Poloidal field system for the ITER HARD design option

A high aspect ratio design (HARD) was conceived as an alternative design option with a much larger bore in the central solenoid to enhance ITER´s (International Thermonuclear Experimental Reactor´s) capabilities for long-burn operation. The HARD PF design achieves the basic goals of a high aspect ratio design option. The total volt-second swing is improved by half, while the volt-seconds available for flattop are increased by an order of magnitude. Most important, the possibility of having inadequate volt-seconds to complete the ITER mission due to uncertainties in volt-second requirements is eliminated. Despite having a lower plasma current than the ITER CDA (conceptual design activity) design, the stored energy of the HARD PF design is increased by half. Increases in coil cost may be partially offset by savings in power supplies and cryogenic refrigeration. If collector sweeping using external coils is necessary, all of the HARD PF subsystems will be more expensive than those in the CDA, but the burn time performance of HARD will remain superior. HARD is designed to the same or more stringent allowables than the ITER CDA. Its safety margins and response to disruptions and quenches are similar to those of the CDA PF system