Atomic beam diagnostics for characterization of edge plasma in TJ-II stellarator.

He and Li beams have been installed and set into operation at the TJ-II stellarator with the aim of measuring electron temperature and density profiles in the edge and scrape-off layer regions of the plasma. The effusive thermal Li beam penetrates up to a normalized effective radius of ρ=0.6–0.7 in typical electron cyclotron heated plasmas. Density profiles deduced from the Li beam are wider than those obtained from extrapolation of the profile measured by Thomson scattering. The He beam is a pulsed supersonic one. Simultaneous detection of three emission lines (667.2, 706.5, and 728.1 nm) is made with a set of three photomultipliers. First He beam measurements of n[sub e] and T[sub e] in TJ-II are presented and the agreement among results of different plasma edge diagnostics is discussed. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]