Assessment of ionization-assisted damage processes in CTR first-wall materials

Assessments have been made of the potential significance for CTR first-wall radiation damage of ionization-assisted processes. Mechanisms are examined in which the energy available for atomic displacements is supplied by transient Coulomb interactions attending ionization and charge transfers induced in relevant materials by primary plasma radiation or by recoils. An energy-deposition cross section appropriate to such mechanisms is defined, compared numerically to the usual Lindhard nuclear stopping cross section, and used to estimate maximal possible effects. It is found that, for materials suggested for first-wall applications and under anticipated fluxes of plasma components, the calculated energy-deposition cross sections for the mechanisms considered are insignificant in comparison to the nuclear stopping cross sections except in some cases of He++ projectiles in non-metals. (Auth.)