Features of plasma radiation at 2ω0 and 3/2ω0 frequencies on interaction of short laser pulses with solid targets

The angular and spectral radiation distributions at frequencies of ω0, 2ω0, and 3/2ω0, and also time dependences of the harmonics intensity were studied. The parameters of a plasma corona were measured by the X-ray methods. The experiments were carried out in the range of the power densities of laser radiation on the surface of targets of 2x1013 - 2x1014 W/cm2 in the Mishen-1 device. Polyethylene and aluminium targets were used. The plasma radiations were detected at angles of 90 deg, 135 deg, 60 deg and 45 deg to the direction of the laser beam propagation. Delay in the appearance of radiation pulses of 2ω0 and 3/2ω0 harmonics found. Experimentally observed delay times of the harmonics pulses from approximately 0.5 to 1 ns enable to estimate the elctron temperature. It was established that the characteristic time of rearrangement of harmonics spectra is approximately 10-9 s, which coincides with the time observed for the change in plasma density