Thick Liquid-Walled, Field-Reversed Configuration-Magnetic Fusion Power Plant

Abstract

A thick flowing layer of liquid (e.g., flibe–a molten salt, Sn80Li20 or Li –liquid metals) protects the structural walls of the field-reversed configuration (FRC) so that they can last the life of the plant even with intense 14 MeV neutron bombardment from the D-T fusion reaction. The surface temperature of the liquid rises as it passes from the inlet nozzles to the exit nozzles due to absorption of line and bremsstrahlung radiation, and neutrons. The surface temperature can be reduced by enhancement of convection near the surface to transport hot surface liquid into the cooler interior. The resulting temperature for evaporation estimates called, Teff, is 660, 714 and 460°C for flibe, SnLi and Li, where thermal conductivity was assumed enhanced by a factor of ten for flibe. The corresponding evaporative flux from the wall must result in an acceptable impurity level in the core plasma. The shielding of the core by the edge plasma is modeled with a 2D transport code for the resulting impurity ions; these ions are either swept out to the distant end tanks, or diffuse to the hot plasma core. The calculations show core impurity levels adequately low for Li and Sn80Li20 but is about ten times too large for flibe. An auxiliary plasma between the edge plasma and the liquid wall can further attenuate evaporating flux of atoms and molecules by ionization. The current in this auxiliary plasma might serve as the antenna for the current drive method, which produces a rotating magnetic field.