Long, lifetime, triggered, spark-gap switch for repetitive pulsed power applications

In this article a critical component for pulsed power applications is described: the heavy-duty switch. The design of a coaxial, high repetition rate, large average power, and long lifetime spark-gap switch is discussed. The switch is used with a fail-free LCR trigger circuit. Critical issues for switch design are presented together with experimental results. It is observed that the switch has a good stability, and its lifetime is estimated to be in the order of 1010 shots (~106 C) at 10 J/pulse, 60 kV and 100 ns pulses. Measurements were performed with 20 and 34 kV average switching voltage (100 ns pulses, energy per pulse 0.4 and 0.75 J, respectively). For up to 450 pulses/s (pps), pre-firing can be prevented by increasing the gap pressure (up to 2.5 and 7 bars, respectively), no gas flush is required. Above 450 pps, up to 820 pps, a forced gas flow of maximal 35 Nm3/h, is required for stable operation. Measurements on the time delay and jitter of the switch demonstrate that these values are influenced by pressure, flow, and pulse repetition rate. For 34 kV average switching voltage the time delay and time jitter vary between 35 and 250 and 10 and 80 µs, respectively. For 20 kV average switching voltage these values are: 30–160 and 4–50 µs. During a test run of 2.5 h (at 100 Hz, 0.75 J/pulse) the feasibility of the switch was proved, and the switching voltage jitter was less than 0.7%. ©2005 American Institute of Physics