Distribution of Chopping Current for Copper Electrodes in Vacuum in Axial Magnetic Field

Previously developed models of chopping current distribution for contacts in vacuum without the presence of magnetic field are discussed. Justification for applying the maximum value asymptotic distribution for evaluation of the expectation of current chopping has been presented. The experimental results have served for the assessment of the axial magnetic field influence on the parameters of the chopping current maximum value distribution. The investigation was carried out in an almost resistive circuit, in a wide range of imposed axial magnetic fields from 0 to 500 mT, with the alternating current between 50 and 860 A. The electrodes were placed in a chamber where the pressure was kept below 10^-3Pa by means of continuous pumping. In order to eliminate the influence of the contact movement speed on chopping current, vacuum arc ignition was effected by a high-voltage impulse. Furthermore the interdependence of the chopping current and the magnetic field for copper electrodes is illustrated