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- Laser wakefield acceleration (7)
- Blowout regime (6)
- Laser wakefield acceleration (theory) (4)
- Electron self-injection (3)
- Laser wakefield acceleration (numerical support of the experiment) (3)
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- Optical shock (3)
- DIOCLES laser (2)
- GeV electrons from laser plasmas (2)
- Particle-in-cell simulation (2)
- Particle-in-cell simulations (2)
- 2 GeV electrons from laser plasmas (1)
- All-optical control of electron trapping (1)
- Beam transport (1)
- Betatron radiation (1)
- Cathode (1)
- Chebyshev formalism (1)
- FEL (1)
- Hegative group velocity dispersion (1)
- Infrared (1)
- Laser (1)
- Light Wave Synthesizer (1)
- Magnetic fields (1)
- Photo (1)
- Pulse (1)
- Relativistic optical shock (1)
- Texas Petawatt laser (1)
- UV (1)
- X-ray (1)
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Articles 1 - 16 of 16
Full-Text Articles in Optics
Petawatt-Laser-Driven Wakefield Acceleration Of Electrons To 2 Gev In 10^{17} Cm^{-3} Plasma, Xiaoming Wang, Rafal B. Zgadzaj, Neil Fazel, Sunghwan A. Yi, X. Zhang, Watson Henderson, Yen-Yu Zhang, Rick Korzekwa, Hai-En Tsai, C.-H. Pai, Zhengyan Li, Hernan Quevedo, Gilliss Dyer, Erhard W. Gaul, Mikael Martinez, Aaron Bernstein, Ted Borger, M. Spinks, M. Donovan, Serguei Y. Kalmykov, Vladimir N. Khudik, Gennady Shvets, Todd Ditmire, Michael C. Downer
Petawatt-Laser-Driven Wakefield Acceleration Of Electrons To 2 Gev In 10^{17} Cm^{-3} Plasma, Xiaoming Wang, Rafal B. Zgadzaj, Neil Fazel, Sunghwan A. Yi, X. Zhang, Watson Henderson, Yen-Yu Zhang, Rick Korzekwa, Hai-En Tsai, C.-H. Pai, Zhengyan Li, Hernan Quevedo, Gilliss Dyer, Erhard W. Gaul, Mikael Martinez, Aaron Bernstein, Ted Borger, M. Spinks, M. Donovan, Serguei Y. Kalmykov, Vladimir N. Khudik, Gennady Shvets, Todd Ditmire, Michael C. Downer
Serge Youri Kalmykov
Electron self-injection into a laser-plasma accelerator (LPA) driven by the Texas Petawatt (TPW) laser is reported at plasma densities 1.7 - 6.2 x 10^{17} cm^{-3}. Energy and charge of the electron beam, ranging from 0.5 GeV to 2 GeV and tens to hundreds of pC, respectively, depended strongly on laser beam quality and plasma density. Angular beam divergence was consistently around 0.5 mrad (FWHM), while shot-to-shot pointing fluctuations were limited to ±1.4 mrad rms. Betatron x-rays with tens of keV photon energy are also clearly observed.
Sub-Millimeter-Scale, 100-Mev-Class Quasi-Monoenergetic Laser Plasma Accelerator Based On All-Optical Control Of Dark Current In The Blowout Regime, Serguei Y. Kalmykov, Xavier Davoine, Bradley A. Shadwick
Sub-Millimeter-Scale, 100-Mev-Class Quasi-Monoenergetic Laser Plasma Accelerator Based On All-Optical Control Of Dark Current In The Blowout Regime, Serguei Y. Kalmykov, Xavier Davoine, Bradley A. Shadwick
Serge Youri Kalmykov
It is demonstrated that by negatively chirping the frequency of a 20-fs, 15-TW driving laser pulse with an ultrabroad bandwidth (corresponding to a sub-2-cycle transform-limited duration it is possible to prevent early compression of the pulse into an optical shock, thus reducing expansion of the accelerating plasma bucket (electron density "bubble") and delaying dephasing of self-injected and accelerated electrons. These features help suppress unwanted continuous self-injection (dark current) in the blowout regime, making possible to use the entire dephasing length to generate low-background, quasi-monoenergetic 200-MeV-scale electron beams from sub-mm-length, dense plasmas (n_{e0} = 1.3 x 10^{19} cm^{−3}).
Commissioning Of The Asta Laser Lab With Uv Pulse Length Characterization, Daniel Kelley, Jeff Corbett
Commissioning Of The Asta Laser Lab With Uv Pulse Length Characterization, Daniel Kelley, Jeff Corbett
STAR Program Research Presentations
The Linac Coherent Light Source (LCLS) at SLAC depends on a photocathode electron gun to provide the linear accelerator with the raw material – electrons – used for making X-ray laser pulses. The photocathode used in the LCLS Injector is a clean copper plate in high vacuum. When the cathode is struck with high energy UV light, electrons are liberated from its surface and then accelerated down the linac with radio-frequency electric fields. These fast-moving bunches of electrons are directed through an undulator magnet to radiate X-ray light.
