Design criteria for high performance, high power pseudospark switches

The main development objective is to replace commercial switching devices with pseudospark switches. The principle is similar to that of a cold-cathode thyratron. The basic mechanisms facilitate a simple construction. On the other hand one gets undesired phenomena by the physics of cold cathode emission at low peak currents (less than 2 kA), like quenching, chopping and impedance fluctuations. At very high peak currents (more than 50 kA) transition to a metal vapor arc occurs with correlated high cathode erosion by cathode spot formation. With molybdenum as electrode material beyond 45 kA additionally anode spot formation contributes considerably to electrode erosion. Below 45 kA erosion rate amounts typically to 100 /spl mu/g/C and jumps by one magnitude up to 100 /spl mu/g/C and more with anode spot formation. A quite early used method to avoid this was to change from one-channel to multichannel configurations; another possibility discovered, is to use silicon-carbide (SiC) as durable electrode material. Experiments over a wide range of discharge currents demonstrate that arc formation is suppressed. As a consequence the power input per square unit is reduced. Strong emphasis was put on the solution of technological problems by optimization of design parameters. In parallel, two-gap switch configurations are under development to achieve reliable hold-off voltage capability up to 40 kV. This paper summarizes the most important results of fundamental research as well as of technological progress.