Reproducibility of a titanium plasma vacuum spark discharge

Abstract

The results of an extensive operation of a Vacuum Spark plasma using Titanium electrodes in a 120 ns 150 kA discharge are presented. The hot spots are found to form with a regular spacing in a zippering Z-pinch plasma, which forms close to the cathode and extends to approximately two thirds of the anode separation over a period of a few ns. The axis of the discharge is well defined by an initial plasma from a Nd:YAG laser focussed onto the cathode electrode surface. The statistics of the formation of the hot spots are given for the life of one anode electrode. Between one and three hotspots form and the favored positions are at 1.5 and 3.0 mm from the cathode and the strongest emission, as observed in a filtered X-ray pinhole camera, comes from the hot spot closest to the cathode. The emission spectra resolved between 50 and 350Å shows a wide range of Ti ionization which allows the temperatures of the anode blow off plasma, the Z-pinch and the hot spot plasma to be distinguished. These results are compared with filtered PIN diode signals and filtered pinhole images.

Fast ion generation in the cathode plasma jet of a multipicosecond laser-triggered vacuum discharge

“…1,2 Formation of micropinches ͑plasma points or hot spots͒ of high temperature ͑T e : 1-10 keV͒ and high density ͑n e :10 22 -10 23 cm −3 ͒ in such discharges has attracted much attention as an intense x-ray source [3][4][5][6][7][8] and also as a source of multiple-charged high-energy ions. 9,10 A different mode of pinch effect, viz., cathode plasma jet pinching, has been observed in moderate-current ͑few hundreds of amperes to few kiloamperes͒ vacuum arcs and sparks.…”