The Development and Testing of Subnanosecond-Rise, Kilohertz Oil Switches

Subnanosecond risetime, kilohertz oil switches have been developed and tested at Pulse Sciences, Inc. The development was divided into two phases. During the first phase, a two-three pulse breakdown test at 130 kV was used to measure the recovery characteristics of a large area oil switch at up to 200 pps. Different geometries were explored along with oil flow rates required. The oil flow experiments and the effect of electrode/flow geometry are reported. Successful test results in the first phase led to the Phase 11 design of a high repetition rate modulator based on flowed oil switches that develop pulses tens of nsec in duration. The modulator incorporates three oil switches: (1) a transfer switch, (2) a sharpening switch, and (3) a peaking/sharpening switch. Initial operation and parameterization has shown operation and recovery of the oil switches at up to 290 kV, and rep-rates of 200 pps respectively. Lower voltage tests at 140 kV and 170 kV have shown recovery at up to 1250 and 1000 pps. Peak energies of 50 Joules per pulse have been transferred into a 97 ohm resistive load, with a 280 ps risetime. The modulator design and performance are reported. The fluence of electrode/flow geometry upon the recovery of oil switches is described, along with the breakdown and other characteristics of the switches.