Abstract
Engineering design issues of a volumetric neutron source (VNS) based on a steady state low aspect ratio DT tokamak are presented. At the present the major radius is 0.8 m, the minor radius 0.6 m for an aspect ratio of 1.33, the plasma current is 10.1 MA, the toroidal field at the major radius is 1.8 T, the fusion power is 39 MW giving an average neutron wall loading of 1.0 MW/m(2) on the outboard side with an available testing area of 10 m(2). Two neutral beams delivering more than 20 MW are used to drive the steady state fusion plasma. A single turn unshielded water cooled dispersion strengthened (DS) Cu centerpost is used in conjunction with a conducting Cu bell jar which acts as a vacuum boundary and the return legs for the toroidal field (TF) coils. The centerpost is 9 m long, carries 7.2 MA and is specially shaped to minimize ohmic heating, which is calculated using temperature dependent DS Cu properties and increases in resistivity due to nuclear transmutations are accounted for. A naturally diverted plasma scrapeoff layer dominated by pressure-driven instabilities is assumed giving a peak heat flux of 5.2 MW/m(2) on the diverter plates. Fabrication approaches for the centerpost and its replacement time lines have been estimated to be feasible and reasonable.