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- Laser wakefield acceleration (3)
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Articles 1 - 8 of 8
Full-Text Articles in Physics
All-Optical Control Of Electron Trapping In Plasma Channels, Serguei Y. Kalmykov, Bradley A. Shadwick, Xavier Davoine
All-Optical Control Of Electron Trapping In Plasma Channels, Serguei Y. Kalmykov, Bradley A. Shadwick, Xavier Davoine
Serge Youri Kalmykov
The accelerating bucket of a laser-plasma accelerator (a cavity of electron density maintained by the laser pulse radiation pressure) evolves slowly, in lock-step with the optical driver, and readily traps background electrons. The trapping process can thus be controlled by purely optical means. Sharp gradients in the nonlinear refractive index produce a large frequency red-shift, localized at the leading edge of the pulse. Negative group velocity dispersion associated with the plasma response compresses the laser pulse into a relativistic optical shock (ROS), slowing the pulse (and the bucket), reducing the electron dephasing length, and limiting energy gain. Even more importantly, …
Stable, Tunable, Quasimonoenergetic Electron Beams Produced In A Laser Wakefield Near The Threshold For Self-Injection, Sudeep Banerjee, Serguei Y. Kalmykov, Nathan D. Powers, Gregory Golovin, Vidiya Ramanathan, Nathan J. Cunningham, Kevin J. Brown, Shouyuan Chen, Isaac Ghebregziabher, Bradley A. Shadwick, Donald P. Umstadter, Benjamin A. Cowan, David L. Bruhwiler, Arnaud Beck, Erik Lefebvre
Stable, Tunable, Quasimonoenergetic Electron Beams Produced In A Laser Wakefield Near The Threshold For Self-Injection, Sudeep Banerjee, Serguei Y. Kalmykov, Nathan D. Powers, Gregory Golovin, Vidiya Ramanathan, Nathan J. Cunningham, Kevin J. Brown, Shouyuan Chen, Isaac Ghebregziabher, Bradley A. Shadwick, Donald P. Umstadter, Benjamin A. Cowan, David L. Bruhwiler, Arnaud Beck, Erik Lefebvre
Donald P. Umstadter
Stable operation of a laser-plasma accelerator near the threshold for electron self-injection in the blowout regime has been demonstrated with 25–60 TW, 30 fs laser pulses focused into a 3–4 millimeter length gas jet. Nearly Gaussian shape and high nanosecond contrast of the focused pulse appear to be critically important for controllable, tunable generation of 250–430 MeV electron bunches with a low energy spread, ~ 10 pC charge, a few-mrad divergence and pointing stability, and a vanishingly small low-energy background. The physical nature of the near-threshold behavior is examined using three-dimensional particle-in-cell simulations. Simulations indicate that properly locating the nonlinear …
Stable, Tunable, Quasimonoenergetic Electron Beams Produced In A Laser Wakefield Near The Threshold For Self-Injection, Sudeep Banerjee, Serguei Y. Kalmykov, Nathan D. Powers, Gregory Golovin, Vidiya Ramanathan, Nathan J. Cunningham, Kevin J. Brown, Shouyuan Chen, Isaac Ghebregziabher, Bradley A. Shadwick, Donald P. Umstadter, Benjamin A. Cowan, David L. Bruhwiler, Arnaud Beck, Erik Lefebvre
Stable, Tunable, Quasimonoenergetic Electron Beams Produced In A Laser Wakefield Near The Threshold For Self-Injection, Sudeep Banerjee, Serguei Y. Kalmykov, Nathan D. Powers, Gregory Golovin, Vidiya Ramanathan, Nathan J. Cunningham, Kevin J. Brown, Shouyuan Chen, Isaac Ghebregziabher, Bradley A. Shadwick, Donald P. Umstadter, Benjamin A. Cowan, David L. Bruhwiler, Arnaud Beck, Erik Lefebvre
Serge Youri Kalmykov
Stable operation of a laser-plasma accelerator near the threshold for electron self-injection in the blowout regime has been demonstrated with 25–60 TW, 30 fs laser pulses focused into a 3–4 millimeter length gas jet. Nearly Gaussian shape and high nanosecond contrast of the focused pulse appear to be critically important for controllable, tunable generation of 250–430 MeV electron bunches with a low energy spread, ~ 10 pC charge, a few-mrad divergence and pointing stability, and a vanishingly small low-energy background. The physical nature of the near-threshold behavior is examined using three-dimensional particle-in-cell simulations. Simulations indicate that properly locating the nonlinear …
Measurements Of Nh3 Linestrengths And Collisional Broadening Coefficients In N2, O2, Co2, And H2o Near 1103.46 Cm−1, Kyle Owen, Et-Touhami Es-Sebbar, Aamir Farooq
Measurements Of Nh3 Linestrengths And Collisional Broadening Coefficients In N2, O2, Co2, And H2o Near 1103.46 Cm−1, Kyle Owen, Et-Touhami Es-Sebbar, Aamir Farooq
Dr. Et-touhami Es-sebbar
