Spectroscopic measurements of ion temperatures in the boundary layer of TEXTOR and their interpretation

We discuss some recent spectroscopic measurements of n-α transitions (8→7 in C VI, 11→10 in Ne X, and 12→11 in Si XII), emitted through charge-exchange between impurity ions and the injected neutral hydrogen beam of TEXTOR. Derivation of radial ion temperatures from line widths requires careful consideration of the Zeeman effect, as well as the processes of l-mixing and diffusion. Since the observation direction was roughly antiparallel to the toroidal magnetic field, the experiment provided data complementary to those from lithium-beam-CXS. Profile measurements were performed with a high-aperture 3/4 m monochromator containing a 135x165 mm plane grating (1200 lines/mm, blaze angle 57o) in Littrow mounting, with an achromatic lens of 125 mm diameter as collimator. Spectral scans were made in the second order with high dispersion (reciprocal dispersion ∼ 4 A mm-1, slit widths ∼ 100 μ), the σ± components being the major contributors to the lines, with weak additional π components. (author) 16 refs., 7 figs., 2 tabs