IAEA Fusion Energy Conference 2010

Proceedings of the 23rd IAEA Fusion Energy Conference
Daejeon, 11-16 October 2010

Organized by the International Atomic Energy Agency
and hosted by the Government of the Republic of Korea

IAEA-CN-180

(THC/P4-12) Inward Pinch of High-Z Impurity due to Atomic Processes in a Rotating Tokamak Plasma and the Effect of Radial Electric Field

K. Hoshino1), M. Toma2), K. Shimizu1), T. Nakano1), A. Hatayama2), T. Takizuka1)
 
1) Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan
2) Keio University, Yokohama, Kanagawa 223-8522, Japan

Abstract.  The transport of high-Z impurity in a toroidally rotating tokamak plasma is investigated analytically and numerically. It is shown 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 derived 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. In the ctr-rotation case, the inward pinch becomes significant with increasing toroidal rotation velocity, because the directions of the both pinches are inward. On the other hand, in the co-rotation case, these pinches have opposite directions. Therefore, the unpinch due to the positive radial electric field is decreased by the inward pinch due to the atomic processes. These tendencies are consistent with the tungsten accumulation observed in the JT-60U rotation scan experiment.

Full paper available (PDF)