Spectroscopic analysis of normal and reversed ion flows in the DIII-D divertor

Flow velocities of C+, C2+, B+, and D+ parallel to the magnetic field in th e DIII-D [J. Luxon, P. Anderson, F. Batty et al., Plasma Physics Controlled Nuclear Fusion Research, Proceedings of the 11th International Conference, Tokyo, 1986 (International Atomic Energy Agency, Vienna, 1987), Vol. I, p. 159] divertor have been measured from Doppler shifts of spectral lines. In general, both normal flows (toward the target plate) and reversed flows (a way from the target plate) are observed in the outer scrape-off layer with the reversed flows occurring near the separatrix. Following the transition from attached to partially detached conditions, normal flow velocities gene rally speed up while in some regions reversed flows are observed to slow do wn. In high density plasmas, deuteron velocities are reflected in Balmer li ne emission which originates mainly from atoms which have thermalized by ch arge exchange or which have been formed by recombination. Low-temperature a reas of nearly stagnated deuteron flow have been observed. In these regions recombination should be efficient for neutralizing the divertor plasma. (C ) 1999: American Institute of Physics. [S1070-664X(99)01102-7].