Study On The Thermal Stability Of Superconducting Magnet Based On REBCO Coated Conductor Annular Plates

Due to its advantages of low power consumption,small volume,light weight and high stability,superconducting magnets have been widely used in the fields of scientific research,industry and medicine and so on.Low temperature superconductor(LTS)has high n value,and soldering technology between the LTS is mature,which has the smaller joint resistance(<10*12?).So the LTS magnet can realize persistent current mode(closed-loop operation).High temperature superconductor(HTS)also has high n value.However,the soldering technology of HTS is not yet mature.The joint resistant between HTS is not enough small,which can not reach the requirements of persistent current mode.So at present the HTS magnet can not realize persistent current mode.In addition,the superconducting magnet needs the current lead to connect with the external power supply during operation,which increases heat leakage of the system and reduces cooling efficiency and stability of the magnetic field.On the basis of fully understanding the existing problems of HTS magnets,this paper presented an HTS magnet based on REBCO coated conductor annular plates.The magnet was alternately stacked by annular REBCO coated conductor annular plates and insulation plates,which was excited by flux pump without current leads and persistent power supply.The REBCO annular plate formed a closed path,allowing the current to flow without resistance,which can realize persistent current mode of HTS magnet.The geometry of REBCO annular plate magnet was introduced and the principle and structure of flux pump was presented.A pulse power used for excitation was designed and manufactured.Then a small REBCO annular plate magnet was fabricated.And an external excitation experiment was conducted to verify the feasibility of persistent current mode for this type HTS magnet.It was proved that the REBCO annular plate magnet can realize the persistent current mode using the excitation method of flux pump.On the basis of experimentally verifying the feasibility of the persistent current mode of the HTS magnet based on REBCO coated conductor annular plates,a 1.5 T practical REBCO annular plate magnet operated at temperature 65 K was designed and the thermal stability of the magnet after excitation was simulated,which included the minimum quench energy(MQE)and the quench propagation velocity(QPV)in adiabatic condition and non-adiabatic condition.The self-inductance and mutual-inductance of REBCO annular plates in this magnet were simulated.And the stored energy in REBCO annular plate was calculated by the results of inductance.By analyzing the temperature distribution in REBCO annular plate magnet when stored energy of REBCO annular plate is fully released,it is proved that the 1.5 T REBCO annular plates HTS magnet has the function of self-protection.