A Novel Idea for Coil Collar Structures in Accelerator Superconducting Magnets

The dipoles for several different machines (LHC, SSC, HERA) were designed using non-magnetic metallic collars to contain the superconducting coils. The coils are of two types, main and floating. This paper describes a structure with combined steel and plastic collars. Since the floating collars do not give an important contribution to the global rigidity of the dipole we propose to suppress them. The plastic collars are just fillers to limit the helium contained in the cold mass. Some data about thermoplastic materials to be possibly used for the collars are given and some estimations of mass and cost of this configuration are made. Finally the results of the tests of a 1-m-long twin aperture dipole with mixed steel-plastic collars are shortly described. The replacement of expensive alloys by high performance plastic in non-structural components can be a cost-effective solution in view of future projects where superconducting magnets are involved and contained costs are a key issue

3D FEM Modeling of the Coil Ends of the LHC Main Dipole

A 3D finite element mechanical model has been developed to simulate the complex geometry of the extremities of the coils for the LHC main dipoles. The final aim is to evaluate the possible impact of coil defects on quench performances. In this paper we describe the first part of the work that has been carried out. This covers an analysis of the contribution of the mechanical properties of the different materials to the rigidity of the coil heads and the experimental validation of the model. For such validation we compared the computed stiffness with the values observed during production measurements in industry. The numerical results are in good agreement with the measured; some discrepancies in the intermediate zone of the end point out also in which direction the modeling should be refined

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

Evaluation of the relative expression of genes associated with adherence after different hours of co-culture between Streptococcus uberis and MAC-T cells

Streptococcus uberis is an environmental pathogen associated with subclinical and clinical IMI in both lactating and non-lactating cows. RC19 strain was isolated from a cow with subclinical mastitis, qualitatively classified as moderate biofilm producer in Todd Hewitt medium (THB), and it showed a high value of the adhered bacteria (CFU/ml). Hence, the aims of this study were (a) to determine ability to adhere to and internalize into epithelial cells MAC-T for 1, 2 and 3 h, (b) to evaluate the relative expression of adherence-associated genes from co-cultures of S. uberis with MAC-T cells at 1, 2 and 3 h. We hypothesized that upon contact with bovine mammary epithelial cells, S. uberis upregulates adherence-associated genes encoding adhesins, which enable it a higher adherence to and/or internalization into host cells. Four to six genes increased their R with regard to the control after initial contact with MAC-T cells (group 1) at 1, 2 and 3 h. The highest value of R was observed at 2 h after co-culture between RC19 and MAC-T cells.Fil: Fessia, Alumine Soledad. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Microbiología e Inmunología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Odierno, Liliana Mónica. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Microbiología e Inmunología; Argentin

Industrial Learning Curves: Series Production of the LHC Main Superconduting Dipoles

By mid August 2006, 1160 of the 1232 of LHC main dipoles have been delivered to CERN by the three suppliers in charge of the production. The training of the staff, mostly hired just for this manufacture, and the improvement of the procedures with the acquired experience, naturally decrease the time necessary for the assembly of a unit. The aim of this paper is to apply methodologies like the cost-based learning curves and the time-based learning curves to the LHC Main Dipole production comparing the estimated learning percentage to the ones experienced in other industries. This type of analysis, already presented on 500 units is here extended to more than 1000 completed units. The work also tries to identify which type of industry presents the learning percentages that are the most similar to our case and to investigate the impact of the production strategy on the process efficiency

Parametric Analysis of Forces and Stresses in Superconducting Quadrupole Sector Windings

This paper presents a review of the existing analytical approximations of the magnetic field of a sector winding quadrupole, evaluating to which extent these formulae are usable as a first estimation of the resultants of the electromagnetic forces and related mechanical stresses produced. The distribution of the forces has been investigated to better understand the stress provided to the structure containing the windings and the compression effect induced on the coil mid plane. Therefore, the study has been carried out setting the magnet current at its critical value, analyzing forces and stresses as functions of the geometrical layout and of the magnetic gradient as well. In the last part the effect of an iron yoke on the magnetic field and forces is presented

First Experience in the Mass Production of Components for the LHC Dipoles

This paper reports on the manufacturing features and difficulties experienced for the preliminary mass production of the main mechanical components of the dipole cold mass. The production of about 600 km of superconducting coil copper wedges, 5'000 coil layer jump spacers and boxes, 12'500'000 austenitic steel collars and 5'800'000 low-carbon yoke laminations is spread over 4 European countries and involves 6 manufactory firms. The general technical requirements for the manufacturing process as well as the imposed production checks and quality controls are reviewed. An overview of the preliminary results is presented with an outlook towards the analysis and statistical which are in a process to be implemented for the follow-up of the mass production

Field quality in the ends of the Large Hadron Collider main dipole: Measurements and correlation to industrial assembly procedures

Magnetic field measurements are an important tool to monitor the LHC main dipole production. In this paper we analyse the data relative to a few tens of collared coils produced for the pre-series dipoles. Strong systematic differences between field at the magnet extremities are observed. Moreover, three different families of coil ends corresponding to the different coil manufacturers can be singled out. A 3D model of the coil ends is used to understand these differences in terms of the assembly parameters and the industrial procedures. We analyse the production trends in order to characterize the geometric parameters and the critical components for the field quality. The field components in the dipole ends are finally compared to the beam dynamics budget allowed for the whole dipole