Thomson-scattering techniques to diagnose local electron and ion temperatures, density, and plasma wave amplitudes in laser produced plasmas (invited)

Abstract

Thomson scattering has been shown to be a valuable technique for measuring the plasma conditions in laser produced plasmas. Measurement techniques that use the ion-acoustic frequency measured from the collective Thomson-scattering spectrum to extract the electron temperature, ion temperature, plasma flow, and electron density in a laser produced plasma are discussed. In a recent study [D. Froula et al., Phys. Rev. Lett. 95, 195005 (2005)], we demonstrated a novel Thomson-scattering technique that employs multiple color Thomson-scattering diagnostics to measure the dispersion of ion-acoustic fluctuations. We obtained frequency-resolved Thomson-scattering spectra of the two separate thermal ion-acoustic fluctuations with significantly different wave vectors. This new technique allows a simultaneous time resolved local measurement of electron density and temperature. The plasma fluctuations are shown to become dispersive with increasing electron temperature. Furthermore, a Thomson-scattering technique to measure the electron temperature profile is presented where recent experiments have measured a large electron temperature gradient (Te=1.4keVtoTe=3.2keV over 1.5mm) along the axis of a 2mm long Hohlraum when heated asymmetrically.