Distribution Of Cathode Spots Research Articles

Experimental Investigation of Vacuum Arcs in Nonuniform Axial Magnetic Fields

Experiments were conducted in a detachable vacuum chamber with conventional cup-shaped axial magnetic field (AMF) electrodes and three types of AMF electrodes with different nonuniform AMFs. The radial distributions of the AMF were varied by introducing ferromagnetic material into the cup-shaped AMF electrodes. The vacuum arc column and the distribution of cathode spots were photographed with a high-speed charge coupled device (CCD) camera. Experimental results indicate that a nonuniform AMF with higher axial magnetic flux density at the contact periphery than that at the center (saddle-shaped AMF) can resist arc constriction and increase the cathode and anode utilization ratios more effectively than the ordinary bell-shaped AMF profile.

Computer-aided reconstruction of cathode images obtained by high speed photography of high current vacuum arcs

The images of the cathode obtained by high-speed photography are ellipsoidal because they are taken at a small angle (about 10/spl deg/) to the cathode surface. For this reason, it is very difficult, if at all possible, to draw conclusions about the spatial distribution of cathode spots and current density over the cathode surface. One may perform inverse parallel projection, but previously it was necessary to free the image from the noise of the interelectrode plasma radiation and other noise sources. In this paper, we propose a method of image filtering based on contours of equal intensity evaluation, with subsequent determination of the cathode spots distribution.

Conditions of self-sustained volume discharge formation and their influence on its glow stability

Abstract Influence of the gas mixture pressure, geometrical dimensions of active volume and the density of initial electrons on stability of a self-sustained volume discharge are discussed. These parameters affect on the stage of the discharge formation, which results in the appearance of a cathode layer. The structure of the latter (the distribution of cathode spots and channels over the cathode surface) depends strongly on the self-sustained discharge. Experimental observations are in a good agreement with the data obtained from the analysis of the cathode channels and spots distribution over the cathode surface.

Arc behaviour and plasma chemistry in electrode erosion

Abstract