Tore Supra and He II Cooling of Large High Field Magnets

Claudet, G.; Aymar, R.

doi:10.1007/978-1-4613-0639-9_8

Cited by 41 publications

(14 citation statements)

References 8 publications

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“…CERN therefore decided to base the LHC project on the use of Nb-Ti operating in superfluid helium at 1.9 K where it retains sufficient current-carrying capacity for building magnets up to about 10 T. This technique, pioneered in the 1980s in the Tore Supra tokamak and other high-field magnets [13], is applied for the first time to the magnets of a large accelerator. The LHC magnets must preserve their field quality over a large dynamic range, in particular at low level when persistent currents in the superconductor produce remanence.…”

Section: High-field Superconducting Magnetsmentioning

confidence: 99%

Advanced superconducting technology for global science: The Large Hadron Collider at CERN

Lebrun

2002

AIP Conference Proceedings

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The Large Hadron Collider (LHC), presently in construction at CERN, the European Organisation for Nuclear Research near Geneva (Switzerland), will be, upon its completion in 2005 and for the next twenty years, the most advanced research instrument of the world's high-energy physics community, providing access to the energy frontier above 1 TeV per elementary constituent. Re-using the 26.7-km circumference tunnel and infrastructure of the past LEP electron-positon collider, operated until 2000, the LHC will make use of advanced superconducting technology -high-field Nb-Ti superconducting magnets operated in superfluid helium and a cryogenic ultra-high vacuum system -to bring into collision intense beams of protons and ions at unprecedented values of center-of-mass energy and luminosity (14 TeV and 10 34 cm -2 .s -1 , respectively with protons). After some ten years of focussed R&D, the LHC components are presently series-built in industry and procured through world-wide collaboration. After briefly recalling the physics goals, performance challenges and design choices of the machine, we describe its major technical systems, with particular emphasis on relevant advances in the key technologies of superconductivity and cryogenics, and report on its construction progress. ABSTRACTThe Large Hadron Collider (LHC), presently in construction at CERN, the European Organisation for Nuclear Research near Geneva (Switzerland), will be, upon its completion in 2005 and for the next twenty years, the most advanced research instrument of the world's high-energy physics community, providing access to the energy frontier above 1 TeV per elementary constituent. Re-using the 26.7-km circumference tunnel and infrastructure of the past LEP electron-positon collider, operated until 2000, the LHC will make use of advanced superconducting technology -high-field Nb-Ti superconducting magnets operated in superfluid helium and a cryogenic ultra-high vacuum system -to bring into collision intense beams of protons and ions at unprecedented values of center-ofmass energy and luminosity (14 TeV and 10 34 cm -2 .s -1 , respectively with protons). After some ten years of focussed R&D, the LHC components are presently series-built in industry and procured through world-wide collaboration. After briefly recalling the physics goals, performance challenges and design choices of the machine, we describe its major technical systems, with particular emphasis on relevant advances in the key technologies of superconductivity and cryogenics, and report on its construction progress.

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Section: High-field Superconducting Magnetsmentioning

confidence: 99%

Advanced superconducting technology for global science: The Large Hadron Collider at CERN

Lebrun

2002

AIP Conference Proceedings

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“…a design field of about 9 T for the 1232, 15-m long twin-aperture superconducting dipole magnets. Using the well-established Nb-Ti conductor technology, this may only be obtained by operating in pressurised superfluid helium below 2 K, a solution pioneered at CEA, France and successfully implemented in the Tore Supra tokamak at the time of the first LHC studies [6]. However, as the specific heat of the superconducting alloy and its copper matrix fall rapidly with decreasing temperature, the full benefit of lower-temperature operation may only be reaped, in terms of stability margin, by making effective use of the particular transport properties of superfluid helium.…”

Section: Duties Constraints and Main Technical Choicesmentioning

confidence: 99%

Cryogenics for the Large Hadron Collider

Lebrun

2000

IEEE Trans. Appl. Supercond.

