Return To: Session EX9/TH6 - Energetic Particles
Prev Page: (EX9/2) Runaway Current Termination in JT-60U
Next Page: (EX9/4) Transition from Ion Root to Electron Root

(EX9/3) Demonstration of Ripple Reduction by Ferritic Steel Board Insertion in JFT-2M

H. Kawashima¹⁾, M. Sato¹⁾, K. Tsuzuki¹⁾, Y. Miura¹⁾, N. Isei¹⁾, H. Kimura¹⁾, T. Nakayama²⁾, M. Abe²⁾, D. Darrow³⁾ and the JFT-2M Group^1)
 
1) Japan Atomic Energy Research Institute, Tokai, Naka, Ibaraki Japan
²⁾ Hitachi Ltd., Hitachi, Ibaraki Japan
³⁾ Princeton Plasma Physics Laboratory, Princeton, New Jersey U.S.A

Abstract.  In the JFT-2M tokamak, application testing of low activation ferritic steel to plasma has been investigated, (so called Advanced Material Tokamak Experiment (AMTEX) program). In the first stage, toroidal field ripple reduction was examined by ferritic steel boards (FBs) insertion between toroidal field coils and vacuum vessel. It is demonstrated that the FB insertion is effective to reduce the toroidal field ripple and to reduce the losses of fast ions produced by tangential co-NBI. By optimizing the FB thickness, such that the fundamental mode ripple is minimized to be 0.07% at the shoulder part, the ripple-trapped loss is reduced to be almost negligible. It is indicated that the reductions of the fundamental mode ripple and the ripple banana diffusion coefficient at the shoulder part are most effective to reduce the ripple ion losses. Ripple loss reduction by FBs is also confirmed with the perpendicular beam injection. The FB insertion gives no deteriorative effect on the plasma production and control.

Read the full paper in PDF format.