The 1962 He3 scale of temperatures. II. Derivation

Abstract

An Experimental ThermodYlllLmic ]~quation (ETE) temperature scale valid from 0.2 to 2.0 oK has been calculated for JIe 3 . The scale is based on new compariso Jl s, (P" p.), of Ile3 a nd He' vapor pressures above 0.9 oK; on the 1958 lIe' temperature scale; and on the best available data for several thermodynamic properties of Ile 3 from 0.2 to 2.0 oK.The '1'62 Full-Ran ge Working Equation (F WE) scale,In P 3=-2.49174/ 7' + 4.80386 -0.286001 7' + 0.198608 1'2 -0.0502237 1'3+ 0.00505486 T' + 2.24846 In T fits t he E T E sCRle and the (P 3, 7'58) data and is therefore valid for use from 0.2 to the critical point, 3.324 oK. The maximum de':.iation from the ETE scale is 0.4 mdeg and ~he standard deviation from the input data is 0.21) mdeg. The fit to the seven recalculated Isotherms of K eller in the range of the 1962 Ile 3 scale ean be determined by conver ting Kell er's P,sto equ ivalent P /s, using di rect P, to P3 interpolation equati.ons. The fit of the 19.62 Ile3 scale is as good as the fit of the 1958 11e' scale to the same Isotherms, the ave rage displacements of the two scales both bein g 1.5 mdeg below t he isotherms. The average standard deviations for ( ' 1 ' 62 -'1'iso) and for ( 7\ 8-1'iso) are 1.2 and 1.0 mdeg, respectively, for these seve n isotherms.

Magnetic thermometry from 1 to 30 K

“…If T^g is in error, then 's also since the latter scale.is based upon comparisons (4) between the vapor 3 4 pressures of He and He . Nevertheless, both of these scales are smooth and thermodynamically consistent internally (5,6,10,11,12) the present data appears in Appendix B, and previously published (14) calibration data on two GER's used in this work are given In Appendix C.…”

“…The Helium region 4 3 Recently the accuracies of the current He and He vapor pressure scales, T^g (3) and T^g (7), respectively, have been questioned (9). 4 Acoustic data (16) indicate that the T^g value for the He boiling point is 10 mK too low, while a difference of T-T^g of 8 + 3 mK at 4.2 K was observed by RTAS (14) from CVGT data.…”

“…The Helium region 4 3 Recently the accuracies of the current He and He vapor pressure scales, T^g (3) and T^g (7), respectively, have been questioned (9). 4 Acoustic data (16) indicate that the T^g value for the He boiling point is 10 mK too low, while a difference of T-T^g of 8 + 3 mK at 4.2 K was observed by RTAS (14) from CVGT data. Furthermore a difference of 6 + 4 mK is suggested by an average (9,14) of other recent CVGT work provided all are analyzed using the so-called KKH (17), MR-5 virial coefficients and are referenced to a common temperature near 20,2 K. The conclusion of Astrov, Orlova, and Kytin (15), based upon their data, however, is that the Tgg value at 4.2 K Is correct.…”

“…" This scale Is based on comparisons between He^ and He^ vapor pressures above 0.9 K (4) and thermodynamic arguments (5,6) are used to extrapolate the scale to 0.2 K.…”

A SQUID-based primary noise thermometer for low-temperature metrology

“…In the history of international temperature scales, which started in 1887 when the first international temperature scale was adopted by the Comité International des Poids et Mesures (CIPM), only four different truly low-temperature scales were adopted, namely the 1958 4 He and 1962 3 He vapour-pressure scales [5,6], the 1976 Provisional 0.5 K to 30 K Temperature Scale (EPT-76) [7] and the PLTS-2000 [2]. The ITS-90 is basically identical to the EPT-76 in the temperature range between 0.65 K and 5 K as it is based on the same experimental dataset for the helium vapour pressure but is represented in a different mathematical form.…”