On the current density limiting effect in SF6-based mixtures

This paper reports on the investigation of the current density limiting effect in a self-sustained volume discharge in SF6-based mixtures due to a self-action of the discharge current on the media it passes through. The mechanism of this phenomenon in terms of electron-impact dissociation is examined. The argument is advanced that in the planar geometry the limiting effect treated may provoke triggering a spatially uniform volume discharge in the media stated even in the absence of pre-ionization. It is shown that the dissociation mathematics developed by the authors allows the quantitative estimation of the averaged expenditures of energy per formation of a dissociation fragment. Specifically, when applied to pure SF6 this finding enables the assessment of the energy spent for F-atom formation. For the first time the influence of current pulse duration on the discharge voltage has been experimentally revealed. Both thorough qualitative and quantitative considerations including relevant numerical simulation have been performed.