Doppler Spectroscopy of crossing flow velocity using optical vortex laser

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K05365
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Plasma science
• Research Institution: National Institute for Fusion Science
• Principal Investigator: Yoshimura Shinji 核融合科学研究所, ヘリカル研究部, 准教授 (50311204)
• Co-Investigator(Renkei-kenkyūsha): ARAMAKI Mitsutoshi 日本大学, 生産工学部, 教授 (50335072) ; TERASAKA Kenichiro 九州大学, 総合理工学研究院, 助教 (50597127)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 光渦 / ラゲールガウスビーム / レーザー吸収分光 / 周方向ドップラーシフト / プラズマ

Outline of Final Research Achievements

Optical vortex has not been used for plasma diagnostics so far. We firstly performed an optical-vortex laser-absorption-spectroscopy experiment of metastable argon neutrals aiming for the proof-of-principle of flow velocity measurement using optical vortex beams. Because the azimuthal Doppler shift in optical vortex has spatial dependence, we evaluated the Doppler shifts at various positions by two-dimensional distribution of transmitted light intensity. Obtained frequency shift qualitatively agreed with theoretically predicted spatial dependence. However, its absolute value was far large from the actual flow velocity of argon neutrals, which is left open and requires further study.

Free Research Field

プラズマ理工学