A High-Energy Graphite Spark Gap Switch

High-energy switch and trigger systems are required for a range of capacitor bank applications such as for electromagnetic rail, coil, and electro-thermal guns. Spark gaps can be made from brass copper or other metallic electrodes. Under high current and high charge transfer the metal may vaporize and create some deviations in trigger performance. A new approach using graphite electrodes avoids the disadvantages of metal electrodes because no metallic plasma is generated. This paper summarizes recent developments in this kind of switch design in our laboratory. The switch is a two-electrode switch and is triggered by an overvolting "series-injection" of a high-voltage pulse. The trigger generator TG-160 is a MARX generator which applied an overvolting pulse directly to one of the spark gap electrodes, open circuit output voltage of TG-160 is 120 kV, with a 30 ns rise time, and the pulse width of 160 ns (FWHM). Electrode erosion surface of different materials was investigated in switch life testing.