Exploratory studies on a passively triggered vacuum spark

Abstract

The results of an experimental investigation on a passively triggered vacuum spark device are presented. The diagnostics include the current, x-ray and optical emission measurements. The sharp dips in the current derivative signal indicate the occurrence of pinching at an early stage of the discharge (at current 5 kA). A well-confined plasma with a central hot region was recorded using a streak camera. The pinched plasma was observed to undergo kink-type oscillations with a time period of 10-15 ns. Repeated plasma fronts were seen to move from the anode to the cathode with an average velocity of 5 × 106 cm s-1. Soft x-ray emission having a radiation intensity of a few hundred mR per discharge was observed. The x-ray signals obtained using photodiodes showed multiple bursts. A soft x-ray pinhole camera recorded micro-pinches of 100 µm. The x-ray emitting regions were confined to the inter-electrode gap. The x-ray emission characteristics were influenced by the electrolytic resistance, which was connected across the spark gap to initiate discharge.

Reproducibility of a titanium plasma vacuum spark discharge

“…Other recent work [15] has studied various methods of electrical triggering of fast capacitor bank vacuum sparks, with characteristic X-ray energies of between 3 and 40 keV. Other work on reliable vacuum spark operation includes the generation of a sliding spark on a PTFE sleeve covering part of the cathode [16]. The system is called passive, as part of the applied generator voltage is resistively fed to a ring electrode on the PTFE sleeve to initiate the sliding spark.…”