Oxidation and contact resistance of Sn–Ag coated superconducting strands for the Large Hadron Collider (LHC)

Scheuerlein, C.; Taborelli, M.; Cantoni, Marco

doi:10.1016/j.apsusc.2006.02.015

Cited by 3 publications

(4 citation statements)

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“…The splice overlap length is 1 cm. not taken into account [10,11]. The resistance of the thin unreacted diffusion Nb-Ta barriers in the RRP strand was neglected as well.…”

Section: Soldered Splicesmentioning

confidence: 99%

“…For the simulations only the bulk resistivities of the Cu parts and the solder have been considered. The additional resistance possibly caused by thin intermetallic layers, constriction resistances due to porosity and contact resistances are not taken into account [10,11]. The resistance of the thin unreacted diffusion Nb-Ta barriers in the RRP strand is neglected as well.…”

Section: Soldered Splicesmentioning

confidence: 99%

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Electrical resistance of Nb₃Sn/Cu splices produced by electromagnetic pulse technology and soft soldering

Schoerling

Heck

Scheuerlein

et al. 2011

Supercond. Sci. Technol.

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The electrical interconnection of Nb 3 Sn/Cu strands is a key issue for the construction of Nb 3 Sn based damping ring wigglers and insertion devices for third generation light sources. We compare the electrical resistance of Nb 3 Sn/Cu splices manufactured by solid state welding using Electromagnetic Pulse Technology (EMPT) with that of splices produced by soft soldering with two different solders. The resistance of splices produced by soft soldering depends strongly on the resistivity of the solder alloy at the operating temperature. By solid state welding splice resistances below 10 n can be achieved with 1 cm strand overlap length only, which is about 4 times lower than the resistance of Sn96Ag4 soldered splices with the same overlap length. The comparison of experimental results with Finite Element simulations shows that the electrical resistance of EMPT welded splices is determined by the resistance of the stabilizing copper between the superconducting filaments and confirms that welding of the strand matrix is indeed achieved. EMPT allows interconnecting the ductile, unreacted strands, which reduces the risk of damaging the brittle reacted Nb 3 Sn strands.To be published in Superconductor Science and Technology Geneva, Switzerland CERN-ATS-2011-230 AbstractThe electrical interconnection of Nb 3 Sn/Cu strands is a key issue for the construction of Nb 3 Sn based damping ring wigglers and insertion devices for third generation light sources. We compare the electrical resistance of Nb 3 Sn/Cu splices manufactured by solid state welding using Electromagnetic Pulse Technology (EMPT) with that of splices produced by soft soldering with two different solders. The resistance of splices produced by soft soldering depends strongly on the resistivity of the solder alloy at the operating temperature. By solid state welding splice resistances below 10 nΩ can be achieved with 1 cm strand overlap length only, which is about 4 times lower than the resistance of Sn96Ag4 soldered splices with the same overlap length. The comparison of experimental results with Finite Element simulations shows that the electrical resistance of EMPT welded splices is determined by the resistance of the stabilizing copper between the superconducting filaments and confirms that welding of the strand matrix is indeed achieved. EMPT allows interconnecting the ductile, unreacted strands, which reduces the risk of damaging the brittle reacted Nb 3 Sn strands.

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“…The splice overlap length is 1 cm. not taken into account [10,11]. The resistance of the thin unreacted diffusion Nb-Ta barriers in the RRP strand was neglected as well.…”

Section: Soldered Splicesmentioning

confidence: 99%

Section: Soldered Splicesmentioning

confidence: 99%

Electrical resistance of Nb₃Sn/Cu splices produced by electromagnetic pulse technology and soft soldering

Schoerling

Heck

Scheuerlein

et al. 2011

Supercond. Sci. Technol.