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The Large Hadron Collider (LHC), a 26.7 km circumference superconducting accelerator equipped with high-field magnets operating in superfluid helium below 1.9 K, has now fully entered construction at CERN, the European Laboratory for Particle Physics. The heart of the LHC cryogenic system is the quasi-isothermal magnet cooling scheme, in which flowing two-phase saturated superfluid helium removes the heat load from the 36'000 ton cold mass, immersed in some 400 m3 static pressurised superfluid helium. The LHC also makes use of supercritical helium for non-isothermal cooling of the beam screens which intercept most of the dynamic heat loads at higher temperature. Although not used in normal operation, liquid nitrogen will provide the source of refrigeration for precooling the machine. Refrigeration for the LHC is produced in eight large refrigerators, each with an equivalent capacity of about 18 kW at 4.5 K, completed by 1.8 K refrigeration units making use of several stages of hydrodynamic cold compressors. The cryogenic fluids are distributed to the cryomagnet strings by a compound cryogenic distribution line circling the tunnel. Procurement contracts for the major components of the LHC cryogenic system have been adjudicated to industry, and their progress will be briefly reported. Besides construction proper, the study and development of cryogenics for the LHC has resulted in salient advances in several fields of cryogenic engineering, which we shall also review. 1 Abstract--The Large Hadron Collider (LHC), a 26.7 km circumference superconducting accelerator equipped with highfield magnets operating in superfluid helium below 1.9 K, has now fully entered construction at CERN, the European Laboratory for Particle Physics. The heart of the LHC cryogenic system is the quasi-isothermal magnet cooling scheme, in which flowing twophase saturated superfluid helium removes the heat load from the 36'000 ton cold mass, immersed in some 400 m 3 static pressurised superfluid helium. The LHC also makes use of supercritical helium for non-isothermal cooling of the beam screens which intercept most of the dynamic heat loads at higher temperature. Although not used in normal operation, liquid nitrogen will provide the source of refrigeration for precooling the machine. Refrigeration for the LHC is produced in eight large refrigerators, each with an equivalent capacity of about 18 kW at 4.5 K, completed by 1.8 K refrigeration units making use of several stages of hydrodynamic cold compressors. The cryogenic fluids are distributed to the cryomagnet strings by a compound cryogenic distribution line circling the tunnel. Procurement contracts for the major components of the LHC cryogenic system have been adjudicated to industry, and their progress will be briefly reported. Besides construction proper, the study and development of cryogenics for the LHC has resulted in salient advances in several fields of cryogenic engineering, which we shall also review.

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“…Since the pioneering work of Claudet [1] and its subsequent developments, He II ("superfluid helium") has become a practical coolant for large cryogenic systems [2]. He II cooling allows the superconducting devices to operate at lower temperature than the 4.2 K saturation of normal boiling helium, thus enhancing the properties of the superconductors.…”

Section: Introductionmentioning

confidence: 99%

Does one need a 4.5 K screen in cryostats of superconducting accelerator devices operating in superfluid helium? lessons from the LHL

Lebrun¹,

Parma²,

Tavian³

2014

AIP Conference Proceedings

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Abstract. Superfluid helium is increasingly used as a coolant for superconducting devices in particle accelerators: the lower temperature enhances the performance of superconductors in high-field magnets and reduces BCS losses in RF acceleration cavities, while the excellent transport properties of superfluid helium can be put to work in efficient distributed cooling systems. The thermodynamic penalty of operating at lower temperature however requires careful management of the heat loads, achieved inter alia through proper design and construction of the cryostats. A recurrent question appears to be that of the need and practical feasibility of an additional screen cooled by normal helium at around 4.5 K surrounding the cold mass at about 2 K, in such cryostats equipped with a standard 80 K screen. We introduce the issue in terms of first principles applied to the configuration of the cryostats, discuss technical constraints and economical limitations, and illustrate the argumentation with examples taken from large projects confronted with this issue, i.e.

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Tore Supra and He II Cooling of Large High Field Magnets

Cited by 41 publications

References 8 publications

Advanced superconducting technology for global science: The Large Hadron Collider at CERN

Advanced superconducting technology for global science: The Large Hadron Collider at CERN

Cryogenics for the Large Hadron Collider

Does one need a 4.5 K screen in cryostats of superconducting accelerator devices operating in superfluid helium? lessons from the LHL

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