Experimental investigation of the onset of evaporation and formation of a plasma layer due to interaction between laser radiation and metals in different gases

The results are given of an experimental investigation of the onset of evaporation and of the appearance of a plasma layer above a target irradiated with neodymium laser pulses of about 1 jusec duration. The targets were aluminum and bismuth in air, argon, and helium. The critical density of the radiation flux, below which no "flash" was observed for pulses of this duration, was determined for near-planar motion. The results obtained were compared with theoretical ideas and the results of other experiments.