Study On MgB₂ Supperconducting Receiving Coil

Receiving coil whose quality factor is the key of the MRI image is one of the important parts in MRI system. Currently the resistance itself is the only issue which limits the copper coil quality with the optimized coil shape after these years development. As we know the current transfer loss in superconducting coil is much less than in copper coil that is to say superconducting coil can make quality factor increase.In this study, the MgB2 superconducting coil quality factor is measured in G-M environment by designing the cryostat system for cooling down. We have done the theory analysis,experiments,simulation research. The test system has been established based on G-M refrigerator, frequency sweeper and LabVIEW software. The sample temperature signals have been measured by a combined system which is made up of the temperature data acquisition circuit with sigle chip machine, PCI card and the control circuit with LabVIEW software. In order to make sure G-M refrigerator can cool down the sample below the critical temperature and keep all parts of the MgB2 superconducting coil in the same temperature, we have made a cryostat for the sample. The quality of the superconducting coil has been measured and compared with the copper coil with the same geometry. We also got the curve of quality factor changed with temperature.In addition, by establishing suitable analytical model, the quality factors of superconducting coil and copper coil have been simulated through the Ansoft HFSS 10.0 software and the results were coincident with measured results.The results also indicated that the solder resistance impacted the performance of the circuit very much.According to the theory analysis and experiment results, the quality factor of superconducting coil has a big increase compared to copper coil. This study gives the theory and experiment foundation of the future research about superconducting coil quality increase.