Impurity toroidal rotation and transport in Alcator C-Mod ohmic high confinement mode plasmas

Central toroidal rotation and impurity transport coefficients have been det ermined in Alcator C-Mod [I. H. Hutchinson et al., Phys. Plasmas 1, 1511 (1 994)] Ohmic high confinement mode (H-mode) plasmas from observations of x-r ay emission following impurity injection. Rotation velocities up to 3 x 10( 4) m/sec in the co-current direction have been observed in the center of th e best Ohmic H-mode plasmas. Purely ohmic H-mode plasmas display many chara cteristics similar to ion cyclotron range of frequencies (ICRF) heated H-mo de plasmas, including the scaling of the rotation velocity with plasma para meters and the formation of edge pedestals in the electron density and temp erature profiles. Very long impurity confinement times (similar to 1 sec) a re seen in edge localized mode-free (ELM-free) Ohmic H-modes and the inward impurity convection velocity profile has been determined to be close to th e calculated neoclassical profile. (C) 2000 American Institute of Physics. [S1070-664X(00)91705-1].