible polarization control ability will absolutely open up new scientific realms. In this paper, several polarization control approaches are presented to investigate the great potential on Dalian coherent light source, which is a government-approved novel FEL user facility with the capability of wavelength continuously tunable in the EUV regime of 50-150 nm. The numerical simulations show that both circularly polarized FELs with highly modulating frequency and 100 microjoule level pulse energy could be generated at Dalian coherent light source.

Zhang, T; Wang, D; Zhao, Z T; Zhang, W Q; Wu, G R; Dai, D X; Yang, X M

2013-01-01T23:59:59.000Z

429

Quatum Thermodynamics and the coherence in Ion channels  

E-Print Network (OSTI)

We showed that quantum mechanical superposition can sustain in the process of ion transfer in protein membrane for a substantial period, in spite of the presence of the interactions with environmental modes of molecular vibration. The spectral temperature, as defined in quantum thermodynamical framework plays a significant role in maintaining the coherence. The ratio of decoherence time and dwell time has been calculated, which can be directly related to the degree of coherence. The results shead new light to build quantum information system of entangled ionic states in the voltage gated biological channels.

Samyadeb Bhattacharya; Sisir Roy

2013-03-08T23:59:59.000Z

430

Efficiency of excitation transfer in photosynthesis under quantum coherence  

E-Print Network (OSTI)

We investigate the role of quantum coherence in the efficiency of excitation transfer in a spin-star arrangement of interacting two-level systems, mimicking a light-harvesting antenna connected to a reaction center, similar to a photosynthetic system in nature. By using the quantum jump approach, we show that the efficiency depends intimately on the quantum interference among states in which the excitation is localized on individual sites in the antenna. Our results indicate how efficiency may be used as an indication of quantum coherence in energy transfer.

Olaya-Castro, Alexandra; Fassioli-Olsen, Francesca; Johnson, Neil F

2007-01-01T23:59:59.000Z

431

Quantum Coherence Conservation by Growth in Environmental Dissipation Rate  

E-Print Network (OSTI)

Quantum coherence conservation is shown to be achieved by a very high rate of dissipation of an environmental system coupled with a principal system. This effect is not in the list of previously-known strategies of noise suppression, such as Zeno effect, dynamical decoupling, quantum error correction code, and decoherence free subspace. An analytical solution is found for a simplified model of a single qubit coupled with an environmental single qubit dissipating rapidly. We also show examples of coherence conservation in a spin-boson linear coupling model with a numerical evaluation.

Akira SaiToh; Robabeh Rahimi; Mikio Nakahara

2007-09-05T23:59:59.000Z

432

Testing and Implementation Progress on the Advanced Photon Source (APS) Linear Accelerator (Linac) High-Power S-band Switching System  

E-Print Network (OSTI)

An S-band linear accelerator is the source of particles and the front end of the Advanced Photon Source injector. In addition, it supports a low-energy undulator test line (LEUTL) and drives a free-electron laser (FEL). A waveguide-switching and distribution system is now under construction. The system configuration was revised to be consistent with the recent change to electron-only operation. There are now six modulator-klystron subsystems, two of which are being configured to act as hot spares for two S-band transmitters each, so that no single failure will prevent injector operation. The two subsystems are also used to support additional LEUTL capabilities and off-line testing. Design considerations for the waveguide-switching subsystem, topology selection, control and protection provisions, high-power test results, and current status are described

Grelick, A E; Berg, S; Dohan, D A; Goeppner, G A; Kang, Y W; Nassiri, A; Pasky, S; Pile, G; Smith, T; Stein, S J

2000-01-01T23:59:59.000Z

433

Time-resolved x-ray imaging of high-power laser-irradiated under-dense silica aerogels and agar foams  

SciTech Connect

This paper presents the results of experiments in which a high-power laser was used to irradiate low density (4 - 9 mg/cm{sup 3}) silica aerogel and agar foam targets. The laser-solid interaction and energy transport through the material were monitored with time-resolved imaging diagnostics, and the data show the production and propagation of an x-ray emission front in the plasma. The emission-front trajectory data are found to be in significant disagreement with detailed simulations, which predict a much more rapid heating of the cold material, and the data suggest that this discrepancy is not explainable by target inhomogeneities. Evidence suggests that energy transport into the cold material may be dominated by thermal conduction; however, no completely satisfactory explanation for the discrepancies is identified, and further experimental and theoretical research is necessary in order to resolve this important problem in laser-plasma interaction physics.

