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License for SQUID-based noise thermometer to measure thermodynamic temperatures in the low-temperature range

Country of Origin: Germany
Reference Number: TODE20210416001
Publication Date: 16 April 2021

Summary

A German research institute has developed a SQUID-based (superconducting quantum interference device) noise thermometer to measure thermodynamic temperatures in the low-temperature range. The application of noise thermometers is useful as a reference thermometer at low temperatures (< 1 K), especially below 10 mK. Noise thermometers cover the entire temperature range of at least 0.9 mK to 4.2 K. The research institute is searching for licensees.

Description

A German research institute active in metrology in Germany has developed a SQUID-based (superconducting quantum interference device) noise thermometer to measure thermodynamic temperatures in the low-temperature range.
Magnetic field fluctuation thermometers (MFFT) are SQUID-based noise thermometers used for deep temperatures (typically below 5K). They detect the fluctuations of the magnetic field on the surface of an electrically conductive body ("temperature sensor"), which are linked to the thermally excited currents flowing inside. Based on the new, fully predictable sensor, it is possible to measure thermodynamic temperature structures with the offered device, which eliminates the otherwise necessary return to the international temperature scales ITS-90 (International Temperature Scale of 1990) and PLTS-2000 (Provisional Low Temperature Scale of 2000) for the first time .

The offered device consists of four main components:
1) A metallic temperature sensor made of high purity copper
2) Two planar, gradiometric detection coils on a Si-chip which are read out by two DC SQUID power sensors
3) One planar calibration coil on a Si-chip
4) A two-channel -SQUID- electronic

The actual temperature sensor is formed by the central area of the copper body above the detection coils. At this point, the thermal magnetic flux noise is measured via two independent SQUID-gradiometers and evaluated by using the cross-correlation method, which reduces all non-thermal noise proportions. With known geometry and electrical conductivity of the sensor, the temperature can be calculated from the noise spectra.
The research institute is searching for licensees to foster the international commercial exploitation of the innovation.
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Advantages and Innovations

The described system offers several advantages compared with state of the art test benches:
- Full and simple predictability of the thermometer
- Thermally robust temperature sensor, easy integration in cryostats
- Two independent signal channels enable the application of the cross correlation method as well as consistency checks
- Assembly with two positions for coil chips in freely selectable distances to the temperature sensor, in situ calibration of the SQUID gradiometer

Stage Of Development

Field tested/evaluated

Stage Of Development Comment

Devices of the current, first version are in operation and will continued to be tested. Further developments to reduce the uncertainty of the relative measurement are planned.
A patent was granted, licenses for the use of this new method are available.

Requested partner

Targeted partners are either active in the development of SQUID-based noise thermometer for deployment as reference thermometer in low temperatures. The institute looks for licensees.

Cooperation offer is closed for requests