19th IAEA Fusion Energy Conference

High Performanc Tokamak Experiments with Ferritic St l Wall on JFT-2M

K.Tsuzuki¹⁾, H.Kimura¹⁾, H.Kawashima¹⁾, M.Sato¹⁾, K.Kamiya¹⁾, K.Shinohara¹⁾, H.Ogawa, K.Hoshino¹⁾, M.Bakhtiar¹⁾, S.Kasai¹⁾, K.Uehara¹⁾, H.Sasao¹⁾, Y.Kusama¹⁾, N.Isei¹⁾, Y.Miura¹⁾, T.Ogawa¹⁾, M.Yamamoto¹⁾, T.Shibata¹⁾, K.Kikuchi¹⁾, K.Miyachi¹⁾, T.Ito²⁾, H.Ajikawa²⁾, S.Nomura²⁾, H.Tsutsui²⁾, R.Shimada²⁾, T.Ido³⁾, Y.amada³⁾, N.Fukumoto⁴⁾, M.Nagata⁴⁾, T.Uyama⁴⁾, H.Niimi⁵⁾, S.Yatsu⁵⁾, N.Kayukawa⁵⁾, T,Hino⁵⁾, Y.Hirohata⁵⁾ and JFT-2M Group¹⁾
1)Naka Fusion Research Establishment,Japan Atomic Energy Research Institute
2)Tokyo Institute of Technology,3)National Institute for Fusion Science,
4)Himeji Institute of Technology,5)Hokkaido University

Abstract.
In the JFT-2M tokamak compatibility between plasma and the low activation ferritic steel,which is candidate material of a fusion reactor,has been investigated step by step.We have entered the 3rd stage of Advanced Material Tokamak EXperiment (AMTEX),where the inside of vacuum vessel wall is fully covered with ferritic steel plates (Ferritic Inside Wall;FIW).The effects of FIW have been investigated on the plasma production,the impurity release,the operation region,and H-mode characteristics. No deteriorative effect has been observed up to now. High normalized beta plasma of ~3 having both internal transport barrier and the steady H-mode edge was obtained.Remarkable reduction of ripple trapped loss from 0.26 MW/m² (w/o ferritic steel) to less than 0.01 MW/m² was demonstrated due to optimization of the thickness profile of FIW. The effect of the localized ripple was also investigated with additional ferritic plates outside the vacuum vessel. In parallel with AMTEX, advanced and basic research for the development of high performance plasma such as evaluation of fluctuation induced particle flux and development of advanced fuelling (compact toroid injection) are also performed on JFT-2M.