Small pseudospark switches

Abstract

Summary form only given. Compact pulsed power technologies require small switches with high hold-off voltages (20/spl sim/30 kV) and reasonable discharge current (several kA) for applications that include plasma ignition and compact repetitive pulsed power sources. The pseudospark has intrinsic advantages in geometry and housekeeping that make it a candidate for compact applications. In this work, an initial design for a compact pseudospark switch with 12.7 mm o.d. glass envelope, is reported. The total switch size was reduced by more than one order of magnitude relative to previously published versions of the switch, primarily by decreasing the switch cross section area by a factor of 9. Hold-off voltage with respect to operation pressure in the switch self-breakdown condition has been studied. A broad operation range, from 100 mTorr to 1000 mTorr, was measured with the hold-off voltage staying almost constant at 20 kV in Helium. Operation as an optical-triggered pseudospark (or BLT) switch, with UV light incident on the back of the cathode surface, was also studied. The current rise rate was measured to be 1/spl times/10/sup 11/ A/s with a switch hold-off voltage of 17 kV and discharge current of 3.3 kA when triggered by a laser beam of 266 nm with an optical energy less than 30 mJ. Higher dI/dt and higher discharge current can be obtained by reducing the circuit inductance and by increasing the charging capacitance.