AC Loss And Electromagnetic-Thermal-Force Coupling Analysis Of High-Temperature Superconducting Materials

With high critical temperature,high critical current density and excellent mechanical properties,REBCO high-temperature superconducting materials have been widely used in many fields such as biomedicine,electric power transportation,aerospace,etc.,which have greatly opened up the application prospects of high-temperature superconducting materials.However,superconducting materials are subject to strong mechanical loads and electromagnetic forces when operating in complex environments such as extremely low temperatures,strong magnetic fields,and high currents,which can lead to deformation of superconducting materials and thus reduce their critical current densities,which can severely damage the uniformity and stability of magnetic fields and affect the application of high-temperature superconducting magnets in superconducting devices.Therefore,it is important to study the mechanical behavior and critical performance of superconducting materials under electromagnetic-thermal-force multiphysics fields for the safe and stable operation of superconducting devices.Firstly,a brief description of the finite element software COMSOL is given,followed by the numerical calculation model by COMSOL,and then the electromagnetic characteristics and AC losses of REBCO HTS stacked strips are investigated based on the H-method,and the effects of different n values,different frequencies,different current amplitudes and different ambient temperatures on the AC losses of superconducting strips are quantitatively analyzed.Then,the captured magnetic field,temperature and stress distribution of the high-temperature superconducting cylinder under the action of the pulsed magnetic field are investigated by combining the superconducting electromagnetic field equation and the heat conduction equation,and compared with the captured magnetic field and temperature of the superconductor at a pulse time of 0.01 s.The distributions of thermal and total stresses in the superconducting cylinder are also obtained,and the radial and circumferential stresses at different moments and positions are analyzed,focusing on the contribution of thermal stresses to the radial stresses.Finally,the anisotropic homogenization technique is introduced to equate REBCO HTS coils,and a two-dimensional axisymmetric equivalence model is established based on the T-A method,which solves the modeling and simulation problems of large coils.The optimized model is widely applied to the electromagnetic analysis and AC loss calculation of large high-temperature superconductors.In addition,the magnetic field attenuation caused by shielding current of HTS magnets is numerically analyzed,and the electromagnetic field,AC losses,and the distribution characteristics of Lorentz force of superconducting coils with(without)shielding current case are studied respectively,and some discussions on the performance characteristics of the generated central magnetic field are made to reveal the influence of shielding current on the central magnetic field and critical current density of coils.