Monohelix research at the MIT Magnet Lab

A discussion is presented of the radially-cooled monohelix to support the high stress and power densities within the highest-field magnets at Francis Bitter National Magnet Laboratory. The design employs a continuous machined helical conductor (to eliminate the radial slits which weaken the Bitter design) whose helical winding is built up from annular plates. The first monohelix is the inner of two coils which constitute the water-cooled insert of a hybrid system of 53-mm bore. The system generates 27.1 T. The coil experiences average hoop stresses up to 370 MPa, and heat fluxes up to 7.2 W/mm² in passages only 0.25-mm deep.