Expansion Mechanism in a Laser-Produced Spark

Abstract

Time-resolved Schlieren studies of the expansion of a laser-produced spark during the rising portion of the initiating laser pulse have been carried out in neon, argon, nitrogen, and air. The results obtained are not compatible with the radiation-supported shock-wave model, nor can they be explained in terms of a radiation transport wave or a simple breakdown wave. A satisfactory explanation involving a traveling ionization-breakdown wave is proposed.