Superconducting double dipolle high field magnet

Recent progress in Nb3Sn superconductor technology provides the base for increasing magnet field in accelerator magnets up to 15-16 T. The work on such magnets based on both block-type and shell-type coils are in progress at Fermilab, LBNL and elsewhere. One of the novel approaches to the design of this magnet is to split the magnet winding into two separate dipole windings powered in series or separately. Each winding generates a homogeneous magnetic field in the magnet aperture. The paper presents conceptual magnetic and mechanical designs of 15 T double dipole magnets and discusses several scenarios of,magnet powering. The inner dipole winding is based on the 2-layer Nb3Sn coils previously developed and tested at Fermilab. The outer dipole winding is made of sub-sized Nb3Sn cable and has about two times higher current density. Both windings have the shell-type configuration. For the different powering scenarios the results of calculation of the field quality, coil magnetization effects, and the stress analysis are presented.