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“…The typical coating thickness is 0.5 to 1 µm. During a first heat treatment Cu and Sn interdiffuse and form Cu 3 Sn [77]. On the outermost surface a very thin layer of CuO grows on top of a Cu 2 O layer.…”

Section: Non-cored Cablementioning

confidence: 99%

Stability of superconducting Rutherford cables for accelerator magnets

Willering

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f c e e r g s o r a c l r a t o m a n e t Gerard Willering S t a b i l i t y o f S u p e r c o n d u c t i n g r C b l e R u t h e f o r d a s PrefaceThe work described in this thesis results from an extensive collaboration between the special chair for Industrial Application of Superconductors in the Low Temperature Division at the University of Twente and the Magnets, Superconductors and Cryostats group at CERN. The research has been carried out at CERN as well as at the University of Twente and it is funded by both institutes. Part of the cable samples were prepared by GSI in the frame of research collaboration on cable stability.I am very grateful to the members of these groups for giving me the opportunity to perform the research, for their interest and useful discussions.i ContentsPreface i Chapter 1 IntroductionAfter the discovery of superconductivity in the beginning of the 20 th century the understanding of the phenomenon has grown. Practical conductors are produced for various magnet applications. Although the number of superconducting materials is high, only a few can be used in high-field and high-current density applications. This thesis deals with cable stability, with the focus on application in accelerator magnets.In this chapter a brief overview of the existing and near future accelerators and their superconducting magnets is presented. The most recent superconducting accelerator, the lhc and the near future superconducting accelerator sis 300 are described.The phenomenon of superconductivity is shortly discussed and practical superconductors are introduced with an emphasis on strands and cables. Different types of cables are presented and the relevance of this thesis for in particular the Rutherford type of cable is discussed.The terms quench and recovery are introduced. The importance of research on stability is illustrated by the large number of training quenches in the lhc main dipole magnets. Superconducting accelerator magnetsIn High Energy Physics the interaction of elementary particles is being studied. Many particle accelerators have been constructed to accelerate particles and collide them at high energy. Synchrotron accelerators provide a circular track with RFcavities to accelerate bunches of particles each cycle.Synchrotron accelerators require dipole magnets to bend the particle beam and keep it in its circular track. Quadrupole magnets are used to focus and defocus the beam and higher-order magnets correct field distortions and chromaticity. The collision energy depends on the magnetic field in the aperture of the dipole B a (T) and the bending radius of the dipole magnets r d (km) following E ≈ 0.3B a r d (TeV). The limitation in the track circumference is strongly dictated by the amount of material and the costs involved. In normal conducting magnets iron is applied to enhance the electromagnetic field produced with copper windings. The magnetic field in iron saturates at about 2 T, therefore the needed amount of copper windings and the costs involved increase strongly for hig...

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“…Subsequently the cable made of coated strands is submitted to a 200 heat-treatment (HT) in air, lasting typically a few hours [1], [2]. In this case the contact resistance increase is due to the oxide layer that remains on top of a intermetallic layer that is formed on the strand during the 200 HT in air [3], [4].…”

Section: Introductionmentioning

confidence: 99%

Aluminum Strand Coating for Increasing the Interstrand Contact Resistance in Rutherford Type Superconducting Cables

Scheuerlein

Willering

Verweij

et al. 2009

IEEE Trans. Appl. Supercond.

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Abstract-The interstrand contact resistance ( ) in Rutherford type cables for fast cycling superconducting magnets must be sufficiently high in order to limit eddy current losses. The required value for c depends on the cable and magnet geometries and on the foreseen cycling rate, but is typically of the order of one m. Such values can be reached with a dedicated strand coating or with a resistive internal cable barrier.

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Oxidation and contact resistance of Sn–Ag coated superconducting strands for the Large Hadron Collider (LHC)

Cited by 3 publications

References 11 publications

Electrical resistance of Nb₃Sn/Cu splices produced by electromagnetic pulse technology and soft soldering

Electrical resistance of Nb₃Sn/Cu splices produced by electromagnetic pulse technology and soft soldering

Stability of superconducting Rutherford cables for accelerator magnets

Aluminum Strand Coating for Increasing the Interstrand Contact Resistance in Rutherford Type Superconducting Cables

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Oxidation and contact resistance of Sn–Ag coated superconducting strands for the Large Hadron Collider (LHC)

Cited by 3 publications

References 11 publications

Electrical resistance of Nb3Sn/Cu splices produced by electromagnetic pulse technology and soft soldering

Electrical resistance of Nb3Sn/Cu splices produced by electromagnetic pulse technology and soft soldering

Stability of superconducting Rutherford cables for accelerator magnets

Aluminum Strand Coating for Increasing the Interstrand Contact Resistance in Rutherford Type Superconducting Cables

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Product

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Electrical resistance of Nb₃Sn/Cu splices produced by electromagnetic pulse technology and soft soldering

Electrical resistance of Nb₃Sn/Cu splices produced by electromagnetic pulse technology and soft soldering