Studies of the Stable Stage of the Electric Arc Burning at the Contact Separation in a Vacuum Gap with a Transverse Magnetic Field

Experimental studies have been carried out on characteristics of the direct current vacuum arc during contact separation in an axially-symmetrical magnetic field that has predominantly a radial component. The study results on the dynamics of the plasma flow and voltage at the vacuum arc are presented for the stable stage of the arc burning at currents in the range of 50-150 A. The experimental dependencies of the stable stage duration on the value of the current and the induction of the magnetic field are obtained. The explanation of the observed phenomena is offered in terms of a one-dimensional stationary model of plasma flow in the transverse magnetic field where the development of instability is caused by the crisis in the plasma flow resulted from the decrease of the velocity of fast cathode ions to the ion-sound velocity. The calculations of the stable stage duration of arc burning made within the frame of this model are in fair agreement with the obtained experimental results