Supporting Systems from 293 K to 1.9 K for the Large Hadron Collider (LHC) Cryo-Magnets
The LHC machine will incorporate some 2000 main ring super-conducting magnets cooled at 1.9 K by super-fuid pressurized helium, mainly 15m-long dipoles with their cryostats and 6m-long quadrupoles housed in the Short Straight Section (SSS) units. This paper presents the design of the support system of the LHC arc cryo-magnets between 1.9 K at the cold mass and 293 K at the cryostat vacuum vessel. The stringent positioning precision for magnet alignment and the high thermal performance for cryogenic efficiency are the main conflicting requirements, which have lead to a trade-off design. The systems retained for LHC are based on column-type supports positioned in the vertical plane of the magnets inside the cryostats. An ad-hoc design has been achieved both for cryo-dipoles and SSS.
Each column is composed of a main tubular thin-walled structure in composite material (glass-fibre/epoxy resin, for its low thermal conductivity properties), interfaced to both magnet and cryostat via stainless steel flanges. The thermal performance of the support is improved by intercepting part of the conduction heat at two intermediate temperature levels (one at 50–75 K and the other at 4.5–20 K). These intercepts, on the composite column, are thermally connected to the helium gas cooled thermal shield and radiation screen of the cryo-magnet.
An overview of the design requirements is given, together with an appreciation of the system design. Particular attention is dedicated to the support system of the SSS where the positioning precision of the quadrupole magnet is the most critical.
KeywordsLarge Hadron Collider Heat Load Thermal Contraction Vacuum Vessel Thermal Shield
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- 1.M. Mathieu, Th. Renaglia, Ch. Disdier, “Supportage de la masse froide du LHC”, Technical Note EST-ESM/96–01, CERN — Geneva.Google Scholar
- 2.M. Mathieu, “Systeme de supportage du LHC: Point sur le development”, Technical Note MT-ESM/94–3, CERN — Geneva.Google Scholar
- 3.M. Mathieu, “Développement de supports en matériau composite pour les aimants prototypes du LHC”, Technical Note MT/93–06, CERN — Geneva.Google Scholar
- 4.J.F. Miles, “Concerning the Strength of Closed Orbit Correction Dipoles in the Arcs of LHC V4.2”, LHC Project Note 43, CERN — Geneva.Google Scholar
- 5.P. Lefevre, for the Working Group on Mechanical Apertures, “Chapaumeter & Layout Committee”, minutes of the 9th meeting.Google Scholar
- 6.J.C. Brunet, “Extrémités des dipoles — Référentiel — Acceptabilité — Situation & Installation”, LHC Project Note 50, CERN — Geneva.Google Scholar
- 7.W. Cameron, Ph. Dambre, T. Kurtyka, V. Parma, T. Renaglia, J.M. Rifflet, P. Rohmig, B. Skoczen, T. Tortschanoff, Ph. Trilhe, P. Vedrine, D. Vincent, “The new superfluid helium cryostats for the Short Straight Sections of the CERN Large Hadron Collider (LHC)”, presented at this conference.Google Scholar
- 8.J.C. Brunet, V. Parma, G. Peon, A. Poncet, P. Rohmig, B. Skoczen, L.R. Williams, “Design of the second series 15 m LHC prototype dipole magnet cryostats”, presented at this conference.Google Scholar
- 9.A. Pardon, “Verification of safety margins for the LHC cold support system”, Technical Note under preChapaution, CERN — Geneva.Google Scholar
- 10.Ch. Disdier, “Validation by calculation of the thermo-elastic behavior of the LHC cold support system”, Technical Note under preChapaution, CERN — Geneva.Google Scholar
- 11.Ch. Disdier, “Contribution a l’étude du décollement interfacial et des propriétés thermiques de composite unidirectionnels sous les aspects micro, meso et macro; applications”, PhD Thesis, Université de Savoie -Chambery, France.Google Scholar
- 12.T. Dobers, G. Peiro, “Détection de mouvements de la masse froide par rapport au cryostat de dipole prototype 12 pour le LHC”, Internal report AT/SU/TD, CERN — Geneva.Google Scholar
- 13.D. Missiaen, “Metrology of superconducting magnets: first experience and facts from the LHC test String”, IWAA, International Workshop on accelerator alignment, Tokyo — Japan 1995.Google Scholar
- 14.L. Tavian, Private communication, CERN — Geneva.Google Scholar
- 15.V. Parma, “Thermalisations of cold supports: minimisation of conduction heat loads: results of calculation, implications on the design of thermal screens for the LHC half cell”, minutes of the Cryostat Design Group meeting, 7 August 1996, CERN — Geneva.Google Scholar
- 16.B. Jenninger, “Influence of reflective surfaces on the LHC Support Posts”, LHC Project Note 65.Google Scholar