High-Current Vacuum Arc in a Strong Axial Magnetic Field

The high-current vacuum arcs (HCVA) with high average current densities in axial magnetic fields (AMF) B_n les 1.2T were studied. The typical V-shape of volt-tesla characteristic (VTC) has been shown to retain in strong AMF and at raising the current density to 3 kA/cm²; the quantitative parameters change, though. It has been confirmed the conclusion of Chaly et al. (1999) that, in strong AMF, the cathode attachment size for an arc in a quasi stationary state is defined by AMF induction and arc length. The quantitative comparison of VTC and voltage of a low-current arc under the action of magnetic field, inclined to the arc axis (Chaly et al., 2006), encounters difficulties arising in describing of HCVA as an aggregate of independent cathode jets at moderate values of AMF induction

INTRODUCTION

Main engineering applications of high-current vacuum arcs (HCVA) are linked to their use in vacuum switchgear. Therefore, the most intense HCVA studies are in the parameter range specified by the tasks to be accomplished by switching apparatus. The most promising for vacuum interrupters (VI) seems to be the use of arcs, stabilized by axial magnetic field (AMF). The studies of HCVA in AMF, are far advanced and underlie the creation of VI with high performance [1].