A 2 MV, Multichannel, Oil-Dielectric, Triggered Spark Gap

Abstract

A 2 MV, low jitter (< 2 nsec), multichannel (~ 10 channels), oil-dielectric spark gap has been developed to be used for switching the transmission lines of proposed new relativistic electron beam (REB) accelerators with substantially increased peak power (10¹³W). The switch is designed for operation in a strip-line geometry with three 122 cm long electrodes, two smooth bars and one sharp-edged trigger blade. When a voltage pulse that rises to 1.5 MV in 20 nsec is applied to the trigger electrode, about 10 arcs will close simultaneously in 30 nsec with a standard deviation < 2 nsec. Data are presented on the variation of the switch closure time with applied voltages. The spark gap was installed on one of two 22 Ω, 20 nsec strip transmission lines connected as a Blumlein during test. The Blumlein output voltage pulse risetime decreases with increasing number of switch channels (13 nsec with 2 channels to 5 nsec for 14 channels). Data are presented on operation of the switch with the trigger electrode location varied from 20–40 percent of the gap spacing from the ground electrode. The effect of the interelectrode capacitance and isolation resistance on the operation of the switch is discussed. Several types of electrodes have been tested. Design data for a prototype REB accelerator using 12 of these switches in parallel are presented.

This work was supported by the U.S. Atomic Energy Commission