Contribution of Nanotechnologies on the Study of the Physical Phenomena of the Arc Birth

The interaction between electrical arc and cathodic surface causes circuit breakers failures which is a crucial problem in their conception. The properties of the electrical arc are governed by the emissive sites which are directly linked to physical parameters of the electrodes like their spacing, their composition, geometry and surface state.The literature provides lots of theoretical results on the formation of cathode spots and their impact on the contacts erosion. Very few experimental studies have been led on the subject at micro and submicronic scale. We propose here to evaluate the arc cathode interaction at submicronic scale by using methods of fabrication offered by nanotechnology such than electron beam lithography (EBL). In order to investigate the influence of microprotrusions on the arc birth in the electrical contact phenomena, tip matrix designs are produced on cathodes with a controlled roughness (under 40 nm). These microprotrusions are created by carbon adsorption on a copper electrode and are subjected to an arc impulse. After discharge, the eroded surfaces are studied by scanning electron microscope (SEM) and optical profilometer. These observations contribute to study the erosion mechanism and to develop a theoretical ablation model of the tip. A comparison between the experimental observation of the cathodic erosion and the numerical results is proposed.