Design and test of a flat-top magnetic field system driven by capacitor banks

Abstract

An innovative method for generating a flat-top pulsed magnetic field by means of capacitor banks is developed at the Wuhan National High Magnetic Field Center (WHMFC). The system consists of two capacitor banks as they are normally used to generate a pulsed field. The two discharge circuits (the magnet circuit and the auxiliary circuit) are coupled by a pulse transformer such that the electromotive force (EMF) induced via the transformer in the magnet circuit containing the magnet coil is opposed to the EMF of the capacitor bank. At a certain point before the current pulse in the coil reaches its peak, the auxiliary circuit is triggered. With optimized parameters for charging voltage and trigger delay, the current in the magnet circuit can be approximately kept constant to obtain a flat-top. A prototype was developed at the WHMFC; the magnet circuit was energized by seven 1 MJ (3.2 mF/25 kV) capacitor modules and the auxiliary circuit by four 1 MJ modules. Fields up to 41 T with 6 ms flat-top have been obtained with a conventional user magnet used at the WHMFC.

Development of material based on nanostructured Cu-Nb alloy for high magnetic field coils of microsecond duration

“…Nanostructure is usually created from Cu-Nb alloy by the process of accumulative drawing and bundling (ADB) [8,9]. Using nanostructured Cu-Nb wires lots of multiturn and/or multilayered inductor systems has been created for generating magnetic fields up to 75 T in subsecond range of duration [10][11][12][13][14]. The thermo-mechanical stresses can be decreased in such systems by increasing the number of turns which will lead to decreasing of current density in each one.…”