| Project/Area Number |
17K18771
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| Research Category |
Grant-in-Aid for Challenging Research (Exploratory)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Plasma science and related fields
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| Research Institution | Nihon University |
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Principal Investigator |
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| Project Period (FY) |
2017-06-30 – 2021-03-31
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| Project Status |
Completed (Fiscal Year 2020)
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| Budget Amount *help |
¥6,240,000 (Direct Cost: ¥4,800,000、Indirect Cost: ¥1,440,000)
Fiscal Year 2019: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2018: ¥3,770,000 (Direct Cost: ¥2,900,000、Indirect Cost: ¥870,000)
Fiscal Year 2017: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
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| Keywords | 光渦 / 速度空間トモグラフィー / プラズマ分光 / 吸収分光法 / トモグラフィー |
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| Outline of Final Research Achievements |
The phase space tomography method proposed in this study utilizes the fact that the excitation volume of the optical vortex is distributed with a different angle in the velocity space and is the first velocity distribution function measurement method that does not require parameter sweeping. Since the configuration of the excitation volume of the optical vortex depends on the position in the beam cross-section, it is inevitably absorbed non-uniformly when applied for absorption spectroscopy. It has been reported that defected optical vortex rotates with propagation, and it is necessary to suppress structural changes due to unnecessary propagation and accurately observe structural changes due to propagation in plasma. In this study, we clarified the characteristics of the optical vortex propagating in the plasma, which is the basis of the velocity space tomography method. We also constructed a measurement system of the optical vortex with a defective structure by absorption.
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| Academic Significance and Societal Importance of the Research Achievements |
プラズマの研究に限らず，物理系のダイナミクスを研究するあらゆる分野において，対象の速度分布関数は現象を理解する鍵となる．従来の速度分布関数測定では，何らかのパラメータ掃引に対する物理系の応答を利用するため，原理的にリアルタイム測定は不可能であった．本研究で提案する速度空間トモグラフィー法は，光渦の励起体積が速度空間で異なる傾きを持って分布することを利用しており，原理的にパラメータ掃引を必要としない初めてのリアルタイム速度分布関数測定法である．本研究では，速度空間トモグラフィー法の基礎となる，吸収体を伝搬する光渦の特性を明らかにし，吸収により欠陥構造を持った光渦に対する測定系を構築した．
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