AC TRANSPORT CURRENT AND APPLIED MAGNETIC FIELD LOSSES IN MgB[sub 2] MULTIFILAMENTARY STRANDS WITH NON-MAGNETIC SHEATH MATERIALS

Majoroš, M.; Bhatia, M.; Sumption, M.D.; Kawabata, S.; Tomsic, M.; Rindfleisch, M.; Collings, E. W.

doi:10.1063/1.2900372

Cited by 5 publications

(8 citation statements)

References 6 publications

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“…The losses by the metallic matrix are due to the strength and change of the magnetic field created by the AC in the MgB filaments, whilst the filament losses are due to the and the self- and mutually-induced magnetization currents appearing in type-II superconductors 53 – 56 . Same happens if other materials with higher thermal conductivity and tensile properties are used for the barrier and outer sheath, such as Nb-Ti, Cu-Nb, or Monel alloys 79 , 80 , as they have an almost negligible impact on the total losses of the SC wire 58 – 60 , 81 , 82 . Therefore, the key for achieving a true reduction of the AC-losses lies on finding how to simultaneously lower the magnetically induced currents in the SC filaments, whilst reducing the eddy currents at its metallic matrix.…”

Section: Possible Alternatives For the Reduction Of Energy Losses In ...mentioning

confidence: 99%

“… *Material properties of the Monocore and Multicore wires from 59 , 60 , respectively . and define the thickness and electrical resistivity of the material.…”

Section: Possible Alternatives For the Reduction Of Energy Losses In ...mentioning

confidence: 99%

“…The monocore and the multicore designs have been used as benchmark (right-insets at Fig. 1 ), as the experimental measurement of their AC-losses is known 59 , 60 . Ergo, for reproducing these experiments we have used the so-called H-formulation 64 , 65 , with our results shown as colour solid lines in Fig.…”

Section: Possible Alternatives For the Reduction Of Energy Losses In ...mentioning

confidence: 99%

“…

Figure 1 Calculated AC-losses for the MgB monocore and multicore wires shown at the right-pane inset. Solid symbols correspond to the experimental measurements at 26.4 K for the monocore wire 59 , and 4.2 K for the six filaments multifilamentary (multicore) wire 60 . …”

Section: Possible Alternatives For the Reduction Of Energy Losses In ...mentioning

confidence: 99%

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Maximum reduction of energy losses in multicore MgB2 wires by metastructured soft-ferromagnetic coatings

Kapolka

2022

Sci Rep

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When compared with rare-earth coated conductors, magnesium diboride superconducting cables are known to show significant advantages by cost and easy production. However, the inherent difficulty for achieving a significant reduction of their magnetization losses in multifilamentary wires, without degrading the high critical current density that is so characteristic of the monowire, is considered as one of the major drawbacks for their practical use in high power density applications. Being this one of the major markets for superconducting cables, from fundamental principles and computational optimization techniques, in this paper we demonstrate how the embedding of the superconducting filaments into soft-ferromagnetic metastructures can render to their full magnetic decoupling, and therefore, to the maximum reduction of the energy losses that can be achieved without deteriorate the critical current density of the cable. The designed multifilamentary metastructure is made of NbTi coated MgB2 superconducting filaments in a Cu-matrix, serving as a reference for validating our model with actual experimental measurements in monowires and multifilamentary wires. The novelty in our computationally aided multifilamentary wires, is that each one of the filaments is embedded within a thin metastructure made of a soft-ferromagnetic layer and a resistive layer. We have found that for soft-ferromagnetic layers with magnetic permeabilities in the range of $$\mu _{r}=$$ μ r = 20–100, nearly a full magnetic decoupling between the superconducting filaments can be achieved, leading to efficiencies higher than $$92\%$$ 92 % , and an overall reduction of the AC-losses (including eddy currents at the Cu-matrix) higher than $$50\%$$ 50 % .

