Pseudospark switches-technological aspects and application

We report results of the development of fast closing switches, so-called pseudospark switches, at Erlangen University. Two different parameter regimes are under investigation: medium power switches (32 kV anode voltage, 30 kA anode current and 0.02 C charge transfer per shot) for pulsed gas discharge lasers and high power switches (30 kV anode voltage, 400 kA anode current and 3.4 C charge transfer per shot) for high current applications. The lifetime of these switches is determined by erosion of the cathode. The total charge transfer of devices with one discharge channel is about 220 kC for the medium and 27 kC for the high power switch. At currents exceeding 45 kA a sudden increase in erosion rate was observed. Multichannel devices are suited to increase lifetime as the current per channel can be reduced. Successful experiments with radial and coaxial arrangements of the discharge channels were performed. In these systems the discharge channels move due to magnetic forces. A skilful use of this phenomena will result in a considerably increase of switch lifetime. Multigap devices enable an increase of anode voltage. A three gap switch has run reliably at an anode voltage of 70 kV.<
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