Total AC loss measurements in a six strand Roebel cable carrying an AC current in an AC magnetic field

Jiang, Zhenan; Komeda, Takashi; Amemiya, Naoyuki; Long, N.J.; Staines, M.P.; Badcock, Rodney A.; Bumby, Chris W.; Buckley, R. G.

doi:10.1088/0953-2048/26/3/035014

Cited by 20 publications

(12 citation statements)

References 37 publications

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“…In the limiting case i→0, this occurs at the maxima of the normalised hysteretic ac magnetisation loss. Figure 2c shows example plots of these curves for a slab and strip of equal width, calculated using the slab model [19], and the Brandt and Indenbom model [17,25] respectively. This approach provides a well-defined unambiguous value for the effective penetration field of the strip, p,⊥ , which describes the point at which the shielding current capacity of the strip is effectively saturated [12,26,27].…”

Section: Introductionmentioning

confidence: 99%

Dynamic resistance of a high-T c coated conductor wire in a perpendicular magnetic field at 77 K

Jiang¹,

Toyomoto²,

Amemiya³

et al. 2021

Preprint

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Superconducting high-Tc coated conductor (CC) wires comprise a ceramic thin film with a large aspect ratio. This geometry can lead to significant dissipative losses when exposed to an alternating magnetic field. Here we report experimental measurements of the 'dynamic resistance' of commercially available SuperPower and Fujikura CC wires in an AC perpendicular field. The onset of dynamic resistance occurs at a threshold field amplitude, which is determined by the total DC transport current and the penetration field of the conductor. We show that the field-dependence of the normalised magnetisation loss provides an unambiguous value for this threshold field at zero transport current. From this insight we then obtain an expression for the dynamic resistance in perpendicular field. This approach implies a linear relationship between dynamic resistance and applied field amplitude, and also between threshold field and transport current and this is consistent with our experimental data. The analytical expression obtained yields values that closely agree with measurements obtained across a wide range of frequencies and transport currents, and for multiple CC wires produced by different wire manufacturers and with significantly differing dimensions and critical currents. We further show that at high transport currents, the measured DC resistance includes an additional nonlinear term which is due to flux-flow resistance incurred by the DC transport current. This occurs once the field-dependent critical current of the wire falls below the DC transport current for part of each field cycle. Our results provide an effective and simple approach to calculating the dynamic resistance of a CC wire, at current and field magnitudes consistent with those expected in superconducting machines. This is the Accepted Manuscript version of an article accepted for publication in 'Superconductor Science and Technology'. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at https://doi.org/10.1088/1361-6668/aa54e5.

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Section: Introductionmentioning

confidence: 99%

Dynamic resistance of a high-T c coated conductor wire in a perpendicular magnetic field at 77 K

Jiang¹,

Toyomoto²,

Amemiya³

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…In the limiting case i→0, this occurs at the maxima of the normalised hysteretic ac magnetisation loss. Figure 2(c) shows example plots of these curves for a slab and strip of equal width, calculated using the slab model [19], and the Brandt and Indenbom model [17,25] respectively. This approach provides a welldefined unambiguous value for the effective penetration field of the strip, B , p, which describes the point at which the shielding current capacity of the strip is effectively saturated [12,26,27].…”

Section: Introductionmentioning

confidence: 99%

Dynamic resistance of a high-T_ccoated conductor wire in a perpendicular magnetic field at 77 K

Jiang

Toyomoto

Amemiya

et al. 2017

Supercond. Sci. Technol.

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102

127

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Superconducting high-Tc coated conductor (CC) wires comprise a ceramic thin film with a large aspect ratio. This geometry can lead to significant dissipative losses when exposed to an alternating magnetic field. Here we report experimental measurements of the 'dynamic resistance' of commercially available SuperPower and Fujikura CC wires in an AC perpendicular field. The onset of dynamic resistance occurs at a threshold field amplitude, which is determined by the total DC transport current and the penetration field of the conductor. We show that the field-dependence of the normalised magnetisation loss provides an unambiguous value for this threshold field at zero transport current. From this insight we then obtain an expression for the dynamic resistance in perpendicular field. This approach implies a linear relationship between dynamic resistance and applied field amplitude, and also between threshold field and transport current and this is consistent with our experimental data. The analytical expression obtained yields values that closely agree with measurements obtained across a wide range of frequencies and transport currents, and for multiple CC wires produced by different wire manufacturers and with significantly differing dimensions and critical currents. We further show that at high transport currents, the measured DC resistance includes an additional non-linear term which is due to flux-flow resistance incurred by the DC transport current. This occurs once the field-dependent critical current of the wire falls below the DC transport current for part of each field cycle. Our results provide an effective and simple approach to calculating the dynamic resistance of a coated conductor wire, at current and field magnitudes consistent with those expected in superconducting machines.

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“…While the potential for high current and the strong flux pinning in high magnetic fields favor the YBCO 2G coated conductors, the effectiveness of current homogenization and magnetization reduction by strand uncoupling using Roebel transposition remains to be optimized and verified. While there have been a number of experimental studies [6][7][8][12][13] on the ac loss in Roebel cables, their scopes have been limited to 77 K. The published results are not quite sufficient for the accelerator applications, in particular for quantifying strand coupling and identifying the transposition effects.…”

Section: Introductionmentioning

confidence: 99%

Magnetization Losses of Roebel Cable Samples With 2G YBCO Coated Conductor Strands

Yang¹,

Pelegrin²,

Falorio³

et al. 2016

IEEE Trans. Appl. Supercond.

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Abstract-Roebel cable with 2G YBCO strands is one of the promising HTS solutions of fully transposed high current conductors for high field accelerator magnets. Following the considerable research effort on the manufacturing of Roebel cables in recent years, sample conductors are now available in useful lengths with reproducible performances to allow detailed characterizations beyond the standard critical current measurements. The ac loss and strands coupling are of significant interest for the field quality of the accelerator magnets. We report a set of systematic ac loss measurements on two different Roebel cable samples prepared for the EuCARD2 collaboration. The measurements were performed over a wide range of temperature between 5 K and 90 K and the results were analyzed in the context of strands architecture and coupling. The results show that the transposed bundles are partially decoupled and the strands in transposition sections behave as an isolated single tape if the strands are insulated. 

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Total AC loss measurements in a six strand Roebel cable carrying an AC current in an AC magnetic field

Cited by 20 publications

References 37 publications

Dynamic resistance of a high-T c coated conductor wire in a perpendicular magnetic field at 77 K

Dynamic resistance of a high-T c coated conductor wire in a perpendicular magnetic field at 77 K

Dynamic resistance of a high-T_ccoated conductor wire in a perpendicular magnetic field at 77 K

Magnetization Losses of Roebel Cable Samples With 2G YBCO Coated Conductor Strands

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Total AC loss measurements in a six strand Roebel cable carrying an AC current in an AC magnetic field

Cited by 20 publications

References 37 publications

Dynamic resistance of a high-T c coated conductor wire in a perpendicular magnetic field at 77 K

Dynamic resistance of a high-T c coated conductor wire in a perpendicular magnetic field at 77 K

Dynamic resistance of a high-Tccoated conductor wire in a perpendicular magnetic field at 77 K

Magnetization Losses of Roebel Cable Samples With 2G YBCO Coated Conductor Strands

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Dynamic resistance of a high-T_ccoated conductor wire in a perpendicular magnetic field at 77 K