Cylindrical Acoustic Gas Thermometry

Published

July 6, 2023

Author(s)

Li Xing, X.J. Feng, Ming-Hao Si, Jintao Zhang, Hong Lin, Keith Gillis, Michael Moldover

Abstract

We review recent determinations of the Boltzmann constant kB and the differences T-T90 that used cylindrical acoustic gas thermometry (c-AGT). These determinations measured the acoustic resonances frequencies of argon gas enclosed by metal-walled, cylindrical cavities. (Here, T is the thermodynamic temperature and T90 is the temperature measured on the International Temperature Scale ITS-90.) In the range 234 K to 303 K, the standard uncertainty of c-AGT ranges from 1.9×10^(-6) T to 2.6×10^(-6) T. This uncertainty is much smaller than the errors in ITS-90; therefore, c-AGT can help improve ITS-90. Moreover, we are extending c-AGT up to 1358 K. With increasing temperatures, c-AGT becomes advantageous relative to AGT based quasi-spherical cavities because long cylindrical cavities: (1) naturally fit into cylindrical heat pipes or multi-shelled thermostats, (2) provide the immersion required by transfer temperature standards such as long-stemmed platinum resistance thermometers, and (3) have more useful, low-frequency acoustic resonances. In preparation for high-temperature c-AGT, we identified suitable materials for fabricating cylindrical cavities and we developed techniques for measuring acoustic resonance frequencies using sources and detectors outside the high-temperature thermostat. We also considered alternative test gases and optimal dimensions of cavities.

Citation

Journal of Physical and Chemical Reference Data

Volume

52

Issue

3

Pub Type

Journals

Download Paper

https://doi.org/10.1063/5.0139385

Local Download

Keywords

thermometry, acoustic gas thermometry, Boltzmann Constant, AGT, resonance, ITS-90

Citation

Xing, L. , Feng, X. , Si, M. , Zhang, J. , Lin, H. , Gillis, K. and Moldover, M. (2023), Cylindrical Acoustic Gas Thermometry, Journal of Physical and Chemical Reference Data, [online], https://doi.org/10.1063/5.0139385, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=936070 (Accessed October 13, 2025)