Koch, J.A.; Estabrook, K.G.; Bauer, J.D. [and others

1995-08-01T23:59:59.000Z

434

Simultaneous Measurement of Ocean Winds and Waves with an Airborne Coherent Real Aperture Radar  

Science Conference Proceedings (OSTI)

A coherent, X-band airborne radar has been developed to measure wind speed and direction simultaneously with directional wave spectra on the ocean. The coherent real aperture radar (CORAR) measures received power, mean Doppler shifts, and mean ...

William J. Plant; William C. Keller; Kenneth Hayes

2005-07-01T23:59:59.000Z

435

Optical measurement of neural action potentials using low coherence heterodyne interferometry  

E-Print Network (OSTI)

We present a novel non-invasive optical method for detection of neural action potentials using low coherence interferometry. The dual beam heterodyne interferometer (DBHI) is a modified Michelson with a low coherence source ...

Chu, Mark Changhao, 1978-

2004-01-01T23:59:59.000Z

436

Minimum Uncertainty, Coherence and Squeezing in Diffusion Processes, and Stochastic Quantization  

E-Print Network (OSTI)

We show that uncertainty relations, as well as minimum uncertainty coherent and squeezed states, are structural properties for diffusion processes. Through Nelson stochastic quantization we derive the stochastic image of the quantum mechanical coherent and squeezed states.

Salvatore De Martino; Silvio De Siena; Fabrizio Illuminati; Giuseppe Vitiello

1993-10-18T23:59:59.000Z

437

Coherent resonant tunneling through an artificial molecule C. A. Stafford  

E-Print Network (OSTI)

Coherent resonant tunneling through an artificial molecule C. A. Stafford Fakulta¨t fu¨r Physik PRB 58C. A. STAFFORD, R. KOTLYAR, AND S. DAS SARMA #12;Coulomb blockade12 for C Cg to a ballistic /e 1 follows from the particle-hole symmetry of Eq. 1 . 7094 PRB 58C. A. STAFFORD, R. KOTLYAR, AND S

Stafford, Charles

438

Coherent. pi. /sup 0/ photoproduction at intermediate energy  

SciTech Connect

Coherent ..pi../sup 0/ photoproduction from nuclei is calculated in the ..delta..-hole framework. Important background production terms are included, and a comparison with data is presented. Sensitivity to various aspects of the dynamics, such as recoil and the ..delta.. spreading potential, are examined.

Koch, J.H.; Moniz, E.J.

1983-02-01T23:59:59.000Z

439

Wind-Field Coherence and Its Variations over West Africa  

Science Conference Proceedings (OSTI)

The wind-field coherence over West Africa is investigated during two contrasted periods, 1953–63 (abnormally wet) and 1963-75 (abnormally dry) in the Sahel. Zonal and meridional components of the monthly mean wind are computed with radiosonde ...

Bernard Fontaine; Serge Janicot

1992-05-01T23:59:59.000Z

440

Cohomological invariants of coherent sheaves over projective schemes - a survey  

E-Print Network (OSTI)

Abstract. We give a survey on certain results related to the cohomology of projective schemes with coefficients in coherent sheaves. In particular we present results on cohomological patterns, cohomological Hilbert functions and cohomological Hilbert polynomials. Bounding results for Castelnuovo-Mumford regularities, Severi coregularities and cohomological postulation numbers are discussed. Moreover, a number of open questions is presented.

M. Brodmann; Cohomological Hilbert Functions

2001-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "high-power coherent terahertz" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
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to obtain the most current and comprehensive results.


441

Coherent Eddies in the Labrador Sea Observed from a Mooring  

Science Conference Proceedings (OSTI)

During June–November 1994, a mooring in the central Labrador Sea near the former Ocean Weather Station Bravo recorded a half-dozen anomalous events that prove to be two different types of coherent eddies. Comparisons with simple analytical models ...

