Laser-induced discharge characteristics in low vacuum with residual helium gas and air

This paper describes the fundamental characteristics of TEA-CO/sub 2/ laser-induced plasma in low vacuum. Experimental results revealed that there existed a threshold pressure for the laser-induced plasma production in He gas and air in low vacuum. The pressure dependence of shape and intensity of plasma was observed and discussed. Laser-triggered breakdown characteristics under uniform field were also measured in atmospheric air.