AC transport current losses of multifilamentary Bi(2223) tapes with varying filament geometries

Eckelmann, H.; Däumling, M.; Quilitz, M.; Goldacker, W.

doi:10.1016/s0921-4534(97)01773-5

Cited by 46 publications

(34 citation statements)

References 30 publications

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“…With these, a direct prove on the magneto-coupling physical mechanism that gives place to the field deformations inside SC-SFM heterostructures, these being observed by magneto optical imaging techniques 39,41,43,69 , has been provided. Likewise, the cause of the intriguing increment in the AC-losses in SC-SFM heterostructures [36][37][38] , is explained as result of the found magneto-steady coupling between the SC and the SFM sheath. Thus, we have proven that the sole coupling between the SC and a SFM sheath is capable to produce a slight rise in the AC-losses at the SC material, even when the SFM does not add any electrical nor magnetic losses to the system.…”

Section: Discussionmentioning

confidence: 99%

“…5. In this sense, we have arrived to a fully analytical solution for the magnetic vector potential and the distribution of the magnetic field inside the SC core of a cylindrical SC-SFM metastructure, it subjected to an AC transport current and under self-field conditions, allowing to demonstrate the physics origin of the deformations of the magnetic field inside the SC observed by magneto optical imaging techniques 39,41,43,69 , and the intriguing increment in the AC-losses as result of the magneto-steady coupling between the SC and the SFM sheath [36][37][38] . The time interval between columns is ∆t = (π/4)ω −1 , such that the dynamics shown between the second column (ωt = 3 * π/2) and last column (ωt = π/2) represents the minimum hysteresis period for the calculation of AC Losses, in accordance with the distribution of profiles of current density shown in Fig.…”

Section: Multipole Expansion Of the Critical State Model In Sc-sfm Romentioning

confidence: 99%

“…However, a direct inclusion of the magnetoestaic coupling between the profiles of current inside a type II superconductor of finite size and the SFM sheath is not directly included, which hinders the actual mechanisms that give rise to an increase of the AC losses inside the SC material by the action of the SFM. In fact, a theoretical explanation for the increment of the AC losses in monocore SC-SFM heterostructures at self-field conditions, i.e., under applied transport current but no external magnetic field, has not been reached for even the simplest configuration of a SC-SFM wire of cylindrical cross section, a problem that has remained open for about two decades [36][37][38] .…”

Section: Introductionmentioning

confidence: 99%

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Why energy lossless ferromagnetic materials can add energy losses onto type-II superconductors?

Fareed

2021

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Understanding the physical coupling between the macroscopic electromagnetic properties of type II superconductors (SC) and soft ferromagnetic materials (SFM), is root for progressing onto the application of SC-SFM metastructures in scenarios such as magnetic cloaking, magnetic shielding, and loss free current transmission systems. However, in the latter case understanding the origin of the rise in the hysteresis losses of the superconductor by effect of the coupling with the SFM has historically resulted in a notable challenge, it because this rise in the AC losses is simply counterintuitive due to the fact that the SFM itself does not add magnetization losses to the system and furthermore, there is no evidence of electrical current sharing between these two materials. Thus, aimed to resolve this long-standing problem, in this paper, we present a semi-analytical model for monocore SC-SFM heterostructures of cylindrical cross-section and self-field conditions, showing the first known map of AC-losses for SC-SFM magnetically shielded wires, with magnetic relative permeabilities for the SFM ranging from mur=5 (NiZn ferrites) to mur =350000 (pure Iron). The distribution of current density and magnetic field inside the SC-SFM metastructure is shown in great detail, revealing a remarkable agreement with the intriguing magneto optical imaging observations that were originally questioning the validness of the critical state theory. In this sense, we have extended the critical state theory within its variational formalism, incorporating a multipole functional approach which allows the direct finding of the coupling terms between a SC current and a SFM sheath, proving that all reported phenomena for the self-filed hysteretic behavior of SC-SFM heterostructures can be understood within the classical critical state model without the need to recur to the ansatz of overcritical currents.

