Optical diagnostics of laser produced plasmas using the 3/2 ω0 harmonic frequency

Spectral distribution measurement at the third harmonic of the half fractional laser frequency is envisaged for the diagnostics of a plasma produced by the iodine laser Perun. Photons at this frequency are generated due to parametric instability in the region with plasma density of one quarter of the critical one. Electron temperature may directly be calculated from the spacing between two characteristic maxima, well identifiable on the line profile, while the Doppler shift of the line as a whole makes it possible to determine the hydrodynamic velocity of the plasma corona motion. (J.U.). 8 refs