Plasma edge studies in ISX-B and EBT-S using surface probes and laser-induced fluorescence

Abstract

Results of recent plasma edge experiments using surface collection probes and laser-induced fluorescence in the ISX-B tokamak and EBT-S bumpy torus are summarized. Data are presented for ion temperatures and fluxes, neutral fluxes and energies, impurity fluxes and introduction mechanisms, and erosion and redeposition rates. Comparison is made where possible with results from other plasma diagnostics. It is found that the edge ion temperature is ∼20 eV in these devices (comparable to the edge electron temperature) and that wall sputtering (by charge exchange neutrals in ISX-B and self-ions in EBT-S) is the dominant heavy impurity introduction mechanism.