HIGH POWER OPENING SWITCH OPERATION ON HAWK

Abstract

Abstract : The Hawk pulsed power generator is used in plasma opening switch (POS) experiments in the 1-micro(s) conduction time regime to study long conduction time switch physics. Experiments reported here include modifying the POS electrode geometry, injecting plasma into thee-beam diode, using gas gun plasma sources (with H2, He, and Ar gases), and using a helical cathode center conductor in the switch region to increase the total insulating magnetic field. Tapering the cathode center conductor over the 8 em POS length from 10 em to, typically, a 2.5 em diam produced peak load powers of0.7 TW with 55 kJ delivered to the diode--20% energy efficiency--with carboncoated flashboards as the plasma source. Performance (voltage, power generated) with a straight 10 em diam cathode deteriorated when the POS anode outer conductor just downstream of the switch was extended toward the load at the same radius as the switch. Load power was up to 70% higher with a plasma-filled diode (PFD) used in conjunction with the POS for short POS conduction times {400 ns and less). Use of a helical center conductor resulted in dramatically degraded switch performance for 350 ns conduction times. Switch performance with gas guns was generally comparable to that with flashboards in a given switch/load configuration and was independent of the gas (H2, He, and Ar) used.