Effects of complex symmetry-breakings on alpha particle power loads on first wall structures and equilibrium in ITER

ITERにおける複雑な対称性の破れが高速イオンの第一壁への熱負荷や平衡に与える影響

篠原 孝司; Kurki-Suonio, T.*; Spong, D. A.*; Asunta, O.*; 谷 啓二*; Strumberger, E.*; Briguglio, S.*; Koskela, T.*; Vlad, G.*; Gnter, S.*; Kramer, G.*; Putvinski, S.*; 濱松 清隆; ITPA Topical Group on Energetic Particles*

Shinohara, Koji; Kurki-Suonio, T.*; Spong, D. A.*; Asunta, O.*; Tani, Keiji*; Strumberger, E.*; Briguglio, S.*; Koskela, T.*; Vlad, G.*; Gnter, S.*; Kramer, G.*; Putvinski, S.*; Hamamatsu, Kiyotaka; ITPA Topical Group on Energetic Particles*

Within the ITPA Topical Group on Energetic Particles, we have investigated the impact of the axisymmetry breaking of the tokamak in ITER. First, the validity of using a 2D equilibrium was investigated: a 3D equilibrium was reconstructed using the VMEC code, and it was verified that no 3D equilibrium reconstruction is needed but it is sufficient to add the vacuum field perturbations onto an 2D equilibrium. Then the alpha particle confinement was studied using ASCOT, and F3D OFMC codes. The distribution of the power load was found to depend on the first wall shape. We also made the first attempt to accommodate the effect of fast ion related MHD on the wall loads in ITER using the HMGC and ASCOT codes. The peak power flux to the wall was found to increase by an order of magnitude. Furthermore, the effect of 3D field which was produced by the ELM mitigation coil on the fast ion confinement was addressed by simulating NBI ions with the F3D OFMC code. The loss power fraction of NBI ions was found to increase from 0.3% to 4-5%.