Impact of the Residual Resistivity Ratio on the Stability of ${\rm Nb}_{3}{\rm Sn}$ Magnets

Bordini, B.; Bottura, L.; Oberli, L.; Rossi, L.; Takala, E.

doi:10.1109/tasc.2011.2180693

Cited by 35 publications

(27 citation statements)

References 12 publications

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“…The peculiar instability behavior of high J c Nb 3 Sn strands at 1.9 K observed in the magnetization measurements, was hypothesized in previous publications [12]- [14] to explain the limited effect (with respect to the 4.3 K case) of the magnetization in the premature quench currents at low field and 1.9 K. It was noticed that while at 4.3 K the quench current in the low field region (0-3 T) was significantly reduced when the sample was magnetized (V-H measurements), that was not the case at 1.9 K. This behavior was explained by assuming that the Nb 3 Sn was so unstable at 1.9 K that the magnetization (and the energy associated to it) in the low field region was even lower than the one at 4.3 K. The magnetization measurements performed confirm this interpretation and the fact that magnetization instability is not a major issue for premature quenches of high field accelerator magnets at 1.9 K. This behavior it is also very interesting for the magnet field quality. The reduced flux jump amplitude at 1.9 K has a much smaller impact on the field quality with respect to the 4.3 K case.…”

Section: Discussionsupporting

confidence: 62%

Magnetization Measurements of High-$J_{\rm c}$$\hbox{Nb}_{3}\hbox{Sn}$ Strands

Bordini

Richter

Alknes

et al. 2013

IEEE Trans. Appl. Supercond.

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High critical current density Nb 3 Sn wires (J c > 2500 A/mm 2 at 4.2 K and 12 T) are the conductors considered for next generation accelerator magnets. At present, the large magnetization of these strands is a concern within the scientific community because of the impact it might have on the magnet field quality. In order to characterize the magnetic behavior of these wires, an extensive campaign of magnetization measurements was launched at CERN. Powder In Tube (PIT) strands by Bruker-EAS and Restacked Rod Process (RRP ® ) strands by Oxford Superconducting Technology (OST) were measured between 0 T and 10.5 T at different temperatures (ranging from 1.9 K to 14.5 K). The samples, based on strands with different subelements dimensions (35 to 80 μm), were measured with a Vibrating Sample Magnetometer (VSM). The experimental data were analyzed to: 1) calculate the effective filament size and the optimal parameters for the pinning force scaling law; 2) define the field-temperature region where there are flux jumps. It was found that the flux-jump can limit the maximum magnetization of the Nb 3 Sn wires and that the maximum magnetization at higher temperatures can be larger than the one at lower temperatures. In this paper the experimental results and the analysis are reported and discussed. The experimental data were analyzed to: 1) calculate the effective filament size and the optimal parameters for the pinning force scaling law; 2) define the field-temperature region where there are flux jumps. It was found that the flux-jump can limit the maximum magnetization of the Nb 3 Sn wires and that the maximum magnetization at higher temperatures can be larger than the one at lower temperatures. In this paper the experimental results and the analysis are reported and discussed.

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Section: Discussionsupporting

confidence: 62%

Magnetization Measurements of High-$J_{\rm c}$$\hbox{Nb}_{3}\hbox{Sn}$ Strands

Bordini

Richter

Alknes

et al. 2013

IEEE Trans. Appl. Supercond.

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“…However, too small a copper fraction may cause high magnetic-field instabilities and increase the risk of damaging the strands during the cabling process. Additional studies are under way, analogous to the studies of the effect of RRR on the magnet stability [34].…”

Section: Quench Marginmentioning

confidence: 99%

Quench Protection of a 16-T Block-Coil Dipole Magnet for a 100-TeV Hadron Collider Using CLIQ

Ravaioli¹,

Verweij²,

Kirby³

et al. 2016

IEEE Trans. Appl. Supercond.

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Abstract-Protection against the effects of a quench is a crucial challenge for 16 T class superconducting dipole magnets for a future 100 TeV Hadron collider. To avoid damage due to overheating of the coil's hot-spot, the heat generated during the quench has to be homogeneously distributed in the winding pack by quickly and uniformly transferring to the normal state voluminous coil sections. Conventional protection systems rely on quench heaters placed on the outer surfaces of the coils. However, this technique has to confront significant challenges in order to achieve the fast transitions required by high magnetic-field magnets. The recently-developed Coupling-Loss-Induced Quench (CLIQ) utilizes inter-filament coupling loss as an effective intra-wire heat deposition mechanism, which in principle is faster than thermal diffusion. Furthermore, the CLIQ technology is based on simple and robust electrical components in contact with the coil only in a limited number of easily accessible and well-insulated points. Hence, expected occurrence of failure and electrical breakdown is significantly reduced. As a case study, the design of a CLIQ-based protection system for a 14 meter long, 16 T, Nb3Sn block-coil dipole magnet is demonstrated here. Various magnet design features can be adjusted for improving CLIQ performance and optimize its integration in the magnet system. CLIQ provides future magnet designers with a solution for a very effective, yet electrically robust, quench protection system, resulting in better magnet performance and lower cost than would be possible with a traditional approach to magnet protection.

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“…The reduced filament diameter (30 m) in this case is beneficial as it brings better field quality at injection. For both strands we relaxed the NED specifications on RRR in view of the recent experimental and analytical results indicating that a lower limit of 100 is appropriate [23].…”

Section: Superconductor Developmentmentioning

confidence: 99%