Conceptual Design for a Next Generation Resistive Large Bore Magnet at the NHMFL

The National High Magnetic Field Laboratory (NHMFL) has successfully operated its 20 Tesla 195 mm large bore magnet for over 20 years. Eventually, as there was a certain slowdown in demand for that magnet at the time, it had been decommissioned in 2016 and its two outer coils have been re-used for parts in a higher energy density configuration to facilitate the fast construction of the world record 41.5 Tesla 32 mm bore resistive magnet. Without any resistive large bore magnet providing fields in the 20 Telsa range available for the last two years, the demand or desire for such a facility has been steadily rising at our laboratory. Again, cost and schedule for the construction of such a magnet are very critical aspects under consideration. One elegant solution to keep these factors most manageable is to not design a new stand-alone magnet but to design one or a set of insert coils that is interchangeable with a smaller bore existing magnet at the NHMFL. Different alternative configurations for such a large bore resistive insert including two different existing magnets to serve as the outsert as well as different usable bore sizes have been considered on a preliminary level of detail for comparison only. Eventually, a more detailed conceptual design has been developed for a chosen magnet system. In this paper, the authors present a summary of the different alternative considerations as well as an introduction to the conceptual design of a next generation 195 mm Large Bore Magnet capable to produce well above 20 Tesla.