Finite element stress analysis of the CMS magnet coil

The Compact Muon Solenoid (CMS) is one of the experiments which are being designed in the framework of the Large Hadron Collider (LHC) project at CERN. The design field of the CMS magnet is 4 T, the magnetic length is 12.38 m and the aperture is 6.36 m. This is achieved with a 4 layer-5 module superconducting Al-stabilized coil energised at a nominal current of 20 kA. The finite element analysis (FEA) carried out is axisymmetric elasto-plastic. FEA has also been carried out on the suspension system and on the conductor. (8 refs)

Possible fabrication techniques and welding specifications for the external cylinder of the CMS coil

The Compact Muon Solenoid (CMS) is one of the experiments, which are being designed in the framework of the Large Hadron Collider (LHC) project at CERN. The design field of the CMS magnet is 4 T, the magnetic length is 12.5 m and the free aperture is 6 m in diameter. This is achieved with a 4 layer and 5 module superconducting Al- stabilized coil energized at a nominal current of 20 kA at 4.5 K. In the CMS coil the structural function is ensured, unlike in other existing Al-stabilized thin solenoids, both by the Al-alloy reinforced conductor and the external cylinder. The calculated stress level in the cylinder at operating conditions is particularly severe. In this paper the different possible fabrication techniques are assessed and compared and a possible welding specification for this component is given. (9 refs)

The CMS conductor

The Compact Muon Solenoid (CMS) is one of the experiments, which are being designed in the framework of the Large Hadron Collider (LHC) project at CERN, the design field of the CMS magnet is 4 T, the magnetic length is 13 m and the aperture is 6 m. This high magnetic field is achieved by means of a 4 layer, 5 modules superconducting coil. The coil is wound from an Al-stabilized Rutherford type conductor. The nominal current of the magnet is 20 kA at 4.5 K. In the CMS coil the structural function is ensured, unlike in other existing Al-stabilized thin solenoids, both by the Al-alloy reinforced conductor and the external former. In this paper the retained manufacturing process of the 50-km long reinforced conductor is described. In general the Rutherford type cable is surrounded by high purity aluminium in a continuous co-extrusion process to produce the Insert. Thereafter the reinforcement is joined by Electron Beam Welding to the pure Al of the insert, before being machined to the final dimensions. During the manufacture the bond quality between the Rutherford cable and the high purity aluminium as well as the quality of the EB welding are continuously controlled by a novel ultrasonic phased array system. The dimensions of the insert and the final conductor are measured by laser micrometer. (8 refs)

Shear test of glass reinforced composite materials at 4.2 K

Finite element analysis of the 4-T, 12.5-m long, 6-m-bore diameter superconducting solenoid for the CMS experiment at LHC shows that the insulation system is subjected mainly to shear forces during magnet operation at 4.5 K. This paper describes the development of a test procedure to evaluate shear properties of the glass reinforced composite material at 4.2 K. The calculation supporting the new specimen shape and the relation between coil and specimen Finite Element Analysis (FEA) are presented. As an application, this-test procedure is used to compare three different surface treatments of the conductor: solvent cleaning, sand blasting and anodic oxidation. Results from these tests are reported. Values up to 110 MPa at 4.2 K have been obtained for the CMS foreseen insulation material, the conductor being treated by anodic oxidation. (5 refs)

Mechanical characterization and assessment of the CMS conductor

The Compact Muon Solenoid (CMS) is one of the experiments which are being designed in the framework of the Large Hadron Collider (LHC) project at CERN. The design field of the CMS magnet is 4 T, the magnetic length is 12.5m and the free aperture is 6 m in diameter. This is achieved with a 4 layer and 5 module superconducting Al stabilized coil, resulting into 20 lengths of conductor of 2.5 km each, energized at a nominal current of 20 kA at 4.5 K. One of the unique features of this thin solenoid is an Al-stabilized conductor reinforced by an Al-alloy. An extensive characterization of mechanical properties at room temperature and 4.2 K has been carried out in order to define the most appropriate alloy and temper for the reinforcement. The effect of the coil curing cycle on the alloy properties has been taken into account. This paper summarizes the main results of these tests. (7 refs)

A Review of the Magnetic Forces in the CMS Magnet Yoke

A summary of the magnetic forces, acting on various ferromagnetic parts of the flux - return yoke of the CMS magnetic system is presented. The latest information about the parameters of the system has been taken into account: coil revision 5/98, yoke revision 6/98, hadronic forward calorimeter revision 6/98. The Vector Fields TOSCA code and the modified CERN POISCR code were used for two - and three - dimensional finite - element calculations of the magnetic field. The forces on ferromagnetic elements were computed using the Maxwell surface integral method. The obtained results are compared with the estimates of the magnetic forces presented in the Magnet Technical Design Report

Final design of the CMS solenoid cold mass

The 4 T, 12.5 m long, 6 m bore diameter superconducting solenoid for the CMS (Compact Muon Solenoid) experiment at LHC will be the largest and the most powerful superconducting solenoid ever built. Part of the CMS design is based on that of previous large superconducting solenoids-the use of a high purity aluminium stabilized conductor, a compact impregnated winding with indirect cooling and quench back protection process. However, the dimensions and the performances of this solenoid have imposed solutions which are more than extrapolations of the previous ones : the use of a mechanically reinforced conductor and a five module winding, each module being made of four layers, internally wound. This design, which is now frozen, relies on numerous magnetic, mechanical and thermal calculations, on various experimental tests (characterization of structural and insulating materials, electrical joints...) and specific mock-ups. Two pre-industrialization programs, concerning the conductor and the winding process have also been carried out with industrial partners to support the foreseen solutions. Both the final design and the experimental results obtained to validate this design are presented in this paper. (10 refs)