Thomson scattering from laser-produced gold plasmas in radiation conversion layer

Abstract

With a 263.3 nm probe laser beam, the Thomson scattering (TS) spectra are measured at the distance from the surface of gold disc targets as close as 50μm. All of the TS spectra become narrower with time, which indicates the overall drop of plasma temperature as the high-Z plasmas blow off. The experimental data show that there are distinct characteristics between the inner region (i.e., 50 and 100μm away from target surface) and the outer region. The gradient of the electron temperature in outer region is toward the target and becomes opposite to that in the inner region. The asymmetries of the TS spectra in the inner region are in good agreement with calculation based on the Spitzer–Härm theory. In the outer region, however, the discrepancies between the experiments and calculations are significant, which may be a hint that the electron energy transport becomes flux limited or nonlocal in this region.