Measured data and model for erosion of a spark gap at continuous 800 Hz, 10 J pulsed operation

Spark gap closing switches suffer from electrode erosion and the switching medium has to recover after each pulse. The recovery is strongly improved by flushing the gap. The performance of the spark gap of our pulsed corona system will be described on the aspect of erosion. The operation is a continuous flow of short kA pulses at kHz repetition rate. The experimental erosion results for six electrode materials are presented. Flushing gas is Nitrogen. An analytical and a numerical erosion model is proposed. Erosion was monitored during 65 million pulses. The investigated materials rank, at decreasing quality of performance, as follows: copper > brass > copper/tungsten > stainless steel > tungsten > aluminum. Time and space resolved heating of the electrode can be simulated, including vaporization and melting. The power input of the models is the product of the measured discharge current and estimated effective fall voltage.