| High stability of the superconductor is needed for the practical application ofsuperconducting power technology. The quench propagation characteristic and AC loss are the key factors for the stability and operating cost of the superconducting power device. In this paper, we first make theoretical research of the quench propagation characteristics for YBCO tapes and coil. The mathematical model is established in order to determine the temperature profile by analysing theheat transfer equation, and a velocity calculation formula is developed. Then quench propagation experiments of YBCO tapes and coils are done, we get the voltage and temperature curves at different currents and input energies. And we get the experimental value of the normal zone propagation velocities (NZPV) both in the longitudinal and radical direction. Then we analyse the experimental results.Draw the following conclusion: the input energy of the superconductor tapes and coils hardly affects NZPV. With larger input energy, quench occurs earlier, however NZPV keeps constant. Quench can’t propagate when the transfer current is too small, even if the input energy is large.Then, AC loss calculation models for two different structures of current leads are built. Based on the Clem model, the effects of external magnetic field are taken into account. We establish coordinate system on the cross section of the current leads. By making use of transformation of coordinate translation, coordinate rotation, we get the expression of the magnetic field, and derive the expressions of the penetration curves. In this paper, calculation programs are compiled using Matlab. And visualization images are generated.Finally, the experiments of the three designed projects are carried out based on the improved electrical method. AC losses of two different structures of current leads are measured at different currents and different frequencies. Then we compared and analyzed the theoretical results and measurement data. |
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