Study of electric-arc erosion of divertor plates in a tokamak

The paper presents the results of investigation into arc erosion of the surface of two specimens cut out from the same guard plate located in the highest power-intensity part of divertor plates in D3-D tokamak. Boron carbide coated on graphite substrate was used as the surface material. Sizes of cathode spot traces were measured and total erosion for separate arc charges was estimated. The paper presents the estimations of thermal source parameters for typical sizes of fused craters. The paper discusses the role of polarization currents transport across strong magnetic field in unipolar arc cathode range. 11 refs., 6 figs