The ITER machine is an experiment large enough to require an international con­sortium. Its mission is to achieve a burning plasma, one in which the alpha particles produced by the D-T reaction can maintain the plasma’s temperature without exter­nal heating. At this stage of construction, not all physics problems have been solved, though they may be solved by the time construction is finished. We hope that these problems will be solved in time for DEMO. However, the physics does not have to be completely understood for something to work. Books have been written on the physics of tennis, baseball, sailing, and even pizza. Sometimes, it is easier just to get on with it.

Fig. 9.26