Scientific and technological progress of pseudospark devices

The paper presents an overview on the state-of-the-art of research and development with pseudospark devices (low pressure gas discharge device). Based on the pseudospark geometry several modified configurations were developed like the channel spark and the preionization-controlled open-ended hollow cathode system. In pulsed electrical circuits for discharge currents below 10 kA distinct discharge phenomena appear which have to be suppressed for any application. One is transient impedance transitions correlated with steps in forward voltage drop. By geometry and choice of electrode material the irregular transitions in impedance can be controlled over a wide parameter range. Another is quenching, observed as a random effect, which is influenced by many parameters. Results from the experiment indicate that quenching is strongly dependent on the number density of gas atoms of gas atoms in the discharge volume. Since silicon carbide (SiC) as part of the switch electrode 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 emission lines of the released silicon and/or carbon atoms. The technological aspects of pseudospark devices naturally are to achieve higher lifetime and improved overall reliability. Multichannel configurations and two-gap systems are under development to reduce erosion rate and to increase hold-off capability, respectively. Under clean conditions a hold-off voltage of 65 kV was realized by a two-gap system.