Primary acoustic thermometers determine the thermodynamic temperature of a monatomic gas from measurements of the speed of sound in the gas. Here, we describe the design and construction of an acoustic thermometer designed to operate at temperatures up to 800 K with uncertainties of a few Milikelvin. Features of our acoustic thermometer include: construction that minimizes sources of gas contamination; a gas contamination; a gas handling system for continuous purging of the resonator during the acoustic measurements; monitoring the purity of the gas exiting the resonator; determination of the thermal expansion and dimensional stability of the resonator cavity by in situ measurements of microwave resonance frequencies; use of navel acoustic transducers; and measurement of the temperature of the resonator shell on the International Temperature Scale of 1990 (ITS-90) with up to five long-stem standard platinum resistance thermometers (SPRTs). We are currently in the process of implementing this thermometer at NIST, and results will be presented at later date.
Proceedings of the TEMPMEKO '99 Symposium
June 1-3, 1999
Symposium on Temperature and Thermal Measurement in Industry and Science
acoustic, high temperature, thermodynamic, thermometer, thermometry