Jonathan M. Lilly; Peter B. Rhines

2002-02-01T23:59:59.000Z

442

Wave-coherent airflow and critical layers over ocean waves  

Science Conference Proceedings (OSTI)

An analysis of coherent measurements of winds and waves from data collected during the ONR HiRes program from R/P FLIP off the coast of northern California in June 2010 is presented. A suite of wind and wave measuring systems was deployed to ...

Laurent Grare; Luc Lenain; W. Kendall Melville

443

Neutron Form Factor from Neutrino-Nucleus Coherent Elastic Scattering  

E-Print Network (OSTI)

We analyze the prospect of measuring the neutron form factor of a nucleus through the detection of neutrino-nucleus coherent elastic scattering. We predict numbers of events in a liquid noble nuclear recoil detector at a stopped pion neutrino source. We discuss the precision required to distinguish between different theoretical models for the form factor.

Philip S. Amanik; Gail C. McLaughlin

2007-07-27T23:59:59.000Z

444

Interactive watercolor rendering with temporal coherence and abstraction  

Science Conference Proceedings (OSTI)

This paper presents an interactive watercolor rendering technique that recreates the specific visual effects of lavis watercolor. Our method allows the user to easily process images and 3d models and is organized in two steps: an abstraction step that ... Keywords: abstraction, non-photorealistic rendering, temporal coherence, watercolor

Adrien Bousseau; Matt Kaplan; Joëlle Thollot; François X. Sillion

2006-06-01T23:59:59.000Z

445

Pulse-to-Pulse Coherent Doppler Sonar Signal Processing Techniques  

Science Conference Proceedings (OSTI)

In this paper we present and discuss techniques for the computation of the mean and spectral variance of a pulse-to-pulse coherent sonar signal, leading to the measurement of mean water velocity and turbulence. The use of an autocovariance ...

Roger Lhermitte; Robert Serafin

1984-12-01T23:59:59.000Z

446

Progressing UK Energy Research for a Coherent Structure with Impact  

E-Print Network (OSTI)

the deployment of affordable green energy technologies that decarbonise our energy supply and increase energy with their collaborators in industry who are so vital to the health of UK Energy research, for rising to the challengesProgressing UK Energy Research for a Coherent Structure with Impact Report of the International

Berzins, M.

447

Atmospheric Lagrangian coherent structures considering unresolved turbulence and forecast uncertainty  

E-Print Network (OSTI)

Atmospheric Lagrangian coherent structures considering unresolved turbulence and forecast, the uncertainty of the forecast FTLE fields is analyzed using ensemble forecasting. Unavoidable errors of the forecast velocity data due to the chaotic dynamics of the atmosphere is the salient reason for errors

Ross, Shane

448

Coherent spin control by electrical manipulation of the magnetic anisotropy  

E-Print Network (OSTI)

High-spin paramagnetic manganese defects in polar piezoelectric zinc oxide exhibit a simple almost axial anisotropy and phase coherence times of the order of a millisecond at low temperatures. The anisotropy energy is tunable using an externally applied electric field. This can be used to control electrically the phase of spin superpositions and to drive spin transitions with resonant microwave electric fields.

Richard E George; James P Edwards; Arzhang Ardavan

2012-09-12T23:59:59.000Z

449

Quantum coherent switch utilizing commensurate nanoelectrode and charge density periodicities  

DOE Patents (OSTI)

A quantum coherent switch having a substrate formed from a density wave (DW) material capable of having a periodic electron density modulation or spin density modulation, a dielectric layer formed onto a surface of the substrate that is orthogonal to an intrinsic wave vector of the DW material; and structure for applying an external spatially periodic electrostatic potential over the dielectric layer.

