Effect of the Axial-Symmetrical Two-Dimensional Magnetic Field on the Configuration of a Vacuum Arc Discharge

The effect of axisymmetric 2D magnetic field on plasma formation and cathode spots configuration in a vacuum-arc discharge has been examined experimentally. It has been demonstrated that the magnetic field with the cross component about the discharge axis, has a significant effect on the plasma column shape and the speed of cathode spots expanding. The arc plasma in the magnetic field looks like a truncated cone, expanding towards the anode. Cathode spots occupy a part of the cathode area that decreases with the magnetic field increase. Arguments proving that the cathode spots location and the arc plasma form can be determined by the principle of the voltage minimum have been given. The mechanism, related to the retrograde movement of the cathode spot, with the effect of the azimuthal magnetic field on the current axial component balanced by the effect of the axial magnetic field on the azimuthal current component, has also been discussed