Voltage response of current carrying Y–Ba–Cu–O tapes to alternating magnetic fields

Uksusman, A.; Wolfus, Y.; Friedman, A.; Shaulov, A.; Yeshurun, Y.

doi:10.1063/1.3125318

Cited by 45 publications

(39 citation statements)

References 19 publications

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“…Additionally, the change in applied field will generate a loss, which can be considered as an equivalent AC loss resistance [22] or dynamic resistance [14,[23][24][25][26][27][28]:…”

Section: Influential Factors On Branch Resistancesmentioning

confidence: 99%

Origin of dc voltage in type II superconducting flux pumps: field, field rate of change, and current density dependence of resistivity

Geng¹,

Matsuda²,

Fu³

et al. 2016

J. Phys. D: Appl. Phys.

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Superconducting flux pumps are the kind of devices which can generate direct current into superconducting circuit using external magnetic field. The key point is how to induce a DC voltage across the superconducting load by AC fields. Giaever [1] pointed out flux motion in superconductors will induce a DC voltage, and demonstrated a rectifier model which depended on breaking superconductivity. Klundert et al. [2, 3] in their review(s) described various configurations for flux pumps all of which relied on inducing the normal state in at least part of the superconductor. In this letter, following their work, we reveal that a variation in the resistivity of type II superconductors is sufficient to induce a DC voltage in flux pumps and it is not necessary to break superconductivity. This variation in resistivity is due to the fact that flux flow is influenced by current density, field intensity, and field rate of change. We propose a general circuit analogy for travelling wave flux pumps, and provide a mathematical analysis to explain the DC voltage. Several existing superconducting flux pumps which rely on the use of a travelling magnetic wave can be explained using the analysis enclosed. This work can also throw light on the design and optimization of flux pumps.

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“…Additionally, the change in applied field will generate a loss, which can be considered as an equivalent AC loss resistance [22] or dynamic resistance [14,[23][24][25][26][27][28]:…”

Section: Influential Factors On Branch Resistancesmentioning

confidence: 99%

Origin of dc voltage in type II superconducting flux pumps: field, field rate of change, and current density dependence of resistivity

Geng¹,

Matsuda²,

Fu³

et al. 2016

J. Phys. D: Appl. Phys.

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“…1 is that if more flux enters the film from one edge than that leaves the same edge, a dc open circuit voltage will appear. For a CC transporting a current I, when it is under a perpendicular ac field, two kinds of flux motion occur 4,10 . When I«I c , the pinning energy 21 is large so the flux motion is mainly caused by the interaction between the ac field and transport current I, i.e.…”

mentioning

confidence: 99%

“…When I«I c , the pinning energy 21 is large so the flux motion is mainly caused by the interaction between the ac field and transport current I, i.e. dynamic resistance [1][2][3][4][5][6][7][8][9][10] ; whereas when I approaches or exceed I c , the pinning energy becomes low, the superconductor will be in flux flow region. Therefore, we propose the following model to explain the result (Fig.…”

mentioning

confidence: 99%

Voltage-ampere characteristics of YBCO coated conductor under inhomogeneous oscillating magnetic field

