Mtg HT_c Ybco Microwave Surface Resistance Research

After the discovery of the high-temperature superconducting materials, researchers have been trying various methods to increase the conversion temperature as well as to improve the mechanical and electromagnetic characteristics of the superconducting materials, so that requirements in different applications can be fulfilled. Wires, microstrip lines, membrane resonators made from superconductors have already been commercialized. However, since it is still very difficult to manufacture superconductors with large diameter or bulk as well as high performance and homogeneity, studies of microwave resonators using bulk superconductors are still rare, and the progress is very slow.la this thesis, I presented the physical basis and the superconducting properties of the high-temperature superconductors, including the zero resistance phenomenon, the Meissner effect and the critical parameters; and introduced the related theories. Furthermore, I performed the theoretical analysis of the surface resistance of the high-temperature superconductors for microwave propagation. According to the experimental requirements, I calculated theoretically the parameters for the design of the resonators of the TE011 mode, developed the microwave resonator using oxygen free copper, performed the surface process and machining analysis of the single domain YBCO high-temperature superconductor, and set up the low temperature testing system for the resonator. In addition, I effectively measured the figure of merit of the column resonator whose copper cavity and the end plane were replaced with single domain YBCO material, and calculated theoretically the surface resistance of the high temperature superconductor. Finally, I analyzed the surface resistance and the theoretical figure of merit for the resonators whose whole cavity uses YBCO bulk material. I also analyzed the error of the experiment.