52nd Annual Meeting of the APS Division of Plasma Physics
Volume 55, Number 15
Monday–Friday, November 8–12, 2010;
Chicago, Illinois
Session KI3: Intense Beams
3:00 PM–5:00 PM,
Tuesday, November 9, 2010
Room: Grand Ballroom EF
Chair: John Booske, University of Wisconsin
Abstract ID: BAPS.2010.DPP.KI3.4
Abstract: KI3.00004 : Detuning, wavebreaking, and Landau damping as limiting effects on laser compression by resonant backward Raman scattering
4:30 PM–5:00 PM
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Abstract
Author:
Nikolai Yampolsky
(Los Alamos National Laboratory)
Plasma waves mediate high-power pulse compression, where the
persistence of the plasma wave is critical. In this scheme, the
plasma wave mediates the energy transfer between long pump and
short seed laser pulses through backward Raman scattering. High
efficiency of the plasma wave excitation defines both the overall
efficiency of the energy transfer and the duration of the
amplified pulse. Based on recent extensive experiments, it is
possible to deduce that the experimentally realized efficiency of
the amplifier is likely constrained by two factors, namely the
pump chirp and the plasma wavebreaking [1]. The limits arise
because for compression the frequency of the plasma wave should
match the bandwidth of the instability and the plasma wave
amplitude should be small enough to be sustained by plasma. Both
the detuning and the wavebreaking effects can be suppressed by
using low pump intensity in plasma having the appropriate density
gradient [1]. When these constraints are avoided, Landau damping
will be the main limiting factor. However, the Landau damping
rate can be significantly reduced in the presence of a strong
plasma wave. Currently, nonlinear Landau damping can be described
within two recently developed models [2,3]. We show that these
two different descriptions result in the same dynamics for the
plasma wave amplitude. We use the quasilinear description of
nonlinear Landau damping [3] to identify a regime where initially
high linear Landau damping can be significantly saturated.
Because of the saturation effect, higher temperatures can be
tolerated in achieving efficient amplification. Significantly,
the plasma temperature can be as much as 50\% larger compared to
the case of unsaturated Landau damping.\\[4pt]
[1] N.A. Yampolsky et al., Phys. Plasmas 15, 113104 (2008).\\[0pt]
[2] D. Benisti et al., Phys. Rev. Lett. 103, 155002 (2009).\\[0pt]
[3] N.A. Yampolsky and N.J. Fisch, Phys. Plasmas 16, 072104 (2009).
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2010.DPP.KI3.4