Effects of electrode materials for arc-firing probability and switching time in UV-laser triggered vacuum gap

The switching time and the arc-firing probability of a self-sustaining discharge in UV-laser triggered vacuum gap (ULTVG) were measured. The third harmonic beam of a Nd:YAG pulse laser (wavelength 355 nm, energy 5 mJ/pulse, power density 4/spl times/10/sup 7/ W/cm/sup 2/) was used as a trigger for ULTVG. The UV-laser pulse injected perpendicularly onto the grounded cathode. The electrode materials were oxygen-free copper and aluminum. The electrodes were 85 mm in diameter. The gap length was 1.6, 1.9, 2.2 mm. The experimental chamber was evacuated to about 1.3/spl times/10/sup -4/ Pa by a turbo molecular pump. The range of the firing voltage in copper electrodes was higher than in aluminum. The jitter of the switching time in copper electrodes was smaller than in aluminum. The arc-firing probability decreased as the circuit inductance increased.