Studies of the static field homogeneity artefacts induced by the diamagnetism of HTS coils and solution to avoid them

High-Temperature Superconducting (HTS) radiofrequency coils can improve sensitivity by more than an order of magnitude, but their propensity to warp the magnetic field as a result superconducting diamagnetism could cause image degradation. We report on the observation of these B₀ artefacts. They are shown to be predominant at lower working temperatures of the HTS coil (60 K) and negligible at 80 K and can be avoided altogether by cooling the HTS coil in B₀. We also propose a phenomenological model of these field perturbations. This work studies and solves an important issue in the integration of HTS coil in MRI.