Open Access. Powered by Scholars. Published by Universities.®
- Discipline
- Keyword
-
- Laser wakefield acceleration (4)
- Blowout regime (3)
- Electron self-injection (2)
- Laser wakefield acceleration (numerical support of the experiment) (2)
- Laser wakefield acceleration (theory) (2)
-
- Optical shock (2)
- Active interrogation (1)
- DIOCLES laser (1)
- GeV electrons from laser plasmas (1)
- Hamiltonian theory of electron self-injection (1)
- Laser wakefield accelerators (1)
- Nuclear activation (1)
- PIC simulations CALDER-Circ code (1)
- Particle beam radiography (1)
- Particle-in-cell simulation (1)
- Particle-in-cell simulations (1)
- Relativistic self-focusing (1)
- Thomson scattering (1)
- Wakefield acceleration (1)
- X-rays (1)
- File Type
Articles 61 - 85 of 85
Full-Text Articles in Physics
Clayton Et Al. Respond, C.E. Clayton, C. Joshi, C. Darrow, Donald P. Umstadter
Clayton Et Al. Respond, C.E. Clayton, C. Joshi, C. Darrow, Donald P. Umstadter
Donald P. Umstadter
Clayton et al. Respond: The authors of the Comment are quite correct when they point out that the ruby-laser scattering system used in our study can only respond to beat-excited density fluctuations with ky = k2, where the CO2 (ruby) beam propagates in the z (y) direction.
Laser Based Synchrotron Radiation, Kim Ta Phuoc, Frederic Burgy, Jean-Philippe Rousseau, Victor Malka, Antoine Rousse, Rahul Shah, Donald P. Umstadter, Alexander Puhkov, Sergei Kiselev
Laser Based Synchrotron Radiation, Kim Ta Phuoc, Frederic Burgy, Jean-Philippe Rousseau, Victor Malka, Antoine Rousse, Rahul Shah, Donald P. Umstadter, Alexander Puhkov, Sergei Kiselev
Donald P. Umstadter
Beams of x rays in the kiloelectronvolt energy range have been produced from laser-matter interaction. Here, energetic electrons are accelerated by a laser wakefield, and experience betatron oscillations in an ion channel formed in the wake of the intense femtosecond laser pulse. Experiments using a 50 TW laser (30 fs duration) are described, as well as comparisons with numerical simulations. These results pave the way of a new generation of radiation in the x-ray spectral range, with a high collimation and an ultrafast pulse duration, produced by the use of compact laser system.
Method For Generating A Plasma Wave To Accelerate Electrons, Donald Umstadter, Eric Esarey, Joon K. Kim
Method For Generating A Plasma Wave To Accelerate Electrons, Donald Umstadter, Eric Esarey, Joon K. Kim
Donald P. Umstadter
The invention provides a method and apparatus for generating large amplitude nonlinear plasma waves, driven by an optimized train of independently adjustable, intense laser pulses. In the method, optimal pulse widths, interpulse spacing, and intensity profiles of each pulse are determined for each pulse in a series of pulses. A resonant region of the plasma wave phase space is found where the plasma wave is driven most efficiently by the laser pulses. The accelerator system of the invention comprises several parts: the laser system, also called beam source, which preferably comprises photo cathode electron source and RF-LINAC accelerator; electron photo-cathode …
Electron Acceleration And The Propagation Of Ultrashort High-Intensity Laser Pulses In Plasmas, Xiaofang Wang, Mohan Krishnan, Ned Saleh, Haiwen Wang, Donald P. Umstadter
Electron Acceleration And The Propagation Of Ultrashort High-Intensity Laser Pulses In Plasmas, Xiaofang Wang, Mohan Krishnan, Ned Saleh, Haiwen Wang, Donald P. Umstadter
Donald P. Umstadter
Reported are interactions of high-intensity laser pulses ( λ = 810 nm and l≤3×1018 W/cm2) with plasmas in a new parameter regime, in which the pulse duration ( τ = 29 fs) corresponds to 0.6–2.6 plasma periods. Relativistic filamentation is observed to cause laser-beam breakup and scattering of the beam out of the vacuum propagation angle. A beam of megaelectronvolt electrons with divergence angle as small as 1° is generated in the forward direction, which is correlated to the growth of the relativistic filamentation. Raman scattering, however, is found to be much less than previous long-pulse results.
