CHARACTERISTICS OF PLASMA SCREENING IN ABLATION SHAPING OF DEEP CHANNELS BY HIGH-INTENSITY LASER-RADIATION

Determination of the rates of laser ablation (etching) of various mate rials by powerful (up to 10(14) W cm(-2)) pulsed radiation revealed a considerable reduction in the etching efficiency during shaping of dee p ablated channels. The optical characteristics of the resultant plasm a-vapour plume were measured. These measurements and numerical estimat es led to the suggestion of two possible physical mechanisms of additi onal screening resulting from the interaction with the channel walls: limitation of plasma expansion and an increase of its density because of evaporation of the wall material by the radiation emitted from the plasma plume.