Analysis of Defective Interconnections of the 13 kA LHC Superconducting Bus Bars

Granieri, Pier Paolo; Casali, Massimiliano; Bianchi, Marco; Breschi, Marco; Bottura, L.; Willering, Gerard

doi:10.1109/tasc.2011.2180275

Cited by 1 publication

(3 citation statements)

References 8 publications

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“…10 are in good agreement, except for the initial transient state of the U temperature sensor. The corresponding voltage traces reported in [21] show as well very good agreement for different transport currents.…”

Section: Model Validationsupporting

confidence: 65%

“…HTC ic can be derived from the investigation of experimental tests reproducing defective interconnections [20], thus allowing further improving the reliability of the calculations. An analysis based on local heat transfer coefficients has provided information in this direction [21] and the main results are summarized in the next section. For the parametric analyses reported in Section 5, two different approaches are considered: either the same bus bar heat transfer coefficient is assumed everywhere, that is HTC ic = HTC bus , or the conservative assumption of an adiabatic interconnection is made (HTC ic = 0).…”

Section: Heat Transfer To the Helium Cooling Bathmentioning

confidence: 99%

“…The extensive description of the model and of the results is reported elsewhere [21]. In particular, the superconducting cables and the Cu stabilizer are defined as separate thermal and electric elements, whereas the heaters constitute the third thermal element.…”

Section: Model Validationmentioning

confidence: 99%

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Thermo-electric analysis of the interconnection of the LHC main superconducting bus bars

Granieri¹,

Breschi²,

Casali³

et al. 2013

Cryogenics

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Spurred by the question of the maximum allowable energy for the operation of the Large Hadron Collider (LHC), we have progressed in the understanding of the thermo-electric behavior of the 13 kA superconducting bus bars interconnecting its main magnets. A deep insight of the underlying mechanisms is required to ensure the protection of the accelerator against undesired effects of resistive transitions. This is especially important in case of defective interconnections which can jeopardize the operation of the whole LHC.In this paper we present a numerical model of the interconnections between the main dipole and quadrupole magnets, validated against experimental tests of an interconnection sample with a purposely built-in defect. We consider defective interconnections featuring a lack of bonding among the superconducting cables and the copper stabilizer components, such as those that could be present in the machine. We evaluate the critical defect length limiting the maximum allowable current for powering the magnets. We determine the dependence of the critical defect length on different parameters as the heat transfer towards the cooling helium bath, the quality of manufacturing, the operating conditions and the protection system parameters, and discuss the relevant mechanisms. t r a c tSpurred by the question of the maximum allowable energy for the operation of the Large Hadron Collider (LHC), we have progressed in the understanding of the thermo-electric behavior of the 13 kA superconducting bus bars interconnecting its main magnets. A deep insight of the underlying mechanisms is required to ensure the protection of the accelerator against undesired effects of resistive transitions. This is especially important in case of defective interconnections which can jeopardize the operation of the whole LHC. In this paper we present a numerical model of the interconnections between the main dipole and quadrupole magnets, validated against experimental tests of an interconnection sample with a purposely built-in defect. We consider defective interconnections featuring a lack of bonding among the superconducting cables and the copper stabilizer components, such as those that could be present in the machine. We evaluate the critical defect length limiting the maximum allowable current for powering the magnets. We determine the dependence of the critical defect length on different parameters as the heat transfer towards the cooling helium bath, the quality of manufacturing, the operating conditions and the protection system parameters, and discuss the relevant mechanisms.

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Section: Model Validationsupporting

confidence: 65%

Section: Heat Transfer To the Helium Cooling Bathmentioning

confidence: 99%