Tabletop Accelerators Are Brighter And Faster, Phil Schewe, Ben Stein, Donald P. Umstadter
Tabletop Accelerators Are Brighter And Faster, Phil Schewe, Ben Stein, Donald P. Umstadter
Donald P. Umstadter
At last week's APS plasma physics meeting, Donald Umstadter of the University of Michigan's Center for Ultrafast Optical Science (734-764-2284, dpu@umich.edu) reported on advances at his lab and elsewhere in tabletop laser accelerators, devices that use light to accelerate beams of electrons and protons to energies of a million volts in distances of only microns. This acceleration rate or "gradient" is up to a thousand times larger than in conventional accelerators because the tabletop laser light can now exert pressures of gigabars, the highest ever achieved, and approaching the pressure of light near the Sun. Not only that, but Umstadter's …
Development Of A Source Of Quasi-Monochromatic Mev Energy Photons, Donald Umstadter, Sudeep Banerjee, Viswanathan Ramanathan, Nathan Powers, Nathaniel Cunningham, Nathan A. Chandler-Smith
Development Of A Source Of Quasi-Monochromatic Mev Energy Photons, Donald Umstadter, Sudeep Banerjee, Viswanathan Ramanathan, Nathan Powers, Nathaniel Cunningham, Nathan A. Chandler-Smith
Donald P. Umstadter
We report current progress on a project to develop an all-optically-driven x-ray photon source. A laser pulse with 40-50 TW of peak power is focused on a supersonic helium nozzle to drive a relativistic plasma wave. Electron beams with energies of 320 MeV (+/- 28 MeV) are accelerated by means of laser wakefield acceleration. Remarkably, the acceleration region is only 3 mm in length. This accelerator is currently being employed to demonstrate the generation of MeV- energy x-ray by means of all-optical Thomson scattering. By this mechanism, a lower power, laser pulse (from the same laser system) is focused onto …
Phase Dependence Of Thomson Scattering In An Ultraintense Laser Field, Fei He, Y. Y. Lau, Donald P. Umstadter, Trevor Strickler
Phase Dependence Of Thomson Scattering In An Ultraintense Laser Field, Fei He, Y. Y. Lau, Donald P. Umstadter, Trevor Strickler
Donald P. Umstadter
The Thomson scattering spectra of an electron by an ultraintense laser field are computed. It is found that the electron orbit, and therefore its nonlinear Thomson scattering spectra, depend critically on the amplitude of the ultraintense laser field and on the phase at which the electron sees the laser electric field. Contrary to some customary notions, the Thomson scattering spectra, in general, do not occur at integer multiples of the laser frequency and the maximum frequency is proportional to the first instead of the third power of the electric field strength for the case of an ultraintense laser. The implications …
Self-Focusing, Channel Formation, And High-Energy Ion Generation In Interaction Of An Intense Short Laser Pulse With A He Jet, G.S. Sarkisov, B. Yu. Bychenkov, V.N. Novikov, V.T. Tikhonchuk, Anatoly Maksimchuk, Shouyuan Chen, R. Wagner, G. Mourou, Donald Umstadter
Self-Focusing, Channel Formation, And High-Energy Ion Generation In Interaction Of An Intense Short Laser Pulse With A He Jet, G.S. Sarkisov, B. Yu. Bychenkov, V.N. Novikov, V.T. Tikhonchuk, Anatoly Maksimchuk, Shouyuan Chen, R. Wagner, G. Mourou, Donald Umstadter
Donald P. Umstadter
Using interferometry, we investigate the dynamics of interaction of a relativistically intense 4-TW, 400-fs laser pulse with a He gas jet. We observe a stable plasma channel 1 mm long and less than 30 μm in diameter, with a radial gradient of electron density ∼5×1022 cm-4 and with an on-axis electron density approximately ten times less than its maximum value of 8×1019 cm-3. A high radial velocity of the surrounding gas ionization of ∼3.8×108 cm/s has been observed after the channel formation, and it is attributed to the fast ions expelled from the laser channel and propagating radially outward. We …
Thomson Scattering And Ponderomotive Intermodulation Within Standing Laser Beat Waves In Plasma, Scott Sepke, Y.Y. Lau, James Paul Holloway, Donald P. Umstadter
