Quantitative evaluation of ionization, recombination and cooling rate of tungsten for transport study and density analysis

2022 Fiscal Year Final Research Report

• Project/Area Number: 16H04088
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Plasma science
• Research Institution: National Institute for Fusion Science
• Principal Investigator: Morita Shigeru 核融合科学研究所, その他部局等, 名誉教授 (80174423)
• Co-Investigator(Kenkyū-buntansha): 大石 鉄太郎 東北大学, 工学研究科, 准教授 (80442523)
• Project Period (FY): 2016-04-01 – 2021-03-31
• Keywords: プラズマ核融合 / タングステン / プラズマ分光 / ＥＵＶ分光 / 疑似連続光 / 放射損失 / 電離・再結合 / 原子物理

Outline of Final Research Achievements

Spectroscopic study of W ions has been carried out for establishment of ion density evaluation method and technical development toward transport study. In LHD the density of W ions was evaluated from number of injected W particles and radial profiles of W EUV spectra, and theoretical model of the emission coefficient of W ions was optimized. The density evaluation method was established for Zn-like W44+, Cu-like W45+, and W24+-W26+ identified in the pseudo-continuum spectra. A C-R model was constructed for intensity analysis of measured magnetic forbidden lines (M1) of W ions, and densities of W26+ and W27+ ions was evaluated as a pioneering work. In EAST tokamak with full W divertor radial profiles of EUV spectra were successfully measured with high-time resolution of 10-20ms by installing a CMOS detector. The transport study of W ions was thus ready. In addition, a multi-fiber-channel visible spectrometer system was newly installed on EAST for observation of M1 transitions of W ions.

Free Research Field

プラズマ科学

Academic Significance and Societal Importance of the Research Achievements

非常に多くの軌道電子を有したタングステンイオンは相対論効果が大きく，スピン-軌道角運動量相互作用や配置間相互作用がスペクトル構造に多大な影響を及ぼす．これら相互作用を考慮に入れた多くのスペクトル発光強度理論モデルが提唱されているが，今回の実験研究により，量子準位混合（レベルミキシング）の重要性が証明された．一方，核融合装置におけるタングステンの挙動は安定した長時間放電の成否を左右する．従ってタングステンの密度制御は現在の核融合研究にとって必須の重要課題である．本研究で得られたタングステン密度計測法の確立は今後の核融合研究の進展に大きく寄与する．