Novel Development in the Fusion Plasma Diagnostics Using a Near-infrared Spectroscopy

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K05631
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Plasma science
• Research Institution: Kyoto University
• Principal Investigator: Kado Shinichiro 京都大学, エネルギー理工学研究所, 准教授 (10300732)
• Research Collaborator: Shikama Taiichi ; Sakamoto Mizuki
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 近赤外分光 / ヘリウム輝線強度比 / MAP-II / ヘリオトロンJ / ホットスポット / 黒体輻射 / 絶対感度較正

Outline of Final Research Achievements

We have focused on near-infrared (NIR) spectroscopy, which had not been extensively exploited, to extend the target wavelength regime. We applied a simple and portable monitoring system to acquire the NIR spectra of Heliotron J plasmas in an attempt to survey the brightness of an unknown/unused line in the spectra, and a continuum spectra in NIR regime. Calibration of the visible(VIS) and NIR spectrometers were performed using the shorter and longer side of the tungsten halogen lamp and the second-order diffraction component of the VIS region was assessed. The He I Line intensity ratio method based on the CR model was extended to the NIR region. As a proof-of principle experiment, the electron density in the edge region was determined for H2-He plasma. Observed black-body radiation was identified to be due to the hot spot caused by super-thermal electrons due to electron cyclotron heating(ECH).

Free Research Field

プラズマ理工学、核融合学、分光学、プラズマ診断法

Academic Significance and Societal Importance of the Research Achievements

従来、可視分光や真空紫外分光が用いられてきた核融合プラズマの分光診断において、近赤外領域の適用可能性に着目し、その有用性を示した。近赤外領域には可視光の２次回折光が重畳される懸念があるため、定量的な検出には注意を要する。一方、近年、この領域の小型分光器や検出器のラインナップが充実してきているため、定量評価・較正の手法を確立することは、意義深い。
ホットスポットはプラズマ対向壁の溶損や不純物発生の原因となり得るため、その観測・制御が不可欠であり、多くの金属の融点を含む1400-3200Kの温度に感受性が高い近赤外分光は、今後イメージ計測や高速化へと発展するニーズが高まってくると期待される。