S.Sakakibara, S.Ohdachi, K.Y.Watanabe, Y. Suzuki, H.Funaba, Y.Narushima, K.Ida, H.Chikaraishi, K.Toi, I.Yamada, K.Narihara, K.Tanaka, T.Tokuzawa, K.Kawahata, H.Yamada, A.Komori and LHD Experiment Group


Exploration of optimal high-beta operation regime by magnetic axis swing in the Large Helical Device

Date of publication:

Nov. 2010

Key words:

22 IAEA Fusion Energy Conference, EXS/P5-13


In Large Helical Device (LHD), the volome averaged beta value <beta_dia> as high as 5.1 % was achieved in FY2007-2008 experiments. High beta operation regime was explorated by the programmed control of magnetic axis position, which characterizes MHD equilibrium, stability and transport. This control became enable by increasing capability of poloidal coil power supply. The experiments made clear the effect of magnetic hill on MHD activities in high-beta plasmas with more than 4 %. Also it enabled to access the ideal stability boundary with keeping high-beta state. The strong m/n = 2/1 mode leading minor collapse in core plasma appeared with the inward shift of the magnetic axis.

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