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Section: Discussionmentioning

confidence: 99%

Section: Multipole Expansion Of the Critical State Model In Sc-sfm Romentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Why energy lossless ferromagnetic materials can add energy losses onto type-II superconductors?

Fareed

2021

Preprint

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“…Firstly, demonstrating that the origin of the deformations of the magnetic field inside SC-SFM wires reported by MOI techniques [ 39 , 41 , 43 , 80 ] is a direct consequence of the magneto-steady coupling between the SC and the SFM sheath. Secondly, with our extended CST it will be proven that a straightforward explanation of the intriguing increment in the AC-losses of SC-SFM metastructures [ 36 , 37 , 38 ] can be achieved without the ansatz of overcritical currents.…”

Section: Multipole Expansion Of the Cst In Rounded Sc-sfm Heterostructuresmentioning

confidence: 99%

“…However, a direct involvement of the inductive coupling elements between the profiles of current density in SC wires and finite SFM sheaths is still to be achieved, such that the understanding of the actual physical mechanism that couples their macroscopic magnetic features is not hindered. In fact, a theoretical explanation for the increment of the AC losses in monocore SC-SFM heterostructures at self-field conditions, that is, under applied transport current but no external magnetic field, has not been reached for even the simplest configuration of an SC-SFM wire of a cylindrical cross section, a problem that has remained open for about two decades [ 36 , 37 , 38 ].…”

Section: Introductionmentioning

confidence: 99%

Critical State Theory for the Magnetic Coupling between Soft Ferromagnetic Materials and Type-II Superconductors

Fareed

2021

Materials

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Improving our understanding of the physical coupling between type-II superconductors (SC) and soft ferromagnetic materials (SFM) is the root for progressing to the application of SC-SFM metastructures in scenarios such as magnetic cloaking, magnetic shielding, and power transmission systems. However, in the latter, some intriguing and yet unexplained phenomena occurred, such as a noticeable rise in the SC energy losses, and a local but not isotropic deformation of its magnetic flux density. These phenomena, which are in apparent contradiction with the most fundamental theory of electromagnetism for superconductivity, that is, the critical state theory (CST), have remained unexplained for about 20 years, given the acceptance of the controversial and yet paradigmatic existence of the so-called overcritical current densities. Therefore, aiming to resolve these long-standing problems, we extended the CST by incorporating a semi-analytical model for cylindrical monocore SC-SFM heterostructures, setting the standards for its validation with a variational approach of multipole functionals for the magnetic coupling between Sc and SFM materials. It is accompanied by a comprehensive numerical study for SFM sheaths of arbitrary dimensions and magnetic relative permeabilities μr, ranging from μr=5 (NiZn ferrites) to μr = 350,000 (pure Iron), showing how the AC-losses of the SC-SFM metastructure radically changes as a function of the SC and the SFM radius for μr≥100. Our numerical technique and simulations also revealed a good qualitative agreement with the magneto optical imaging observations that were questioning the CST validness, proving therefore that the reported phenomena for self-field SC-SFM heterostructures can be understood without including the ansatz of overcritical currents.

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Superconducting-magnetic heterostructures as a new method of decreasing transport AC losses in multifilamentary and coated superconductors

Glowacki¹,

Majoroš²,

Rutter³

et al. 2001

Cryogenics

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AC transport current losses of multifilamentary Bi(2223) tapes with varying filament geometries

Cited by 46 publications

References 30 publications

Why energy lossless ferromagnetic materials can add energy losses onto type-II superconductors?

Why energy lossless ferromagnetic materials can add energy losses onto type-II superconductors?

Critical State Theory for the Magnetic Coupling between Soft Ferromagnetic Materials and Type-II Superconductors

Superconducting-magnetic heterostructures as a new method of decreasing transport AC losses in multifilamentary and coated superconductors

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