Skin effect as a factor in the movement of cold-cathode arcs

An arc established between parallel metal electrodes is found to move under the influence of the transverse magnetic field set up by the arc current in the electrodes. The velocity of movement varies with cathode material and characteristic velocity-current curves may be separated into two groups, one comprising the magnetic and the other the non-magnetic metals. It is suggested that the higher velocity of the former group is due to a form of skin effect phenomenon which both radially and circumferentially compresses the current close to the cathode spot and thus gives an enhanced magnetic driving force in the critical region just outside the cathode surface. Experimental results are given to support the proposed mechanism.