Precision measurement of self-heating effect of resistance thermometers installed on material artifacts

Abstract

Measurement of a self-heating effect (SHE) of a platinum resistance thermometer (PRT), which is to be performed under real experimental conditions, is the trickiest part in the calibration procedure of PRTs for precise temperature measurements of material artifacts. New double-channel synchronous detection technique has been developed for precise measurement of the SHE of a resistance thermometer, located on the surface of a material artifact. With new technique, we demonstrate that a PRT modifies the temperature distribution in the artifact, and the SHE of a PRT measuring a selected point on the artifact surface, is shown to depend on the distance from the thermometer to the selected point, the heat flux conditions in the artifact, and on the temperature rate, recorded by the thermometer. New approach, based on the use of pairs of specially calibrated thermometers, which are installed at a fixed distance on the artifact surface, realizes temperature measurements of the artifact surface without temperature gradient and velocity error. The demonstrated uncertainty in temperature measurement of gauge blocks inside our interferometers is at the level below 100 mK.