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Section: Possible Alternatives For the Reduction Of Energy Losses In ...mentioning

confidence: 99%

“… *Material properties of the Monocore and Multicore wires from 59 , 60 , respectively . and define the thickness and electrical resistivity of the material.…”

Section: Possible Alternatives For the Reduction Of Energy Losses In ...mentioning

confidence: 99%

Section: Possible Alternatives For the Reduction Of Energy Losses In ...mentioning

confidence: 99%

“…

Section: Possible Alternatives For the Reduction Of Energy Losses In ...mentioning

confidence: 99%

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Maximum reduction of energy losses in multicore MgB2 wires by metastructured soft-ferromagnetic coatings

Kapolka

2022

Sci Rep

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“…The scope of this paper is to determine the total transport losses generated by the tape sample that come primarily from the MgB 2 filaments, sheath material and matrix elements (stabilizer and barrier). Usually in the case of a transport current the AC losses are driven by the magnetic field associated with the transport current, and for high resistivity matrices and sheath material the loss contribution from eddy currents is small and can be neglected [9,10]. However, in certain circumstances and wire architectures, losses from the magnetic sheath or barrier are significant and could dominate the loss behavior of the conductor.…”

Section: Introductionmentioning

confidence: 99%

Calorimetric AC loss measurement of MgB₂superconducting tape in an alternating transport current and direct magnetic field

See

Horvat

et al. 2012

Supercond. Sci. Technol.

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Applications of MgB 2 superconductors in electrical engineering have been widely reported, and various studies have been made to define their alternating current (AC) losses. However, studies on the transport losses with an applied transverse DC magnetic field have not been conducted, even though this is one of the favored conditions in applications of practical MgB 2 tapes. Methods and techniques used to characterize and measure these losses have so far been grouped into 'electrical' and 'calorimetric' approaches with external conditions set to resemble the application conditions. In this paper, we present a new approach to mounting the sample and employ the calorimetric method to accurately determine the losses in the concurrent application of AC transport current and DC magnetic fields that are likely to be experienced in practical devices such as generators and motors. This technique provides great simplification compared to the pickup coil and lock-in amplifier methods and is applied to a long length (∼10 cm) superconducting tape. The AC loss data at 20 and 30 K will be presented in an applied transport current of 50 Hz under external DC magnetic fields. The results are found to be higher than the theoretical predictions because of the metallic fraction of the tape that contributes quite significantly to the total losses. The data, however, will allow minimization of losses in practical MgB 2 coils and will be used in the verification of numerical coil models.

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AC losses in monofilamentary MgB₂round wire carrying alternating transport currents

Komori

Kawano

Osaka

et al. 2010

Supercond. Sci. Technol.

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AC losses in a monofilamentary MgB 2 round wire with niobium and copper metal sheaths and carrying alternating transport currents are evaluated at several temperatures and frequencies. First, the transport current losses are observed electrically using a lock-in amplifier. Experimental results show that the AC losses decrease with an increase in the temperature if the amplitude of the transport current normalized by the corresponding critical current is maintained constant. On the other hand, the AC losses increase slightly with the frequency. Next, the AC losses are calculated numerically by a finite difference method. The numerical results for the superconductor filament show a good agreement with the results of the conventional theoretical expression formulated using the Bean model over a wide range of current amplitudes. It is also found that the AC losses in the niobium sheath are negligible whereas those in the copper sheath are comparable with those in the superconductor. On the basis of the numerical calculations, an expression is analytically derived for estimating the eddy current loss occurring in a metal sheath. The derived expression well reproduces the AC loss properties of both the copper and niobium sheaths.

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AC TRANSPORT CURRENT AND APPLIED MAGNETIC FIELD LOSSES IN MgB[sub 2] MULTIFILAMENTARY STRANDS WITH NON-MAGNETIC SHEATH MATERIALS

Cited by 5 publications

References 6 publications

Maximum reduction of energy losses in multicore MgB2 wires by metastructured soft-ferromagnetic coatings

Maximum reduction of energy losses in multicore MgB2 wires by metastructured soft-ferromagnetic coatings

Calorimetric AC loss measurement of MgB₂superconducting tape in an alternating transport current and direct magnetic field

AC losses in monofilamentary MgB₂round wire carrying alternating transport currents

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AC TRANSPORT CURRENT AND APPLIED MAGNETIC FIELD LOSSES IN MgB[sub 2] MULTIFILAMENTARY STRANDS WITH NON-MAGNETIC SHEATH MATERIALS

Cited by 5 publications

References 6 publications

Maximum reduction of energy losses in multicore MgB2 wires by metastructured soft-ferromagnetic coatings

Maximum reduction of energy losses in multicore MgB2 wires by metastructured soft-ferromagnetic coatings

Calorimetric AC loss measurement of MgB2superconducting tape in an alternating transport current and direct magnetic field

AC losses in monofilamentary MgB2round wire carrying alternating transport currents

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Product

Resources

About

Calorimetric AC loss measurement of MgB₂superconducting tape in an alternating transport current and direct magnetic field

AC losses in monofilamentary MgB₂round wire carrying alternating transport currents