Laser-based ammonia gas sensors have useful applications in many fields including combustion, atmospheric monitoring, and medical diagnostics. Calibration-free trace gas sensors require the spectroscopic parameters including linestrengths and collisional broadening coefficients to be known. Ammonia's strong ν2 vibrational band between View the MathML source has the high absorption strength needed for sensing small concentrations. Within this band, the 1103.46 cm−1 feature is one of the strongest and has minimal interference from CO2 and H2O. However, the six rotational transitions that make up this feature have not been studied previously with absorption spectroscopy due to their small line spacing ranging from …
Dark-Current-Free Laser-Plasma Acceleration In Blowout Regime Using Nonlinear Plasma Lens, Serguei Y. Kalmykov
Dark-Current-Free Laser-Plasma Acceleration In Blowout Regime Using Nonlinear Plasma Lens, Serguei Y. Kalmykov
Serge Youri Kalmykov
It is demonstrated that a thin dense plasma slab (lens), placed before a multi-centimeter-length, low-density plasma (accelerator), overfocuses an incident petawatt laser pulse at a controlled location inside the accelerator, creating an expanding electron density bubble that traps plasma electrons over a brief time interval. As soon as the pulse stabilizes and self-guiding begins, the bubble stabilizes and transforms into the first (non-broken) bucket of a conventional three-dimensional nonlinear plasma wave, eliminating any chance for further injection. A well collimated, quasi-monoenergetic electron bunch with a zero low-energy background further accelerates to a multi-GeV energy.
Effects Of N2o And O2 Addition To Nitrogen Townsend Dielectric Barrier Discharges At Atmospheric Pressure On The Absolute Ground-State Atomic Nitrogen Density, Et. Es-Sebbar, N. Gherardi, F. Massines
Effects Of N2o And O2 Addition To Nitrogen Townsend Dielectric Barrier Discharges At Atmospheric Pressure On The Absolute Ground-State Atomic Nitrogen Density, Et. Es-Sebbar, N. Gherardi, F. Massines
Dr. Et-touhami Es-sebbar
Absolute ground-state density of nitrogen atoms N (2p3 4S3/2) in non-equilibrium Townsend dielectric barrier discharges (TDBDs) at atmospheric pressure sustained in N2/N2O and N2/O2 gas mixtures has been measured using Two-photon absorption laser-induced fluorescence (TALIF) spectroscopy. The quantitative measurements have been obtained by TALIF calibration using krypton as a reference gas. We previously reported that the maximum of N (2p3 4S3/2) atom density is around 3 × 1014 cm−3 in pure nitrogen TDBD, and that this maximum depends strongly on the mean energy dissipated in the gas. In the two gas mixtures studied here, results show that the absolute N …
Temperature-Dependent Absorption Cross-Section Measurements Of 1-Butene (1-C4h8) In Vuv And Ir, Et-Touhami Es-Sebbar, Yves Benilan, Aamir Farooq
Temperature-Dependent Absorption Cross-Section Measurements Of 1-Butene (1-C4h8) In Vuv And Ir, Et-Touhami Es-Sebbar, Yves Benilan, Aamir Farooq
Dr. Et-touhami Es-sebbar
Vacuum ultraviolet (VUV) and infrared (IR) absorption cross-section measurements of 1-butene (1-C4H8; CH2=CHCH2CH3; Butylene) are reported over the temperature range of 296–529 K. The VUV measurements are performed between 115 and 205 nm using synchrotron radiation as a tunable VUV light source. Fourier Transform Infrared (FTIR) spectroscopy is employed to measure absorption cross-section and band strengths in the IR region between 1.54 and 25 μm (∼6500–400 cm−1). The measured room-temperature VUV and IR absorption cross-sections are compared with available literature data and are found to be in good agreement. The oscillator strength for the electronic transition (A1A′→X1A′) around 150–205 nm …
Syllabus_Lecture_Notes_Collective_Phenomena_In_Laser_Plasmas_Phy998_2_Fall_2013, Serge Y. Kalmykov
Syllabus_Lecture_Notes_Collective_Phenomena_In_Laser_Plasmas_Phy998_2_Fall_2013, Serge Y. Kalmykov
Serge Youri Kalmykov
Interaction of high-power laser radiation with rarefied, fully ionized plasmas is rich in nonlinear collective phenomena. It is essentially three-dimensional and is dominated by the excitation of various modes of plasma oscillations, most important of which are electron Langmuir waves. These waves may trap externally injected electrons or initially quiescent plasma electrons, accelerating them to GeV-scale energies. Laser pulses can also launch collisionless shocks, which may accelerate plasma ions to MeV energies. Furthermore, relativistic mass effect and electron density perturbations by the radiation pressure cause laser pulse self-focusing and filamentation, leading to the radiation pulse self-guiding over many Rayleigh lengths. …