The Erosion Performance Of Graphite Electrodes In High Current, High Coulomb, Spark Gaps

The erosion performance of graphite electrodes has been characterized in high current (100-500 kA), high coulomb (1-900 C), switches. Six different graphite materials were tested including state-of-the-art pyrolytic graphite which exhibited superior erosion performance at high-Q. At least two different regimes of operation were identified, low Q (< 5 C), and high Q (> 25 C). For high Q, the erosion is primarily a function of the energy required to sublime the material and its thermal conductivity. In addition, at high Q the thermal model for erosion predicted, within 10%, the scaling law (proportional to Q) and the erosion rate of a recently developed high Q switch at Physics International Corp.