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- Laser wakefield acceleration (29)
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Articles 31 - 60 of 108
Full-Text Articles in Plasma and Beam Physics
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. …
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}).
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 …
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 …
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 …
Binary Nanoparticle Dispersed Metamaterial Implementation And Characterization, Han Li
Binary Nanoparticle Dispersed Metamaterial Implementation And Characterization, Han Li
Han Li
No abstract provided.
Nonlinear Waves And Solitons On Contours And Closed Surfaces, Andrei Ludu
Nonlinear Waves And Solitons On Contours And Closed Surfaces, Andrei Ludu
Andrei Ludu
No abstract provided.
Physics Of Quasi-Monoenergetic Laser-Plasma Acceleration Of Electrons In The Blowout Regime, Serguei Y. Kalmykov, Bradley A. Shadwick, Arnaud Beck, Erik Lefebvre
Physics Of Quasi-Monoenergetic Laser-Plasma Acceleration Of Electrons In The Blowout Regime, Serguei Y. Kalmykov, Bradley A. Shadwick, Arnaud Beck, Erik Lefebvre
Serge Youri Kalmykov
No abstract provided.
Scientists At Cern Are Wrong About Faster Than Light Particles, Or They Are Being Misrepresented, Hontas Farmer
Scientists At Cern Are Wrong About Faster Than Light Particles, Or They Are Being Misrepresented, Hontas Farmer
Hontas F Farmer
The postulate of special relativity, which in common terms means that no particle can travel faster than the speed of light, has been tested and shown to be correct in literally billions of measurements. So the scientists at CERN who report measuring neutrino's moving faster than light are either WRONG or are being grossly misrepresented in many media outlets. Every other time a packet of particles collided with another packet of particles special relativity has been borne out. The experiment reported in many outlets, conducted at CERN, has been reported as "showing Einstein was wrong". I don't think so.
Vuv Absorption Cross Section Of Benzene, Relevance For Titan’S Atmosphere, F-J. Capalbo, Y. Bénilan, N. Fray, M. Schwell, Et. Es-Sebbar, N. Champion, T. Koskinen, R. Yelle
Vuv Absorption Cross Section Of Benzene, Relevance For Titan’S Atmosphere, F-J. Capalbo, Y. Bénilan, N. Fray, M. Schwell, Et. Es-Sebbar, N. Champion, T. Koskinen, R. Yelle
Dr. Et-touhami Es-sebbar
Saturn's largest satellite, Titan, is the only one in the Solar System known to have a thick N2/CH4, planet like atmosphere. The dissociation of these principal components and the recombination of the products make this atmosphere to be rich in organic compounds of high interest for astrobiology. Solar and stellar occultations observed by the Ultraviolet Imaging Spectrograph (UVIS) on board the Cassini spacecraft can be used to characterize the composition of Titan’s upper atmosphere (400 – 1400 km). The results depend strongly on the knowledge of the molecular absorption cross sections of the atmospheric constituents (Ferradaz et al. 2009). This …
Electron Self-Injection Into An Evolving Plasma Bubble: Quasi-Monoenergetic Laser-Plasma Acceleration In The Blowout Regime, Serguei Y. Kalmykov, Arnaud Beck, Sunghwan A. Yi, Vladimir N. Khudik, Michael C. Downer, Erik Lefebvre, Bradley A. Shadwick, Donald P. Umstadter
Electron Self-Injection Into An Evolving Plasma Bubble: Quasi-Monoenergetic Laser-Plasma Acceleration In The Blowout Regime, Serguei Y. Kalmykov, Arnaud Beck, Sunghwan A. Yi, Vladimir N. Khudik, Michael C. Downer, Erik Lefebvre, Bradley A. Shadwick, Donald P. Umstadter
Donald P. Umstadter
An electron density bubble driven in a rarefied uniform plasma by a slowly evolving laser pulse goes through periods of adiabatically slow expansions and contractions. Bubble expansion causes robust self-injection of initially quiescent plasma electrons, whereas stabilization and contraction terminate self-injection thus limiting injected charge; concomitant phase space rotation reduces the bunch energy spread. In regimes relevant to experiments with hundred terawatt- to petawatt-class lasers, bubble dynamics and, hence, the self-injection process are governed primarily by the driver evolution. Collective transverse fields of the trapped electron bunch reduce the accelerating gradient and slow down phase space rotation. Bubble expansion followed …
Electron Self-Injection Into An Evolving Plasma Bubble: Quasi-Monoenergetic Laser-Plasma Acceleration In The Blowout Regime, Serguei Y. Kalmykov, Arnaud Beck, Sunghwan A. Yi, Vladimir N. Khudik, Michael C. Downer, Erik Lefebvre, Bradley A. Shadwick, Donald P. Umstadter
Electron Self-Injection Into An Evolving Plasma Bubble: Quasi-Monoenergetic Laser-Plasma Acceleration In The Blowout Regime, Serguei Y. Kalmykov, Arnaud Beck, Sunghwan A. Yi, Vladimir N. Khudik, Michael C. Downer, Erik Lefebvre, Bradley A. Shadwick, Donald P. Umstadter
Serge Youri Kalmykov
