Viscosity and mean free path of very diluted solutions of He-3 in He-4.

Citation
H. Kerscher et al., Viscosity and mean free path of very diluted solutions of He-3 in He-4., J L TEMP PH, 124(1-2), 2001, pp. 163-168
Citations number
15
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
JOURNAL OF LOW TEMPERATURE PHYSICS
ISSN journal
00222291 → ACNP
Volume
124
Issue
1-2
Year of publication
2001
Pages
163 - 168
Database
ISI
SICI code
0022-2291(200107)124:1-2<163:VAMFPO>2.0.ZU;2-Q
Abstract
We have measured thc laminar friction of various diluted He-3-He-4 mixtures , of natural He-4 and of isotopically pure He-4 on an oscillating sphere be low 1 K. For He-3 concentrations x(3) ranging fron, 10(-2) to 10(-4) we fin d a reduction of the drug above 0.5 K when compared to the pure liquid and a large enhance,ment below which is almost independent of x(3). At low conc entrations 5 (.) 10(-5) > x(3) > 5 (.) 10(-7) the drag becomes proportional to x(3) which implies a transition from a hydrodynamic to a ballistic regi me. This is confirmed by deducing the mean free path of the He-3 atoms from the data. The temperature dependence. of the drag in, thr, ballistic regim e, however. is found to be proportional to T and therefore different from t he expected T-1/2 behaviour.