Quantum turbulence of bellows-driven .sup.4./sup.He superflow: decay

0455291 - FZÚ 2016 RIV US eng J - Journal Article
Babuin, Simone - Varga, E. - Vinen, W. F. - Skrbek, L.
Quantum turbulence of bellows-driven ⁴He superflow: decay.
Physical Review. B. Roč. 92, č. 18 (2015), "184503-1"-"184503-13". ISSN 1098-0121
Institutional support: RVO:68378271
Keywords : vortex-line density * counterflow turbulence * quantum turbulence
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 3.736, year: 2014

In this paper we report on studies of the temporal decay of the vortex-line density, observed when the bellows is stopped, and we compare the results with those obtained from the temporal decay of thermal counterflow remeasured in the same channel and under the same conditions. In both cases there is an initial fast decay which, for low enough initial line density, approaches for a short time the form t−1 characteristic of the decay of a random vortex tangle. This is followed at late times by a slower t−3/2 decay, characteristic of the decay of large “quasiclassical” eddies. However, in the range of investigated parameters, we observe always in the case of thermal counterflow, and only in a few cases of high steady-state velocity in superflow, an intermediate regime in which the decay either does not proceed monotonically with time or passes through a point of inflexion. This difference, established firmly by our experiments, might represent one essential ingredient for the full theoretical understanding of counterflow turbulence.
Permanent Link: http://hdl.handle.net/11104/0255920