de Podesta, M; Sutton, G; Underwood, R J; Legg, S*; Steinitz, A* (2010) Practical acoustic thermometry with acoustic waveguides. Int. J. Thermophysics, 31 (8-9). pp. 1554-1566.

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Abstract

Acoustic Thermometry is capable of phenomenal accuracy, but it is a difficult technique to apply in many practical situations. Here we describe a modification of the technique, which permits robust temperature measurements to be made, potentially with milli-kelvin resolution, over a temperature range extending from cryogenic temperatures to over 1000 °C.

The technique uses measurements of the time-of-flight of acoustic pulses in tubes usually filled with an inert gas such as argon. The tubes - typically made of stainless steel with an outer diameter of 6 mm - act as acoustic waveguides and can be several metres long and bent into complex shapes. The time-of-flight reflects the average temperature along the entire length of the tube. Local temperature information can be inferred in several ways. Typically a second shorter tube is used and the difference in time-of-flight reflects the temperature in the region at the end of the first tube. If the measurement length is sufficiently long - typically 1 metre of tube - then a measurement resolution of less than 1 mK is achievable.

The technique is well suited to measurements in harsh environments in which conventional sensors degrade. We show results from early tests, which highlight the strengths and weaknesses of the technique.

Item Type:	Article
Keywords:	Acoustic, Thermometry, Temperature, Speed of sound, High accuracy
Subjects:	Engineering Measurements Engineering Measurements > Thermal
Identification number/DOI:	10.1007/s10765-010-0793-x
Last Modified:	02 Feb 2018 13:15
URI:	https://eprintspublications.npl.co.uk/id/eprint/4866