Ultrafast laser-based thermal X-ray sources

The effects of hot electrons on the thermal radiative properties (brightnes s, duration and spectral shape) and dynamics of solid density plasmas, gene rated during the interaction of a femtosecond laser and a solid target, are assessed. Line and broadband thermal emissions with duration between 500 f s and 700 fs, have been successfully produced with peak power between 1 and 10 MW, when the fraction of laser energy in the hot electron population wa s less than 2%, and when the hot electron energy density at the target surf ace was less than 1 KJ/cm(2). (C) 2000 Academie des sciences/Editions scien tifiques et medicales Elsevier SAS.