Inward Pinch of High-Z Impurity due to Atomic Processes in a Rotating Tokamak Plasma and the Effect of Radial Electric Field

Full text: The transport of high-Z impurity in a toroidally rotating tokamak plasma is investigated numerically and analytically. It is found that the inward pinch is driven by the atomic processes of ionization/recombination both in co- and ctr- rotating plasmas. This inward pinch is enhanced by the radial electric field. It is also found that the negative and positive radial electric fields cause the inward pinch and the outward movement (unpinch) of the high-Z impurity, respectively, under the influence of Coulomb collisions with the rotating background plasma. The pinch and the unpinch due to the radial electric field are as large as the inward pinch due to atomic processes in the case of large radial electric field. Therefore, the inward pinch due to atomic processes and the unpinch due to the radial electric field can be suppressed by each other in the co-rotation case, while the large inward pinch occurs in the ctr-rotation case. (author)