A Multi-spark Preionization Source for Diffuse Discharges Containing Attachers*

Diffuse discharge opening switches usually operate with gas mixtures containing attachers when short opening times are desired. For arc free discharge 1nitiation, a preionization source should produce a sufficient electron density at the time when the voltage rises across the discharge. Therefore, a preionizer must have 1) a short rise and fall time, 2) sufficient power, and 3) a sufficiently precise timing system to synchronize preionization and main discharge. A device to generally fulfill these requirements is described. The energy for the preionization source is stored in eight individual coax cables and switched with one master gap into eight cables that are terminated by individual multi-spark gaps arrays. The gap for the main discharge and the master gap for the preionizer are triggered by a single laser using a beam splitter. The optical delay of the light pulse controls the synchronization. Experiments showing delay, preionization pulse length, and jitter are presented.