The high-temperature superconducting(HTS)bulk has a higher critical current density and can trap the larger magnetic field.When the high-temperature superconducting bulk is magnetized by the pulsed-field,it will be su...The high-temperature superconducting(HTS)bulk has a higher critical current density and can trap the larger magnetic field.When the high-temperature superconducting bulk is magnetized by the pulsed-field,it will be subjected to electromagnetic stress and thermal stress.Furthermore,the bulk may be damaged under larger mechanical stress or strain during the pulsed-field magnetization.In this paper,the electromagnetic field,the temperature and the mechanical response of the ring-shaped bulk are simulated based on the electromagnetic and mechanical governing equations,and the simulated trapped field is consistent with the experimental results given in the reference.The stress distribution on the top surface of the ring-shaped bulk during pulsedfield magnetization is opposite to the case of field cold magnetization.Moreover,the inner edge on the middle plane of the bulk may be broken more easily than the outer edge during the pulsed-field magnetization.Afterward,the influences of the size of the inner radius,ambient temperature and rise time of the applied field are presented.Finally,the mechanical stress of the bulk with the cooling process is investigated,and the tensile stress on the surface can be enhanced by the cooling process.展开更多
The layer-wound coil has a great potential in nuclear magnetic resonance and magnetic resonance imaging owing to the better spatial homogeneity of the magnetic field.However,high-temperature superconducting(HTS)coil w...The layer-wound coil has a great potential in nuclear magnetic resonance and magnetic resonance imaging owing to the better spatial homogeneity of the magnetic field.However,high-temperature superconducting(HTS)coil wound by no-insulation(NI)layer-wound technique has been verified with a long field delay time.A new method named the intra-layer no-insulation(LNI)winding technique has been proposed to reduce the charging delay time of the coil.This paper is mainly to study and compare the ramping loss and mechanical characteristics of the layer-wound coil and LNI coil.The results indicate that the total ramping loss can be significantly reduced by using the LNI winding method.The effects of the ramping rate of power supply current and the contact resistivity on the ramping loss are also discussed in the paper.Furthermore,the stress distributions in the layer-wound coil and LNI coil are compared,where the cooling process and Lorentz force are both considered.It can be found that the copper sheet of the LNI coil experiences relatively higher stress than its(RE)Ba;Cu;O;(REBCO)conductor layer.Meanwhile,the magnitude of stress generated in the REBCO conductor of the LNI coil is slightly different from that of the layer-wound coil.展开更多
基金supported by the National Natural Science Foundation of China (Grant No.11872195)。
文摘The high-temperature superconducting(HTS)bulk has a higher critical current density and can trap the larger magnetic field.When the high-temperature superconducting bulk is magnetized by the pulsed-field,it will be subjected to electromagnetic stress and thermal stress.Furthermore,the bulk may be damaged under larger mechanical stress or strain during the pulsed-field magnetization.In this paper,the electromagnetic field,the temperature and the mechanical response of the ring-shaped bulk are simulated based on the electromagnetic and mechanical governing equations,and the simulated trapped field is consistent with the experimental results given in the reference.The stress distribution on the top surface of the ring-shaped bulk during pulsedfield magnetization is opposite to the case of field cold magnetization.Moreover,the inner edge on the middle plane of the bulk may be broken more easily than the outer edge during the pulsed-field magnetization.Afterward,the influences of the size of the inner radius,ambient temperature and rise time of the applied field are presented.Finally,the mechanical stress of the bulk with the cooling process is investigated,and the tensile stress on the surface can be enhanced by the cooling process.
基金supported by the National Natural Science Foundation of China(Grant Nos.11872195,11472120)the Fundamental Research Funds for the Central Universities(Grant No.lzujbky-2020-1)。
文摘The layer-wound coil has a great potential in nuclear magnetic resonance and magnetic resonance imaging owing to the better spatial homogeneity of the magnetic field.However,high-temperature superconducting(HTS)coil wound by no-insulation(NI)layer-wound technique has been verified with a long field delay time.A new method named the intra-layer no-insulation(LNI)winding technique has been proposed to reduce the charging delay time of the coil.This paper is mainly to study and compare the ramping loss and mechanical characteristics of the layer-wound coil and LNI coil.The results indicate that the total ramping loss can be significantly reduced by using the LNI winding method.The effects of the ramping rate of power supply current and the contact resistivity on the ramping loss are also discussed in the paper.Furthermore,the stress distributions in the layer-wound coil and LNI coil are compared,where the cooling process and Lorentz force are both considered.It can be found that the copper sheet of the LNI coil experiences relatively higher stress than its(RE)Ba;Cu;O;(REBCO)conductor layer.Meanwhile,the magnitude of stress generated in the REBCO conductor of the LNI coil is slightly different from that of the layer-wound coil.
