The ability of permanent ferromagnets to resist (or survive) attacks on their permanent field orientations is related to their intrinsic coercivity Hci. In gene

The ability of permanent ferromagnets to resist (or survive) attacks on their permanent field orientations is related to their intrinsic coercivity Hci. In general, rare earth magnets are much more resistant, however, radiation, excessive heat, serious EM pulses, extreme magnetic field pressure as in this case, will degrade magnets. The degree of symmetry is relevant, as highly asymmetrical designs are much less resistant to magnetic field pressure such as in the case of Halbach arrays. I have constructed several Halbach arrays from N35 Neo magnets purchased from K&J magnetics 10 years ago that have lost approx 50% of their force compared to when newly built. Magnet manufacturers can produce a custom run of a high, extremely high, or even ultra high Hci magnets for a price. In past times this was done by increasing expensive dysprosium content, but now there are multiple ways, and I would suggest the Japanese lead in these efforts. I believe Ames Labs patented a form of nitrogen doped carbon which has an Hci that is rather astounding, but to date it is not a stable product.