Thomson Scattering And Ponderomotive Intermodulation Within Standing Laser Beat Waves In Plasma, Scott Sepke, Y.Y. Lau, James Paul Holloway, Donald P. Umstadter
Donald P. Umstadter
Electrons in a standing electromagnetic wave—an optical lattice—tend to oscillate due to the quiver and ponderomotive potentials. For sufficiently intense laser fields (lλ2≤5×1017 W cm-2 µm2) and in plasmas with sufficiently low electron densities (n≤1018 cm-3), these oscillations can occur faster than the plasma can respond. This paper shows that these oscillations result in Thomson scattering of light at both the laser and ponderomotive bounce frequencies and their harmonics as well as at mixtures of these frequencies. We term this mixing ponderomotive intermodulation. Here, the case of counterpropagating laser beams creating a one-dimensional (1D) optical lattice is analyzed. The near-equilibrium …
A Cone Of Coherent Light, S.-Y. Chen, A. Maksimchuk, E. Esarey, Donald Umstadter
A Cone Of Coherent Light, S.-Y. Chen, A. Maksimchuk, E. Esarey, Donald Umstadter
Donald P. Umstadter
Lasers come in infrared and visible varieties, but none yet in the x-ray band. A compact and powerful source of coherent x rays is the dream of many physicists, who see applications such as making atomic scale, three-dimensional movies of a melting crystal or an operating photosynthesis protein. In a step toward that goal, a research team has detected high frequency coherent light generated by a new process. As they report in the 12 June PRL, intense laser pulses can stimulate free electrons in a plasma to emit coherent light at triple the input frequency in a narrowly-directed cone. The …
Plasma Density Gratings Induced By Intersecting Laser Pulses In Underdense Plasmas, Z.-M. Sheng, J. Zhang, Donald Umstadter
Plasma Density Gratings Induced By Intersecting Laser Pulses In Underdense Plasmas, Z.-M. Sheng, J. Zhang, Donald Umstadter
Donald P. Umstadter
Electron and ion density gratings induced by two intersecting ultrashort laser pulses at intensities of 1016 W/cm2 or lower are investigated. The ponderomotive force generated by the inhomogeneous intensity distribution in the intersecting region of the interfering pulses produces deep electron and ion density modulations at a wavelength less than a laser wavelength in vacuum. Dependence of the density modulation on the plasma densities, temperatures, and the ion mass, as well as the laser pulse parameters are studied analytically and by particle-in-cell simulations. It is found that the density peaks of such gratings can be a few times that of …
Observation Of Relativistic Cross-Phase Modulation In High-Intensity Laser-Plasma Interactions, Shouyuan Chen, Matthew Rever, P. Zhang, W. Theobald, Donald Umstadter
Observation Of Relativistic Cross-Phase Modulation In High-Intensity Laser-Plasma Interactions, Shouyuan Chen, Matthew Rever, P. Zhang, W. Theobald, Donald Umstadter
Donald P. Umstadter
A nonlinear optical phenomenon, relativistic cross-phase modulation, is reported. A relativistically intense light beam (I=1.3×1018 W cm-2, λ =1.05 μm) is experimentally observed to cause phase modulation of a lower intensity, copropagating light beam in a plasma. The latter beam is generated when the former undergoes the stimulated Raman forward scattering instability. The bandwidth of the Raman satellite is found to be broadened from 3.8–100 nm when the pump laser power is increased from 0.45–2.4 TW. A signature of relativistic cross-phase modulation, namely, asymmetric spectral broadening of the Raman signal, is observed at a pump power of 2.4 TW. The …
A Unidirectional, Pulsed Far-Infrared Ring Laser, W.A. Peebles, Donald Umstadter, D.L. Brower, N.C. Luhmann
A Unidirectional, Pulsed Far-Infrared Ring Laser, W.A. Peebles, Donald Umstadter, D.L. Brower, N.C. Luhmann
Donald P. Umstadter
The first study of a pulsed, far-infrared, ring laser is described. Unidirectional, traveling-wave operation is observed, thereby eliminating the spatial hole burning effects present in linear cavities. Single-mode output powers of 100 kW have been obtained.
