A bulk MgB2 magnet demonstrator for biomedical applications

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Bulk superconductors are dense pellets of superconducting material that can be used as compact permanent magnets. Harnessing the ability of these materials to produce considerably higher magnetic fields than conventional ferromagnets will be transformative for a wide range of devices for biomedical and energy applications. These materials have the added safety benefit that the magnetic field can be switched off. However, their enormous potential has yet to be realised in commercial devices for a number of reasons. High temperature superconducting bulk materials, such as YBCO, have the ability to produce very high fields, but they are expensive to produce, cannot be made with large diameter and suffer from relatively poor sample-to-sample reproducibility. Lower temperature superconductors like magnesium diboride (MgB2) are much cheaper and easier to process, but they require expensive and bulky cooling systems. Furthermore, all bulk samples present the additional challenge that they initially need to be magnetised using an external field.This project involves designing and building a desktop sized magnet to demonstrate that these challenges can be overcome in practical devices by integrating state-of-the-art cryogenics and pulsed magnetisation systems with high performance, low-cost MgB2 superconductor. A bespoke cryostat will be developed by our team at the Rutherford Appleton Laboratory, who are experts in compact and efficient cryocoolers for space applications and coils will be incorporated into the cryostat, enabling the bulk superconductor to be magnetised in situ. The nano-scale structure of the MgB2 material will be optimised for operation at higher temperatures using a novel powder processing strategy, and large, high density samples will be manufactured using the commercial diamond presses at Element Six. Preliminary experiments will be carried out using the demonstrator magnet, to assess the feasibility of using this technology for magnetically targeted drug delivery, with collaborators at the Institute of Biomedical Engineering in Oxford. More complex shapes of superconductor will be explored, with a view towards developing more sophisticated devices for selected applications such as MRI in future projects.