Transient heating in fixed length optical cavities for use as temperature and pressure standards

Published

February 25, 2021

Author(s)

Jacob Edmond Ricker, Kevin O. Douglass, Jay H. Hendricks, Jack Stone, Sergei Syssoev, Sefer Avdiaj

Abstract

Optical refractometry techniques can enable realization of both pressure and temperature directly from properties of the gas. For achieving the highest possible accuracy, temperature uniformity across the refractometer must be less than 1 mK. However, the gas dynamics of pressurization cause a temperature increase which effects the uniformity and impedes the ability to make accurate gas temperature measurements. Comparing computer modelling to physical measurements allows us to predict thermal behavior and determine uncertainty of the technique. The measurements and computer modelling show that temperature of the glass elements of the refractometer and copper chamber are equivalent after 3800 s (when going from 1 kPa to 100 kPa) and therefore measurements of the copper chamber provide accurate measurements of the gas temperature to within an uncertainty of 0.5 mK. Here the NIST refractometer is evaluated for operation as temperature standard with direct traceability to the SI.

Citation

Metrologia

Pub Type

Journals

Download Paper

https://doi.org/10.1088/1681-7575/abe8e0

Local Download

Keywords

Optical Thermometer, Pressure, FLOC, Refractive index, Thermal Modeling, Standard

Citation

Ricker, J. , Douglass, K. , Hendricks, J. , Stone, J. , Syssoev, S. and Avdiaj, S. (2021), Transient heating in fixed length optical cavities for use as temperature and pressure standards, Metrologia, [online], https://doi.org/10.1088/1681-7575/abe8e0, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=931062 (Accessed October 9, 2025)