Experimental Observation Of Relativistic Nonlinear Thomson Scattering, Szu-Yuan Chen, Anatoly Maksimchuk, Donald Umstadter
Experimental Observation Of Relativistic Nonlinear Thomson Scattering, Szu-Yuan Chen, Anatoly Maksimchuk, Donald Umstadter
Donald P. Umstadter
Classical Thomson scattering—the scattering of low-intensity light by electrons—is a linear process, in that it does not change the frequency of the radiation; moreover, the magnetic-field component of light is not involved. But if the light intensity is extremely high (~1018 Wcm–2), the electrons oscillate during the scattering process with velocities approaching the speed of light. In this relativistic regime, the effect of the magnetic and electric fields on the electron motion should become comparable, and the effective electron mass will increase. Consequently, electrons in such high fields are predicted to quiver nonlinearly, moving in figure-eight patterns rather than in …
Evolution Of A Plasma Waveguide Created During Relativistic-Ponderomotive Self-Channeling Of An Intense Laser Pulse, Shouyuan Chen, G.S. Sarkisov, Anatoly Maksimchuk, R. Wagner, Donald P. Umstadter
Evolution Of A Plasma Waveguide Created During Relativistic-Ponderomotive Self-Channeling Of An Intense Laser Pulse, Shouyuan Chen, G.S. Sarkisov, Anatoly Maksimchuk, R. Wagner, Donald P. Umstadter
Donald P. Umstadter
An on-axis plasma density depression channel was observed during and after the passage of a relativistically and ponderomotively self-guided laser pulse through a plasma. Optical interferometry was used to produce time-resolved plasma density distributions, revealing the formation of a plasma waveguide. These results were complemented by the guiding of a collinear trailing pulse.
Application Of A Picosecond Soft X-Ray Source To Time-Resolved Plasma Dynamics, J. Workman, M. Nantel, Anatoly Maksimchuk, Donald P. Umstadter
Application Of A Picosecond Soft X-Ray Source To Time-Resolved Plasma Dynamics, J. Workman, M. Nantel, Anatoly Maksimchuk, Donald P. Umstadter
Donald P. Umstadter
We demonstrate the application of an ultrashort x-ray source as an external probe to measure plasma dynamics. The plasma is generated by a 100-fs Ti: sapphire laser focused onto thin metallic films. Time-resolved spectroscopy of the gold x-ray probe transmission through a perturbed 1000 Å aluminum film reveals redshifts of the L-shell photoabsorption edge. We show that the dynamic behavior of this shift is consistent with the relaxation of the aluminum following the compression generated by a shock wave traveling through the film. An analytic plasma model, with comparison to a numerical hydrodynamics model, indicates compression up to 1.4 times …
Fast Ignitor Concept With Light Ions, V. Yu. Bychenkov, W. Rozmus, Anatoly Maksimchuk, Donald Umstadter, C.E. Capjack
Fast Ignitor Concept With Light Ions, V. Yu. Bychenkov, W. Rozmus, Anatoly Maksimchuk, Donald Umstadter, C.E. Capjack
Donald P. Umstadter
A short-laser-pulse driven ion flux is examined as a fast ignitor candidate for inertial confinement fusion. Ion ranges in a hot precompressed fuel are studied. The ion energy and the corresponding intensity of a short laser pulse are estimated for the optimum ion range and ion energy density flux. It is shown that a lightion beam triggered by a few-hundreds-kJ laser at intensities of ~1021W/cm2 is relevant to the fast ignitor scenario.
