Effect of plasma physics on choices of first wall materials and structures for a thermonuclear reactor

Impurity ions adversely affect the behavior of present-day tokamaks, and control of impurities is expected to be a key element in determining the feasibility of thermonuclear fusion reactors. In this paper, we describe the plasma-surface interactions for tokamaks and several techniques for controlling impurities. The plasma-surface problem of next generation devices PLT, PDX, DIII and TFTR is expected to be similar to those encountered in a reactor. For these devices calculations indicate that most of the particle energy efflux will be in the 1 keV region. Ironically this energy region has not yet been investigated thoroughly by the surface physicists. (auth)