The ARIES team is presently assessing the feasibility of a low aspect ratio (LAR) or spherical torus (ST) to serve as a commercial power plant. Development of a credible design for the centerpost is one of the key feasibility issues.

Several centerpost design options have been identified. Conductor options include: an integrated blanket coil (IBC) cooled by liquid metal (200-400 C); water-cooled copper coils (20-150 C); nitrogen-cooled copper coils (80-120 K); helium-cooled copper or aluminum coils (4-50 K); and helium-cooled high temperature superconducting coils (30-50 K). These designs have been assessed in the context of compatibility and constraints imposed by the overall plant design and requirements.

In this paper, design criteria are proposed for the design of the centerpost. Centerpost design options are then systematically assessed and compared. Each design option has a set of issues including fabrication, nuclear and materials responses, and plant performance impacts. The addition of shielding between the conductor and plasma in the centerpost reduces the neutron flux, radiation damage, and nuclear heating in the conductor at the expense of higher current density and Joule losses. Design issues related to conductor embrittlement, waste disposal, and electrical insulators were given special attention, and recommendations on the centerpost configuration are made.

*Work supported by U.S. DOE Contract No. DE-AC02-76-CHO3073.