AC losses in composite superconducting wires

Salmon, D R; Catterall, J. A.

doi:10.1088/0022-3727/3/7/305

Cited by 21 publications

(8 citation statements)

References 13 publications

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“…This proves that in self-field conditions, the filaments in (BiPb) 2 Sr 2 Ca 2 Cu 3 O 9 and YBa 2 Cu 3 O 7 tapes are still magnetically coupled. The same is valid also for self-field losses in classical low-T c superconductors [26].…”

Section: (Bipb) 2 Sr 2 Ca 2 Cu 3 O 9 Conductorsmentioning

confidence: 59%

“…It was found experimentally that while most of the methods of decreasing the AC losses in (BiPb) 2 Sr 2 Ca 2 Cu 3 O 9 (Bi-2223) and YBa 2 Cu 3 O 7 tapes exposed to an external AC magnetic field [22][23][24] are successful, they are not effective in decreasing the transport AC losses, i.e. the self-field losses [26]. The self-field losses of (BiPb) 2 Sr 2 Ca 2 Cu 3 O 9 and YBa 2 Cu 3 O 7 tapes, regardless of whether they have a high resistivity matrix, oxide barriers around the filaments or twisted filaments, still scale with the theoretical relations for a monocore superconductor [24,25].…”

Section: (Bipb) 2 Sr 2 Ca 2 Cu 3 O 9 Conductorsmentioning

confidence: 99%

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Superconducting–magnetic heterostructures: a method of decreasing AC losses and improving critical current density in multifilamentary conductors

Glowacki

Majoroš

2009

J. Phys.: Condens. Matter

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Magnetic materials can help to improve the performance of practical superconductors on the macroscale/microscale as magnetic diverters and also on the nanoscale as effective pinning centres. It has been established by numerical modelling that magnetic shielding of the filaments reduces AC losses in self-field conditions due to decoupling of the filaments and, at the same time, it increases the critical current of the composite. This effect is especially beneficial for coated conductors, in which the anisotropic properties of the superconductor are amplified by the conductor architecture. However, ferromagnetic coatings are often chemically incompatible with YBa(2)Cu(3)O(7) and (Pb,Bi)(2)Sr(2)Ca(2)Cu(3)O(9) conductors, and buffer layers have to be used. In contrast, in MgB(2) conductors an iron matrix may remain in direct contact with the superconducting core. The application of superconducting-magnetic heterostructures requires consideration of the thermal and electromagnetic stability of the superconducting materials used. On one hand, magnetic materials reduce the critical current gradient across the individual filaments but, on the other hand, they often reduce the thermal conductivity between the superconducting core and the cryogen, which may cause destruction of the conductor in the event of thermal instability. A possible nanoscale method of improving the critical current density of superconducting conductors is the introduction of sub-micron magnetic pinning centres. However, the volumetric density and chemical compatibility of magnetic inclusions has to be controlled to avoid suppression of the superconducting properties.

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Section: (Bipb) 2 Sr 2 Ca 2 Cu 3 O 9 Conductorsmentioning

confidence: 59%

Section: (Bipb) 2 Sr 2 Ca 2 Cu 3 O 9 Conductorsmentioning

confidence: 99%

Superconducting–magnetic heterostructures: a method of decreasing AC losses and improving critical current density in multifilamentary conductors

Glowacki

Majoroš

2009

J. Phys.: Condens. Matter

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show abstract

“…This proves that, in self-field conditions, the filaments in (BiPb) 2 Sr 2 Ca 2 Cu 3 O 9 and YBa 2 Cu 3 O 7 tapes are still magnetically coupled. The same is also valid for self-field losses in classical low-T c superconductors [26]. To decouple the filaments, quite a large separation is needed, much larger than the filament diameters [27][28][29].…”

Section: (Bipb) 2 Sr 2 Ca 2 Cu 3 O 9 Conductorsmentioning

confidence: 82%

“…It was found experimentally that, while most of the methods of decreasing ac losses in (BiPb) 2 Sr 2 Ca 2 Cu 3 O 9 (Bi-2223) and YBa 2 Cu 3 O 7 tapes exposed to an external ac magnetic field [22][23][24] are successful, they are not effective in decreasing the transport ac losses, i.e. the self-field losses [26]. The self-field losses of (BiPb) 2 Sr 2 Ca 2 Cu 3 O 9 and YBa 2 Cu 3 O 7 tapes, regardless of whether they have a high resistivity matrix, oxide barriers around the filaments or twisted filaments, still scale with the theoretical relations for a monocore superconductor [24,25].…”

Section: (Bipb) 2 Sr 2 Ca 2 Cu 3 O 9 Conductorsmentioning

confidence: 99%

Influence of magnetic materials on the transport properties of superconducting composite conductors

Glowacki

Majoroš

Campbell

et al. 2009

Supercond. Sci. Technol.

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Magnetic materials can help to improve the performance of practical superconductors on the macro/microscale as magnetic diverters and also on the nanoscale as effective pinning centres. It has been established by numerical modelling that magnetic shielding of the filaments reduces ac losses in self-field conditions due to decoupling of the filaments and, at the same time, it increases the critical current of the composite. This effect is especially beneficial for coated conductors, in which the anisotropic properties of the superconductor are amplified by the conductor architecture. However, ferromagnetic coatings are often chemically incompatible with YBa 2 Cu 3 O 7 and (Pb, Bi) 2 Sr 2 Ca 2 Cu 3 O 9 conductors, and buffer layers have to be used. In contrast, in MgB 2 conductors an iron matrix may remain in direct contact with the superconducting core. The application of superconducting-magnetic heterostructures requires consideration of the thermal and electromagnetic stability of the superconducting materials used. On the one hand, magnetic components reduce the critical current gradient across the individual filaments but, on the other hand, they often reduce the thermal conductivity between the superconducting core and the cryogen, which may cause the destruction of the conductor in the event of thermal instability. A possible nanoscale method of improving the critical current density of superconducting conductors is the introduction of sub-micron magnetic pinning centres. However, the volumetric density and chemical compatibility of magnetic inclusions has to be controlled to avoid suppression of the superconducting properties.

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“…The energy losses per cycle at 4.2 K were measured by techniques described previously (Salmon and Catterall 1970). The losses as a function of the RMS current and the corresponding peak surface field are shown in figure 1 for four specimens annealed at various temperatures.…”

Section: Resultsmentioning

confidence: 99%

AC losses at 4$middot$2 K in heat-treated niobium wire

Salmon¹,

Catterall²

1973

J. Phys. D: Appl. Phys.

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Samples of heavily worked, cold-drawn niobium wire were heat-treated at temperatures between 200 and 700°C to produce changes in the magnetization behaviour of the material. An investigation was then carried out to determine the influence of these changes on the AC power losses produced in the wires at 4·2 K due to 50Hz transport currents of up to 120 A. The results show that the power losses at a particular current increase as the field of initial penetration into the niobium, Hp, decreases.

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AC losses in composite superconducting wires

Cited by 21 publications

References 13 publications

Superconducting–magnetic heterostructures: a method of decreasing AC losses and improving critical current density in multifilamentary conductors

Superconducting–magnetic heterostructures: a method of decreasing AC losses and improving critical current density in multifilamentary conductors

Influence of magnetic materials on the transport properties of superconducting composite conductors

AC losses at 4$middot$2 K in heat-treated niobium wire

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