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The 1962 He3 Scale of Temperatures II. Derivation
S G Sydoriak1, T R Roberts1, R H Sherman1
1Los Alamos Scientific Laboratory, University of California Los Alamos, N. Mex.
Summary
A new experimental thermodynamic equation temperature scale for Helium-3 (He3) was developed from 0.2 to 2.0 °K. This scale, valid to the critical point, shows high accuracy and comparable performance to the Helium-4 scale.
Area of Science:
- Thermodynamics
- Low-temperature physics
- Helium-3 properties
Background:
- Accurate temperature scales are crucial for low-temperature research.
- Existing Helium-4 (He4) temperature scales provide a basis for Helium-3 (He3) scale development.
- Thermodynamic data for He3 below 2.0 °K requires precise definition.
Purpose of the Study:
- To establish an Experimental Thermodynamic Equation (ETE) temperature scale for He3 from 0.2 to 2.0 °K.
- To develop a Full-Range Working Equation (FWE) scale (T62) valid from 0.2 °K to the critical point (3.324 °K).
- To compare the accuracy and fit of the new He3 scale with the established He4 scale.
Main Methods:
- Utilized new comparisons of He3 and He4 vapor pressures above 0.9 °K.
- Incorporated the 1958 He4 temperature scale and best available thermodynamic data for He3.
- Developed interpolation equations to convert He4 pressures to He3 pressures for comparative analysis.
Main Results:
- The T62 FWE scale accurately fits the ETE scale and experimental data, with a maximum deviation of 0.4 mdeg.
- The T62 scale demonstrates comparable performance to the 1958 He4 scale when fitted to Keller's isotherms.
- Average standard deviations for the T62 scale and the 1958 He4 scale against isotherms were 1.2 mdeg and 1.0 mdeg, respectively.
Conclusions:
- The T62 scale provides a reliable thermodynamic temperature scale for He3 from 0.2 °K to its critical point.
- The new He3 scale exhibits high precision and accuracy, meeting the needs of low-temperature thermodynamic research.
- The developed scale is a significant advancement for experiments requiring precise temperature measurements in He3.
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