AC loss and contact resistance of different CICC cable patterns: Experiments and numerical modeling

Anvar, V.A.; Qin, Jinggang; Wang, Yu; Bagni, Tommaso; Devred, A.; Haugan, Timothy J.; Hossain, Md. Shahriar A.; Zhou, Chao; Nijhuis, Arend

doi:10.1016/j.fusengdes.2020.111898

Cited by 6 publications

(7 citation statements)

References 55 publications

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“…∼ 24.6%). In this last case, the peak of the losses was in the very low frequency range, and we have not yet been able to completely explain these inconsistencies, even if it has been shown [40] that cable pattern, sub-cable wraps and void fraction significantly affect the coupling loss and, overall, could be responsible for the AC losses' curves similarities and differences.…”

Section: Ac Lossesmentioning

confidence: 78%

“…Without wrapping (that is our case), the inter-petal transverse resistance is of the same order of magnitude as the intra-petal transverse resistance, so that the last cabling stage dominates the loss behaviour, because coupling currents with large loops flow through neighbouring petals. In particular, the coupling time constants are dominated by the twist pitches of the last cabling stages [39,40], which have similar values for the two legs.…”

Section: Ac Lossesmentioning

confidence: 99%

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DTT toroidal field conductor samples test in Sultan: DC and AC characterization

Fiamozzi Zignani,

De Marzi,

Scarantino

et al. 2024

Supercond. Sci. Technol.

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The superconducting magnet system of the Divertor Tokamak Test (DTT) facility, composed of 18 Toroidal Field (TF) coils, 6 Poloidal Field (PF) coils and a Central Solenoid (CS), has been designed and many procurements have been launched. Some manufacturing aspects and some conductor features require characterization under relevant close-to-operative conditions. To confirm the design choices in all details, cryogenic tests in qualified facilities have been foreseen. In this work, the results of the TF samples characterization at the SULTAN facility at the Swiss Plasma Centre (SPC, EPFL) are presented. The 3 weeks test campaign started on July the 8th, 2022. The DTT TF SULTAN sample was made of two Nb3Sn Cable-in-Conduit conductor “legs”, namely “TF-A” and “TF-B”, made with wires produced by Kiswire Advanced Technology (KAT), differing for the cabling twist pitch sequence only, and designed to work in DTT at 42.5 kA at 11.9 T peak field.The extensive characterization comprised 3000 Electro-Magnetic (EM) cycles and two Warm-Up-Cool-Down (WUCD) steps, and in detail it included: AC measurements on the virgin conductors, on cyclic loaded conductors and after WUCDs; DC tests at 10.85 T / 42.5 kA with intermediate electro-magnetic (EM) cycles at 10.85 T / 45 kA before and after WUCDs; DC tests using partial Lorentz force loads, and Minimum Quench Energy (MQE) tests at 9 T / 42.5 kA after cycles and WUCDs. The results of the DC measurements analysis verified the design, in terms of current sharing temperature (Tcs) and critical current (Ic), as both samples are over the minimum acceptance values. In particular, the “TF-A” sample, characterized by a so-called “long twist pitch” cabling sequence, showed higher performance without any degradation with loading and WUCD cycles, whereas sample “TF-B” presented an initial Tcs reduction that afterwards substantially remained unchanged. In terms of strain acting at the Nb3Sn filaments level, this result can be described by a lower effective strain in the “TF-A” sample. AC losses were measured with a calorimetric method as a function of frequency for each series of AC sinusoidal pulsing measurements, and the characteristic coupling time constants were determined.

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Section: Ac Lossesmentioning

confidence: 78%

Section: Ac Lossesmentioning

confidence: 99%

DTT toroidal field conductor samples test in Sultan: DC and AC characterization

Fiamozzi Zignani,

De Marzi,

Scarantino

et al. 2024

Supercond. Sci. Technol.

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“…Fisher et al have developed a simple calibrationfree method based on the dipole approximation, which allows for obtaining both the AC loss and orientation of the sample magnetic moment [172]. More recent experimental measurement work based on the magnetic method can be found in [173,174].…”

Section: Magnetic Methodsmentioning

confidence: 99%

Alternating Current Loss of Superconductors Applied to Superconducting Electrical Machines

