Carbon flows in attached divertor plasmas

Parallel flow velocities of carbon ions in the DIII-D divertor [J. Luxon et al., Plasma Physics Controlled Nuclear Fusion Research, 1986 (Internationa l Atomic Energy Agency, Vienna, 1987), Vol. I, p. 159; S. L. Allen et al., Controlled Fusion and Plasma Physics, 1987 (Proc. 24th European Conf. Berch tesgaden, 1997), Vol. 21 A, Part III, p. 1129] have been studied under vari ous operating conditions: L-mode (low-confinement mode), H-mode (high-confi nement mode) with low-frequency ELMs (edge-localized modes), and H-mode wit h high-frequency ELMs. Both normal and reversed flows (toward the target pl ate and away from the target plate, respectively) are observed under all co nditions, with the reversed speeds being as much as a factor of four greate r than normal speeds. Magnitudes are approximately the same for L-mode and H-mode operation with high-frequency ELMs. In H-mode conditions with low-fr equency ELMs, normal velocities are frequently observed to decline while re versed velocities increase in comparison to the other two conditions. (C) 1 999 American Institute of Physics. [S1070-664X(99)90505-0].