| Project/Area Number |
17K18761
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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 |
Condensed matter physics and related fields
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| Research Institution | Osaka City University |
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Principal Investigator |
Yano Hideo 大阪市立大学, 大学院理学研究科, 准教授 (70231652)
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| Project Period (FY) |
2017-06-30 – 2020-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥6,500,000 (Direct Cost: ¥5,000,000、Indirect Cost: ¥1,500,000)
Fiscal Year 2019: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Fiscal Year 2018: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
Fiscal Year 2017: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
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| Keywords | 低温物性 / 超流体 / 量子渦 / 超流動流 / 量子渦集中 |
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| Outline of Final Research Achievements |
We report the results obtained in the present study as follows, for the purpose of developing new aspects of quantized vortex structures in a vortex tower of superfluid helium.
1) We developed the vortex pump of superfluid helium and found that a vortex tower, namely a suction vortex, is produced in superfluid helium. 2) Measuring the height of fluid surface as a function of the distance from the vortex center, we estimated the circulation of the suction vortex flow. The circulation is proportional to the revolution speed of the rotor of the pump, suggesting that the angular momentum of the superfluid flow drained from the pump is related to the vortex circulation. 3) Measuring the dumping of the second sound signal, we estimated the vortex line density around the suction vortex. Using the circulation and the vortex line density of the vortex, we found that vortex lines concentrate in a cylinder with the twice diameter of the vortex tube in superfluid helium.
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| Academic Significance and Societal Importance of the Research Achievements |
本研究は、巨視的量子凝縮相で研究されてこなかった渦の基本定理を応用し、新たな概念である超流動の流れによる量子渦集中を確立した点に意義がある。量子渦の構造、複数の渦の結合、量子数２以上の量子渦など、超流動の安定性に関する未解決問題への研究方法を提供する。また、渦が発生する過程での循環の集中は古典流体でもいまだ未解決であるが、循環が量子渦で特徴づけられ、その運動を可視化できる超流動ヘリウムによってのみ、詳細に研究することができる。渦の発生メカニズムの解明は、工学的応用や竜巻など気象学でも重要で、本研究の成果は、量子流体にとどまらず流体工学や地球流体力学へも応用される。
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