Excitation and damping of a self-modulated laser wakefield

Spatially, temporally, and angularly resolved collinear collective Thomson scattering was used to diagnose the excitation and damping of a relativisti c-phase-velocity self-modulated laser wakefield. The excitation of the elec tron plasma wave was observed to be driven by Raman-type instabilities. The damping is believed to originate from both electron beam loading and modul ational instability. The collective Thomson scattering of a probe pulse fro m the ion acoustic waves, resulting from modulational instability, allows u s to measure the temporal evolution of the plasma temperature. The latter w as found to be consistent with the damping of the electron plasma wave. (C) 2000 American Institute of Physics. [S1070-664X(00)04201-4].