Harrison, Neil (Santa Fe, NM); Singleton, John (Los Alamos, NM); Migliori, Albert (Santa Fe, NM)

2008-08-05T23:59:59.000Z

450

Non-Markovian decoherence dynamics of entangled coherent states  

Science Conference Proceedings (OSTI)

We microscopically model the decoherence dynamics of entangled coherent states of twooptical modes under the influence of vacuum fluctuation. We derive an exact masterequation with time-dependent coefficients reflecting the memory effect of the environ-ment, ... Keywords: decoherence theory, exact master equation, non-Markovian dynamics

Jun-Hong An; Mang Feng; Wei-Min Zhang

2009-03-01T23:59:59.000Z

451

High power regenerative laser amplifier  

DOE Patents (OSTI)

A regenerative amplifier design capable of operating at high energy per pulse, for instance, from 20-100 Joules, at moderate repetition rates, for instance from 5-20 Hertz is provided. The laser amplifier comprises a gain medium and source of pump energy coupled with the gain medium; a Pockels cell, which rotates an incident beam in response to application of a control signal; an optical relay system defining a first relay plane near the gain medium and a second relay plane near the rotator; and a plurality of reflectors configured to define an optical path through the gain medium, optical relay and Pockels cell, such that each transit of the optical path includes at least one pass through the gain medium and only one pass through the Pockels cell. An input coupler, and an output coupler are provided, implemented by a single polarizer. A control circuit coupled to the Pockels cell generates the control signal in timed relationship with the input pulse so that the input pulse is captured by the input coupler and proceeds through at least one transit of the optical path, and then the control signal is applied to cause rotation of the pulse to a polarization reflected by the polarizer, after which the captured pulse passes through the gain medium at least once more and is reflected out of the optical path by the polarizer before passing through the rotator again to provide an amplified pulse.

Miller, John L. (Livermore, CA); Hackel, Lloyd A. (Livermore, CA); Dane, Clifford B. (Dublin, CA); Zapata, Luis E. (Livermore, CA)

1994-01-01T23:59:59.000Z

452

High power regenerative laser amplifier  

DOE Patents (OSTI)

A regenerative amplifier design capable of operating at high energy per pulse, for instance, from 20-100 Joules, at moderate repetition rates, for instance from 5-20 Hertz is provided. The laser amplifier comprises a gain medium and source of pump energy coupled with the gain medium; a Pockels cell, which rotates an incident beam in response to application of a control signal; an optical relay system defining a first relay plane near the gain medium and a second relay plane near the rotator; and a plurality of reflectors configured to define an optical path through the gain medium, optical relay and Pockels cell, such that each transit of the optical path includes at least one pass through the gain medium and only one pass through the Pockels cell. An input coupler, and an output coupler are provided, implemented by a single polarizer. A control circuit coupled to the Pockels cell generates the control signal in timed relationship with the input pulse so that the input pulse is captured by the input coupler and proceeds through at least one transit of the optical path, and then the control signal is applied to cause rotation of the pulse to a polarization reflected by the polarizer, after which the captured pulse passes through the gain medium at least once more and is reflected out of the optical path by the polarizer before passing through the rotator again to provide an amplified pulse. 7 figures.

Miller, J.L.; Hackel, L.A.; Dane, C.B.; Zapata, L.E.

1994-02-08T23:59:59.000Z

453

High power gas transport laser  

SciTech Connect

Continuous wave output power from a gas transport laser is substantially increased by disposing a plurality of parallel cylindrically tubular cathodes in the main stream transversely of the direction of gas flow and spaced above a coextensive segmented anode in the opposite wall of the channel. Ballast resistors are connected between the cathodes, respectively, and the power supply to optimize the uniform arcless distribution of current passing between each cathode and the anode. Continuous output power greater than 3 kW is achieved with this electrode configuration.

Fahlen, T.S.; Kirk, R.F.

