The nucleation of vortices in superfluid [sup 4]He: Answers and questions
- Centre d'Etudes de Saclay (France)
- Universite Paris-Sud, Orsay (France)
The velocity threshold for phase slips, v[sub c], has been measured in ultra-pure [sup 4]He and ultra-dilute [sup 3]He-[sup 4]He mixtures, down to a temperature of 15 mK. These experiments have revealed a crossover from a temperature-dependent regime above [approximately]150 mK to a plateau of v[sub c] below in ultra-pure [sup 4]He. Concentrations of [sup 3]He impurities as low as a few parts in 10[sup [minus]9] greatly affect the plateau regime, causing v[sub c] to decrease markedly at low temperature. These observations are interpreted in the framework of the nucleation, either thermally activated or by quantum tunnelling, of vortices in the appropriate shape of half-rings. These vortices form on wall asperities at local velocities u[sub s] estimated to be [approximately]22 m/s in these experiments. The half-ring model is shown to yield a critical velocity of the same magnitude but leaves many basic questions unanswered.
- OSTI ID:
- 5343993
- Report Number(s):
- CONF-9308208-; CODEN: JLTPAC
- Journal Information:
- Journal of Low Temperature Physics; (United States), Vol. 93:5-6; Conference: Conference on the role of the condensate and vorticity in dense bose systems, Minneapolis, MN (United States), 1-3 Aug 1993; ISSN 0022-2291
- Country of Publication:
- United States
- Language:
- English
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