Performance of the hermes-III laser-triggered gas switches

This paper reports the performance of the SF/sub 6/ insulated, multistage, laser-triggered gas switch used in the Hermes-III accelerator.sup 1/ In this accelerator, 20 of these switches are used to transfer energy from intermediate energy storage water dielectric capacitors to the pulse forming lines (PFLs). Approximately 8,000 laser-triggered switch shots have been taken with seven prefires. Nearly 70% of these shots have been at nominal operating parameters. The average first-to last spread in firing times for 20 switches is approximately 8 ns. Removal of systematic differences reduces this spread to /spl tilde/6 ns. This spread implies a one-sigma jitter for a single switch of <2 ns at 70-75% of self-breakdown voltage. Results show that the jitter does not change significantly over an operating range of 70-90% of self-breakdown. In addition, the jitter is insensitive to the factor of two variation in the laser energy delivered to the various switches by the optical system. A detailed summary on the performance, reliability, and maintenance of the switches and optical system is presented. Initial results of a study to investigate the performance of these switches under varying laser trigger conditions is also presented.