An electron density bubble driven in a rarefied uniform plasma by a slowly evolving laser pulse goes through periods of adiabatically slow expansions and contractions. Bubble expansion causes robust self-injection of initially quiescent plasma electrons, whereas stabilization and contraction terminate self-injection thus limiting injected charge; concomitant phase space rotation reduces the bunch energy spread. In regimes relevant to experiments with hundred terawatt- to petawatt-class lasers, bubble dynamics and, hence, the self-injection process are governed primarily by the driver evolution. Collective transverse fields of the trapped electron bunch reduce the accelerating gradient and slow down phase space rotation. Bubble expansion followed …
Characterization Of Continuous Vacuum Ultraviolet Lamps-Implication On The Study Of Methane Photolysis At Lyman Alpha (121.6 Nm), M-C. Gazeau, Y. Benilan, Et. Es-Sebbar, A. Jolly, E. Arzoumanian, N. Fray, H. Cottin
Characterization Of Continuous Vacuum Ultraviolet Lamps-Implication On The Study Of Methane Photolysis At Lyman Alpha (121.6 Nm), M-C. Gazeau, Y. Benilan, Et. Es-Sebbar, A. Jolly, E. Arzoumanian, N. Fray, H. Cottin
Dr. Et-touhami Es-sebbar
Low-temperature hydrogen plasmas are widely used as continuous vacuum ultraviolet irradiation sources in photochemical studies and, in particular, in laboratory simulations of planetary atmospheres. One of the most challenging objectives of such experiments is to retrieve accurate quantitative laboratory data allowing a reliable comparison with theoretical and/or observational ones. This task can only be achieved when the irradiation source delivers a well characterised radiation in terms of flux and wavelength dependency. As an example, we will present a study, developed in the frame of a program dedicated to simulations of Titan’s atmosphere, on methane photolysis at Lyman alpha (121.6 nm). …
Formation Of Hcn And Nh3 As Primary Compounds Of Titan’S Atmosphere Simulations Using N2-Ch4 Afterglow Plasma’’, M-C. Gazeau, Y. Bénilan, E. Arzoumanian, Et. Es-Sebbar, A. Jolly, C.D. Pintassilgo
Formation Of Hcn And Nh3 As Primary Compounds Of Titan’S Atmosphere Simulations Using N2-Ch4 Afterglow Plasma’’, M-C. Gazeau, Y. Bénilan, E. Arzoumanian, Et. Es-Sebbar, A. Jolly, C.D. Pintassilgo
Dr. Et-touhami Es-sebbar
No abstract provided.
Dark-Current-Free Petawatt Laser-Driven Wakefield Accelerator Based On Electron Self-Injection Into An Expanding Plasma Bubble, Serguei Y. Kalmykov, Sunghwan A. Yi, Arnaud Beck, Agustin F. Lifschitz, Xavier Davoine, Erik Lefebvre, Vladimir N. Khudik, Gennady Shvets, Michael C. Downer
Dark-Current-Free Petawatt Laser-Driven Wakefield Accelerator Based On Electron Self-Injection Into An Expanding Plasma Bubble, Serguei Y. Kalmykov, Sunghwan A. Yi, Arnaud Beck, Agustin F. Lifschitz, Xavier Davoine, Erik Lefebvre, Vladimir N. Khudik, Gennady Shvets, Michael C. Downer
Serge Youri Kalmykov
A dark-current-free plasma accelerator driven by a short (~ 150 fs) self-guided petawatt laser pulse is proposed. The accelerator uses two plasma layers, one of which, short and dense, acts as a thin nonlinear lens. It is followed by a long rarefied plasma (~ 10^{17} electrons cm^{−3}) in which background electrons are trapped and accelerated by a nonlinear laser wakefield. The pulse overfocused by the plasma lens diffracts in low-density plasma as in vacuum and drives in its wake a rapidly expanding electron density bubble. The expanding bubble effectively traps initially quiescent electrons. The trapped charge given by quasi-cylindrical three-dimensional …
Hamiltonian Analysis Of Electron Self-Injection And Acceleration Into An Evolving Plasma Bubble, Sunghwan A. Yi, Vladimir N. Khudik, Serguei Y. Kalmykov, Gennady Shvets
Hamiltonian Analysis Of Electron Self-Injection And Acceleration Into An Evolving Plasma Bubble, Sunghwan A. Yi, Vladimir N. Khudik, Serguei Y. Kalmykov, Gennady Shvets
Serge Youri Kalmykov
Injection and acceleration of the background plasma electrons in laser wakefield accelerators (LWFA) operated in the blowout (‘bubble’) regime are analysed. Using a model of a slowly expanding spherical plasma bubble propagating with an ultra-relativistic speed, we derive a sufficient condition for the electron injection: the change in the electron’s Hamiltonian in the co-moving with the bubble reference frame must exceed its rest mass energy m_{e}c^2. We demonstrate the existence of the minimal expansion rate of the bubble needed for electron injection. We demonstrate that if the bubble’s expansion is followed by its stabilization or contraction, then a quasi-monoenergetic electron …
All-Optical Control Of Nonlinear Self-Focusing In Plasmas Using Non-Resonantly Driven Plasma Wave, Serguei Y. Kalmykov, Bradley A. Shadwick, Michael C. Downer
All-Optical Control Of Nonlinear Self-Focusing In Plasmas Using Non-Resonantly Driven Plasma Wave, Serguei Y. Kalmykov, Bradley A. Shadwick, Michael C. Downer
Serge Youri Kalmykov
Excitation of plasma density perturbations by an initially bi-color laser pulse helps to control nonlinear refraction in the plasma and enables various types of laser self-guiding. In this report we consider a setup that not only makes possible the transport of laser energy over cm-long relatively dense plasmas (n_0 = 10^{18} cm^{−3}) but also transforms the pulse into the unique format inaccessible to the conventional amplification techniques (relativistically intense periodic trains of few-cycle spikes). This well focusable pulse train is a novel light source interesting for ultra-fast high-field science applications. The opposite case of suppression of nonlinear self-focusing and dynamical …