Aachen PK 2003 – wissenschaftliches Programm

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K: Kurzzeitphysik

K 2: Pulsed power technology

K 2.2: Vortrag

Mittwoch, 19. März 2003, 11:45–12:00, F04

Characterisation of the transient discharge phases of a Pseudospark discharge — •Jürgen Urban and Klaus Frank — Physikalisches Institut I, Universität Erlangen-Nbg., Erwin-Rommel-Str. 1, 91058 Erlangen, Germany

The Pseudospark discharge is a pulsed high current low pressure gas discharge which is located at the left branch of the so called Paschen curve. It operates in a special hollow cathode geometry with plane parallel electrodes having small boreholes connecting the main electrodes and the hollow electrodes. During a high current pulse discharge the electrical discharge processes vary from low current hollow cathode discharge, a medium current dense glow discharge, a cathode spot regime to a metal vapour arc.

Partly this transitions between different discharge phases are almost instantaneously. Especially the transition from the homogeneously dense glow discharge, also known as borehole phase, to the cathode spot discharge process is very fast and additionally connected with a sharp drop of the switch impedance. Time fluctuations of this transition result also in pulse to pulse variations of the discharge current amplitude, especially at low discharge currents in the range of some kA or below. Different cathode materials were investigated to reduce this effect of impedance fluctuations. For copper electrodes time resolved spectroscopic measurements were performed to gain a better understanding of the above mentioned critical discharge phases. A significant reduction of impedance fluctuations could be reached.