2D COUPLED STRUCTURAL MAGNETIC ANALYSIS OF SSC CQM

The deformation of a Collider Quadrupole Magnet (CQM) coil under pre-c ompression, cool down and Lorentz forces may cause some significant ch anges in magnetic multipoles. The magnetic measurements of the CQM sho rt model magnets at 4.2K showed an average b(5) of -2.866 units compar ed to a numerical prediction of -0.162 units. Out of these -2.866 unit s, -1.5 units are due to a shim placed at the mid-plane to increase co il precompression. We also suspect that the permeability of the stainl ess steel collar may contribute some of the missing b(5). For example, a permeability of 1.004 for the collar adds -0.5 units of b(5). Inclu ding the collar, we are still missing -0.8 to -1.0 units. We believe t hat the mechanical deformation due to pre-compression of the coil is r esponsible for the remaining units. This study builds a 2D magneto-str uctural coupled model, calculates the magnetic multipoles under differ ent loading conditions and establishes a correlation between multipole changes and coil pre-compression and Lorentz force stresses.