Plasma and Fusion Research

Volume 16, 1405085 (2021)

Regular Articles

Effect of the Pitch Modulation of Helical Coils on the Core Plasma Performance of the LHD-Type Helical Fusion Reactor
Takuya GOTO1,2), Katsuji ICHIGUCHI1,2), Hitoshi TAMURA1,2), Junichi MIYAZAWA1,2), Shinsuke SATAKE1,2), Hiroyuki YAMAGUCHI1,2), Nagato YANAGI1,2) and the FFHR Design Group1)
1)
National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, Gifu 509-5292 Japan
2)
The Graduate University for Advanced Studies, SOKENDAI, Toki, Gifu 509-5292 Japan
(Received 20 January 2021 / Accepted 13 May 2021 / Published 18 June 2021)

Abstract

The effect of the pitch modulation of the helical coils on the core plasma performance of the LHD-type helical fusion reactor has been examined. The analysis of the MHD stability and neoclassical transport for the pitch modulation α = 0.0 and 0.1 has been conducted based on the finite-beta equilibrium calculated by the HINT code. It was found that the MHD stability is clearly improved without deteriorating the energy transport property by changing the pitch modulation α from 0.1 to 0.0. The reachable operation region expands to the higher density and the expected fusion gain can increase from ∼10 to ∼20. Because the change of the pitch modulation α from 0.1 to 0.0 requires only a slight change in the shape of the helical coils, the engineering design including the maintenance method that has been examined for the reactor with α = 0.1 can be applied without a major modification.

Keywords

LHD-type helical reactor, pitch modulation, MHD stability, neoclassical transport, operation region

DOI: 10.1585/pfr.16.1405085

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