Geometrical Constraints on Plasma Couplers for Raman Compression
Authors: Z. Toroker, V.M. Malkin, G.M. Fraiman, A.A. Balakin, and N.J. Fisch
Abstract:
Backward Raman compression in plasma is based on a 3-wave resonant interaction, which includes two-
counter propagating laser pulses (pump and seed pulses) and an electron plasma wave (Langmuir wave).
A high-density, roughly homogeneous, plasma mediates the energy transfer between the lasers by ensuring
resonance with the plasma wave. However, in practice, a laser pulse entering or leaving plasma source
encounters plasma at the edges of the homogeneous section that is far too tenuous to maintain resonance.
When these tenuous plasma regions are extensive, such as for the wider plasma necessary for compression at
higher powers, significant inverse bremsstrahlung and seed dispersion may occur. These deleterious effects
may, however, be mitigated by chirping the seed and pump pulses.
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Submitted to: Physics of Plasmas (May 2012)
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