Physics aspects of the ITER design

The physics of ITER (International Thermonuclear Experimental Reactor) is based on demonstrated tokamak physics and credible extrapolations of that physics. Assessment of the energy confinement and MHD stability requirements led to the choice of the major plasma parameters of 22 MA for the plasma current, a toroidal field of approximately 5 T, an aspect ratio of approximately 3, and an elongation of approximately 2. Among the major accomplishments of the physics group has been the development of a database and an empirical scaling for L-mode energy confinement and the facilitation of an H-mode database and scaling. The divertor heat loads have been estimated by using experimentally validated models. The thermal and mechanical loads due to off-normal events such as disruptions have been based on analysis of the data from other tokamaks. To achieve the required availability of 10%, the pulse length has been extended by the use of current drive using 75 MW 1.3 MeV neutral beam and 45 MW lower hybrid systems. A relatively complete set of plasma diagnostics is planned for ITER. Finally, a physics R and D program has been developed. >