Effect of epoxy debonding and cracking on stability of superconducting composites

Dotsenko, V. I.; Kislyak, I.F.

doi:10.1016/0011-2275(91)90027-t

Cited by 9 publications

(6 citation statements)

References 11 publications

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“…Avoiding extensive training and/or performance degradation has proven to be a difficult challenge for epoxy-resinimpregnated high-field Nb 3 Sn accelerator magnets wound from Rutherford cable [1][2][3][4][5][6]. Several recent magnets with designs ranging from canted-cosine-theta (CCT) [7][8][9][10] to classical cosine-theta [1,11], exhibited severe training that complicates their application on a large scale in future * Author to whom any correspondence should be addressed.…”

Section: Introductionmentioning

confidence: 99%

“…3 Sn cables within the University of Twente's test facility by which transverse pressure can be applied up to 200 MPa onto the broad face of the cable at 4.2 K, representative for the transverse pressure load on cables in 11-16 T high-field accelerator magnets[37]. (b) Furthermore, the fatigue properties of the wax-filled cable samples deserve further investigation.…”

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confidence: 99%

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Improved training in paraffin-wax impregnated Nb₃Sn Rutherford cables demonstrated in BOX samples

Daly

Auchmann

Brem

et al. 2022

Supercond. Sci. Technol.

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Resin-impregnated high-field Nb3Sn type of accelerator magnets are known to require extensive training campaigns and even may exhibit performance-limiting defects after thermal or electromagnetic cycling. In order to efficiently explore technological solutions for this behaviour and assess a wide variety of impregnation material combinations and surface treatments, the BOnding eXperiment (BOX) sample was developed. BOX provides a short-sample test platform featuring magnet-relevant Lorentz forces and exhibits associated training. Here we report on the comparative behaviour of BOX samples comprising the same Nb3Sn Rutherford cable but impregnated either with common resins used in high-field magnets, or with less conventional paraffin wax. Remarkably, the two paraffin wax-impregnated BOX samples reached their critical current without training and are also resilient to thermal and mechanical cycling. These rather encouraging results strongly contrast to those obtained with resin impregnated samples, which show the characteristic extensive training and at best barely reach their critical current value.

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Section: Introductionmentioning

confidence: 99%

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confidence: 99%

Improved training in paraffin-wax impregnated Nb₃Sn Rutherford cables demonstrated in BOX samples

Daly

Auchmann

Brem

et al. 2022

Supercond. Sci. Technol.

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“…Dipole magnets using low temperature superconductors (LTS) typically exhibit training as the conductor limit is approached [4]. Failure of the epoxy and/or epoxy interfaces is believed to be one of the primary sources of training in epoxy impregnated magnets wound from Rutherford cables [5][6][7]. There have been recent finite element modeling efforts on the epoxy-structure interface failure and the associated implications on training in CCT magnets [8].…”

Section: Introductionmentioning

confidence: 99%

Training-free demonstration of a 5.4 T Nb₃Sn Canted–Cosine–Theta accelerator dipole impregnated with paraffin wax

Arbelaez,

Teyber,

Rudeiros Fernández

et al. 2024

Supercond. Sci. Technol.

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Lawrence Berkeley National Laboratory (LBNL) is pursuing stress-managed Nb3Sn Canted-Cosine-Theta (CCT) magnet technology for high field accelerator magnets. Although promising results have been reported, improvements in the training performance are desired. This work describes the fabrication and testing campaigns of two subscale Nb3Sn CCT magnets; a baseline impregnated with National High Magnetic Field Laboratory (NHMFL) Mix-61 and a magnet impregnated with paraffin wax. The paraffin magnet reached the short sample limit of the conductor, to within the measurement uncertainty, with no training quenches inside the magnet. In contrast, the baseline magnet reached 80% of the short sample limit after approximately 20 quenches and exhibits some loss of memory after thermal cycles. Inter-layer flexible quench antennas combined with voltage tap data show that all quenches appear identical and originate from a region corresponding to the location of peak field in the cable. Although this success should be replicated at higher fields, these first test results demonstrate the potential for training free Nb3Sn accelerator magnets operating near the short-sample limit.

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“…Filling the porosity in the coil with a resin is needed to avoid the mechanical stresses that are exerted on the coil during assembly and operation irreversibly degrading the conductor [8]. It has been suggested that cracking of the impregnation resin can generate superconductor instabilities [9,10].…”

Section: Introductionmentioning

confidence: 99%

Fracture Toughness, Radiation Hardness, and Processibility of Polymers for Superconducting Magnets

Gaarud,

Scheuerlein,

Parragh

et al. 2024

Polymers

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High fracture toughness at cryogenic temperature and radiation hardness can be conflicting requirements for the resins for the impregnation of superconducting magnet coils. The fracture toughness of different epoxy-resin systems at room temperature (RT) and at 77 K was measured, and their toughness was compared with that determined for a polyurethane, polycarbonate (PC) and poly(methyl methacrylate) (PMMA). Among the epoxy resins tested in this study, the MY750 system has the highest 77 K fracture toughness of KIC = 4.6 MPa√m, which is comparable to the KIC of PMMA, which also exhibits linear elastic behaviour and unstable crack propagation. The polyurethane system tested has a much higher 77 K toughness than the epoxy resins, approaching the toughness of PC, which is known as one of the toughest polymer materials. CTD101K is the least performing in terms of fracture toughness. Despite this, it is used for the impregnation of large Nb3Sn coils for its good processing capabilities and relatively high radiation resistance. In this study, the fracture toughness of CTD101K was improved by adding the polyglycol flexibiliser Araldite DY040 as a fourth component. The different epoxy-resin systems were exposed to proton and gamma doses up to 38 MGy, and it was found that adding the DY040 flexibiliser to the CTD101K system did not significantly change the irradiation-induced ageing behaviour. The viscosity evolution of the uncured resin mix is not significantly changed when adding the DY040 flexibiliser, and at the processing temperature of 60 °C, the viscosity remains below 200 cP for more than 24 h. Therefore, the new resin referred to as POLAB Mix is now used for the impregnation of superconducting magnet coils.

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Effect of epoxy debonding and cracking on stability of superconducting composites

Cited by 9 publications

References 11 publications

Improved training in paraffin-wax impregnated Nb₃Sn Rutherford cables demonstrated in BOX samples

Improved training in paraffin-wax impregnated Nb₃Sn Rutherford cables demonstrated in BOX samples

Training-free demonstration of a 5.4 T Nb₃Sn Canted–Cosine–Theta accelerator dipole impregnated with paraffin wax

Fracture Toughness, Radiation Hardness, and Processibility of Polymers for Superconducting Magnets

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Effect of epoxy debonding and cracking on stability of superconducting composites

Cited by 9 publications

References 11 publications

Improved training in paraffin-wax impregnated Nb3Sn Rutherford cables demonstrated in BOX samples

Improved training in paraffin-wax impregnated Nb3Sn Rutherford cables demonstrated in BOX samples

Training-free demonstration of a 5.4 T Nb3Sn Canted–Cosine–Theta accelerator dipole impregnated with paraffin wax

Fracture Toughness, Radiation Hardness, and Processibility of Polymers for Superconducting Magnets

Contact Info

Product

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About

Improved training in paraffin-wax impregnated Nb₃Sn Rutherford cables demonstrated in BOX samples

Improved training in paraffin-wax impregnated Nb₃Sn Rutherford cables demonstrated in BOX samples

Training-free demonstration of a 5.4 T Nb₃Sn Canted–Cosine–Theta accelerator dipole impregnated with paraffin wax