A new principle in vacuum arc interruption using magnetic fields

A new concept of enhanced vacuum arc interruption is based on the premise that the self-generated magnetic field of the contacts should be optimized to effectively diffuse the vacuum arc during the high-current power-frequency cycle. This paper uses a mathematical formulation of the interelectrode plasma of the high current vacuum arc to explain the behavior of the arc in the external (to the arc) magnetic field. This formulation also takes into account the self-generated magnetic field and therefore provides an insight to the global plasma behavior in the magnetic field. The approach presented neglects the phenomena associated with the individual cathode spots and assumes the so called MCS (multi-cathode spot) model. It does however, take into account the near-anode phenomena which result from the interaction of the electrode with the plasma.