Fractal study of the fluctuation characteristic in the calibration of the cryogenic thermocouples Original Research Article

The accuracy of the temperature measurement depends strongly on the accuracy of the temperature sensor. The commonly used cryogenic thermocouples are calibrated by using a specially designed calibration system. The calibration is performed in the temperature range of from liquid nitrogen temperature (about 77 K) to the room temperature (300 K). The calibration results show that the accuracy is around several tens of mK, which meets the requirement of the experiments. However, it is found that the temperature fluctuation of the thermocouple is quite larger even if the temperature is well controlled, which indicates that the non-linear aspect characteristic plays a certain role in the calibration. The temperature fluctuation of the calibration process is analyzed by using the non-linear analysis method.