The Design And Research Of The Bi-2223Superconducting Coil

As the basics and core of the electric power applications of superconducting materials, superconducting magnet is becoming of the most mature field of the application of superconducting materials, which is widely used in many fields. Superconducting magnet has attracted more and more interests for the obvious advantages compared to conventional magnets.Bi series high temperature superconductor has become the best material as the high field superconducting magnet inserted coil due to its excellent current carrying capacity in high magnetic field at liquid helium temperature region. Besides, Bi series high temperature superconductor can be used for making the magnet which is only made of high temperature superconducting materials because of its excellent critical current density in the range of the refrigerator temperature.The paper studied designing and manufacturing of Bi-2223superconducting coil. First of all, the calculation formula of coil magnetic field was acquired according to the basic theory of electromagnetic field. Based on the calculation formula, the optimal parameters of magnet by the genetic algorithm were designed and VB program which was used for calculating the coil magnetic field distribution was compiled. The paper introduced the basic knowledge of the finite element method, ANSYS software that was used for the finite element analysis and the analysis process of the coil magnetic field using ANSYS finite element method. The distribution situation of magnetic field around the coil and the homogeneous field range, and the uniformity of the homogeneous field were obtained.Secondly, critical current properties of Bi-2223strip used for winding coil were tested. The results suggested that the critical current of the short sample in77K was67A. The effect of bending strain on the critical current of the strip was obtained through the critical current tests of the strip at different bending radius. Different current joints were made through different welding methods. Optimal welding method was obtained by comparing the resistance of the joints. The problems of the manual winding method and coil insulation were researched. The Bi-2223superconducting coil winding was manufactured successfully.Finally, test method of the magnetic field of the coil in liquid nitrogen temperature zones was researched. Measurement system of the magnetic field which uses single-chip and Hall sensor as the core was designed. The distribution situation of the magnetic field in the coil bore diameter was measured; the homogeneous degree of the homogeneous area was calculated. On the basis of the above results, compared to calculation value with VB program and finite element analysis value of ANSYS, the accuracy of the three values was proved.