Although scientists have been using photocathode techniques at SLAC for 25 years, …
Capacitively Coupled Radio-Frequency Discharges In Nitrogen At Low Pressures, L. L Alves, L. Marques, C. D Pintassilgo, W. Wattieaux, Et. Es-Sebbar, J. Berndt, E. Kovačević, N. Carrasco, L. Boufendi, G. Cernogora
Capacitively Coupled Radio-Frequency Discharges In Nitrogen At Low Pressures, L. L Alves, L. Marques, C. D Pintassilgo, W. Wattieaux, Et. Es-Sebbar, J. Berndt, E. Kovačević, N. Carrasco, L. Boufendi, G. Cernogora
Dr. Et-touhami Es-sebbar
This paper uses experiments and modelling to study capacitively coupled radio-frequency (rf) discharges in pure nitrogen, at 13.56 MHz frequency, 0.1–1 mbar pressures and 2–30 W coupled powers. Experiments performed on two similar (not twin) setups, existing in the LATMOS and the GREMI laboratories, include electrical and optical emission spectroscopy (OES) measurements. Electrical measurements give the rf-applied and the direct-current-self-bias voltages, the effective power coupled to the plasma and the average electron density. OES diagnostics measure the intensities of radiative transitions with the nitrogen second-positive and first-negative systems, and with the 811.5 nm atomic line of argon (present as an …
Application Of Chebyshev Formalism To Identify Nonlinear Magnetic Field Components In Beam Transport System, Michael Spata
Application Of Chebyshev Formalism To Identify Nonlinear Magnetic Field Components In Beam Transport System, Michael Spata
Physics Theses & Dissertations
An experiment was conducted at Jefferson Lab's Continuous Electron Beam Accelerator Facility to develop a beam-based technique for characterizing the extent of the nonlinearity of the magnetic fields of a beam transport system. Horizontally and vertically oriented pairs of air-core kicker magnets were simultaneously driven at two different frequencies to provide a time-dependent transverse modulation of the beam orbit relative to the unperturbed reference orbit. Fourier decomposition of the position data at eight different points along the beamline was then used to measure the amplitude of these frequencies. For a purely linear transport system one expects to find solely the …
Ionization Photophysics And Rydberg Spectroscopy Of Diacetylene, M. Schwell, Y. Benilan, N.. Fray, M.-C. Gazeau, Et. Es-Sebbar, F.-G. Levrel, N. Campion, S. Leach
Ionization Photophysics And Rydberg Spectroscopy Of Diacetylene, M. Schwell, Y. Benilan, N.. Fray, M.-C. Gazeau, Et. Es-Sebbar, F.-G. Levrel, N. Campion, S. Leach
Dr. Et-touhami Es-sebbar
Photoionization of diacetylene was studied using synchrotron radiation over the range 8–24 eV, with photoelectron-photoion coincidence (PEPICO) and threshold photoelectron–photoion coincidence (TPEPICO) techniques. Mass spectra, ion yields, total and partial ionization cross-sections were measured. The adiabatic ionization energy of diacetylene was determined as IEad = (10.17 ± 0.01) eV, and the appearance energy of the principal fragment ion C4H+ as AE = (16.15 ± 0.03) eV. Calculated appearance energies of other fragment ions were used to infer aspects of dissociation pathways forming the weaker fragment ions , C3H+, and C2H+. Structured autoionization features observed in the PEPICO spectrum of diacetylene …
Computationally Efficient Methods For Modelling Laser Wakefield Acceleration In The Blowout Regime, Benjamin M. Cowan, Serguei Y. Kalmykov, Arnaud Beck, Xavier Davoine, Kyle Bunkers, Agustin F. Lifschitz, Erik Lefebvre, David L. Bruhwiler, Bradley A. Shadwick, Donald P. Umstadter
Computationally Efficient Methods For Modelling Laser Wakefield Acceleration In The Blowout Regime, Benjamin M. Cowan, Serguei Y. Kalmykov, Arnaud Beck, Xavier Davoine, Kyle Bunkers, Agustin F. Lifschitz, Erik Lefebvre, David L. Bruhwiler, Bradley A. Shadwick, Donald P. Umstadter
Donald P. Umstadter
