FIRST EXPERIMENTAL-DETERMINATION OF ION FLOW VELOCITIES AND TEMPERATURES IN THE ASDEX UPGRADE DIVERTOR

For the analysis of ion dynamics (i.e. ion temperature and ion flow ve locity distributions) in the divertor I of ASDEX Upgrade an optical sp ectroscopic system with high spectral, temporal and spatial resolution was brought into operation. Integrated along up to 74 lines of sight with different orientations to the magnetic field lines, emission spec tra of atoms and ions were recorded with high resolution by an Echelle spectrometer and a 2D CCD camera. With this setup, ion flow velocitie s and temperatures in a divertor plasma could be determined experiment ally for the first time. In the attached high-recycling divertor regim es analysed, neutrals such as helium do not flow preferentially parall el to any of the installed lines of sight. In contrast, all the ions i nvestigated always showed pronounced Doppler shifts. The corresponding ion Bow is directed towards the target plates, in the outer as well a s in the inner divertor. For typical L- and H-mode discharges (attache d high-recycling divertor conditions) the C2+ ions flow at speeds of a bout 10 km s(-1) in the L-mode and 10-20 km s(-1) in the ELMy H-mode p hases. The temperatures of the C2+ ions near the divertor plates range from about 5 eV (L-mode) to up to 20 eV (ELMy H-mode phases). The com parison of these results with computer code calculations showed good a greement.