Geng

Shen

et al. 2016

Applied Physics Letters

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Direct current carrying type II superconductors present a dynamic resistance when subjected to an oscillating magnetic field perpendicular to the current direction. If a superconductor is under a homogeneous field with high magnitude, the dynamic resistance value is nearly independent of transport current. Hoffmann and coworkers [C. Hoffmann, D. Pooke, and A. D. Caplin, IEEE Trans. Appl. Supercond. 21, 1628 (2011)] discovered, however, flux pumping effect when a superconducting tape is under an inhomogeneous field orthogonal to the tape surface generated by rotating magnets. Following their work, we report the whole Voltage-Ampere (V-I) curves of an YBCO coated conductor under permanent magnets rotating with different frequencies and directions. We discovered that the two curves under opposite rotating directions differ from each other constantly when the transport current is less than the critical current, whereas the difference gradually reduces after the transport current exceeds the critical value. We also find that for different field frequencies, the difference between the two curves decreases faster with lower field frequency. The result indicates that the transport loss is dependent on the relative direction of the transport current and field travelling, which is distinct from traditional dynamic resistance model. The work may be instructive for the design of superconducting motors. It is well known that type II superconductors carrying a direct current present a resistance when they are under a perpendicular oscillating magnetic field. 1-10 Theoretical analysis 1,3,7,8 and experimental results 1-7,10 have shown that this resistance is due to flux flow caused by the interaction between the transport current and the applied field, and it is defined as dynamic resistance. The dynamic resistance value is proportional to the applied field magnitude and frequency if the superconductor in a homogeneous field, and it is nearly independent of transport current if the field magnitude is high. 7 Hoffmann and coworkers 11 discovered flux pumping effect when a piece of superconducting stator connecting to a superconducting load was subjected to inhomogeneous magnetic fields orthogonal to the tape surface generated by rotating permanent magnets. Researchers from VUW 12 pointed out that dynamic resistance is the main limiting factor of saturation current in the flux pump. Concerning the open circuit voltage, they proposed a geometrical explanation considering screening current. 13 All these existing researches 11-13 focus on the flux pumping effect, where the superconducting stator generates dc power. In this letter, we extend the research to the V-I characteristics of YBCO Coated Conductor (CC) under rotating permanent magnets. The experimental system is shown in Fig. 1(a), which is similar to rotating magnets flux pumps 11-15. Eight Neodymium 52 magnets with a diameter of 20mm are uniformly mounted on a round copper disc. The outer diameter of the disc is about 81mm. All magnets were mounted with their north poles fa...

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“…[43] is solving the field profile and the dependencies on the amplitude of the AC magnetic field, no numerical results or explicit derivations were reported for the I-V curves. AC losses measurements [44] in strong pinning YBCO superconductors also display an ohmic behavior above a threshold in current. Although the asymmetry in the Bean profile is different from the pulsed-field case, we find similar values of the effective resistance using the model we present here.…”

Section: Discussionmentioning

confidence: 94%

Dynamics and Critical Currents in Fast Superconducting Vortices at High pulsed Magnetic Fields

et al. 2019

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Non-linear electrical transport studies at high-pulsed magnetic fields, above the range accessible by DC magnets, are of direct fundamental relevance to the physics of superconductors, domain-wall, charge-density waves, and topological semi-metal. All-superconducting very-high field magnets also make it technologically relevant to study vortex matter in this regime. However, pulsed magnetic fields reaching 100 T in milliseconds impose technical and fundamental challenges that have prevented the realization of these studies. Here, we present a technique for sub-microsecond, smart, current-voltage measurements, which enables determining the superconducting critical current in pulsed magnetic fields, beyond the reach of any DC magnet. We demonstrate the excellent agreement of this technique with low DC field measurements on Y 0.77 Gd 0.23 Ba 2 Cu 3 O 7 coated conductors with and without BaHfO 3 nanoparticles. Exploring the uncharted high magnetic field region, we discover a characteristic influence of the magnetic field rate of change (dH/dt) on the current-voltage curves in a superconductor. We fully capture this unexplored vortex physics through a theoretical model based on the asymmetry of the vortex velocity profile produced by the applied current. arXiv:1903.04658v2 [cond-mat.supr-con]

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Voltage response of current carrying Y–Ba–Cu–O tapes to alternating magnetic fields

Cited by 45 publications

References 19 publications

Origin of dc voltage in type II superconducting flux pumps: field, field rate of change, and current density dependence of resistivity

Origin of dc voltage in type II superconducting flux pumps: field, field rate of change, and current density dependence of resistivity

Voltage-ampere characteristics of YBCO coated conductor under inhomogeneous oscillating magnetic field

Dynamics and Critical Currents in Fast Superconducting Vortices at High pulsed Magnetic Fields

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