Abstract Details
Plasma Wave Packet Etching and Localization Relevant to Stimulated Raman Scattering
Author: Jay E Fahlen
Requested Type: Oral Only
Submitted: 2009-04-21 21:36:57
Co-authors: B.J. Winjum, T. Grismayer, V.K. Decyk, W.B. Mori
Contact Info:
University of California, Los Angeles
405 Hilgard Ave
Los Angeles, CA 90095
United States
Abstract Text:
Stimulated Raman scattering (SRS), in which incident laser energy is coupled to the plasma through electron plasma waves, has been shown to be bursty in time and space. As the instability grows and saturates, plasma wave packets propagate away, allowing new bursts to grow. Using one-dimensional particle-in-cell (PIC) simulations, we present results demonstrating that finite-length wave packets lose energy at a constant rate by continually trapping new particles at their rear edges. This etching effect eventually leads to the complete erosion of the packet, despite fact that particle trapping in infinite waves is commonly believed to lead to a quasi steady state, or BGK mode. The etching is observed in SRS simulations and may affect the recurrence and reflectivity of the instability. We also present the results of two-dimensional simulations indicating that particle trapping effects lead to nearly continuous energy loss at the sides of the wave. This energy loss causes the waves to localize about their center, potentially altering the saturation of SRS.
Work supported by DOE under Grant Nos. DE-FG52-03-NA00065, DE-FG52-06NA26195, and DE-FG02-03ER54721.
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