An update of the design and capabilities of doublet III in a large dee configuration

In 1985 the Doublet III tokamak will be partially disasembled and reconfigured to a large, dee-shaped plasma cross section (Big Dee). A new dee-shaped vacuum vessel (R = 1.67 m, a = 0.67 m, kappa less than or equal to 2) will replace the present indented chamber, and new outer poloidal field coils will be installed with structure to support them and the vessel. Two moveable, pumped, graphite limiters will be installed at the vessel midplane. Armor to protect the vessel from neutral beam incidence and divertor heating will also be installed with provision for pumping of the divertor region at the bottom of the vessel. System design has focused on maximizing the performance of the existing hardware and matching that capability with the new equipment. The primary features of the design are high plasma current/pressure (5 MA/2.4 atm with limiter-defined kappa = 2 dee plasma and 4 MA/1.6 atm with kappa = 1.6 expanded boundary divertor plasmas) and significant long pulse capabilities at more modest plasma current/pressure (2.5 MA/0.6 atm, 30 sec)