1978-02-28T23:59:59.000Z

454

THz near-field imaging of biological tissues employing synchrotron radiation  

E-Print Network (OSTI)

A. Kleinman, “Cherenkov radiation from femtosecond opticalcoherent u u synchrotron radiation detected at BESSY II,”High-power terahertz radiation from relativistic electrons,”

Schade, Ulrich; Holldack, Karsten; Martin, Michael C.; Fried, Daniel

2004-01-01T23:59:59.000Z

455

Coherence-Centric Logging and Recovery for Home-Based Software Distributed Shared Memory  

E-Print Network (OSTI)

Coherence-Centric Logging and Recovery for Home-Based Software Distributed Shared Memory Angkul, called the coherence-centric logging (CCL) and re- covery protocol, for home-based SDSM. Our CCL mini access latency by overlapping disk accesses with coherence-induced com- munication existing in home-based

Tzeng, Nian-Feng

456

Analysis of cache-coherence bottlenecks with hybrid hardware/software techniques  

Science Conference Proceedings (OSTI)

Application performance on high-performance shared-memory systems is often limited by sharing patterns resulting in cache-coherence bottlenecks. Current approaches to identify coherence bottlenecks incur considerable run-time overhead and do not scale. ... Keywords: Hardware performance monitoring, SMPs, cache analysis, coherence protocols, dynamic binary rewriting, program instrumentation

Jaydeep Marathe; Frank Mueller; Bronis R. de Supinski

2006-12-01T23:59:59.000Z

457

Sub-terahertz, microwaves and high energy emissions during the December 6, 2006 flare, at 18:40 UT  

E-Print Network (OSTI)

The presence of a solar burst spectral component with flux density increasing with frequency in the sub-terahertz range, spectrally separated from the well-known microwave spectral component, bring new possibilities to explore the flaring physical processes, both observational and theoretical. The solar event of 6 December 2006, starting at about 18:30 UT, exhibited a particularly well-defined double spectral structure, with the sub-THz spectral component detected at 212 and 405 GHz by SST and microwaves (1-18 GHz) observed by the Owens Valley Solar Array (OVSA). Emissions obtained by instruments in satellites are discussed with emphasis to ultra-violet (UV) obtained by the Transition Region And Coronal Explorer (TRACE), soft X-rays from the Geostationary Operational Environmental Satellites (GOES) and X- and gamma-rays from the Ramaty High Energy Solar Spectroscopic Imager (RHESSI). The sub-THz impulsive component had its closer temporal counterpart only in the higher energy X- and gamma-rays ranges. The spatial positions of the centers of emission at 212 GHz for the first flux enhancement were clearly displaced by more than one arc-minute from positions at the following phases. The observed sub-THz fluxes and burst source plasma parameters were found difficult to be reconciled to a purely thermal emission component. We discuss possible mechanisms to explain the double spectral components at microwaves and in the THz ranges.

Pierre Kaufmann; Gerard Trottet; C. Guillermo Gimenez de Castro; Jean-Pierre Raulin; Sam Krucker; Albert Y. Shih; Hugo Levato

2008-11-21T23:59:59.000Z

458

Generation and use of high power 213 nm and 266 nm laser radiation and tunable 210-400 nm laser radiation with BBO crystal matrix array  

SciTech Connect

A 213 nm laser beam is capable of single photon ablative photodecomposition for the removal of a polymer or biological material substrate. Breaking the molecular bonds and displacing the molecules away from the substrate in a very short time period results in most of the laser photon energy being carried away by the displaced molecules, thus minimizing thermal damage to the substrate. The incident laser beam may be unfocussed and is preferably produced by quintupling the 1064 nm radiation from a Nd:YAG solid state laser, i.e., at 213 nm. In one application, the 213 nm laser beam is expanded in cross section and directed through a plurality of small beta barium borate (BBO) crystals for increasing the energy per photon of the laser radiation directed onto the substrate. The BBO crystals are arranged in a crystal matrix array to provide a large laser beam transmission area capable of accommodating high energy laser radiation without damaging the BBO crystals. The BBO crystal matrix array may also be used with 266 nm laser radiation for carrying out single or multi photon ablative photodecomposition. The BBO crystal matrix array may also be used in an optical parametric oscillator mode to generate high power tunable laser radiation in the range of 210-400 nm.

