Heat transfer characteristics of Rutherford-type superconducting cables in pressurized He II

Kimura, N.; Yamamoto, A.; Shintomi, T.; Terashima, A.; Kovachev, V.; Murakami, Masahide

doi:10.1109/77.783489

Cited by 16 publications

(10 citation statements)

References 7 publications

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“…The thermal characterization of the LHC standard insulation allowed estimating the thickness of the equivalent channel responsible for He II heat exchange to be around 10 μm [3][4]. Nevertheless, the heat transport through μ-channels in He IIp was not much investigated: few papers report results for cooling channels of several mm [7][8], and to our knowledge the only work investigating channels of hydraulic diameter smaller than 1 mm was [9], down to 56 μm.…”

Section: Introductionmentioning

confidence: 99%

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Steady-State heat transfer through micro-channels in pressurized He II

Granieri¹,

Baudouy²,

Four³

et al. 2012

AIP Conference Proceedings

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The operation of the Large Hadron Collider superconducting magnets for current and high luminosity future applications relies on the cooling provided by helium-permeable cable insulations. These insulations take advantage of a He II micro-channels network constituting an extremely efficient path for heat extraction. In order to provide a fundamental understanding of the underlying thermal mechanisms, an experimental setup was built to investigate heat transport through single He II channels typical of the superconducting cable insulation network, where deviation from the macro-scale theory can appear. Micro-fabrication techniques were exploited to etch the channels down to a depth of ~ 16 μm. The heat transport properties were measured in static pressurized He II and analyzed in terms of the laminar and turbulent He II laws, as well as in terms of the critical heat flux between the two regions.

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Section: Introductionmentioning

confidence: 99%

“…In order to overcome this limitation, the LHC Nb-Ti superconducting cables were insulated with overlapped polyimide tapes creating μ-channels, therefore featuring He II permeability [2][3][4]. Furthermore, a new thermally enhanced insulation based on an even more porous wrapping scheme was recently proposed [5].…”

Section: Introductionmentioning

confidence: 99%

Steady-State heat transfer through micro-channels in pressurized He II

Granieri¹,

Baudouy²,

Four³

et al. 2012

AIP Conference Proceedings

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“…The cables were uniformly heated by supplying current to the resistive strands, as in [11]. The heat generated was calculated, with an error smaller than 0.1%, using the measurement of the voltage at the cable extremities and of the injected current.…”

Section: A Sample Preparation and Experimental Setupmentioning

confidence: 99%

Heat Transfer in an Enhanced Cable Insulation Scheme for the Superconducting Magnets of the LHC Luminosity Upgrade

Granieri

Fessia

Richter

et al. 2010

IEEE Trans. Appl. Supercond.

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Abstract-The next generation of superconducting magnets for the interaction regions of particle colliders, as well as for fast cycled accelerators, will be confronted with large heat loads. In order to improve the evacuation of heat from the Nb-Ti coil towards He-II bath, a porous (enhanced) all-polyimide cable insulation scheme was proposed recently. The first results were promising, featuring a larger permeability to helium with respect to existing schemes under low compressive stress. In this paper we present an extended experimental study of heat transfer through the Enhanced Insulation into He-II bath, and comparison to the standard LHC insulation, at different levels of applied pressure. The thermal coupling between adjacent cables was investigated, as well as the impact of a localized heat deposition versus a distributed one. The results of this study show that, up to high pressure levels, the enhanced insulation scheme can provide a major improvement of heat transfer compared to the standard scheme used in the main LHC magnets.Index Terms-Accelerator superconducting magnets, enhanced heat transfer, LHC upgrade phase I, porous cable insulation.

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“…Although the conductor surface was machined to reproduce the external cable surface, helium could not penetrate inside the conductor; therefore the cable cross-section below the λ temperature T λ was not isothermal. The setup developed at KEK to qualify the LHC MQXA interaction region quadrupoles made use of resistive cables with the same geometry of the superconducting ones, thus allowing superfluid helium (He II) to fill the interstices among strands [12] [13]. Heat transfer studies carried out at CERN were performed in a first stage on a segment of a superconducting LHC dipole coil [14].…”

Section: T 5oraa-03mentioning

confidence: 99%

Deduction of Steady-State Cable Quench Limits for Various Electrical Insulation Schemes With Application to LHC and HL-LHC Magnets

Granieri

Weelderen

2014

IEEE Trans. Appl. Supercond.

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Abstract-Undesired quenches of superconducting magnets can be a limiting factor for the operation of the LHC accelerator, both for its forthcoming exploitation at full energy as well as for its future upgrades. An accurate knowledge of the quench limit, the maximum amount of heat deposit the magnets can withstand, is required to be able to prevent beam induced quenches.In this paper we provide an overview of the heat extraction through the multitude of cable insulation schemes used in particle accelerators in the past 20 years and foreseen for the coming years. Based on the relevant heat transfer measurements, we deduce steady-state cable quench limits both for the LHC Nb-Ti magnets and for the future HL-LHC Nb 3 Sn ones. We provide them for different operating conditions and different locations within the coil.  Index Terms-Electrical insulation, heat transfer, superconducting high field magnets, LHC, LHC upgrade, Nb 3 Sn, Nb-Ti, quench limit.

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Heat transfer characteristics of Rutherford-type superconducting cables in pressurized He II

Cited by 16 publications

References 7 publications

Steady-State heat transfer through micro-channels in pressurized He II

Steady-State heat transfer through micro-channels in pressurized He II

Heat Transfer in an Enhanced Cable Insulation Scheme for the Superconducting Magnets of the LHC Luminosity Upgrade

Deduction of Steady-State Cable Quench Limits for Various Electrical Insulation Schemes With Application to LHC and HL-LHC Magnets

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