Plasma Switches for High-Repetition, High-Power Applications

There is a continuous requirement for high power, high rep-rate, long life switches in Air Force applications. Two application examples are high power microwave (HPM) and atmospheric pressure air plasma generation for self protection. Both require rep rates in the order of ¡Y 1 kHz at voltages of hundred to several hundred kV and currents into the multi kA range. Present technology uses capacitive energy storage and variations of the triggered spark gap for switching, even though they have limited rep rate capability and their lifetime is limited to the order of 105 -106 shots. These requirements exceed the capabilities of even large hydrogen thyratrons, which also require large amounts of DC auxiliary power. For several years, an alternative switch has been developed and become commercially available for lower power requirements. The pseudospark switch reduces electrode wear due to its ¡°super-emission¡± operating mode, has demonstrated rep rates in the high kHz range and in some versions hold-off voltages in the 100 kV range. Its operating life time far exceeds that of comparable spark gap switches and it requires very little or no DC auxiliary power. Very recently miniature versions of this switch with almost the same performance as standard versions have been developed at USC. While this technology is still being actively developed in several countries, to meet Air Force needs the research will have to be focused on meeting the operating voltage, rep rate and lifetime requirements simultaneously. It is proposed to identify the areas where research is still necessary to increase hold-off voltage, rep-rate and peak current, select design parameters based on current knowledge, address specific areas and provide the improved designs. Since USC is actively involved in pseudospark research, some pilot experiments will also be conducted during phase I to validate novel design concepts.