2023 Fiscal Year Final Research Report

Messages from laboratory experiments on the observation of X-ray emission from multiply charged ions in the solar wind

Research Project

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Project/Area Number	19H00701
Research Category	Grant-in-Aid for Scientific Research (A)
Allocation Type	Single-year Grants
Section	一般
Review Section	Medium-sized Section 16:Astronomy and related fields
Research Institution	Tokyo Metropolitan University
Principal Investigator	Tanuma Hajime 東京都立大学, 理学研究科, 教授 (30244411)
Co-Investigator(Kenkyū-buntansha)	坂上裕之核融合科学研究所, 研究部, 助教 (40250112) 中村信行電気通信大学, レーザー新世代研究センター, 教授 (50361837) 飯田進平東京都立大学, 理学研究科, 助教 (20806963)
Project Period (FY)	2019-04-01 – 2024-03-31
Keywords	Ｘ線天文学 / 太陽風電荷交換
Outline of Final Research Achievements	We have developed a device to generate a fast neutral hydrogen atom beam with a velocity equivalent to that of the solar wind by a quasi-resonant charge-transfer reaction in which a hydrogen ion beam is collided with methane, which has almost the same ionization potential as hydrogen. Highly ionized iron ions ranging from bare to helium-like were produced in the electron beam ion trap developed at the University of Electro-Communications, and X-ray emission was measured with a silicon drift detector while introducing a small amount of neutral gas. With the electron beam flowing, emission from hydrogen-like and helium-like ions due to electron impact excitation was observed, while with the electron beam off, only emission from excited states produced by charge transfer reactions was observed. There was a marked difference between the two spectra.
Free Research Field	原子分子物理学
Academic Significance and Societal Importance of the Research Achievements	準安定励起状態を含まない高速中性水素ビームの生成には，負イオンビームの光脱離が適当であるとされてきたが，イオン化ポテンシャルがほとんど同じメタンを標的気体として用いることで，正イオンビームであっても基底状態だけの中性水素ビームが生成できることを実証した。また，電子ビームイオントラップを用いた実験では，裸および水素様の鉄イオンの電荷移行反応によるX線発光を世界で初めて観測した。宇宙で観測されたスペクトルとの比較によって，宇宙空間における励起メカニズムの理解の助けになることを期待している。