Cognizant of the need to characterize and project the economic and environmental attractiveness of future commercial magnetic-fusion power plants on a scientific basis, the multi-institutional ARIES Team is considering the spherical tokamak (ST) approach, denoted ARIES-ST. A broad attention to emerging issues of economic ecology, coupled to consideration of exogenous market-penetration issues (including deregulation), extends the scope of such studies beyond the traditional interaction of plasma physics, engineering technology, and cost estimation. Provided a competitive end-product based on the ST can be identified, the possibility of an accelerated introduction of such power plants can be entertained.

The ST approach, at plasma aspect ratios in the range 1.25-1.75, is the subject of several experiments worldwide and portends high-beta operation with high bootstrap-current performance. Whether the ST approach is amenable to resistive-coil, high-power-density operation must be revisited in light of modern 'customer' requirements. Joule dissipation in the central toroidal-field-coil leg remains the largest contributor to the recirculating power fraction. Provision of adequate shielding of the central coil affects the service life and maintenance downtime. Adequate (outboard-only) blanket performance is deemed likely. Key cost drivers continue to be plant size, recirculating power fraction, use of expensive and exotic materials, and operational availability.

* Work supported by U.S. DOE, Office of Fusion Energy Sciences.