Laser-triggered Surface Flashover Characteristics of Nylon in Vacuum Condition with Pulsed Voltage

Based on the platform of laser-triggered surface flashover in pulsed voltage, experiment of laser-triggered surface flashover is carried out in vacuum condition with pulsed voltage. A single/double harmonic, with wavelength lambda of 1064/532 nm, Q-switched Nd: YAG laser is applied to trigger the surface flashover. The synchronization problem of laser pulse and voltage pulse is solved using a self-made digital delay/pulse generator. The test system consists of flat electrodes and columned insulator. The material of electrode is copper and the electrode diameter is 40mm. The material of insulator is nylon, the diameter of insulator is 20mm, and insulator's thicknesses are 2mm and 4mm. Laser pulse's wavelength are 532nm and 1064nm, and laser is focused with 0.1mmx30mm rectangle. The results of experiment show that flashover delay time and jitter time decrease with increase of pulsed voltage and laser energy density, the delay time of 1064nm laser trigger is larger than that of 532nm laser trigger, and the delay time is decreased with the thickness of insulator is decreased. At last, possible mechanism of laser-triggered surface flashover is brought foreword.