Experimental analysis of the electrode products emitted by high-current vacuum arcs

Abstract

The mass distribution of particles produced in the high-current vacuum arc was investigated. The experiments were concentrated on evaluating the spatial mass distribution emitted in radial as well as in azimuthal directions calculated from mass deposition profile on the collectors surrounding the arc discharge. The experiments were carried out in a vacuum chamber evacuated to ambient pressure <10/sup -4/ Pa. The high-current arcs in the range from 2 kA to 7.5 kA were drawn between butt contacts of 31 and 55 mm in diameter (anode and cathode respectively) both of copper-chromium alloy (CuCr25). The surface mass deposit along the multi-segment collectors were measured by micro-densitometer, a scanning microscope and also by ICP spectrometer. Two angular mass deposit distributions were determined: the azimuthal distribution represented by function f/sub m/(/spl beta/) on the plane parallel to the cathode surface; and the radial distribution f/sub m/(/spl phi//sub c/) as a function of angle /spl phi//sub c/ with respect to the cathode plane. Both distributions are anisotropic and the structure of the deposition layer depends on the angle of particles incident upon the substrate, the density of particles flux and other factors. The component of mass deposit on collectors consists mostly the chromium molecules (approx. 80% of Cr and 20% Cu) for CuCr25 or CuCr40 electrodes.