Design and analysis of the tooling upgrade for the production of the superconductive main dipole magnet prototypes of LHC

Design and analysis of the tooling upgrade for the production of the superconductive main dipole magnet prototypes of LHC Master of Science Thesis, 110 pages, 12 Appendix pages September 2013 Major: Design of machines and systems Examiner: Professor Reijo Kouhia Keywords: CERN, LHC, High Luminosity LHC project, superconductive dipole magnet, welding press, Nb$_{3}$Sn, pre-stress, Ar-inert gas furnace This thesis work has been carried out as a contribution to the development program of superconductive magnets within the LHC High Luminosity study. The thesis provides an insight to the steps that need to be taken in order to produce a superconductive magnet mainly focusing on mechanical assembly. Tooling upgrade is necessary for the production of the superconductive dipole magnet prototypes in near future. Major attention is given by the introduction of the welding assembly in chapter three. The structural compression is given by the so called shell stress defined by the thermal shrinkage of the weld. The associated aspects include the closure of the gap in the half symmetry of the assembled mock-up. All this is important to minimize the risk for the quenches in the superconductive coil assembly. In the chapter four all the related constraints seen by the magnet are implied into the FEA model to find out the required minimum shrinkage of the weld. It was necessary to verify that the coil stresses stay below the defined limit during the pressing of the magnet and welding, after the welding procedure, as well as the cooling to 1.9 K followed by operation at nominal current 13 kA (12 T). An aspect is given to the modifications performed for the sample press. The specification of the press implied the analysis of the required hydraulic system, user control interface and coordination of related activities. The luminosity upgrade involves the utilization of the Nb$_{3}$Sn superconductor. The diffusion process of the Nb$_{3}$Sn towards superconductive characteristics implies the stringent heat treatment cycle. An Ar-inert gas furnace is used. It is important to select the appropriate numerical methods to verify critical process parameters as the ramping rate [Celcius/h] and the circulation speed of the used Ar-inert gas [m/s]. This implies the definition of the appropriate numerical methods to carry out an analysis with the aid of CFD. The analysis should provide solid backround for further development of the analysis of heat transfer between the furnace and the coil.