Electron self-injection and acceleration until dephasing in the blowout regime is studied for a set of initial conditions typical of recent experiments with 100-terawatt-class lasers. Two different approaches to computationally efficient, fully explicit, 3D particle-in-cell modelling are examined. First, the Cartesian code VORPAL (Nieter, C. and Cary, J. R. 2004 VORPAL: a versatile plasma simulation code. J. Comput. Phys. 196, 538) using a perfect-dispersion electromagnetic solver precisely describes the laser pulse and bubble dynamics, taking advantage of coarser resolution in the propagation direction, with a proportionally larger time step. Using third-order splines for macroparticles helps suppress the sampling noise while …
Computationally Efficient Methods For Modelling Laser Wakefield Acceleration In The Blowout Regime, Benjamin M. Cowan, Serguei Y. Kalmykov, Arnaud Beck, Xavier Davoine, Kyle Bunkers, Agustin F. Lifschitz, Erik Lefebvre, David L. Bruhwiler, Bradley A. Shadwick, Donald P. Umstadter
Computationally Efficient Methods For Modelling Laser Wakefield Acceleration In The Blowout Regime, Benjamin M. Cowan, Serguei Y. Kalmykov, Arnaud Beck, Xavier Davoine, Kyle Bunkers, Agustin F. Lifschitz, Erik Lefebvre, David L. Bruhwiler, Bradley A. Shadwick, Donald P. Umstadter
Serge Youri Kalmykov
Electron self-injection and acceleration until dephasing in the blowout regime is studied for a set of initial conditions typical of recent experiments with 100-terawatt-class lasers. Two different approaches to computationally efficient, fully explicit, 3D particle-in-cell modelling are examined. First, the Cartesian code VORPAL (Nieter, C. and Cary, J. R. 2004 VORPAL: a versatile plasma simulation code. J. Comput. Phys. 196, 538) using a perfect-dispersion electromagnetic solver precisely describes the laser pulse and bubble dynamics, taking advantage of coarser resolution in the propagation direction, with a proportionally larger time step. Using third-order splines for macroparticles helps suppress the sampling noise while …
Gaussian Beam Steering On A Target Plane Via High Speed Orthogonal Mirror-Mounted Galvanometers, Keith Gresiak
Gaussian Beam Steering On A Target Plane Via High Speed Orthogonal Mirror-Mounted Galvanometers, Keith Gresiak
Physics
No abstract provided.
Generation Of Tunable, 100–800 Mev Quasi-Monoenergetic Electron Beams From A Laser-Wakefield Accelerator In The Blowout Regime, Sudeep Banerjee, Nathan D. Powers, Vidiya Ramanathan, Isaac Ghebregziabher, Kevin J. Brown, Chakra M. Maharjan, Shouyuan Chen, Arnaud Beck, Erik Lefebvre, Serguei Y. Kalmykov, Bradley A. Shadwick, Donald P. Umstadter
Generation Of Tunable, 100–800 Mev Quasi-Monoenergetic Electron Beams From A Laser-Wakefield Accelerator In The Blowout Regime, Sudeep Banerjee, Nathan D. Powers, Vidiya Ramanathan, Isaac Ghebregziabher, Kevin J. Brown, Chakra M. Maharjan, Shouyuan Chen, Arnaud Beck, Erik Lefebvre, Serguei Y. Kalmykov, Bradley A. Shadwick, Donald P. Umstadter
Donald P. Umstadter
In this paper, we present results on a scalable high-energy electron source based on laser wakefield acceleration. The electron accelerator using 30 - 80 TW, 30 fs laser pulses, operates in the blowout regime, and produces high-quality, quasi-monoenergetic electron beams in the range 100 - 800 MeV. These beams have angular divergence of 1 - 4 mrad, and 5 - 25 percent energy spread, with a resulting brightness 10^{11} electrons mm^{-2} MeV^{-1} mrad^{-2}. The beam parameters can be tuned by varying the laser and plasma conditions. The use of a high-quality laser pulse and appropriate target conditions enables optimization of …
Generation Of Tunable, 100–800 Mev Quasi-Monoenergetic Electron Beams From A Laser-Wakefield Accelerator In The Blowout Regime, Sudeep Banerjee, Nathan D. Powers, Vidiya Ramanathan, Isaac Ghebregziabher, Kevin J. Brown, Chakra M. Maharjan, Shouyuan Chen, Arnaud Beck, Erik Lefebvre, Serguei Y. Kalmykov, Bradley A. Shadwick, Donald P. Umstadter
Generation Of Tunable, 100–800 Mev Quasi-Monoenergetic Electron Beams From A Laser-Wakefield Accelerator In The Blowout Regime, Sudeep Banerjee, Nathan D. Powers, Vidiya Ramanathan, Isaac Ghebregziabher, Kevin J. Brown, Chakra M. Maharjan, Shouyuan Chen, Arnaud Beck, Erik Lefebvre, Serguei Y. Kalmykov, Bradley A. Shadwick, Donald P. Umstadter
Serge Youri Kalmykov