Gruen, Dieter M. (Downers Grove, IL)

2000-01-01T23:59:59.000Z

459

Resonant Regimes in the Fock-Space Coherence of Multilevel Quantum Dots  

E-Print Network (OSTI)

The coherence between quantum states with different particle numbers --- the Fock-space coherence --- qualitatively differs from the more common Hilbert-space coherence between states with equal particle numbers. For a quantum dot with multiple channels available for transport, we find the conditions for decoupling the dynamics of the Fock-space coherence from both the Hilbert-space coherence as well as the population dynamics. We further find specific energy and coupling regimes where a long-lived resonance in the Fock-space coherence of the system is realized, even where no resonances are found either in the populations or Hilbert-space coherence. Numerical calculations show this resonance remains robust in the presence of both boson-mediated relaxation and transport through the quantum dot.

Eduardo Vaz; Jordan Kyriakidis

2011-05-26T23:59:59.000Z

460

Apparatus for generating coherent infrared energy of selected wavelength  

SciTech Connect

A tunable source (11) of coherent infrared energy includes a heat pipe (12) having an intermediate region (24) at which cesium (22) is heated to vaporizing temperature and end regions (27, 28) at which the vapor is condensed and returned to the intermediate region (24) for reheating and recirculation. Optical pumping light (43) is directed along the axis of the heat pipe (12) through a first end window (17) to stimulate emission of coherent infrared energy which is transmitted out through an opposite end window (18). A porous walled tubulation (44) extends along the axis of the heat pipe (12) and defines a region (46) in which cesium vapor is further heated to a temperature sufficient to dissociate cesium dimers which would decrease efficiency by absorbing pump light (43). Efficient generation of any desired infrared wavelength is realized by varying the wavelength of the pump light (43).

Stevens, Charles G. (Danville, CA)

1985-01-01T23:59:59.000Z

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461

Coherence of an optically illuminated single nuclear spin qubit  

E-Print Network (OSTI)

We investigate the coherence properties of individual nuclear spin quantum bits in diamond [Dutt et al., Science, 316, 1312 (2007)] when a proximal electronic spin associated with a nitrogen-vacancy (NV) center is being interrogated by optical radiation. The resulting nuclear spin dynamics are governed by time-dependent hyperfine interaction associated with rapid electronic transitions, which can be described by a spin-fluctuator model. We show that due to a process analogous to motional averaging in nuclear magnetic resonance, the nuclear spin coherence can be preserved after a large number of optical excitation cycles. Our theoretical analysis is in good agreement with experimental results. It indicates a novel approach that could potentially isolate the nuclear spin system completely from the electronic environment.

Liang Jiang; M. V. Gurudev Dutt; Emre Togan; Lily Childress; Paola Cappellaro; Jacob M. Taylor; Mikhail D. Lukin

2007-07-09T23:59:59.000Z

462

Development of coherent Raman measurements of temperature in condensed phases  

SciTech Connect

We report theoretical considerations and preliminary data on various forms of coherent Raman spectroscopy that have been considered as candidates for measurement of temperature in condensed phase experiments with picosecond time resolution. Due to the inherent broadness and congestion of vibrational features in condensed phase solids, particularly at high temperatures and pressures, only approaches that rely on the ratio of anti-Stokes to Stokes spectral features are considered. Methods that rely on resolution of vibrational progressions, calibration of frequency shifts with temperature and pressure in reference experiments, or detailed comparison to calculation are inappropriate or impossible for our applications. In particular, we consider femtosecond stimulated Raman spectroscopy (FSRS), femtosecond/picosecond hybrid coherent Raman spectroscopy (multiplex CARS), and optical heterodyne detected femtosecond Raman induced Kerr Effect spectroscopy (OHD-FRIKES). We show that only FSRS has the ability to measure temperature via an anti-Stokes to Stokes ratio of peaks.

