Role of arc formation in overheating of tungsten limiter in the T-10 tokamak at high heat loads expected in the ITER tokamak

Abstract

Arc erosion of tungsten plates, which occurred after they were tested at the T-10 tokamak in shots with high-power ECR heating, was observed and analyzed. In the T-10 tokamak, the regimes with nonambipolar energy flow onto the tungsten limiter plates were obtained. In such shots, the tungsten plates at the inner contour of the limiter were heated up to a temperature above 2000 °C. Apparently, the nonambipolar energy flow onto the metal surface, which is caused by the effect of sparks and arcs, can be responsible for the surface overheating. The nonambipolar energy flow appears as a result of the explosive electron emission occurring in the course of spark formation which increases the electron flux from the surface into plasma by an order of magnitude.