Behaviour and measurements on the interpancakejoints of the B0 ATLAS model coil

摘要

The B0 model coil is a full width, full cross section, onethird length, prototype of the ATLAS Barrel Toroid coils (BTs), whichassembled in a toroidal configuration, will provide the magnetic field forthe ATLAS muon spectrometer. These are racetrack shapedsuperconductive coil, 25m in length, 5m wide based on NbTi Rutherfordcable, extruded in a pure Al cladding; the conductor is wound in doublepancakes and two double pancakes assembled in a single Al alloy casingform one BT coil. Each double pancake contains one welded, resistiveinterpancake joint. Transverse field change produces eddy currents in theinterpancake joint and its length and location needed specialconsideration, not to pose undue limitations on the BT operation. The B0coil, built to validate the BT design, has been tested at CERN, reproducingthe working conditions of the final BT coils and was also instrumented,by mean of voltage taps and Hall probes, to measure eddy currents at theinterpancake joints.