Thermal conductivity and torsional oscillations of solid 4He
Thermal conductivity and torsional oscillations of solid 4He
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DOI：
10.1063/1.4765093
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发表时间：
2012-11
影响因子：
0.8
通讯作者：
M. Y. Brazhnikov;D. Zmeev;A. Golov
中科院分区：
文献类型：
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作者：
M. Y. Brazhnikov;D. Zmeev;A. Golov
采用封闭毛细管法在环形容器中生长摩尔体积Vm = 19.5 cm3的hcp 4He多晶样品，其中含有少量3He杂质。研究了三种浓度的3He， x3：同位素纯化的4He（估计x3 < 10−10），商业“井级”氦（x3 ~ 3·10−7）和x3 = 2.5·10−6的混合物。研究了132.5 Hz和853.6 Hz两个频率下的扭转振荡和退火前后的导热系数。所研究的固体氦不仅位于环形容器内，而且位于双频扭转振荡器的两根扭转杆和假杆内的轴向填充线上。对加载氦气和改变振荡器不同部位温度时的频移的分析表明，这三种技术在三个不同的位置探测了固体氦的性质：两种不同的扭转模式响应了固体氦在任意一个位置的剪切模量的变化。
Polycrystalline samples of hcp 4He of molar volume Vm = 19.5 cm3 with small amount of 3He impurities were grown in an annular container by the blocked-capillary method. Three concentrations of 3He, x3, were studied: isotopically purified 4He with the estimated x3 < 10−10, commercial ‘well-grade’ helium with x3 ∼ 3·10−7 and a mixture with x3 = 2.5·10−6. Torsional oscillations at two frequencies, 132.5 and 853.6 Hz, and thermal conductivity were investigated before and after annealing. The solid helium under investigation was located not only in the annular container but also in the axial fill line inside two torsion rods and dummy bob of the double-frequency torsional oscillator. The analysis of the frequency shifts upon loading with helium and changing temperatures of different parts of the oscillator suggests that the three techniques probe the properties of solid helium in three different locations: the two different torsion modes respond to the changes of the shear modulus of solid helium in either of ...