INITIAL RESULTS OF SYSTEMS ANALYSIS OF THE ETR/ITER DESIGN SPACE.

Preliminary versions of the engineering test reactor (ETR) systems code TETRA (Tokamak Engineering Test Reactor Analysis), which solves design problems by the method of constrained optimization, are used to characterize the International Thermonuclear Experimental Reactor (ITER) and its design parameter space. It is found that the physics objectives of high ignition margin and high plasma current lead to minimum size at relatively low aspect ratios (A equals 2. 5-3. 0), while the engineering objective of high neutron wall load leads to minimum size at higher A (approx. 3. 5). For minimium-size ITERs, the optimal toroidal field coil designs fall within a narrow range of maximum fields (10-11 T) with R varying over only a few percent despite a factor of two change in the winding pack current density. The major radius of the design is sensitive to changes in elongation, inboard distances, inductive flux capability, plasma temperature, beta limit, and ignition margin. A preliminary characterization of the US ITER design with plasma current I//p greater than 15 MA and R less than 4. 5 m has been obtained. These devices can accommodate a range of full- to reduced-bore, driven (Q less than 10), steady-state plasmas for the engineering phase that produces high neutron wall load and fluence.