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(EXP2/15) Comparative Studies of a Spherical Tokamak and a Conventional Tokamak: Magnetic Turbulence-Induced Transport

H. Toyama, K. Hanada¹, H. Totsuka², E. Ishiyama, S. Shiraiwa, S. Duorah, I. Nakajima³, M. Ushigome, N. Uetake, K. Tanji, N. Kasuya, Y. Nagashima, K. Yamagishi, A. Ejiri, Y. Takase

Department of Physics, Graduate School of Science, University of Tokyo, Tokyo, Japan
¹ Advanced Fusion Research Center, Research Institute for Applied Mechanics, Kyusyu University, Japan
² Hitachi, Ltd., Tokyo, Japan
³ Fujitsu, Ltd., Tokyo, Japan

Abstract.  The paper reports experiments on turbulence-induced transport in plasmas with aspect ratios A of 1.4 $\sim$ 2.5 in a single machine. There is little aspect ratio dependence in electrostatic fluctuations. The relative levels of magnetic fluctuations in the core region are 0.01% and 0.05% for A = 1.4 and 2.5, respectively. The electron heat transport estimated from the magnetic fluctuation level of 0.01% is 0.2 kW/m², which is less than 2% of the electron heat flux of 13 kW/m² estimated from the global power balance. Thus in spherical tokamaks, the present results show that magnetic fluctuations are not responsible for electron heat transport, as in conventional tokamaks.

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