In this paper, we present results on a scalable high-energy electron source based on laser wakefield acceleration. The electron accelerator using 30 - 80 TW, 30 fs laser pulses, operates in the blowout regime, and produces high-quality, quasi-monoenergetic electron beams in the range 100 - 800 MeV. These beams have angular divergence of 1 - 4 mrad, and 5 - 25 percent energy spread, with a resulting brightness 10^{11} electrons mm^{-2} MeV^{-1} mrad^{-2}. The beam parameters can be tuned by varying the laser and plasma conditions. The use of a high-quality laser pulse and appropriate target conditions enables optimization of …
Laser Plasma Acceleration With A Negatively Chirped Pulse: All-Optical Control Over Dark Current In The Blowout Regime, Serguei Y. Kalmykov, Arnaud Beck, Xavier Davoine, Erik Lefebvre, Bradley A. Shadwick
Laser Plasma Acceleration With A Negatively Chirped Pulse: All-Optical Control Over Dark Current In The Blowout Regime, Serguei Y. Kalmykov, Arnaud Beck, Xavier Davoine, Erik Lefebvre, Bradley A. Shadwick
Serge Youri Kalmykov
Recent experiments with 100 terawatt-class, sub-50 femtosecond laser pulses show that electrons self-injected into a laser-driven electron density bubble can be accelerated above 0.5 gigaelectronvolt energy in a sub-centimetre length rarefied plasma. To reach this energy range, electrons must ultimately outrun the bubble and exit the accelerating phase; this, however, does not ensure high beam quality. Wake excitation increases the laser pulse bandwidth by red-shifting its head, keeping the tail unshifted. Anomalous group velocity dispersion of radiation in plasma slows down the red-shifted head, compressing the pulse into a few-cycle-long piston of relativistic intensity. Pulse transformation into a piston causes …
Volatile Products Controlling Titan’S Tholins Production, N. Carrasco, T. Gautier, Et. Es-Sebbar, P. Pernot, G. Cernogora
Volatile Products Controlling Titan’S Tholins Production, N. Carrasco, T. Gautier, Et. Es-Sebbar, P. Pernot, G. Cernogora
Dr. Et-touhami Es-sebbar
A quantitative agreement between nitrile relative abundances and Titan’s atmospheric composition was recently shown with a reactor simulating the global chemistry occurring in Titan’s atmosphere [Gautier et al. (2011) Icarus, 213: 625]. Here we present a complementary study on the same reactor using an in-situ diagnostic of the gas phase composition. Various initial N2-CH4 gas mixtures (methane varying from 1 to 10%) are studied, with a monitoring of the methane consumption and of the stable gas neutrals by in-situ mass spectrometry. Atomic hydrogen is also measured by optical emission spectroscopy. A positive correlation is found between atomic hydrogen abundance and …
Vuv Photoionization Of Acetamide Studied By Electron / Ion Coincidence Spectroscopy In The 8-24 Ev Photon Energy Range, M. Schwell, Y. Bénilan, N. Fray, M.-C Gazeau, Et. Es-Sebbar, Gustavo A. Garcia, L. Nahon, N. Champion, S. Leach
Vuv Photoionization Of Acetamide Studied By Electron / Ion Coincidence Spectroscopy In The 8-24 Ev Photon Energy Range, M. Schwell, Y. Bénilan, N. Fray, M.-C Gazeau, Et. Es-Sebbar, Gustavo A. Garcia, L. Nahon, N. Champion, S. Leach
Dr. Et-touhami Es-sebbar
A VUV photoionization study of acetamide was carried out over the 8-24 eV photon energy range using synchrotron radiation and photoelectron/photoion coincidence (PEPICO) spectroscopy. Threshold photoelectron photoion coincidence (TPEPICO) measurements were also made. Photoion yield curves and branching ratios were measured for the parent ion and six fragment ions. The adiabatic ionization energy of acetamide was determined as I.E (12A’) = (9.71±0.02) eV, in agreement with an earlier reported photoionization mass spectrometry (PIMS) value. The adiabatic energy of the first excited state of the ion, 12A”, was determined to be ≈ 10.1 eV. Assignments of the fragment ions and the …
Assessing The Feasibility Of Cosmic-Ray Acceleration By Magnetic Turbulence At The Magnetic Center, M. Fatuzzo, F. Melia
Assessing The Feasibility Of Cosmic-Ray Acceleration By Magnetic Turbulence At The Magnetic Center, M. Fatuzzo, F. Melia
Faculty Scholarship
No abstract provided.
Quantitative Study Of Spin-Flip Co-Tunneling Transport In A Quantum Dot, S. Herbert, T-M. Liu, A. N. Ngo
Quantitative Study Of Spin-Flip Co-Tunneling Transport In A Quantum Dot, S. Herbert, T-M. Liu, A. N. Ngo
Faculty Scholarship
No abstract provided.