Prompt and non-prompt contributions to fusion product bombardment of a tokamak first wall

Abstract

High-energy fusion-product losses from an axisymmetric tokamak plasma to the first wall are studied. Prompt-escape bombardment fluxes (i.e. before slowing-down) are calculated including the non-separable dependence of flux as a function of poloidal angle and local angle of incidence at the first wall. The resulting rate of blistering-injected impurities might then reduce reactor burn times by 50–70%. The sensitivity of the bombardment flux to various device parameters is examined; plasma-wall separation is found to be the most crucial factor. Modest increases (≤20%) in wall radius (plasma radius fixed) of a device such as the ORNL-EPR are found to reduce blistering-injected impurities to a level which should no longer limit the burn time. Non-prompt losses (during slowing-down) are also calculated; the resulting flux at the wall ≲ 0.1 × (prompt flux) × .