Evaporation and thermal stresses in molybdenum irradiated by electrons

Abstract

Plasma disruption in the thermonuclear facility leads to a release of large energy flows to the chamber wall. The pulse duration is 10-6 -10-4 s, energy fluxes are of the order of 108 - 1011 Wm-2 . High temperature of the protective coating surface causes its evaporation and, probably, destruction under the action of thermal stresses. A promising material for the first wall protection is, in particular, molybdenum. In order to check suitability of molybdenum as a protective coating, an experiment on irradiation of a molybdenum sample with electrons (parallelepiped - 2x10x0.3 mm) was carried out. The energy flux was J =4x1011 W m-2 ; pulse duration t = 2 micros . The weight loss of the sample was 2.1 mg; cracking of the trained surface was observed. The purpose of this analysis is to calculate the temperature fields to estimate the mass of evaporated molybdenum and to determine critical thermal stresses.

Keywords

• electron irradiation
• molybdenum
• evaporation
• stress