Scientific and technological progress of pseudospark devices

This paper presents an overview on the state-of-the-art of research and dev elopment with pseudospark devices. There is an ongoing interest worldwide i n this novel low pressure gas discharge device, This is proven by the sever al papers recently published. Careful studies of breakdown characteristics with two-electrode pseudospark devices show that the simple relation of the old Paschen law is modified for this geometry, Especially for operating th e pseudospark reliably at low gas pressure, it is necessary to superimpose external magnetic fields to initiate the discharge. At low pressure intense beam formation is enhanced but in parallel is hampered by less efficient s pace-charge-neutralization. Based on the original pseudospark geometry seve ral modified beam configurations were developed Like the channel spark and the preionization-controlled open-ended hollow cathode system. In pulsed el ectrical circuits for discharge currents below 10 kA, distinct discharge ph enomena appear which have to be suppressed far any application. One of them are transient impedance transitions correlated with steps in forward volta ge drop, By geometry and choice of electrode material the irregular transit ions in impedance can be controlled over a wide parameter range. Another an noying effect is quenching obvious by sudden and irregular interruption of the discharge current. Quenching is observed as a random effect, which is i nfluenced by a manifold of parameters. Results from the experiment indicate that quenching is strongly dependent on the number density of gas atoms in the discharge volume. Since siliconcarbide (SIC) as part of the switch ele ctrode downsizes the quenching current to negligible values (<1 kA) optical spectroscopy was used to investigate the influence of this semiconducting material on the temporal development of the discharge, by looking for emiss ion lines of the released silicon and/or carbon atoms. The technological as pects of pseudospark devices are naturally to achieve higher lifetime and i mproved overall reliability. Multichannel configurations and two-gap system s are under development to reduce erosion rate and to increase hold-off cap ability, respectively, Under clean conditions a hold-off voltage of 65 kV w as realized by a two-gap system.