Plasma and Fusion Research

Volume 16, 1405018 (2021)

Regular Articles

Development of a Wide Dynamic Range Neutron Flux Measurement Instrument Having Fast Time Response for Fusion Experiments
Daijiro ITO, Hiroyuki YAZAWA, Makoto TOMITAKA, Tsuyoshi KUMAGAI, Shigehiro KONO, Michinori YAMAUCHI, Tsuyoshi MISAWA1), Takashi KOBUCHI2), Hiroshi HAYASHI2), Hitoshi MIYAKE2), Kunihiro OGAWA2,3), Takeo NISHITANI2) and Mitsutaka ISOBE2,3)
Toshiba Energy Systems & Solutions Corporation, Fuchu 183-8511, Japan
1)
Institute for Integrated Radiation and Nuclear Science, Kyoto University, Sennan-gun, Osaka 590-0494, Japan
2)
National Institute for Fusion Science, National Institutes of Natural Sciences, Toki 509-5292, Japan
3)
The Graduate University for Advanced Studies, SOKENDAI, Toki 509-5292, Japan
(Received 7 October 2020 / Accepted 15 December 2020 / Published 26 February 2021)

Abstract

A wide-range neutron flux measurement instrument is developed herein for monitoring the total neutron emission rate and yield of the Large Helical Device (LHD) during deuterium experiments implemented from March 2017 in the National Institute for Fusion Science (NIFS), Japan. The instrument is designed for and installed on the Neutron Flux Monitoring (NFM) system, which measures the counting rate using a 235U Fission Chamber. By combining the pulse counting and Campbell methods, the Digital Signal Processing Unit (DSPU) realized a wide dynamic range of over six orders of magnitude from 1 × 103 counts/s (cps) to 5 × 109 cps. This study explains and discusses how the instrument is developed, including topics from the predevelopment activities to the verification test at the Kyoto University Critical Assembly (KUCA). Experimental results in the LHD using the finished products suggest that the NFM system works well during deuterium experiments.

Keywords

neutron flux measurement, fission chamber, wide dynamic range, fast time response, Campbell method, Kyoto University Critical Assembly, Large Helical Device

DOI: 10.1585/pfr.16.1405018

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