Structure for an LHC 90 mm Nb3Sn quadrupole magnet

A full-scale mechanical model of the LHC Nb₃Sn quadrupole magnet structure has been designed, built and tested. The structure will support a 90 mm bore, lm long magnet prototype as part of the US LHC Accelerator Research Program (LARP). The structure utilizes Bladder and Key Technology to control and transfer pre-stress from an outer aluminum shell to an inner coil. Axial aluminum rods take care of pre-stress at the ends-ensuring that the coil is fully constrained along all three axes. The outer aluminum shell and an inner "dummy coil" (aluminum tube) were extensively instrumented with strain gauges. The gauges were used to monitor and map the effectiveness of the stress relation between the loading structure and a "dummy" coil through varying mechanical load conditions-from bladder and key pre-stress at room temperature through cool-down. Test results of the stress distribution in the structure and the in dummy coil is reported and compared with expected results calculated with the structural analysis program ANSYS.