Challenges for insulating materials in fusion applications

Abstract

It is envisaged that early in this new century International Thermonuclear Experimental Reactor (ITER) will come into operation to bridge the gap between the present day large “physics” machines and the pre-commercial DEMO fusion reactor. Although ITER will undoubtedly help to solve many of the problems which still remain in the field of plasma physics, it will also present additional operational and experimental problems due to radiation damage effects as a result of the intense radiation field from the “burning” plasma. For structural metallic materials the problem of radiation damage is expected to be severe, although tolerable, only near to the first wall, however the problem facing the numerous insulating components is far more serious due to the necessity to maintain not only the mechanical, but also the far more sensitive physical properties intact. Insulating materials will be required in a number of key systems ranging from heating and current drive, to diagnostics, and remote handling which affect not only the operation, but also the safety and control of the machine, as well as maintenance and repair. The effects of radiation on the electrical and optical properties will be discussed, in particular radiation induced conductivity (RIC), radiation induced electrical degradation (RIED), radiation induced electromotive force (RIEMF) and radioluminescence.