Design Optimization of Ignited Tokamaks^†

In this paper we write the 0-D energy balance in terms of the parameters , and . The minimum value of W required to achieve ohmic ignition (i.e. II = 0) in the generic case (i.e. no n or T dependance on τ), and for various dependencies of τ on n and T is W ∼ 15 in all cases. Also the value of W below which no access, even with the aid of auxiliary power, to high temperature alpha dominated operation is possible is W ∼ 2 in all cases. Optimized designs are obtained by minimizing the ratio of the auxiliary power p_a to the ohmic power p_Ω at the Cordey pass. The optimization is consistent with the physics requirements, the toroidal field coil volume and stress constraints, and with the volt-second and stress constraints of the ohmic transformer. Results under various τ dependencies are presented.