Shear viscosity measurements of liquid 3He-4He mixtures above 0.5 K

Abstract

Simultaneous measurements of (p~l) and of the molar volume are reported for liquid mixtures of 3He in 4He over the temperature range between 0.5 and 2.5 K. Here ~q is the shear viscosity and p is the mass density. In the superfluid phase, the product of the normal components, Pn and ~n, is measured. The mixtures with 3He molefractions 0.30 < X < 0.80 are studied with emphasis on the region near the superfluid transition T~ and near the phase-separation curve. Along the latter, they are compared with data by Lai and KitChens. For X > 0.5, the viscosity singularity near Tx becomes a faint peak, which however fades into the temperature-dependent background viscosity as X tends to the tricritical concentration Xt. Likewise, no singularity in 7 I is apparent when Tt is approached along the phase separation branches o-_ and or+. Furthermore, viscosity data are reported for 3He and compared with previous work. Finally, for dilute mixtures with 0.01 -< X -< 0.05, the results for 71 are compared with previous data and with predictions.

Thermodynamic Properties of Liquid 3He-4He Mixtures Between 0.15 K and 1.8 K

“…(shifted -see text), Roe et al [29], Qin et al [27], Ahlers and Greywall [31], Yorozu et al [30], and Lahuerte [32]. The dilute phase-separation curve is extended from 0.15 K to 0 K using values calculated by Kuerten et al [2].…”

“…The tricritical point at zero pressure is assumed to lie at a temperature t T = 0.867 K and 3 He concentration t x = 0.674 [27]. The 3 He concentration along the phase-separation curves was determined as a function of the temperature by curve-fits to available experimental data.…”

“…In order to get an equation that is easier to manipulate, a curve was fitted to the experimental phaseseparation data of Qin et al [27], Kierstead [28], Roe et al [29], Goellner et al [13] (whose data was once again shifted downward by 5 mK) and Lahuerte [32], resulting in the following expression for + σ x as a function of temperature:…”

“…The 3 He concentration along the phase-separation curves was determined as a function of the temperature by curve-fits to available experimental data. For the dilute phase-separation curve, a curve was fitted to the experimental phase-separation data of Qin et al [27], Kierstead [28], Roe et al [29], Goellner et al [13], Yorozu et al [30], and Ahlers and Greywall [31]. 3 He mole fraction along the concentrated phase-separation curve.…”

THERMODYNAMIC PROPERTIES OF LIQUID [sup 3]He-[sup 4]He MIXTURES BETWEEN 0.15 K AND 1.5 K

“…The tri-critical point at saturated pressure is assumed to lie at x t (0) = 0.674 and T t (0) = 0.867 K [7]. The 3 He concentration and temperature along the tricritical line, x t (p) and T t (p), can be determined as a function of pressure from the data of del Cueto et al [8] and Hoffer and Sinha [9].…”