Low-threshold generation of harmonics and hard X-ray radiation in laser plasma. I - Single-peak generation. II - Multipeak generation

A hard X-ray radiation source of laser plasma is considered under conditions of the excitation of parametric instabilities in the source at low intensities of thermal radiation (up to 10 GW/sq cm). Hard X-ray multipeak generation in plasma heated by long pulses of a freely generating CO2-laser at a low pump intensity is examined in detail. It is shown that, under optimal conditions, multipeak generation provides a tenfold gain in hard X-ray radiation per laser pulse due to the presence of extra peaks in the X-ray signal.