Development of low-cost MgB2/solid N2 MRI magnets

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DESCRIPTION (provided by applicant): The specific aim of this program is to demonstrate the feasibility and practicality of a low-cost, i.e., commercially viable, superconducting magnetic resonance imaging (MRI) magnet system specifically targeted for use in small hospitals, rural communities, and underdeveloped nations. The MRI system incorporates Magnesium Diboride (MgB2) composite conductor and an innovative cryogenic design/operation concept. We achieve this specific aim by building and operating a 0.5 Tesla (T)/80 cm bore demonstration magnet that, except for its lack of an MRI-grade spatial homogeneity, satisfies key operational requirements of 0.5 T/80 cm MRI magnet systems. We are confident that commercial MRI magnet manufacturers will base their design for such MRI magnets on the demonstration system proposed herein. The demonstration system introduces two important firsts to MRI superconducting magnet technology, both benefiting the operation of the next generation low-cost MRI magnet systems: 1) a trend-setting MgB2 magnet for the next-generation of MRI magnets; and 2) an innovative cryogenic design/operation concept that introduces a volume of solid nitrogen in the magnet housing. The presence of solid nitrogen in the system, maintained by a cryocooler, enhances the magnet's heat capacity enormously, enabling the magnet to maintain its operating field over a limited time period even with its cryocooler shut off as would be in case of a power outage, an event not rare in rural communities and underdeveloped nations. Only during this shut off period, the magnet and the solid nitrogen, otherwise kept at a nominal operating temperature of 10 K by its cryocooler, will warm up to a design limit of 15 K over a period of one day. These specific temperatures and shut off duration are for the proposed demonstration magnet and a full-scale MRI magnet, a reference design of which is included in the application. The significance of this proposed demonstration magnet system is that its successful operation is expected to spur commercial production (and demand) of low-cost MgB2-based MRI systems. The innovative cryogenic design/operation concept coupled to this low-cost magnet enables the MRI system to perform reliably even under working conditions much less reliable than those tacitly assumed for standard MRI systems.