A design of high-power water-cooled magnet suitable for hybrid magnet

A hybrid magnet project is now being pushed forward at Tohoku University, where 3.5 MW Bitter magnets have been operated since 1959. A new Bitter coil with a smaller outer diameter has been prepared for the first hybrid magnet of 20 T with a conservative design. In order to exceed 30 T, however, the second magnet is designed on the basis of detailed optimization calculations. Polyhelix-type coils are simulated by a ´continuum´ to perform analytical calculations. Both optimum coil shape and optimum current distribution are determined by taking thermal and mechanical limitations into account.