Laser absorption waves in metal capillaries

Experimental and numerical investigations were made of the propagation of laser absorption waves in metal capillaries subjected to CO₂ laser pulses. The dependence of the velocity of propagation of a plasma front on the initial pressure of air in a capillary was determined. It was found that in a wide range of parameters the time needed for the formation of a layer of an optically opaque plasma was governed by the total energy of a pulse from the beginning from its action to the moment of appearance of screening and was not greatly affected by the pulse profile or by the gas pressure.