Experimental results of the interaction of short (1.5 ns) CO2 laser pulses with solid targets at a flux reaching 1013 W/cm2 are presented. An attempt is made to carry out a global series of measurements and interpret them in the light of currently available theory. The absorption, reflection, ion and X-ray emission (line and continuum) and in considerable detail the infra-red emission spectra of the plasma in the vicinity of the incident 10.6 µm radiation as well as its harmonics were measured. From the emission spectra the existence of the parametric decay and the stimulated Brillouin backscatter instabilities was identified. Furthermore, the energy and angular dependence of the reflected-light calorimetry in addition to the X-ray and ion emission results are found to be consistent with the hypothesis that the interaction of high power CO2 lasers with plasmasis dominated by non-linear effects such as the parametric decay instability.
Radiation reaction induced harmonics generation in ultra-relativistic intense laser interaction with plasmas