Plasma heating near a metal target by nanosecond pulses of the first, second, and fourth Nd-laser harmonics

Measurements were made of the electron temperature $T_e$ of a laser plasma formed on the surface of a metal target by the action of nanosecond pulses of wavelengths $\lambda$ = 1060, 530, and 265 nm. The laser radiation intensity was $I\simeq10^9$–$10^{13}$ W cm$^2$. The electron temperature was determined from the emf of a double charge layer at the plasma boundary. Within the limits of the scatter of the experimental results, the plasma temperature was independent of the laser radiation wavelength (in the range 1060–265 nm). The dependence of this temperature on the radiation intensity obeyed approximately $T_e\sim I^{1/3}$ throughout the investigated range.