Measuring the expansion velocity of plasma formed during electrical breakdown along an exploding al foil in a medium of desorbed gases

Abstract

This paper reflects the experimental results on the measurement of the expansion rate of the plasma formed during an electrical breakdown along the exploding Al foil. Electric breakdown took place in a mixture of gases that being desorbed from the surface of the foil as it heated by a current passing. Aluminum foil size: length 20 mm, thickness 6 µm and the width was varied in the range from 0.93 mm to 1.05 mm. The explosion of the foil was carried out by a sinusoidal current with an oscillation period of 1780 ns. The amplitude of the current I varied depending upon the voltage charge (Uch = 10, 20 and 30 kV) of 0.25 µF capacitor was about 6.5, 14 and 22 kA accordingly. The measurements of the expansion rate of the plasma was carried out using three electrical probes located beneath an ground potential, near the edges and in the middle of the exploding foil, in the process, the distance from the foil to the electrical probe was varied from 2 mm to 16 mm. In the experiment we measured the time of the signal appearance relative to the moment of electrical breakdown occurrence along the foil. The rate of plasma expansion was calculated by measuring the time of plasma span from the foil to the probe with consideration of the distance to the probes.