On the road to the fusion reactor

Deuterium and lithium, the primary materials needed to fuel a nuclear fusion reactor, occur in large quantities in various places of the earth and are easily accessible. Major efforts have been taken in all industrialized countries over the past twenty years to make use also of nuclear fusion in order to meet the energy requirement. So far, there have been various approaches in the development of fusion research. On the basis of very encouraging results achieved over the past few years the Tokamak principle is now the technique on which most of the attention is concentrated. Presently, a large Tokamak, JET, is being designed as a joint project in the European Community. Nevertheless, this approach should be supported and backed up by such alternative concepts as, for instance, the stellarators and high-beta assemblies. Improved understanding of the physics of high temperature plasmas justifies the hope that it will be possible to design a demonstration fusion reactor in three more steps beyond JET. However, it is imperative even at this early stage to devote particular attention to the technical problems involved. As far as can be judged from our present knowledge, it may be expected that by the beginning of the next century fusion reactors will supplement the commercial line of reactors of that time and will help to meet the energy requirement. Major problems will arise from the first wall surrounding the plasma, which is exposed to the intense flux of fusion neutrons. (orig.)