Development path of low aspect ratio tokamak power plants

A spherical tokamak (ST) may offer a magnetic fusion development path that can be started with a small size pilot plant and progress smoothly to large power plants. The ST could produce 800 MW thermal, 160 MW net electric and would have a ratio of gross electric power over recirculating power (QPLANT) of 1.9. The ST has a favorable size scaling so that at 2-3 times the pilot plant size, the QPLANT rises to 4-5, an economic range and 4 GW thermal power plants result. Current drive power requirements for 10% of the plasma current are consistent with the plant efficiencies quoted.