Experimental investigation of methods to improve the field gradient produced by a superconducting Halbach array

Abstract

This Master’s thesis investigates the enhancement of magnetic field gradients using superconducting Halbach arrays, with the ultimate aim of improving applications such as magnetic drug targeting. While Halbach arrays made of permanent magnets offer enhanced magnetic fields compared to single magnets, their performance is fundamentally limited by magnetic saturation. To overcome this, the study explores the use of bulk high-temperature superconductors (HTS), which can trap significantly stronger magnetic fields. Two novel configurations are experimentally tested: the elevated Halbach array, designed to reduce central demagnetisation, and the five-superconductor Halbach array, aimed at increasing the field gradient despite expected demagnetisation. Theoretical models based on electromagnetism and Biot-Savart's law are developed and adjusted to account for defects within superconducting samples. Comparisons between experimental measurements and simulations reveal the influence of demagnetisation, sample geometry, and material defects on the magnetic field profile. The results confirm that superconducting Halbach arrays can generate higher magnetic gradients than their permanent magnet counterparts. These findings open perspectives for designing more efficient magnetic assemblies in medical and engineering applications, with future work suggested on optimising sample alignment and geometry.