Mechanical design and analysis of 2-in-1 shell-type Nb3Sn dipole models for VLHC

Fermilab has begun investigating Nb₃Sn twin aperture dipole magnet designs as a next step towards the realization of high field magnets for a Very Large Hadron Collider (VLHC). The magnet design is based on two-layer shell-type Nb₃Sn coils with 43.5 mm aperture. Two different mechanical designs were investigated, one with “cold” iron yoke and the other with “warm” iron yoke. The former has a vertically split three-piece iron yoke with a cut parallel to a flux line to reduce the transverse magnetic flux. The two outer halves are locked in place by aluminum clamps. Both the clamps and the stainless skin provide the required pre-stress to the coils. The “warm” iron yoke design consists of thick freestanding stainless steel collars with wide keys and an insert separating the two coil blocks. The paper presents both the mechanical design and analysis for the two designs