Mcgrane, Shawn D [Los Alamos National Laboratory; Dang, Nhan C [Los Alamos National Laboratory; Bolme, Cindy A [Los Alamos National Laboratory; Moore, David S [Los Alamos National Laboratory

2010-12-08T23:59:59.000Z

463

Probing mechanical quantum coherence with an ultracold-atom meter  

Science Conference Proceedings (OSTI)

We propose a scheme to probe quantum coherence in the state of a nanocantilever based on its magnetic coupling (mediated by a magnetic tip) with a spinor Bose Einstein condensate (BEC). By mapping the BEC into a rotor, its coupling with the cantilever results in a gyroscopic motion whose properties depend on the state of the cantilever: the dynamics of one of the components of the rotor angular momentum turns out to be strictly related to the presence of quantum coherence in the state of the cantilever. We also suggest a detection scheme relying on Faraday rotation, which produces only a very small back-action on the BEC and is thus suitable for a continuous detection of the cantilever's dynamics.

Lo Gullo, N.; Busch, Th. [Department of Physics, University College Cork, Cork (Ireland); Palma, G. M. [NEST Istituto Nanoscienze-CNR and Dipartimento di Fisica, Univerisita' degli Studi di Palermo, Via Archirafi 36, I-90123 Palermo (Italy); Paternostro, M. [Centre for Theoretical Atomic, Molecular and Optical Physics, School of Mathematics and Physics, Queen's University, Belfast BT7 1NN (United Kingdom)

2011-12-15T23:59:59.000Z

464

Coherent manipulation of atomic qubits in optical micropotentials  

E-Print Network (OSTI)

We experimentally demonstrate the coherent manipulation of atomic states in far-detuned dipole traps and registers of dipole traps based on two-dimensional arrays of microlenses. By applying Rabi, Ramsey, and spin-echo techniques, we systematically investigate the dephasing mechanisms and determine the coherence time. Simultaneous Ramsey measurements in up to 16 dipole traps are performed and proves the scalability of our approach. This represents an important step in the application of scalable registers of atomic qubits for quantum information processing. In addition, this system can serve as the basis for novel atomic clocks making use of the parallel operation of a large number of individual clocks each remaining separately addressable.

A. Lengwenus; J. Kruse; M. Volk; W. Ertmer; G. Birkl

2007-02-09T23:59:59.000Z

465

Holographic entanglement and causal information in coherent states  

E-Print Network (OSTI)

Scalar solitons in global AdS4 are holographically dual to coherent states carrying a non-trivial condensate of a scalar operator. We study the holographic information content of these states, focusing on a particular spatial region, by examining the entanglement entropy and causal holographic information. We show generically that whenever the dimension of the condensed operator is sufficiently low (characterized by the double-trace operator becoming relevant), such coherent states have lower entanglement and causal holographic information than the vacuum state of the system, despite having greater energy. We also use these geometries to illustrate the fact that causal wedges associated with a simply-connected boundary region can have non-trivial topology even in causally trivial spacetimes.

Simon A. Gentle; Mukund Rangamani

2013-10-31T23:59:59.000Z

466

From cardinal spline wavelet bases to highly coherent dictionaries  

E-Print Network (OSTI)

Wavelet families arise by scaling and translations of a prototype function, called the {\\em {mother wavelet}}. The construction of wavelet bases for cardinal spline spaces is generally carried out within the multi-resolution analysis scheme. Thus, the usual way of increasing the dimension of the multi-resolution subspaces is by augmenting the scaling factor. We show here that, when working on a compact interval, the identical effect can be achieved without changing the wavelet scale but reducing the translation parameter. By such a procedure we generate a redundant frame, called a {\\em{dictionary}}, spanning the same spaces as a wavelet basis but with wavelets of broader support. We characterise the correlation of the dictionary elements by measuring their `coherence' and produce examples illustrating the relevance of highly coherent dictionaries to problems of sparse signal representation.

Andrle, Miroslav

2008-01-01T23:59:59.000Z

467

Optimal design and quantum benchmarks for coherent state amplifiers  

E-Print Network (OSTI)

We establish the ultimate quantum limits to the amplification of an unknown coherent state, both in the deterministic and probabilistic case, investigating the realistic scenario where the expected photon number is finite. In addition, we provide the benchmark that experimental realizations have to surpass in order to beat all classical amplification strategies and to demonstrate genuine quantum amplification. Our result guarantees that a successful demonstration is in principle possible for every finite value of the expected photon number.

Giulio Chiribella; Jinyu Xie

2013-01-07T23:59:59.000Z