Low-Intensity Laser-triggering of
Multichannel Spark Gaps



W. Frey


Forschungszentrum Karlsruhe GmbH, D76021, Karlsruhe, Germany


The parallel-series connection of several pulse lines in large pulsed power facilities demands for a high degree of synchronization of the single pulse line switches. In order to achieve an optimum output pulse rise-time the switching jitter should be in the sub-nanosecond range.

Conventional laser-triggering of spark gaps uses energies in the mJ range for low-jitter laser-triggering. Consequently, the required trigger laser energy for a large scale pulsed power generator, involving several 10s of laser triggered switches is high.

A new approach for low-intensity, low-energy laser triggering will be presented. Magnesium aerosol particles are added to the switching gas. The photoemission of seed electrons from small aerosol particles exhibits an extreme high quantum yield.

Even at trigger-laser energies of 200 nJ, the jitter of a multichannel spark gap was less than 1 ns.

The switch geometry, the laser beam guidance and the switch performance, depending on the gas composition, the trigger voltage and the laser energy, will be presented.