부산대학교 도서관

Langmuir probe measurements have been made across the plasma boundary in helium discharges of varying central electron densities in the Tokamak Fusion Test Reactor (TFTR). Radial profiles of ion saturation current density, I{sub s}, electron density, n{sub e}, and electron temperature, T{sub e}, were achieved by small displacements of the plasma relative to a stationary probe. Scrape-off lengths outside the plasma boundary decreased somewhat with increasing plasma density. Inside the plasma, I{sub s}, n{sub e}, and T{sub e} rose more steeply for the higher densities than the scrape-off lengths would predict. The floating potential, V{sub f}, decreased sharply inside the boundary as expected, with some density dependence. I{sub s} and n{sub e} increased with plasma density, while T{sub e} decreased a few eV. Measurements of C II emission at the inner wall combined with probe data support a relatively constant edge T{sub e} with increasing plasma density and a constant ratio between the fluxes of helium and carbon ions. 14 refs., 5 figs.