Laser fluorescence measurements of hydrogen and metal densities in the Doublet III tokamak

Abstract

A general overview of the Doublet III laser spectroscopy program is presented. This program includes tokamak diagnostic experiments and laboratory development work. Measurements of titanium and deuterium in Doublet III are presented along with recent laboratory results. Sputtering of the vacuum walls by energetic charge-exchange neutrals from the plasma center appears to be responsible for the observed Ti impurities in Doublet III. Resonance fluorescence scattering from deuterium atoms near the plasma center has been observed using a broadband dye laser and a narrow band detector. The feasibility of determining ion temperatures using this technique is discussed. Using the measured deuterium densities we have calculated a local electron particle confinement time. Laboratory measurements of carbon and oxygen densities using two-photon laser excitation and of Fe i speed distributions (temperatures) using a laser double-pulse excitation technique are shown to be applicable to the tokamak conditions of Doublet III.