Influences of electric field on the jitter of ultraviolet-illuminated switch under pulsed voltages

In a wide variety of high-power pulsed facilities, megavolt switches play a key role in determining the system performance. In particular, ultraviolet (UV)-illuminated switches have been widely used for their high-voltage, low-jitter characteristics. In this paper, two factors that may affect the breakdown jitter of a 3 MV UV-illuminated switch under pulsed voltages were investigated, namely, the electric field enhancement factor of a UV-illuminating gap (UV gap) and the number of UV gaps. The experimental results show that the electric field enhancement factor is important for adjusting the average E/p of the main switch gap when the UV gaps breaks down under certain N₂ pressures. When the electric field enhancement factor of the UV gaps is approximately that of the main switch gap, the breakdown jitter percentage goes down to less than 1.9%. Comparatively, the number of UV gaps affects breakdown voltage and jitter in a limited-way. When only one UV gap is functioning and the electric field enhancement factor of UV gap is approximately that of the main switch gap, the breakdown jitter is less than 1.3%.