Relativistic Plasma-Wave Excitation By Collinear Optical Mixing, C.E. Clayton, C. Joshi, C. Darrow, Donald P. Umstadter
Relativistic Plasma-Wave Excitation By Collinear Optical Mixing, C.E. Clayton, C. Joshi, C. Darrow, Donald P. Umstadter
Donald P. Umstadter
The relativistic plasma wave excited when the frequency difference between two copropagating CO2 laser beams equals the plasma frequency is detected for the first time. The plasma-wave frequency, wave number, spatial extent, and saturation time are directly measured by use of 7-mrad, collective, ruby Thomson scattering and the forward-scattered ir spectrum. The wave amplitude ñ/n0 is inferred to be (1-3)% which gives a longitudinal electric field of 0.3 to 1 GV/m at a laser intensity of 1.7×1013 W/cm2, in reasonable agreement with theory.
High-Energy Ion Generation In Interaction Of Short Laser Pulse With High-Density Plasma, Y. Sentoku, V. Y. Bychenkov, K. Flippo, Anatoly Maksimchuk, K. Mima, G. Mourou, Z. M. Sheng, Donald Umstadter
High-Energy Ion Generation In Interaction Of Short Laser Pulse With High-Density Plasma, Y. Sentoku, V. Y. Bychenkov, K. Flippo, Anatoly Maksimchuk, K. Mima, G. Mourou, Z. M. Sheng, Donald Umstadter
Donald P. Umstadter
Multi-MeV ion production from the interaction of a short laser pulse with a high-density plasma, accompanied by an underdense preplasma, has been studied with a particle-in- cell simulation and good agreement is found with experiment. The mechanism primarily responsible for the acceleration of ions is identified. Comparison with experiments sheds light on the ion-energy dependence on laser intensity, preplasma scale length, and relative ion energies for a multi-species plasma. Two regimes of maximum ion-energy dependence on laser intensity, I, have been identified: subrelativistic, μ I ; and relativistic, μ √I. Simulations show that the energy of the accelerated ions versus …
High-Energy Laser-Accelerated Electron Beans For Long-Range Interrogation, Nathaniel Cunningham, Sudeep Banerjee, Viswanathan Ramanathan, Nathan D. Powers, Nathan A. Chandler-Smith, Randy Vane, David Schultz, Sara Pozzi, Shaun Clark, James Beene, Donald Umstadter
High-Energy Laser-Accelerated Electron Beans For Long-Range Interrogation, Nathaniel Cunningham, Sudeep Banerjee, Viswanathan Ramanathan, Nathan D. Powers, Nathan A. Chandler-Smith, Randy Vane, David Schultz, Sara Pozzi, Shaun Clark, James Beene, Donald Umstadter
Donald P. Umstadter
We are studying the use of 0.1 - 1.0 GeV laser-accelerated electron beams as active interrogation probes for long-standoff radiography or nuclear activation of concealed special nuclear material. Use of beams in this energy range is largely unexplored, but such beams could provide notable advantages over lower-energy beams and x-rays. High-energy laser-accelerated electrons exhibit large penetration range through air and solids, and low beam divergence for both direct beams and secondary Bremsstrahlung x-rays. We present laboratory measurements of radiography and activation using the high power Diocles laser system at the University of Nebraska, as well as MCNP and GEANT Monte …
Nonlinear Analysis Of Relativistic Harmonic Generation By Intenselasers In Plasmas, Eric Esarey, A. Ting, P. Sprangle, Donald Umstadter, X. Liu
Nonlinear Analysis Of Relativistic Harmonic Generation By Intenselasers In Plasmas, Eric Esarey, A. Ting, P. Sprangle, Donald Umstadter, X. Liu
Donald P. Umstadter
A linearly polarized, ultra-intense laser field induces transverse plasma currents which are highly relativistic and nonlinear, resulting in the generation of coherent harmonic radiation in the forward direction (i.e., copropagating with the incident laser field). A nonlinear cold fluid model, valid for ultrahigh intensities, is formulated and used to analyze relativistic harmonic generation. The plasma density response is included self-consistently and is shown to significantly reduce the current driving the harmonic radiation. Phase detuning severely limits the growth of the harmonic radiation. The effects of diffraction are considered in the mildly relativistic limit. No third-harmonic signal emerges from a uniform …
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 …
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 …
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 …
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 …