Comparison of Halbach arrays made of superconductors and permanent magnets

Due to their high trapped field capability, Halbach arrays containing permanently magnetized superconductors offer significant potential for generating large magnetic field gradients compared to traditional Halbach arrays using permanent magnets. In order to use superconductors efficiently, the main challenge is to reduce the partial demagnetization occurring in the central superconductor when the lateral samples are approaching. In this work, three new configurations of Halbach arrays are studied experimentally and using semi-analytical modelling. The first two configurations are assembled to prevent demagnetization: (a) an elevated Halbach array, in which the lateral superconductors are vertically offset and (b) a hybrid Halbach array combining a permanent magnet at the centre with two superconductors on the lateral sides. In addition, we investigate a configuration involving five superconductors (c). Modelling is used to determine which configuration performs best among permanent magnets, superconducting magnets or hybrid Halbach array, considering variation in either the size of the samples or the current density in the superconductors.