Examination of an influence of winding geometry and operating temperature on basic parameters of superconducting coils made of MgB2 wire – Theoretical analysis

Abstract

Development and consecutive improvement of the properties of superconductor such as MgB2 raise the natural question about its potential with respect to application in magnets. A magnet designer is confronted with the question what quantitative values of the basic parameters of coils such as critical current, central field and stored energy can be expected at various operating temperature. In fact, the overall wire length can be considered as one of the key factors which determines the final price of the magnet. Therefore, a simple mathematical model was developed, and a detailed theoretical analysis of the influence of the winding geometry on the parameters of the cylindrical coils was performed with respect to the constant wire length. As an example the experimental data of the 30 filament MgB2 wire which was developed at the Department of Superconductor Physics, Institute of Electrical Engineering, Slovak Academy of Sciences, were used in calculations at operating temperatures between 4.2 and 20K. An influence of the inner winding diameter and overall wire length on the values of the coils’ critical current, central field and stored energy, was studied theoretically with the aim to specify the significance of respective parameters. An optimization of the winding geometry was performed with respect to achieving the maximum central field.