Noise Thermometry for Ultralow Temperatures

AbstractIn recent years, current-sensing dc-SQUIDs have enabled the application of noise thermometry at ultralow temperatures. A major advantage of noise thermometry is the fact that no driving current is needed to operate the device and thus the heat dissipation within the thermometer can be reduced to a minimum. Such devices can be used either in primary or relative primary mode and cover typically several orders of magnitude in temperature extending into the low microkelvin regime. Here we will review recent advances of noise thermometry for ultralow temperatures.

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Noise thermometry at ultra-low temperatures

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2015.0051 ◽

2016 ◽

Vol 374 (2064) ◽

pp. 20150051 ◽

Cited By ~ 6

Author(s):

D. Rothfuss ◽

A. Reiser ◽

A. Fleischmann ◽

C. Enss

Keyword(s):

Magnetic Flux ◽

Power Dissipation ◽

Low Temperatures ◽

Quantum Interference ◽

Heat Dissipation ◽

Correlation Technique ◽

Primary Thermometry ◽

Current Sensing ◽

Noise Thermometry ◽

Cold Worked

The options for primary thermometry at ultra-low temperatures are rather limited. In practice, most laboratories are using 195 Pt NMR thermometers in the microkelvin range. In recent years, current sensing direct current superconducting quantum interference devices (DC-SQUIDs) have enabled the use of noise thermometry in this temperature range. Such devices have also demonstrated the potential for primary thermometry. One major advantage of noise thermometry is the fact that no driving current is needed to operate the device and thus the heat dissipation within the thermometer can be reduced to a minimum. Ultimately, the intrinsic power dissipation is given by the negligible back action of the readout SQUID. For thermometry in low-temperature experiments, current noise thermometers and magnetic flux fluctuation thermometers have proved to be most suitable. To make use of such thermometers at ultra-low temperatures, we have developed a cross-correlation technique that reduces the amplifier noise contribution to a negligible value. For this, the magnetic flux fluctuations caused by the Brownian motion of the electrons in our noise source are measured inductively by two DC-SQUID magnetometers simultaneously and the signals from these two channels are cross-correlated. Experimentally, we have characterized a thermometer made of a cold-worked high-purity copper cylinder with a diameter of 5 mm and a length of 20 mm for temperatures between 42 μ K and 0.8 K. For a given temperature, a measuring time below 1 min is sufficient to reach a precision of better than 1%. The extremely low power dissipation in the thermometer allows continuous operation without heating effects.

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Recent Advances in Design and Preparation of Polymer-Based Thermal Management Material

Polymers ◽

10.3390/polym13162797 ◽

2021 ◽

Vol 13 (16) ◽

pp. 2797 ◽

Cited By ~ 2

Author(s):

Hongli Zhang ◽

Tiezhu Shi ◽

Aijie Ma

Keyword(s):

Thermal Management ◽

High Performance ◽

Heat Dissipation ◽

Electronic Devices ◽

High Heat ◽

Consumer Electronics ◽

Recent Advances ◽

Processing Strategies ◽

Innovative Material ◽

Processing Properties

The boosting of consumer electronics and 5G technology cause the continuous increment of the power density of electronic devices and lead to inevitable overheating problems, which reduces the operation efficiency and shortens the service life of electronic devices. Therefore, it is the primary task and a prerequisite to explore innovative material for meeting the requirement of high heat dissipation performance. In comparison with traditional thermal management material (e.g., ceramics and metals), the polymer-based thermal management material exhibit excellent mechanical, electrical insulation, chemical resistance and processing properties, and therefore is considered to be the most promising candidate to solve the heat dissipation problem. In this review, we summarized the recent advances of two typical polymer-based thermal management material including thermal-conduction thermal management material and thermal-storage thermal management material. Furtherly, the structural design, processing strategies and typical applications for two polymer-based thermal management materials were discussed. Finally, we proposed the challenges and prospects of the polymer-based thermal management material. This work presents new perspectives to develop advanced processing approaches and construction high-performance polymer-based thermal management material.

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