AN EXPERIMENTAL 11.5-T NB3SN LHC TYPE OF DIPOLE MAGNET

As part of the magnet development program for the LHC an experimental 1 m long 11.5 T single aperture Nb3Sn dipole magnet has been designed and is now under construction. The design is focused on full utilisation of the high current density in the powder tube Nb3Sn. A new field optimisation has led to a different winding layout and cable sizes as compared to the reference LHC design. Another important feature of the design is the implementation of a shrink fit ring collar system. An extensive study of the critical current of the Nb3Sn cables as a function of the transverse stress on the cables shows a permanent degradation by the cabling process of about 20 %, still leaving a safety margin at the operation field of 11.5 T of 15 %. A revised glass/mica glass insulation system is applied which improves the thermal conductivity of the windings as well as the impregnation pro-cess considerably. This paper describes various design and production details of the magnet system as well as component tests.