Investigation of High-Stability Temperature Control in Primary Gas Thermometry

Abstract

We present a relationship between the temperature control and measurement stability limit and its temperature resolution, particularly for using rhodium-iron resistance thermometers and AC resistance bridges.Based on which, temperature control was investigated and demonstrated in primary gas thermometry at various working conditions. With optimized parameters, micro-kelvin level temperature control stability was realized in the temperature region from 5 K to 24.5 K. The temperature control stabilities are better than 8 K over 180 h with an integration time of 33.6 s in the concerned temperature range, closing to the limit that the sensors and the instruments can control and measure. These stabilities were improved about (44 ± 8) % at 24.5 K and (70 ± 7) % at 5 K comparing with our previous work (Chen et al., Cryogenics 2019 97 1-6).