Measurement of the Thermodynamic Temperature of<sup>4</sup>He at Various Vapour Pressures by a Noise Thermometer

Klein, H. H.; Klempt, G.; Storm, Louise Kamuk

doi:10.1088/0026-1394/15/3/005

Cited by 46 publications

(45 citation statements)

References 8 publications

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“…so that the output is proportional to the mean noise power as required, with (typically) very small errors due to the input noise currents of the amplifiers. Most correlating noise thermometers use a preamplifier with a common-source FET and bipolar-cascode input stage [64][65][66] with high transconductance FETs to give a very low noise current and low equivalent-input noise voltage. The input stage should be operated without feedback to minimise the input noise current [65] and the cascode stage must present a purely resistive load to the FET to maintain a 90° phase shift between the FET input noise current and noise voltage [65,67], and therefore ensure zero correlation between them.…”

Section: The Switched Cross-correlatormentioning

confidence: 99%

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Johnson noise thermometry

Benz

Rogalla

et al. 2019

Meas. Sci. Technol.

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Johnson noise thermometers infer thermodynamic temperature from measurements of the thermally-induced current fluctuations that occur in all electrical conductors. This paper reviews the status of Johnson noise thermometry and its prospects for both metrological measurements and for practical applications in industry. The review begins with a brief description of the foundations and principles of Johnson noise thermometry before outlining the many different techniques and technological breakthroughs that have enabled the application of Johnson noise thermometry to high-accuracy, cryogenic, and industrial thermometry. Finally, the future of noise thermometry is considered. As the only purely electronic approach to thermodynamic temperature measurement, Johnson noise thermometry has appeal for metrological applications at temperatures ranging from below 1 mK up to 800 K. With the rapid advances in digital technologies, there are also expectations that noise thermometry will become a practical option for some industrial applications, perhaps reaching temperatures above 2000 K.

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Section: The Switched Cross-correlatormentioning

confidence: 99%

“…The first significant metrological application of correlators to JNT was by Klein et al who measured the temperature dependence of the vapour pressure of liquid 4 He with a relative uncertainty of about 10 −4 [64]. The accuracy was limited in part by imperfections in the analogue multiplier used in the correlator.…”

Section: The Switched Cross-correlatormentioning

confidence: 99%

Johnson noise thermometry

Benz

Rogalla

et al. 2019

Meas. Sci. Technol.

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“…Only in the latter case can the Boltzmann constant be directly determined from the ratio U 2 /R of two macroscopic quantities if the temperature T is known. For details see [6,14,[67][68][69][70][71][72].…”

Section: Noise Thermometrymentioning

confidence: 99%

Determination of the Boltzmann constant—status and prospects

Fellmuth

Gaiser

Fischer

2006

Meas. Sci. Technol.

119

126

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The present definition of the kelvin links the unit of temperature with a material property, namely the triple point temperature of water. It would be more consistent with the current approaches to other base units of the International System of Units to fix the value of the Boltzmann constant k, instead. This would rationalize the definition and make it separate from any technique of realization. Furthermore, it is needed to improve temperature measurement, particularly at temperatures far away from the triple point of water. For this purpose, k must first be determined with appropriately small uncertainty applying different measurement methods. In this paper, the primary-thermometry methods for determining the Boltzmann constant (acoustic gas thermometry, thermal-equation-of-state methods, radiation thermometry and methods based directly on statistics and quantization) and their state-of-the-art level of uncertainty are discussed. Special emphasis is given to the basic physics underlying these methods, the fundamental error sources and the uncertainty, which seems to be attainable on a five-year timescale in view of some new developments and the foreseeable progress. Finally, a possible simple new definition of the kelvin is proposed.

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“…Fibre Bragg gratings have been shown to work effectively at extremely low temperatures 64 , as have a number of other devices 65,66 . At moderately low temperatures, approximately − 50°C, problems occur with the packaging and the batteries in devices.…”

Section: Low Temperaturementioning

confidence: 99%

Precision in harsh environments

2016

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Microsystems are increasingly being applied in harsh and/or inaccessible environments, but many markets expect the same level of functionality for long periods of time. Harsh environments cover areas that can be subjected to high temperature, (bio)-chemical and mechanical disturbances, electromagnetic noise, radiation, or high vacuum. In the field of actuators, the devices must maintain stringent accuracy specifications for displacement, force, and response times, among others. These new requirements present additional challenges in the compensation for or elimination of cross-sensitivities. Many state-of-the-art precision devices lose their precision and reliability when exposed to harsh environments. It is also important that advanced sensor and actuator systems maintain maximum autonomy such that the devices can operate independently with low maintenance. The next-generation microsystems will be deployed in remote and/or inaccessible and harsh environments that present many challenges to sensor design, materials, device functionality, and packaging. All of these aspects of integrated sensors and actuator microsystems require a multidisciplinary approach to overcome these challenges. The main areas of importance are in the fields of materials science, micro/nano-fabrication technology, device design, circuitry and systems, (first-level) packaging, and measurement strategy. This study examines the challenges presented by harsh environments and investigates the required approaches. Examples of successful devices are also given.

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Measurement of the Thermodynamic Temperature of⁴He at Various Vapour Pressures by a Noise Thermometer

Abstract: A noise thermometer has been developed, which operates by the correlation method suggested by van der Ziel. The temperature of the liquid 4He at seven different vapour pressures was measured with an accuracy of about Within 0.4 mK the noise temperatures coincide with the new T,,-scale

Cited by 46 publications

References 8 publications

Johnson noise thermometry

Johnson noise thermometry

Determination of the Boltzmann constant—status and prospects

Precision in harsh environments

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Measurement of the Thermodynamic Temperature of4He at Various Vapour Pressures by a Noise Thermometer

Abstract: A noise thermometer has been developed, which operates by the correlation method suggested by van der Ziel. The temperature of the liquid 4He at seven different vapour pressures was measured with an accuracy of about Within 0.4 mK the noise temperatures coincide with the new T,,-scale

Cited by 46 publications

References 8 publications

Johnson noise thermometry

Johnson noise thermometry

Determination of the Boltzmann constant—status and prospects

Precision in harsh environments

Contact Info

Product

Resources

About

Measurement of the Thermodynamic Temperature of⁴He at Various Vapour Pressures by a Noise Thermometer