Leader propagation in uniform background fields in SF₆

Abstract

The breakdown mechanism of compressed SF6 in gas insulation is known to be controlled by stepped leader propagation. This process is still not well understood in uniform and weakly non-uniform background fields with small electrode protrusions, such as particles or surface roughness. In a previous publication an investigation of partial discharges and breakdown in uniform background fields that focused on streamer and leader inception mechanisms was presented (Seeger et al 2008 J. Phys. D: Appl. Phys. 41 185204). In this paper we present for the first time a physical leader propagation model that consistently describes the observed phenomena in uniform background fields in SF6. The model explains two different types of leader breakdown; these can be associated with the precursor and the stem mechanisms. It also yields the parameters of stepped leader propagation, which include step lengths, associated step charges, step times and fields and temperatures in the leader channel. Further, it explains the features of arrested leaders in uniform background fields. The model predicts the range of parameters under which arrested and breakdown leaders occur in good agreement with the experimental data.

High-order fluid model for streamer discharges: I. Derivation of model and transport data

“…For a cluster issue on streamers, sprites and lightning, we refer to [4] and the 19 original articles therein, discussing common issues of streamer dynamics in atmospheric discharges and plasma technology, including discharge evolution and subsequent chemical reactions. Streamers are a key element in gas processing in so-called corona reactors [5,6] as well as in high voltage technology [7]; they are used for the treatment of polluted gases [8] and water [9] or for plasma enhanced vapor deposition [10]. The plasma bullets observed in plasma jets in noble gases have now been identified with streamers [11,12,13,14,15,16].…”

Partial discharges and breakdown in C3F8

“…For SF 6 there exist a detailed understanding of the discharge processes, the conditions leading to breakdown and the modelling thereof [8,9,10,11,12]. In the course of searching for replacement candidates for SF 6 , there will be the need to understand and model the discharge and breakdown behaviour of this new insulating gas.…”

“…If this would be achievable, one could predict the phenomenological behaviour of novel gases without time consuming breakdown experiments in real size geometrical arrangements. For the investigation we use the model of stepped leader propagation [9] extended and applied to technical relevant geometries by Seeger and co-workers [12].…”

An Efficient Procedure to Identify and Quantify New Molecules for Insulating Gas Mixtures

“…The above mentioned leader propagation model in SF 6 was presented in [58,59], experimentally validated for different cases in [60,61]. Experiments to test this model in other electronegative gases are currently in preparation.…”