Zhang¹,

Wen²,

Grilli

et al. 2021

Energies

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Superconductor technology has recently attracted increasing attention in power-generation- and electrical-propulsion-related domains, as it provides a solution to the limited power density seen by the core component, electrical machines. Superconducting machines, characterized by both high power density and high efficiency, can effectively reduce the size and mass compared to conventional machine designs. This opens the way to large-scale purely electrical applications, e.g., all-electrical aircrafts. The alternating current (AC) loss of superconductors caused by time-varying transport currents or magnetic fields (or both) has impaired the efficiency and reliability of superconducting machines, bringing severe challenges to the cryogenic systems, too. Although much research has been conducted in terms of the qualitative and quantitative analysis of AC loss and its reduction methods, AC loss remains a crucial problem for the design of highly efficient superconducting machines, especially for those operating at high speeds for future aviation. Given that a critical review on the research advancement regarding the AC loss of superconductors has not been reported during the last dozen years, especially combined with electrical machines, this paper aims to clarify its research status and provide a useful reference for researchers working on superconducting machines. The adopted superconducting materials, analytical formulae, modelling methods, measurement approaches, as well as reduction techniques for AC loss of low-temperature superconductors (LTSs) and high-temperature superconductors (HTSs) in both low- and high-frequency fields have been systematically analyzed and summarized. Based on the authors’ previous research on the AC loss characteristics of HTS coated conductors (CCs), stacks, and coils at high frequencies, the challenges for the existing AC loss quantification methods have been elucidated, and multiple suggestions with respect to the AC loss reduction in superconducting machines have been put forward. This article systematically reviews the qualitative and quantitative analysis methods of AC loss as well as its reduction techniques in superconductors applied to electrical machines for the first time. It is believed to help deepen the understanding of AC loss and deliver a helpful guideline for the future development of superconducting machines and applied superconductivity.

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“…The homogeneity length along the central axis magnetic field (98.3%) is 400 mm. The AC loss of the subsize MgB 2 CICC is measured at the University of Twente using the test facility [8] shown in figure 5. The assembled cable sample with chamber is inserted into a dipole magnet generating an AC magnetic field up to ±1.5 T. The whole setup is immersed in a liquid helium bath, the evaporated liquid helium in the calorimeter caused by the AC loss heat and the off-set heat-leakage of the cryostat is measured through a precise mass flow meter at room temperature.…”

Section: Measurement Setupsmentioning

confidence: 99%

“…Given the potential use of MgB 2 in superconducting cables and magnet coils at 10 to 25 K, the MgB 2 wire is a promising candidate for lower field coils in fusion reactors like poloidal field (PF), correction coil and lower field sections of graded high-field coils, as well as their feeders. The international collaboration for advancement of magnesium-diboride superconductors (ICAMS) between laboratories, universities and industries is therefore launched for the purpose of researching and developing the magnet fusion technology beyond ITER state-of-the-art [8]. One of the key goals of ICAMS is to demonstrate the feasibility and performance verification of a large size MgB 2 PF conductor based on ITER requirements.…”

Section: Introductionmentioning

confidence: 99%

DC performance and AC loss of sub-size MgB₂ CICC conductor for fusion magnet application

Gao¹,

He²,

Ma³

et al. 2022

Nucl. Fusion

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Given the low price and relatively high transition temperature (39 K) of MgB2 conductor, MgB2-based superconductors are a potential candidate for the lower field fusion coils, such as Poloidal Field (PF) coils, Correction Coils (CC) and Feeders. However, to date, the application of MgB2 is limited to demonstrators in a low magnetic field of up to 5 T and at temperatures of up to 10 to 20 K, relying on cryogen-free, helium gas or liquid hydrogen cooling, which significantly reduce the cost of cryogenic systems. To demonstrate the feasibility and performance verification of large size MgB2 PF conductors based on ITER and CFETR requirements, a 4th-stage subsize MgB2 Cable-In-Conduit Conductor (CICC) cable sample is made at the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP). The CICC contains 96 in-situ MgB2 superconducting wires, manufactured by Western Superconducting Technology Ltd. (WST) and 48 copper wires. The critical current of the sub-size cables and MgB2 witness wires are examined with different background magnetic fields at 4.2 K. In addition, the AC loss is measured utilizing magnetization and calorimetric methods. To further clarify the influence of electromagnetic force on the AC loss performance, the cable sample is pressed transversely at room temperature and then inserted into a dipole magnet for AC loss measurement at 4.2 K. The critical current at 4.2 K of the subsize MgB2 CICC cable shows 20% degradation compared to the witness wires at 2 T background magnetic field. However, no further critical current degradation is visible during ramping up and down the magnetic field. The coupling loss time constant for 1 T background magnetic field amounts to 480 ms. No significant effect of the applied transverse stress on the coupling loss is observed between 0 and 10 MPa.

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AC loss and contact resistance of different CICC cable patterns: Experiments and numerical modeling

Cited by 6 publications

References 55 publications

DTT toroidal field conductor samples test in Sultan: DC and AC characterization

DTT toroidal field conductor samples test in Sultan: DC and AC characterization

Alternating Current Loss of Superconductors Applied to Superconducting Electrical Machines

DC performance and AC loss of sub-size MgB₂ CICC conductor for fusion magnet application

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AC loss and contact resistance of different CICC cable patterns: Experiments and numerical modeling

Cited by 6 publications

References 55 publications

DTT toroidal field conductor samples test in Sultan: DC and AC characterization

DTT toroidal field conductor samples test in Sultan: DC and AC characterization

Alternating Current Loss of Superconductors Applied to Superconducting Electrical Machines

DC performance and AC loss of sub-size MgB2 CICC conductor for fusion magnet application

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Product

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DC performance and AC loss of sub-size MgB₂ CICC conductor for fusion magnet application