Conical Insert Design for the HZB Series-Connected Hybrid

The National High Magnetic Field Laboratory (NHMFL) is designing series-connected hybrid magnets for the Helmholtz Center Berlin (HZB). The hybrid has a horizontal, conical warm bore with a 30 degree opening angle for neutron scattering experiments. The resistive insert includes two coils. The outer coil is a regular bitter coil, while the inner one has a varied inner radius to meet the requirement of large opening angle. Such technology as in the inner coil was developed in the NHMFL, and called Florida conical bitter technology. The conical configuration makes the cooling hole length varied with radius causing unique hydraulic design challenge. This paper presents the detail design features of the conical insert along with many analysis results.