Study on Vortex Lattice in Superfluid 3He-A phase with Rotating Cryostat

2018 Fiscal Year Final Research Report

• Project/Area Number: 15K05169
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Condensed matter physics II
• Research Institution: Kyoto University
• Principal Investigator: Akira Matsubara 京都大学, 理学研究科, 准教授 (00229519)
• Co-Investigator(Kenkyū-buntansha): 高木 丈夫 福井大学, 学術研究院工学系部門, 教授 (00206723) ; 上野 智弘 京都大学, 医学研究科, 助教 (10379034)
• Project Period (FY): 2015-04-01 – 2019-03-31
• Keywords: 超流動ヘリウム３ / 量子渦 / 第２音波 / NMR / MRI

Outline of Final Research Achievements

In this research, we planned to observe the quantum vortices and the vortex lattices generated in the anisotropic superfluid 3He-A phase under rotation. We aimed to study the structure and dissipation mechanism of the quantum vortices. In this study, we constructed a rotary dilution refrigerator measurement system, and achieved the condition that it could be operated as a dilution refrigerator under one rotation per second. The lowest temperature reached without rotation was about 9 mK, the circulating amount of 3He-4He mixed gas was 200 μmol/s, and the freezing capacity was 100 μW at 100 mK. Although the minimum temperature rises under rotation, around 13 mK, and it has been confirmed that it can be used as a nuclear adiabatic demagnetization cooling refrigerator. Moreover, the preliminary experiment of the second sound wave measurement for rotary refrigerator evaluation was done, and the temperature dependence of the sound velocity and the attenuation coefficient could be obtained.

Free Research Field

低温物理学

Academic Significance and Societal Importance of the Research Achievements

高磁場超低温回転冷凍機へ向けた回転冷凍機の完成は未だ解明されていない超流動ヘリウム３における渦のダイナミックスの研究の大きな足がかりとなる。超流動ヘリウム３の渦のダイナミックスの理解が進めば、量子流体全体の統一的な理解へとつながると期待される。これにより、自然を構成する物質の理解をより一層深めていくことにつながる。