Spark gap erosion in Marx generators for electroporation

In industrial-size electroporation devices, in which longevity is of concern, it is advantageous to use the Marx-generator class pulse sources. As these devices may be deployed for long periods of time, the erosion of the Marx generator spark gaps is of considerable importance, and can be considered to be a fundamental design criterion. The paper describes experiments on the erosion of a single spark gap. The spark gap switches an RLC pulse circuit. By pressure variation of the surrounding nitrogen atmosphere the ignition voltage of the spark gap has been varied. The shape of the current pulse was chosen to be aperiodically damped in order to investigate the wear of the electrodes for anode and cathode independently. Peak currents were set by the value of the load resistor whereby the pulse widths lay in the order of 2 to 5 μs. Spark gap erosion has been measured by weighting the electrodes before and after an experimental run by means of an analytical balance. Different erosion characteristics for anode and cathode have been found.