T. Goto, Y. Suzuki, N. Yanagi, K. Y. Watanabe, S. Imagawa, A. Sagara


Importance of Helical Pitch Parameter in LHD-type Heliotron Reactor Designs

Date of publication:

Nov. 2010

Key words:

22 IAEA Fusion Energy Conference, FTP/P6-02


In the design studies of the LHD-type heliotron reactors, one of the key issues is to secure sufficient blanket spaces. In this respect, helical pitch parameter gamma is quite important because it significantly affects both the coil and plasma shapes. In order to understand the effect of helical pitch parameter on the design window quantitatively, a system design code for the LHD-type heliotron reactors has been developed and parametric scans were carried out with 3 cases of gamma =1.15, 1.20 and 1.25. It becomes clear that the possible design window of heliotron reactors strongly depends on the engineering constraints: stored magnetic energy of coil system, blanket space, and neutron wall load. gamma = 1.20 is optimum from the viewpoint of moderating the physics requirements, but gamma = 1.15 has a robustness to the change in the physics and engineering conditions. Since the design windows are quite sensitive to the engineering constraints and physics conditions, the further detailed study on design feasibility of advanced engineering components and the effect of gamma on the physics conditions is expected to optimize the value of gamma.

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