Voltage Recovery Time of Small Spark Gaps

A two-pulse method is used to determine how fast and to what degree a small spark gap can recover its voltage holdoff capability after breaking down. The first pulse is used to overvolt and break down the gap. The second pulse is used, after a time delay, to determine the voltage recovery of the gap. By varying the time delay to the second pulse, a recovery voltage versus time plot can be obtained. Time delays from 10 μs to 100 ms have been recorded. The spark gap discharges millijoules of energy with a gap spacing of less than 1 mm. Recovery has been measured at breakdown voltages of up to 10 kV in argon, hydrogen, and a mixture of the 2 gases. The experimental setup, pulse circuits, and data collection methods are described. Percent voltage recovery versus time plots for various parameters (gas species, gap spacing, and pressure) are discussed.