Normal and Anomalous Self-Heating in Capsule-type Resistance Thermometers in the Range 1 K to 273 K
Weston L. Tew, Christopher W. Meyer
The normal self-heating coefficient for standard capsule-type resistance thermometers is gas-mediated over most of their designed range of use. This is readily modeled and calculated for thermometers with helium fill gas from known transport properties for temperatures above the superfluid-film transition at 1.3 K. Anomalous self-heating exists in certain capsules where air contamination has occurred, and this observed self-heating is compared with predictions from the thermal conductivity of gas mixtures. The experimental aspects of the self-heating measurements are described as well as certain aspects of the thermal transport modeling. Some associated interpolation errors are described and useful screening techniques are suggested for capsule thermometers over cryogenic temperature ranges.
Temperature, Its Measurement and Control in Science and Industry, Volume 8