Dependence of a pseudospark breakdown voltage characteristic on the hollow cavity dimension

The pseudospark, which is a low pressure gas discharge between a hollow cathode and a planar anode, has an interesting discharge characteristic and capability of producing a high-quality electron beam. An important characterization of such a discharge is the breakdown voltage characteristic. The authors reported previously that the breakdown voltage characteristic of a pseudospark is determined empirically in terms of gas pressure and anode-cathode gap distance as v(p,d) = 0.19/(p2d)2.2, which is strikingly different from that of a parallel-plate system that is described by Paschen's law. In this study, dependence of the breakdown voltage characteristic on the hollow cavity dimension is experimentally determined in addition to those of the gas pressure, and anode-cathode separation distance. The breakdown voltages are being measured systematically for a wide range of the cavity length and a few different diameters. Preliminary results show that when the aspect ratio of the cavity dimension is beyond unity, R = h/d ≥ 1, the breakdown voltages are nearly equal to that given above. Details of the experimental results and analysis will be presented