Development Of A Testing Device About R_S Distribution In High Temperature Superconducting Thin Film

High temperature superconducting thin film with small surface resistance in microwave frequency range is widely used in the microwave passive devices. But there is also a problem that the resolution is generally not compatible with the test device for the measurement of microwave surface resistance distribution of high temperature superconducting thin film. Therefore, it is urgent to establish a distributed test device which can solve the above problem.In this paper, a new distributed testing device with high resolution at low frequency is built based on the theory of mirror image method to test the resistance of high temperature superconducting thin film. Works are completed as follows:1. A new model of measuring the resistance of superconducting thin film is carried out based on the theory of measuring the resistance of superconducting thin film.2. The device is simulated and optimized using the simulation software to realize the design of the distributed the test device which has high resolution and sensitivity. Meanwhile, the coupling device is designed to achieve a higher resolution when the test device is in the medium coupling.3. A new test device which ensures the structure symmetry between test chamber and calibration cavity is used to obtain high calibration accuracy. At the same time, the pin tight fitting manner is introduced to ensure the installation of coaxial symmetric distribution. In order to accurately obtain the resistance of the metal plate, so as to guarantee the accurate calibration of test devices, the working chamber in the same frequency gold cavity is designed and tested, then simulated by simulation software to design coupling structure and optimize the gold cavity structure.4. The distributed test device is built and tested to verified the feasibility of the new method for measuring the distribution of the surface resistance of high temperature superconducting thin film. The resonate frequency of the new distributed test device is about 32 GHz, where the precision is about 5mm for diameter and 19.6mm2 for area. In addition, there is no other vibration mode interference with the operating frequency in the 1.4GHz range.5. A two-inches superconducting films’ 25 points is tested using the distribution test device to obtain the resistance distribution. Finally, the distributed test device is tested by 15 times to verify the stability. Where, the uncertainty is only 5.2%, which is far below the national standard that should below 20%.