Preliminary Study On Quench Detection Of ReBCO Tape Based On Fiber Optic Sensing

With high critical current in high-field situation,High-Temperature Superconducting(HTS)ReBCO is a candidate for superconducting magnets which will be used in next-generation particle accelerators and nuclear fusion devices.Quench detection is the prerequisite for the safe operation of the superconducting magnet system.Due to the characteristics of the quench of HTS such as overheating,and low speed of quench propagation,the magnet voltage detection which is the main method used in low-temperature superconductivity(LTS)cannot detect the quench and locate the quench point.To keep the HTS magnets operating safely.it is of significant importance to research and find a new quench detection technic.In this thesis,two technique,distributed optical fiber sensing(DOFS)based on optical frequency domain reflectometry(OFDR)and fiber Bragg grating sensing are employed to detect the quench of HTS belts by monitoring their temperature.The main work in this thesis includes as follows:1.The quench of ReBCO belt is studied,the quench current is carried our and the temperature change during the quench is analyzed.2.A distributed optical fiber sensing system is built and the experimental results shows that the quench can be detected by measure the temperature of the HTS belts and the quench can be located.3.A fiber Bragg grating(FBG)sensing system is built.A string of FBGs are attached to the HTS belts and by measuring the shifts of the center wavelength of the reflective light of each FBG,the temperature change can be monitored.The results shows that the quench and the quench location can be both well detected.