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Absolute Temperature Measurement

IP.com Disclosure Number: IPCOM000034822D
Original Publication Date: 1989-Apr-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Reihl, B: AUTHOR [+2]

Abstract

In many experimental and manufacturing set-ups, the knowledge of the absolute temperature of a specimen is essential. In specific cases, such as vacuum chambers, cryostats, etc., the direct and absolute temperature determination is cumbersome and/or requires separate calibration measurements due to external fix-point temperatures, contact voltages, non-linear thermocouples, etc. The broad temperture range (0.5 K < Tc < 125 K) offered by high-Tc superconductors allows creation of a scale of reference temperatures corresponding to the transition temperatures Tc of the superconductors used. Fig. 1 shows a sandwich structure consisting of stacked superconductor films 1...11 (having a thickness of < 10 mm) resting on an insulating substrate 12 of strontium titanate, for example.

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Absolute Temperature Measurement

In many experimental and manufacturing set-ups, the knowledge of the absolute temperature of a specimen is essential. In specific cases, such as vacuum chambers, cryostats, etc., the direct and absolute temperature determination is cumbersome and/or requires separate calibration measurements due to external fix-point temperatures, contact voltages, non-linear thermocouples, etc. The broad temperture range (0.5 K < Tc < 125 K) offered by high-Tc superconductors allows creation of a scale of reference temperatures corresponding to the transition temperatures Tc of the superconductors used. Fig. 1 shows a sandwich structure consisting of stacked superconductor films 1...11 (having a thickness of < 10 mm) resting on an insulating substrate 12 of strontium titanate, for example. Diffusion among the various complex materials can be prevented by metal layers separating the superconductor films. Leads 13 and 14 are fixed to the first and last layers of the sandwich structure. An alternative arrangement is shown in Fig. 2 where a string of interconnected pads 15...25 of different superconductor materials is arranged on an insulating substrate 26. Leads 27 and 28 are provided for connection to external measurement equipment. There are two modes of measuring temperature with the arrangements of Figs. 1 and 2: In the first mode, the resistance R is monitored; in the second mode, the changes in magnetic AC susceptibility k are monitored. The second mode has the obvious advantage of enabling contact...