Effect of the cavity structure on the discharge features of pseudosparks

Summary form only given, as follows. A pseudospark discharge is a specific type of gas discharge, which operates at low pressure with axially symmetric parallel electrodes and central holes on the electrodes. The discharge is characterized by a very rapid breakdown phase, during which high-density particle beams can be extracted and rapid increasing rate of current can be achieved. Based on these, the pseudospark has become of interest in closing switches, in producing well-pinched high intensity electron or ion beams. The cavity structure of cathode in pseudospark device is important factor to determine the performance of the device. With and without a cavity behind the cathode aperture, the erosion pattern of the pseudospark discharge was experimentally investigated. With the hollow cathode cavity, a very small and stable erosion pattern by electron-beam generated from the spark was formed on the opposite surface inside the anode cavity and stable concentric ring-shaped erosion patterns were observed at the central area around the apertures on the electrodes. Without the hollow cathode cavity, the patterns became irregular and unstable. These results revealed that the hollow cathode cavity plays an essential role to the stability of pseudospark discharge in the pseudospark and to the generation of a well-pinched electron-beam. The cavity structure of intermediate floating electrode can also improve the self-breakdown performance of pseudospark switch. We have compared the hold-off voltage of two kinds of pseudospark switches: one with plane intermediate electrode, another with an intermediate cavity electrode. The experimental result revealed the later one has higher self-breakdown voltage (over 80 kV) and can be operated at higher gas pressure. Relevant figures, pictures and data will be presented.