Physics, Engineering, and Economics

Performance scaling of fusion power sources shows that Maxwellian, magnetic, localthermodynamic equilibrium MM/LTE devices require much larger sizes and B fields than do electrondriven, inertial electrostatic confinement EXL/IEC systems for the same output. Basic economics analyses show that systems of either type must be small in size to be economically viable. This requires operation at high fusion power density and firstwall thermal fluxes; flux levels needed are well within those of practical power engineering experience. The EXL/IEC systems can satisfy these demands more readily than can MM/LTE systems. They can be oper ated to avoid particle thermalization, preserve ion core convergence, and yield a large power gain against losses e.g., bremsstrahlung for all fuels from deuterium tritium to p11B and 3He3He. Direct conversion of chargedparticle energy, without arcing, is inherently straightforward in the quasispherical field geometry. If losses prove to be governed by classical physics phe nomena rather than turbulent transport, all research and development R&D from physics studies to power plants can be done at a single size 3m radius and B field 1.2 T, 12 kG; no scaling growth in size or field is required. Consequent R&D costs and time scales are estimated to be <12 years and 1 billion for development of prototype EXL / IEC fusion power systems. Research investment seems warranted in this smallscale alterna tive to largescale MM/LTE systems. I