Superconducting Material Electromagnetic Performance Testing System Development And Preliminary Application

The thesis introduces the test syetem of the critical temperature T_c of superconductor using resistance method and the test system of the AC magnetic susceptibility of the high tempereture superconductor. The magnetic capability of C,Ti and C doped with Ti- MgB₂ has been measured, the changements of their critical current density,upper critical magnetic field and irreversible field and their flux pinning properties have been analyzed by the numbers.At first the fundamental properties of the advanced programming language-Visual Basic 6.0 are introduced in the thesis, also the principles and requirements to design the interface by using it are discussed, the essential bus knowledge in the dynamic test is elucidated, the respective characteristics and advantages of the buses like GPIB,USB,PCI,and RS-232 are analyzed and the suitable bus has been chosen according to our factual experiment.The basical method to measure the critical temperature of the superconductor is introduced in succession, and compares their advantages and disadvantages respectively, in view of the factual experimental condition, and then choose the resistance method to measure and introduce its experiment circuitry and devices and the method and steps of testing particularly, and eliminate the influence of look genuine electromotive force using the positive -negtive alternating,constant,high precision output current based on the experimental operation program with VB, consequently the measure precision has been improved. An application example is introduced, which is "High Temperature Superconductive Demonstration System" sponsored by College of Science of Southwest jiaotong University. Then the thesis analyzes the basical method and principles of measuring the AC magnetic susceptibility of high temperature superconductor and compares one with another, points out the problems in the measure method. In factual method the magnetic one is adopted and introduces its experiment circuitry and devices,the measure method and steps and the experiment operation procedure.Finally, with the result of magnetism measure of C,Ti and C doped with Ti- MgB₂, the thesis analyzes the changements of their critical current density,upper critical magnetic field and irreversible field and analyzes the flux pinning properties of C,Ti and C doped with Ti- MgB₂, Emphasizes the research of the AC magnetic susceptibility of MgB₂ block. From the experiment datum, we can conclude that the pinning of the MgB₂ in the high field has been improved prominently by doping with C and Ti.