1 / 9

Two types of quantum turbulence: mechanically VS thermally driven 4 He superflow in a channel

Two types of quantum turbulence: mechanically VS thermally driven 4 He superflow in a channel. Simone Babuin , Mathias Stammeier , Miloš Rotter , Ladislav Skrbek. SUPERFLUIDITY GROUP Joint Low Temperature Laboratory. Institute of Physics, Academy of Sciences of the Czech Republic &

elijah-england
Download Presentation

Two types of quantum turbulence: mechanically VS thermally driven 4 He superflow in a channel

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Two types of quantum turbulence:mechanically VS thermally driven 4He superflow in a channel Simone Babuin, Mathias Stammeier, MilošRotter,LadislavSkrbek SUPERFLUIDITY GROUP Joint Low Temperature Laboratory Institute of Physics, Academy of Sciences of the Czech Republic & Faculty of Mathematics and Physics, Charles University Prague, Czech Republic

  2. The system counterflow N S sq 7 mm Liquid Helium-4 1.3 K < T < 2.0 K @ saturated vapour pressure 115 mm [Chagovets & Skrbek, PRL 100, 215302 (2008) JLTP 153,162 (2008)] (A) Mechanical flow generation: bellows [present work] (B) Thermal flow generation: counterflow heater

  3. What we measure Peak maximum Second sound resonance flow speed = 10 cm/s A0 A w0 A0 Temperature = 1.45 K A • Scattering of second sound waves against vortex lines • Assume vortex tangle homogeneous and isotropic • Take into account scattering depends on angle B(T): mutual friction coefficient k: quantum of circulation average vortex line length per unit volume

  4. Vortex line density Mechanically driven flow (A) Comparison with thermally drive flow Open symbols: from full resonant curve Full symbols: from peak maximum A B 1.58K 1.73K 1.92K 1.49K A B

  5. Slopes A B C D (SchwarzPRB 18 (1978) 245) 0.13 X 80 mm C Tough et al. PRL 46 (1981) 658

  6. A from extrapolation Critical velocity A B C from direct measurement

  7. Summary of the main facts • B: TC&LS (2008) • pure superflow • thermally driven • 7x7 mm2 sq channel • second sound att. • C: Tough (1981) • -pure superflow • thermally driven • 0.13 mm circ channel • temp gradients • D: Schwarz theory (1978) • counterflow in frame of normal component • no boundaries • A: present work • -pure superflow • mechanically driven • 7x7 mm2 sq channel • second sound att. • A and Bdisagree in (1), (2) and (3) • A, C and D agree in (1) and (2), but disagree in (3) • B, C and D agree in (3), but disagree in (1) and (2) Functional relation between L and v Magnitude of L across whole range of v Critical velocity

  8. Extra: comparison withL from other systems

  9. Extra: temperature differences The temperature is measured inside the bellows, and the difference is before and during a bellows compression

More Related