A theoretical model is proposed to calculate the internal contact distributions and contact forces of a 3×4×4×4 twisted NbSn cable under applied axial strain.The critical current density reduction of th...A theoretical model is proposed to calculate the internal contact distributions and contact forces of a 3×4×4×4 twisted NbSn cable under applied axial strain.The critical current density reduction of the whole cable can be calculated.The thin rod theory is employed to analyze the mechanical behavior of each strand.According to the regular helical structure,the contact distribution of each strand is obtained,and the contact force in the cable is analyzed.At last,a prediction about the critical current density of the twisted cable is made.The results show that decreasing the pitch length can reduce the contact forces between strands.展开更多
When type-II superconductors are in external magnetic field,the magnetic flux would penetrate the superconductors in the form of flux vortex[1].If the superconductor is subjected to a local thermal disturbance,this ma...When type-II superconductors are in external magnetic field,the magnetic flux would penetrate the superconductors in the form of flux vortex[1].If the superconductor is subjected to a local thermal disturbance,this may trigger a surge of flux vortices into the superconductor.展开更多
Flux avalanches,prevalently existing in superconducting thin films,can cause catastrophic breakdowns of electromagnetic properties and even irreversible damage to superconducting materials.Metal coating is an effectiv...Flux avalanches,prevalently existing in superconducting thin films,can cause catastrophic breakdowns of electromagnetic properties and even irreversible damage to superconducting materials.Metal coating is an effective way to suppress the flux avalanches in superconducting thin films.Nevertheless,it is difficult to reveal the suppression mechanisms due to the challenge of effectively separating the simultaneous eddy currents and heat exchange in the metal coating.In this work,the eddy currents and heat exchange in the Ag metal coating are separated by setting a thermal insulation layer,and its inhibiting effect on the flux avalanches of the YBCO superconducting thin films is elucidated.The results indicate that eddy currents play an important part in suppressing magnetic flux avalanches,and their effect strengthens with increasing Ag thickness.Meanwhile,employing the double-exposure method,the flux avalanche velocity of YBCO superconducting thin films was measured,revealing a significant decrease in the magnetic flux avalanche velocity due to suppression by eddy currents.Moreover,a theoretical model was established to investigate the influence of eddy currents on the motion of a single vortex,and the calculated results showed good agreement with the experiments.These findings provide a better understanding of the flux avalanches and their suppression in YBCO superconducting thin films.展开更多
基金Project supported by the National Natural Science Foundation of China(Nos.11202087,11472120 and 11421062)the National Key Project of Magneto-Constrained Fusion Energy Development Program(No.2013GB110002)+1 种基金the National Key Project of Scientific Instrument and Equipment Development(No.11327802)New Century Excellent Talents in University of Ministry of Education of China(NCET-13-0266)
文摘A theoretical model is proposed to calculate the internal contact distributions and contact forces of a 3×4×4×4 twisted NbSn cable under applied axial strain.The critical current density reduction of the whole cable can be calculated.The thin rod theory is employed to analyze the mechanical behavior of each strand.According to the regular helical structure,the contact distribution of each strand is obtained,and the contact force in the cable is analyzed.At last,a prediction about the critical current density of the twisted cable is made.The results show that decreasing the pitch length can reduce the contact forces between strands.
基金the National Natural Science Foundation of China(Grant Nos.11602185,11972271,and 12322208)the Young Elite Scientists Sponsorship Program by CAST(Grant No.2020QNRC001)the Fundamental Research Funds for the Central Universities.
基金supported by the National Natural Science Foundation of China(Grant Nos.11327802,11472120,11421062,and 11602185)the 111Project(Grant No.B14044)Fundamental Research Funds for the Central Universities(Grant Nos.lzujbky-2017-k18,and lzujbky-2017-it63)
文摘When type-II superconductors are in external magnetic field,the magnetic flux would penetrate the superconductors in the form of flux vortex[1].If the superconductor is subjected to a local thermal disturbance,this may trigger a surge of flux vortices into the superconductor.
基金National Natural Science Foundation of China(No.12325205,No.12232005,U2241267,12272155)Major Scientific and Technological Special Project of Gansu Province(23ZDKA0009)Natural Science Foundation of Gansu Province of China(No.23JRRA1118).
文摘Flux avalanches,prevalently existing in superconducting thin films,can cause catastrophic breakdowns of electromagnetic properties and even irreversible damage to superconducting materials.Metal coating is an effective way to suppress the flux avalanches in superconducting thin films.Nevertheless,it is difficult to reveal the suppression mechanisms due to the challenge of effectively separating the simultaneous eddy currents and heat exchange in the metal coating.In this work,the eddy currents and heat exchange in the Ag metal coating are separated by setting a thermal insulation layer,and its inhibiting effect on the flux avalanches of the YBCO superconducting thin films is elucidated.The results indicate that eddy currents play an important part in suppressing magnetic flux avalanches,and their effect strengthens with increasing Ag thickness.Meanwhile,employing the double-exposure method,the flux avalanche velocity of YBCO superconducting thin films was measured,revealing a significant decrease in the magnetic flux avalanche velocity due to suppression by eddy currents.Moreover,a theoretical model was established to investigate the influence of eddy currents on the motion of a single vortex,and the calculated results showed good agreement with the experiments.These findings provide a better understanding of the flux avalanches and their suppression in YBCO superconducting thin films.
