Hydrogen Boron-11 Fusion in a High-Beta Cusp Mirror: Bremsstrahlung Accounting and a Negative Net-Power Verdict

This paper presents a complete, computed design study of a fusion power plant based on a high-beta cusp mirror: an axisymmetric cusp mirror operated at plasma pressure comparable to the magnetic pressure. The fuel is hydrogen boron-11, releasing 8.7 MeV per reaction shared among three alpha particles. Heating is by neutral-beam injection with ion cyclotron heating and direct conversion of the alpha-particle exhaust, and the blanket concept is boron-carbide and water shielding only, sized for photoneutron and side-reaction neutrons, with no breeding function. Sizing follows from a zero-dimensional energy balance evaluated in the accompanying computation: fusion power 15.7 MW, auxiliary heating 150 MW, plasma gain Q 0.1047, neutron power 0.0157 MW, first-wall neutron loading 8.12e-05 MW per square metre, gross electric output 83.32 MW, recirculating power 258.9 MW and net electric output -175.6 MW. Radiated bremsstrahlung removes 4.773 MW and transport removes 1166 MW, against alpha-particle self-heating of 15.7 MW. The plant verdict on the stated assumptions is net negative. 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.