Dynamic behavior of high-pressure arcs near the flow stagnation point

The conservation equations of high-pressure arc near the flow stagnation point have been solved for a current ramp before current zero (di/dt), and for an electrical field ramp (dE/dt) after current zero. The analysis is based on laminar flow and local thermal equilibrium. Two arc-quenching gases, sulphur-hexafluoride (SF₆) and nitrogen (N₂), have been investigated. The relative importance of radiation, convection, and thermal conduction under a wide range of discharge conditions is discussed. Before current zero the computed temperature of the nitrogen arc is in fair agreement with the experimental results. The predicted dependence of the critical rate of rise of the recovery electric field on di/dt and pressure is much weaker than the empirical relationship, which remains unexplained. The theory also fails to confirm the superior arc-quenching capability of SF₆ over N₂