Share

A practical vapour pressure equation for helium-3 from 0.01 K to the critical point.

Author(s) : HUANG Y. H., CHEN G. B.

Type of article: Article

Summary

A saturation vapour pressure equation, p(T), is an essential component in the 3He state equation currently under development. The state equation is valid over the range 0.01-20 K with pressures from 0 to the melting pressure or 15 MPa. The vapour pressure equation consequently must be valid from 0.01 K to the critical temperature. This paper surveys available 3He critical temperature and pressure measurements, leading to new recommended critical values of 3.3157 K and 114603.91 Pa. The ITS-90 temperature scale is defined by the 3He vapour pressure from 0.65 to 3.2 K. A new vapour pressure equation is developed for the interval from the upper end of the T90 scale to this newly defined critical point, employing a mathematical form in which the second derivative d2p/dT2 diverges in agreement with scaling laws at the critical point. Below 0.65 K, an empirical vapour pressure expression is adopted, consistent with a theoretical expression valid in the limit T= 0. These two new components are fitted to be piecewise continuous with the EPT-76 p(T) scale rather than the ITS-90 T(p) scale between 0.65 and 3.2 K. Probable deviations between this vapour pressure scale and PLTS-2000 melting pressure-temperature scale are recognized, but not reconciled. [Reprinted with permission from Elsevier. Copyright, 2006].

Details

  • Original title: A practical vapour pressure equation for helium-3 from 0.01 K to the critical point.
  • Record ID : 2007-0472
  • Languages: English
  • Source: Cryogenics - vol. 46 - n. 12
  • Publication date: 2006/12

Links


See other articles in this issue (4)
See the source

Indexing