3He Vapour-Pressure Measurements at PTB

Abstract

The paper reports on extensive 3 He vapour-pressure measurements carried out at PTB. To investigate in detail the main error sources, three different types of vapour-pressure cells and three different arrangements of pressuresensing tubes were used. In the temperature range from 0.65 K to 1.2 K, the repeatability of the realisation of 3 He vapour-pressure temperatures T 90 according to the International Temperature Scale of 1990, ITS-90, over eight runs was of order of 0.12 mK, whereas the repeatability over four runs using one and the same, optimised cryogenic set-up was of order of 0.03 mK. Below 1 K, the T 90 realisation is compared to data available in the literature via wire scales.

Numerical and Experimental Study of the Hydrostatic Pressure Correction in Gas Thermometry: A Case in the SPRIGT

“…Any heat input to the pressure tube (e.g. via the flanges) influences the HPC and hence the calculated pressure at the centre of resonator, a knowledge of the zero of which is important in RIGT [2] and other low-temperature measurements [3,36]. To estimate this effect on the pressure tube, the effect of heating on the section VT-3 was simulated 2 .…”