The Arc Cathode Regime: An Approach from Basic Laws

Abstract

Abstract The question is examined whether or not the existence of a cathode mechanism with high power density may be predicted from general physical laws, as well as the order of magnitude of the main cathode parameters of such a discharge. The answer is yes, though – because of many feedbacks and simplifications – the numerical values calculated in this way are not more than crude estimations. Essentially two conditions have to be fulfilled: The first is the dominance of collective electron emission processes, the second is the dominance of Joule heating combined with the limit of stationarity. Both conditions result in similar values of the cathode parameters. In this low‐current region (about 10…100 A) the existence of a high‐current density cathode mechanism (order of magnitude: 10 8 A/cm 2 ) is proved, with consequences for all the other parameters, in rough agreement with the results of measurements in arc cathode spots. Thus the typical arc spot regime may be founded theoretically by these argumentations.