Materials for the First Wall of Fusion Reactors and Their Analytical Characterization

Abstract

The critical path towards controlled thermonuclear fusion as an energy source has often been sub-divided into three phases which end in demonstration of the physical, technical and economic feasibility, respectively. It is expected that the first step will be reached within this century. The proving of technical feasibility, however, has already started since many problems have been clearly recognized. They are, to a large extent, concerned with materials, in particular materials of the first wall. By first wall is meant generally not only the vacuum vessel but all components therein which are — or might come — in contact with the plasma. These components are therefore subjected to quantum, electron, ion and neutral particle irradiation. This plasma radiation is absorbed in a surface layer of 10–100 μm thickness. Moreover, it is not uniformly distributed over the surface of the wall but imposes locally a particularly high power load on specific components. The effect of plasma radiation is thus of an entirely different nature than that of the 14.1 MeV fusion neutrons; owing to their large mean free path, fusion neutrons essentially constitute a uniform volume load.