K. Hanada, K.N. Sato, H. Zushi, K. Nakamura, M. Sakamoto, H. Idei, M. Hasegawa, Y. Takase, O. Mitarai, T. Maekawa, Y. Kishimoto, M. Ishiguro, T. Yoshinaga, H. Igami, S. Kawasaki, H. Nakashima, A. Higashijima, Y. Higashizono, A. Ando, N. Asakura, A. Ejiri, Y. Hirooka, A. Ishida, A. Komori, M. Matsukawa, O. Motojima, Y. Ogawa, N. Ohno, Y. Ono, M. Peng, S. Sudo, H. Yamada, N. Yoshida, Z. Yoshida.
Physical Design of MW-class Steady-state Spherical Tokamak, QUEST
Date of publication:
21 IAEA Fusion Energy Conference, FT/P3-25
QUEST (R=0.68m, a=0.4m) focuses on the steady state operation of the spherical tokamak (ST) by controlled PWI and electron Bernstain wave (EBW) current drive (CD). The QUEST project will be developed along two phases, phase I: steady state operation with plasma current, I_p=20-30kA on open divertor configuration and phase II: steady state operation with I_p=100kA and of 10% in short pulse on closed divertor configuration. Feasibility of the missions on QUEST was investigated and the suitable machine size of QUEST was decided based on the physical view of plasma parameters. Electron Bernstein wave (EBW) current drive are planned to establish the maintenance of plasma current in steady state. Mode conversion efficiency to EBW was calculated and the conversion of 95% will be expected. A new type antenna for QUEST has been fabricated to excite EBW effectively. The situation of heat and particle handling is challenging, and W and high temperature wall is adopted. The start-up scenario of plasma current was investigated based on the driven current by energetic electron and the most favorable magnetic configuration for start-up is proposed.