116 research outputs found
Statistical Studies of the Robustness of the LHC Main Dipole Mechanical Structure
This paper describes two methods used to study the effect of the tolerances of the components on the structure of the LHC main dipole. The first method, called semi-statistical, is useful for the study of the effect of single different parameters and allows the determination of the acceptable variance of the dimensions of magnet components. The second one, fully statistical, allows the study of the combined effect of many parameters. The use of these two methods allowed to evaluate with good confidence the robustness of two different dipole cross-section designs, featuring austenitic and aluminium alloy collars, respectively
FEM Computations Concerning the Effect of Friction in Two LHC Main Dipole Structures
The mechanical behaviour of a dipole structure is considered when also friction is taken into account, studying its effect on different components and in different conditions. In particular the difference in behavior between a structure with aluminium collars and one with austenitic steel ones was studied
Mechanical Design of the SMC (Short Model Coil) Dipole Magnet
The Short Model Coil (SMC) working group was set in February 2007 within the Next European Dipole (NED) program, in order to develop a short-scale model of a NbSn dipole magnet. The SMC group comprises four laboratories: CERN/TE-MSC group (CH), CEA/IRFU (FR), RAL (UK) and LBNL (US). The SMC magnet was originally conceived to reach a peak field of about 13 T on conductor, using a 2500 A/mm2 Powder-In-Tube (PIT) strand. The aim of this magnet device is to study the degradation of the magnetic properties of the NbSn cable, by applying different level of pre-stress. To fully satisfy this purpose, a versatile and easy-to-assemble structure has to be realized. The design of the SMC magnet has been developed from an existing dipole magnet, the SD01, designed, built and tested at LBNL with support from CEA. In this paper we will describe the mechanical optimization of the dipole, starting from a conceptual configuration based on a former magnetic analysis. Two and three-dimensional Finite Element Method (FEM) models have been implemented in ANSYS™ and in CAST3M, aiming at setting the mechanical parameters of the dipole magnet structure, thus fulfilling the design constraints imposed by the materials
Geometric and Magnetic Axes of the LHC Dipole
The 15-m long superconducting dipoles of the Large Hadron Collider (LHC) with two-in-one design are curved by about 5 mrad to follow the beam trajectory. They are supported on three cold feet to minimise the vertical sagitta induced by their 35 tonnes weight. The cold masses contain at both ends local multipolar correctors to compensate for the detrimental effect of persistent current during injection. We discuss how we measure and control the geometrical shape of the cold mass and the alignment of the associated correctors and how we identify the magnetic axis of the field-shape harmonics with respect to the expected beam reference orbit. We present results relative to prototype dipoles obtained both at room temperature and in operational conditions at 1.9 K
Models and experimental results from the wide aperture Nb-Ti magnets for the LHC upgrade
MQXC is a Nb-Ti quadrupole designed to meet the accelerator quality
requirements needed for the phase-1 LHC upgrade, now superseded by the high
luminosity upgrade foreseen in 2021. The 2-m-long model magnet was tested at
room temperature and 1.9 K. The technology developed for this magnet is
relevant for other magnets currently under development for the high-luminosity
upgrade, namely D1 (at KEK) and the large aperture twin quadrupole Q4 (at CEA).
In this paper we present MQXC test results, some of the specialized heat
extraction features, spot heaters, temperature sensor mounting and voltage tap
development for the special open cable insulation. We look at some problem
solving with noisy signals, give an overview of electrical testing, look at how
we calculate the coil resistance during at quench and show that the heaters are
not working We describe the quench signals and its timing, the development of
the quench heaters and give an explanation of an Excel quench calculation and
its comparison including the good agreement with the MQXC test results. We
propose an improvement to the magnet circuit design to reduce voltage to ground
values by factor 2. The program is then used to predict quench Hot-Spot and
Voltages values for the D1 dipole and the Q4 quadrupole.Comment: 8 pages, Contribution to WAMSDO 2013: Workshop on Accelerator Magnet,
Superconductor, Design and Optimization; 15 - 16 Jan 2013, CERN, Geneva,
Switzerlan
Electrical Integrity Tests during Production of the LHC Dipoles
For the LHC dipoles, mandatory electrical integrity tests are performed to qualify the cold mass (CM) at four production stages: individual pole, collared coil, CM before end cover welding and final CM. A description of the measurement equipment and its recent development are presented. After passing the demands set out in the specification, the results of the tests are transmitted to CERN where they are further analyzed. The paper presents the most important results of these measurements. We also report a review of the electrical non-conformities encountered e.g. interturn shorts and quench heater failure, their diagnostic and the cures
LHC Superconducting Dipole Production Follow-up: Results of Audit on QA Aspects in Industry
The manufacturing of the 1232 Superconducting Main Dipoles for LHC is under way at three European Contractors: Alstom-Jeumont (Consortium), Ansaldo Superconduttori Genova and Babcock Noell Nuclear. The manufacturing is proceeding in a very satisfactory way and in March 2005 the mid production was achieved. To intercept eventually âワweak pointsâ of the production process still present and in order to make a check of the Quality Assurance and Control in place for the series production, an Audit action was launched by CERN during summer-fall 2004. Aspects like: completion of Production and Quality Assurance documentation, structure of QC Teams, traceability, calibration and maintenance for tooling, incoming components inspections, were checked during a total of seven visits at the five different production sites. The results of the Audit in terms of analysis of âワsystematicâ and âワrandomâ problems encountered as well as corrective actions requested are presented
Quality Control Techniques Applied to the Large Scale Production of Superconducting Dipole Magnets for LHC
The LHC accelerator, under construction at CERN, is characterized by the use on a large scale of high field superconducting dipoles: the 27-km ring requires 1232 15-m long dipole magnets designed for a peak field of 9 T. The coils are wound with Rutherford-type cable based on copper-stabilized Nb-Ti superconductors and will be operated at 1.9 K in pressurized superfluid helium. The challenge that had to be faced has been an efficient, cost-effective and reproducible mass production to very tight tolerances: the field quality must be better than 10-4 and the geometry of the cold bore tube and magnet controlled to 0.1 mm over the whole length, any deviation being liable to induce delays and significant cost increase. This paper presents the main methods and tools chosen to face successfully this challenge: some methods were foreseen in the technical specification, others were implemented based on the experience gained in several years of fabrication
Design, Manufacturing Status, First Results of the LHC Main Dipole Final Prototypes and Steps towards Series Manufacture
This paper reports about the program of six LHC superconducting main dipole final prototypes and the steps towards series manufacture. The above program, launched in summer 1998, relies on collared coils manufactured by industry and cold masses assembled at the CERN Magnet Assembly Facility. Following design, stability and robustness studies, the magnet design for series manufacture features a "6-block" coil and austenitic steel collars. A general description of the magnet with its main components is given and the main working parameters and the most important manufacturing features are presented. Results of mechanical and magnetic measurements are given as well as the performances of the first prototype. A comparison with results from the previous generation of dipole magnet models and prototypes is also made. Finally an outlook towards series manufacture is given
Description of the Main Features of the Series Production of the LHC Main Dipole Magnets
The series production of the LHC main dipole magnets was completed in November 2006. This paper presents the organization implemented at CERN and the milestones fixed to fullfil the technical requirements and to respect the master schedule of the machine installation. The CERN organization for the production follow-up, the quality assurance and the magnet testing, as well as the organization of the three main contractors will be described. A description of the design work and procurement of most of the specific heavy tooling and key components will be given with emphasis on the advantages and drawbacks
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