Lambda Transformation of Liquid ${He}^{4}$ at High Pressures

Measurements are reported of the pressure coefficient

β_{V} = {(\frac{\partial P}{\partial T})}_{V}

{He}^{4}

I and

{He}^{4}

II along the isochore which crosses the

λ

line at

T_{λ} = 1.7683

°K and

P_{λ} = 29.56

atm, and of the compressibility

ρ κ_{T} = {(\frac{\partial ρ}{\partial P})}_{T}

along the isotherm

T = 1.7683

°K, the closest points being 2.5 μdeg, 50 μatm, and

10^{- 7}

{cm}^{3}

from the lambda line in temperature, pressure, and density, respectively. The data are well represented by the equations:

{He II : β_{V} = - 14.22 + 3.54 {log}_{10} (T_{λ} - T), 2.4 \times 10^{- 6} \leq T_{λ} - T \leq 3 \times 10^{- 3}} {He I : β_{V} = 9.00 + 7.50 {log}_{10} (T - T_{λ}), 2.5 \times 10^{- 6} \leq T - T_{λ} \leq 6 \times 10^{- 3}} {He II : {(ρ κ_{T})}^{- 1} = 1000.4 + 78.9 {log}_{10} (ρ_{λ} - ρ), 10^{- 7} \leq ρ_{λ} - ρ \leq 10^{- 5},} {He I : {(ρ κ_{T})}^{- 1} = 1675.0 \pm 167.2 {log}_{10} (ρ - ρ_{λ}), 10^{- 7} \leq ρ - ρ_{λ} \leq 10^{- 5},}

where

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Lambda Transformation of LiquidHe4at High Pressures