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Electron Self-Injection And Trapping Into An Evolving Plasma Bubble, Serguei Y. Kalmykov, Sunghwan A. Yi, Vladimir N. Khudik, Gennady Shvets
Electron Self-Injection And Trapping Into An Evolving Plasma Bubble, Serguei Y. Kalmykov, Sunghwan A. Yi, Vladimir N. Khudik, Gennady Shvets
Serge Youri Kalmykov
The blowout (or bubble) regime of laser wakefield acceleration is promising for generating monochromatic high-energy electron beams out of low-density plasmas. It is shown analytically and by particle-in-cell simulations that self-injection of the background plasma electrons into the quasistatic plasma bubble can be caused by slow temporal expansion of the bubble. Sufficient criteria for the electron trapping and bubble’s expansion rate are derived using a semianalytic nonstationary Hamiltonian theory. It is further shown that the combination of bubble’s expansion and contraction results in monoenergetic electron beams.
All-Optical Control Of Nonlinear Focusing Of Laser Beams In Plasma Beat Wave Accelerator, Serguei Y. Kalmykov, Sunghwan A. Yi, Gennady Shvets
All-Optical Control Of Nonlinear Focusing Of Laser Beams In Plasma Beat Wave Accelerator, Serguei Y. Kalmykov, Sunghwan A. Yi, Gennady Shvets
Serge Youri Kalmykov
Nonlinear focusing of a bi-color laser in plasma can be controlled by varying the difference frequency \Omega. The driven electron density perturbation forms a co-moving periodic focusing (de-focusing) channel if \Omega is below (above) the electron Langmuir frequency \omega_p. Hence, the beam focusing is enhanced for \Omega < \omega_p and is suppressed otherwise. In particular, a catastrophic relativistic self-focusing of a high-power laser beam can be prevented all-optically by a second, much weaker, co-propagating beam shifted in frequency by \Omega > \omega_p. A bi-envelope equation describing the early stage of the mutual de-focusing is derived and analyzed. Later stages, characterized by a well-developed electromagnetic cascade, are investigated numerically. Stable propagation of the over-critical laser pulse over several Rayleigh lengths is predicted. The non-resonant plasma beat wave (\Omega \not= \omega_p) can accelerate pre-injected electrons above …