The Compact Muon Solenoid (CMS) is one of the general-purpose detectors to be provided for the LHC project at CERN. The design field of the CMS superconducting magnet is 4T, the magnetic length is 12.5 m and the free bore is 6 m. The magnetic field is achieved by means of a four-layer superconducting solenoid. The stored magnetic energy is 2.7 GJ at nominal current of 20 kA (at 4.5 K operating temperature). The coil is wound from a high purity aluminium-stabilized Rutherford type conductor. Unlike other existing AL-stabilized thin solenoids, the structural integrity of the CMS coil is ensured both by the Al-alloy reinforcement welded to the conductor and an external support clinder. The flat NbTi cable is embedded in high purity aluminium by a continuous co-extrusion process. The mechanical strength of the so-called insert is substantially increased by two Al-alloy sections joined by continous electron beam welding to the pure aluminium of the insert. During manufacturing the bond quality between the Rutherford cable and the high purity aluminium as well as the quality of the EB welding seam are continuously monitored by a novel ultrasonic phased-array system. The dimensions of the insert and of the final conductor are controlled during production by Laser micrometers. This paper presents the main features of the CMS conductor as well as the different steps of the manufacturing process of the 45 km long conductor. First technical experience of industrial production of the complete conductor is reported. |
