A Quasi-Isodynamic Stellarator Power Plant with Steady-State Energy Balance and a Helium-Ash Exhaust Budget

This paper presents a complete, computed design study of a fusion power plant based on a stellarator: a toroidal device whose rotational transform comes entirely from shaped external coils, requiring no net plasma current. The fuel is deuterium tritium, releasing 17.6 MeV per reaction, of which 14.1 MeV leaves with the neutron and 3.5 MeV stays with the alpha particle. Heating is by electron cyclotron resonance heating with a small neutral-beam component for fuelling control, and the blanket concept is dual-coolant lead-lithium blanket behind a tungsten-armoured first wall. Sizing follows from a zero-dimensional energy balance evaluated in the accompanying computation: fusion power 1731 MW, auxiliary heating 60 MW, plasma gain Q 28.85, neutron power 1387 MW, first-wall neutron loading 1.734 MW per square metre, gross electric output 852.4 MW, recirculating power 159.9 MW and net electric output 692.5 MW. Radiated bremsstrahlung removes 28.42 MW and transport removes 359.7 MW, against alpha-particle self-heating of 344.2 MW. The plant verdict on the stated assumptions is net positive. Where a quantity depends on an assumption that experiments have not yet demonstrated at the required value, that dependence is stated numerically so that the design can be re-scored as measurements improve. This study is simulated and computed from stated assumptions; it is not a measurement, and no part of the plant has been built. SIMULATED, NOT MEASURED.