Characterization of a Raman-based distributed fiber optical temperature sensor in liquid nitrogen

Abstract

• As an evaluation index, mechanical performance of optical fibers in different packages is tested by experiments, the test results are given and tensile strength and compressive strength of these optical fibers are compared. The reason of strength difference is analyzed and the most reasonable type of optical fiber is given. • As a result of stress loaded on the optical fiber, the optimal loss of the optical fiber with different design parameters and fixation methods in LN 2 is tested and compared. • The cooling temperature measurement experiment of HTS cable is carried out. In this experiment, the temperature measurement value of optical fiber and thermo couple is compared. Discrepancy between these two is largely compensated by calibration using LR fitting method. Distributed Temperature Sensor (DTS) based on Raman scattering have a promising application in temperature monitoring and quench detection of high-temperature superconducting (HTS) fiber optic cable. In this paper, a series of mechanical property tests were carried out on fiber optical cables with different encapsulation materials to select the best material for the engineering environment. This was followed by loss testing of fiber optic cables with different outer diameters under liquid nitrogen (LN 2 ) and the optimal outer diameter to meet measurement accuracy and engineering practicability was determined. Finally, the temperature measurement of fiber optic cables laid on HTS fiber optic cables were calibrated using thermocouple as a reference. The results of this research results provide a suitable fiber optic cable for engineering applications. At the same time, it provides a reference for the selection of optical cable structure parameters in HTS optical cable projects.