N. NODA AND Y. KUBOTA,
National Institute for Fusion Science, Toki 509-5292, Japan
E-mail: noda@LHD.nifs.ac.jp
Q. G. GUO
Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, 030001, P. R. China,
E-mail: qgguo@21cn.com
J. L. CHEN , J. G. LI
Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031, P. R. China
E-mail: jlch@mail.ipp.ac.cn
X. LIU, Z. XU
Southwestern Institute of Physics, P.O.Box 432, Chengdu 610041, P. R. China
E-mail: xuzy@swip.ac.cn
S. TAMUTA, K. TOKUNAGA AND N. YOSHIDA
Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan,
E-mail: yoshida@riam.kyushu-u.ac.jp

Plasma facing walls of Large Helical Device (LHD) consist of a set of helical divertors, to which heat and particles from the plasma flow and concentrate, and first walls other than the divertor. As the first step, divertor striking points are covered by graphite tiles and the other walls are covered by stainless steel panels in the second experimental year 1999. The divertor tiles and the first wall panels are cooled by water. High power heating with NBI, ICRF, ECH become possible. Central electron temperature as high as 10 keV has been achieved with ECH and NBI. The steady-state discharge is extended up to 120 seconds with ICRF and 110 seconds. One of the keys for these achievements is choice in plasma facing materials. Hours long discharge is tried in near future. Aiming at the real steady state operations, erosion resistance is important. From this view point, tungsten materials are considered as a candidate of the divertor material. Tungsten...