Laboratory investigations of pulsed RF plasmas relevant to CW arc pluming at high-power aerials. Part 2: Relevance of scale-model studies based on pulsed RF techniques

The paper describes experiments which extend the observations of RF breakdown events in nonuniform fields reported in Part 1 of the paper. In particular, emphasis is given to examining the relevance of laboratory observations on pulsed RF discharges to the understanding of the ‘pluming’ phenomenon occurring under CW conditions at high-power aerial arrays. This is achieved by examining the effects of various scaling factors on the breakdown characteristics using both scaled sphere-to-plane and scaled toroid-to-plane geometries. It is shown how the intrusion of objects with needle-point geometries can lead to dramatic reductions in the critical electric fields needed to initiate the unwanted ‘pluming’ phenomeonon.