Thermal Resistances of Mounted Cryogenic Temperature Sensors
Operation of most temperature sensors requires the dissipation of power in the sensor. The flow of the heat generated by the measurement creates a temperature difference and a potential temperature measurement error. The self-heating temperature difference is directly proportional to the thermal resistance. A procedure for measuring the thermal resistance of a mounted temperature sensor is described.
Thermal resistances were measured at cryogenic temperatures (50 mK to 10 K) on several commercially available temperature sensors. The sensors were mounted to a copper block in either a vacuum, helium gas or helium liquid environment. The thermal resistance was found to depend on temperature, thermal environment and details of sensor mounting and packaging.
Minimization of the temperature measurement uncertainty requires a balance between the uncertainties due to self-heating and measurement of the output signal. Equations are provided for calculating the operating point for minimum combined temperature measurement uncertainty.
KeywordsThermal Resistance Temperature Sensor Power Dissipation Cryogenic Temperature Sensor Power
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