Discharge initiation by a laser pulse in a vacuum gap

Abstract

Abstract Laser-induced discharge within a vacuum gap of few millimeters between electrodes is experimentally studied. The discharge is triggered by 1064 nm Nd:YAG laser pulses with intensities varied from 107 W/cm2 to 109 W/cm2 on the surface of target electrode The current formation time dependences from both the gap length and the residual gas pressure at a fixed electrode voltage were determined. Residual gas pressure varied from 10−6 to 10−2 torr, and voltage varied from 100 V to 5 kV. The dependences of current formation time on the laser pulse intensity and the voltage difference on the electrodes of different polarity are presented. The laser intensity thresholds for discharge are determined in our experimental conditions. We also performed atomistic and hydrodynamics modeling of laser heating and evaporation of metal from electrode surface. The experimental and modeling results are used for development of qualitative mechanism of ionization and charge multiplication processes in metal vapor.