Hot electron generation in a dense plasma by femtosecond laser pulses of subrelativistic intensity

We report a study of hot electron generation via the interaction of femtosecond laser pulses of subrelativistic intensity (1015 to 2x1017 W cm-2), having different linear polarisations and nanosecond-scale contrasts, with the surface of 'transparent' (quartz glass) and 'absorbing' (silicon) targets. As the incident pulse intensity increases from 1015 to 1017 W cm-2, the difference in hard X-ray yield and average hot electron energy between s- and p-polarised beams rapidly decreases. This effect can be understood in terms of relativistic electron acceleration mechanisms. (special issue devoted to the 80th birthday of S.A. Akhmanov)