PULSED-FIELD COILS WITH OPTIMIZED CURRENT-DENSITY DISTRIBUTION

Analytical and numerical solutions for the radial distribution of the current density in coils with constant stress throughout the layers are developed to discuss the design of pulsed magnets approaching the 100 T level. The results focus on the pulse duration which is shown to depend critically on the peaks in the current distribution at the inner and outer surfaces. The trade-off between cutting off these peaks and the peak field, wire strength, coil size and energy are determined. For large coils, the axial stresses result in a substantial increase in the total stress. This effect is included in the calculation of the current density distribution. Design principles and limitations are illustrated with a practical example.