The spherical torus approach to magnetic fusion development

摘要

The low aspect ratio tokamak or spherical torus (ST) approach offers two key elements needed for an attractive magnetic fusion development path: a low power, small size market entry vehicle and a strong economy of scale in larger devices. In their studies of the ST approach, the authors found a very small device (A = 1.4, major radius about 1 m, a similar size to the DIII-D toakamak) that would produce approx 800 MW thermal power and 160 MW net electric power, and would have a gain, defined as Q_PLANT = gross electric power over recirculating power, of approx 1.7. Such a device would have all the operating systems and features of a power plant and would therefore be acceptable as a pilot plant. At about double the linear dimension of the pilot plant, the authors find 4 GW thermal power plats with an economically viable Q_PLANT= 4-5 but which remain a factor of 3 smaller than super-conducting tokamak power plants. Large ST power plants might be able to burn the advanced fuel D-He~3 if the copper toroidal field coil can be replaced with a superconducting toroidal field coil and suitable shield.