Quench Characteristics of the ATLAS Central Solenoid

A thin superconducting solenoid has been constructed for ATLAS, one of the four LHC experiments at CERN. The single layer coil wound with an Al stabilized NbTi superconductor, with overall dimensions of 5.3 m length and 2.6 m diameter and operating at 7.6 kA provides the 2 T magnetic field for the inner detector. The coil was successfully tested at the company before shipment and re-tested at CERN on surface in its final configuration before commencing the installation in the ATLAS cavern 100 m underground. The tests include an extensive study of the quench evolution and in particular the normal zone propagation through the coil windings and in the superconducting bus-lines. A special feature of this coil is the use of aluminum quench propagation strips glued to the windings inner surface. This design enhances the turn-to-turn normal zone propagation velocity, reaching up to 0.8 m/s, and limits the hot spot temperature to 110 K. Along the conductor, normal zone propagation reaches velocities up to 14 m/s at nominal current