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Regression Approach for Acquiring a Quantitative Guidance toward Updating the Deuterium-Deuterium Fusion Neutron Emission Rate in the Large Helical Device

Kunihiro OGAWA^1,2), Masayuki YOKOYAMA^1,2) and Mitsutaka ISOBE^1,2)

1)

National Institute for Fusion Science, National Institutes of Natural Sciences, Toki 509-5292, Japan

2)

The Graduate University for Advanced Studies, SOKENDAI, Toki 509-5292, Japan

(Received 15 October 2020 / Accepted 2 November 2020 / Published 11 December 2020)

Abstract

A regression approach has been adopted to acquire a quantitative guidance for updating the total neutron emission rate (S_n) in the Large Helical Device (LHD) with employing the externally controllable parameters such as heating power and plasma density. A deduced regression expression is worthwhile to understand for the contribution of an individual parameter during high S_n discharges, and then to be exploited in the experiment planning to update the record S_n value in LHD in the coming campaigns. It was found that S_n in high S_n discharges in LHD is expressed as S_n = 10^14.25 × n_{e_avg}^0.52 × P_N-NB^0.69 × P_P-NB^0.37, where n_{e_avg}, P_N-NB, and P_P-NB represent the line-averaged electron density [10¹⁹ m⁻³] and the injection power of negative and positive ions based neutral beam injection [MW], respectively. This expression shows that, among three parameters, P_N-NB is essential for achieving high S_n in this employed high S_n discharge database.

Copyright (c) 2020 The Japan Society of Plasma Science and Nuclear Fusion Research

Keywords

Large Helical Device (LHD), total neuron emission rate, deuterium fusion reaction, regression approach

DOI: 10.1585/pfr.15.1202087

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