Thermal model of the evolution of fragments inside a microscopic spot: A multiscale approach of the interaction plasma/cathode

In this paper we propose an explanation for the great dispersion (several orders of magnitude) which exists in literature for the various values of essential parameters (such as surface power density or current density) of influence in the power balance at the surface of a copper cathode submitted to an electric arc. In this work this dispersion is explained by the difference in the space and time scales considered in the different works published. A simple model is proposed which constitutes a first step allowing to explain the difference in the values for the surface power density brought to the cathode surface.