Copper cathode erosion by an electric arc - the causes of the variations of the erosion rate with the electrode gap

In this paper we present a study concerning the influence of the electrode gap on the erosion of a copper cathode under the sole action of an electric are in air at atmospheric pressure. The causes of the variations of the er osion rate with this parameter are studied. It is shown that, certainly, th e variations of the erosion rates with the electrode gap should be imputed to two factors: the are mobility which changes strongly with the electrode Sap and a 'supplementary' heating of the cathode surface due to interaction s that occur at small electrode gap values between the cathode surface and the anode plasma jets.