The vacuum arc in an axial magnetic field

An experimental and theoretical study of the behaviour of a vacuum arc on Cu and Mo electrodes in an axial magnetic field at currents between 150 A and 16 kA has been carried out. The maximum magnetic field strength was 0.25 T. It was found that the influence of the magnetic field on both the high- and low-current arc was determined by the ratio between the cyclotron frequency and collision frequency of the electrons. The relatively small difference in behaviour of the Mo and Cu arcs was explained by the presence of neutrals in the Cu arc, while in the Mo arc these particles were practically absent. Some conclusions have been made about the electron temperature and the energy losses of the individual arc columns observed at high magnetic field strengths.