Mechanical design and analysis of the Fermilab 11 T Nb3Sn dipole model

The goal of the Fermilab High Field Magnet (HFM) R&D project is to explore various designs and production technology of a high-field, low-cost Nb3Sn a ccelerator magnet suitable for a future Very Large Hadron Collider (VLHC). The model under fabrication consists of two-layer shell-type coil with 43.5 mm aperture and cold iron yoke. Fermilab concept of magnet design and fabr ication technology involves some specific features such as curing of half-c oil with ceramic binder/matrix before reaction, and then simultaneous react ion and impregnation of both half-coils to get a "coil pipe" structure. The coil pipe is mechanically supported by the vertically-split iron yoke lock ed by two aluminum clamps and a thick stainless steel skin, 2D finite eleme nt analysis has been performed to study and optimize the prestress in the c oil and in the structural elements at room temperature and at 4.2 K, Model description, material properties and the results of mechanical analysis are reported in this paper.