Measurement of lithium and deuterium on NSTX carbon tiles

Abstract

Here, we report results from nuclear reaction analysis of lithium and deuterium on 50 carbon tiles removed from NSTX (National Spherical Torus Experiment) after campaigns in 2006 and 2007 during which lithium was evaporated onto the vessel wall. Measurements give lithium and deuterium concentrations versus depth and the variation in coverage with position in the machine. The lithium was within a few microns of the surface indicating little transport by diffusion through the carbon. Lithium coverage was higher on tiles facing the lithium evaporator than on tiles shadowed from it by the center stack. The deuterium coverage was highest in the private flux region between inner and outer strike points of the high triangularity plasmas used.