Calibration of Thermocouples at Low Temperatures
Scientists and engineers have been confronted with the problem of a low cost, accurate thermometer for low temperatures. The thermocouple is one of the most logical answers. However, conventional thermocouples have inadequate sensitivities at 20°K and below. From previous investigations by the Kamerlingh Onnes Laboratories in Leiden, it has been found that dilute alloys of transition metals in Group 1B can have high thermoelectric power near absolute zero and the alloy of gold-2.1 atomic per cent cobalt has been suggested as a practical thermoelement. Consequently, the purpose of this investigation has been to find the sensitivity at temperatures from 4° to 300°K and to study the stability of the thermoelement. An apparatus is required that is capable of maintaining one junction of the thermocouple at a fixed reference temperature (4°, 20°, and 76°K), while allowing the temperature of the other junction to be varied.
KeywordsThermoelectric Power Calibration Apparatus Measuring Block Differential Thermocouple Cent Cobalt
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