Thomson scattering measurements of heat flow in a laser-produced plasma

Abstract

Measurements of the electron distribution and heat flow between the critical and ablation surfaces in a laser-produced plasma have been obtained using Thomson scattering. A frequency-quadrupled probe beam was used to obtain Thomson spectra at above-critical densities in a plasma produced by irradiation of solid targets with the fundamental laser light at irradiances of 3 × 1014 W cm−2. Comparison of Thomson spectra at the ion acoustic frequency (sensitive to the cold return current) with simulated spectra shows that the data are consistent with Fokker–Planck simulations of the electron distribution function, providing the first direct information on the electron distribution function.