Optimization and thermal stability studies of Ignitor and ITER

A comparison between the operational states of Ignitor and ITER needed to obtain a maximal energy gain is presented for a range of temperatures and densities, under the assumption that the ratio of electron to ion temperatures is held fixed for all the steady states considered. A criterion for the optimal operation of ITER is obtained in terms of the auxiliary heating to ions. The optimal states for Ignitor are achieved when auxiliary heating to both ions and electrons is minimized. The thermal stability is also studied for the same range of parameters, finding that the development of this instability is not a concern for ITER, while a certain range of plasma densities and temperatures has to be maintained in order to avoid the thermonuclear instability in Ignitor.