Abstract

Previously we proposed a new thin film target to obtain femtosecond plasma overheating using artificially limited thermoconductivity [1]. We discussed the results of computer modeling of interaction of superintense femtosecond laser pulse with freely suspended thin carbon film. It was shown that for film thicknesses of 50 nm and less the electron temperature rises up to 500 eV and even higher with decrease in thickness. This causes increase in x-ray yield from H- and He-like C ions. In this paper we present for the first time the experimental results demonstrating the phenomenon for freely suspended carbon films as thin as 20-30 nm. It was obtained that for these superthin films x-ray yield increased more than twofold for p-polarized light. The comparison of the experimental results with predictions of the computer code shows good quantitative agreement and leads to the conclusion that there is threefold overheating of plasma layer up to 500 eV.

© 1997 Optical Society of America