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 materials by powerful (up to 10¹⁴ W cm^–2) pulsed radiation revealed a considerable reduction in the etching efficiency during shaping of deep ablation channels. The optical characteristics of the resultant plasma — vapour plume were measured. These measurements and numerical estimates led to the suggestion of two possible physical mechanisms of additional 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.