A Consistent Description of Scaling Law for Flux Pinning in&lt;tex&gt;$rm Nb_3rm Sn$&lt;/tex&gt;Strands Based on the Kramer Model

Oh, Sangjun; Kim, Keeman

doi:10.1109/tasc.2006.871303

Cited by 6 publications

(16 citation statements)

References 11 publications

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“…Although this cannot be ruled out, it can be argued that the required change in pinning efficiency of at least a factor of 2 over the relevant strain regime (below 1% axial strain) [7,70] is unrealistically large. A more reasonable approach, in our opinion, is to assume that the main effect of strain is a modification of the electron-phonon interaction spectrum, which is supported by recent calculations [11,12,[24][25][26]. This will obviously directly change T c , H c2 and H c and thus κ 1 .…”

Section: Introductionmentioning

confidence: 90%

“…It is thus not suitable for precise extrapolations of measured results across a wide range. These deficiencies are generally recognized and lead to continuing discussions in the literature on improvements [2][3][4][5][6][7][8][9][10][11][12]. Presently, much of the interpretation of measured results and ensuing discussions remain largely empirical and the proposed relations depend, for a significant part, on the initial assumptions.…”

Section: Introductionmentioning

confidence: 99%

“…Presently, much of the interpretation of measured results and ensuing discussions remain largely empirical and the proposed relations depend, for a significant part, on the initial assumptions. A notable exception is the recent work by Oh and Kim [11,12], who use Eliashberg theory [13,14] in their attempt to arrive at a better founded scaling formalism.…”

Section: Introductionmentioning

confidence: 99%

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A general scaling relation for the critical current density in Nb₃Sn

Godeke

Haken

Kate

et al. 2006

Supercond. Sci. Technol.

183

180

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We review the scaling relations for the critical current density (J c ) in Nb 3 Sn wires and include recent findings on the variation of the upper critical field (H c2 ) with temperature (T ) and A15 composition. Measurements of H c2 (T ) in inevitably inhomogeneous wires, as well as analysis of literature results, have shown that all available H c2 (T ) data can be accurately described by a single relation from the microscopic theory. This relation also holds for inhomogeneity averaged, effective, H * c2 (T ) results and can be approximated byimplies that also J c (T ) is known. We highlight deficiencies in the Summers/Ekin relations, which are not able to account for the correct J c (T ) dependence. Available J c (H) results indicate that the magnetic field dependence for all wires from µ 0 H ∼ = 1 T up to about 80% of the maximum H c2 can be described with Kramer's flux shear model, if non-linearities in Kramer plots when approaching the maximum H c2 are attributed to A15 inhomogeneities. The strain (ǫ) dependence is introduced through a temperature and strain dependent H * c2 (T, ǫ) and Ginzburg-Landau parameter κ 1 (T, ǫ) and a strain dependent critical temperature T c (ǫ). This is more consistent than the usual Ekin unification of strain and temperature dependence, which uses two separate and different dependencies on H * c2 (T ) and H * c2 (ǫ). Using a correct temperature dependence and accounting for the A15 inhomogeneities leads to the remarkable simple relation J c (H, T, ǫwhere C is a constant, s(ǫ) represents the normalized strain dependence of H * c2 (0) and h = H/H * c2 (T, ǫ). Finally, a new relation for s(ǫ) is proposed, which is an asymmetric version of our earlier deviatoric strain model and based on the first, second and third strain invariants. The new scaling relation solves a number of much debated issues with respect to J c scaling in Nb 3 Sn and is therefore of importance to the applied community, who use scaling relations to analyze magnet performance from wire results.

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Section: Introductionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A general scaling relation for the critical current density in Nb₃Sn

Godeke

Haken

Kate

et al. 2006

Supercond. Sci. Technol.

183

180

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“…11(b). This is a pretty clear result because the magnitude of F p,max is largely proportional to the K s , and this temperature dependency of K s is related to the rigidity of the vortex lines [63,65]. Fig.…”

Section: Mgb 2 Columnar Thick Filmsmentioning

confidence: 74%

“…Fig. 13(a) presents the reduced field dependence of the flux pinning force densities normalized to the parameter K s at temperature of 5, 10, 20, 30, and 35 K. The scaling behavior is fairly fixed up to a temperature of 20 K, but the maximum size of F p /K s is slightly depressed at 30 and 35 K, which is due to the mean pinning strength, K p = K s (1 -b peak ) 4 being less than the values of the K s [63,65]. However, the pinning force behaviors were saturated at high fields of b ≥ 0.4, indicating the dominance of a single pinning mechanism in the MB-300nm due to strong pinning sites, such as the columnar grain boundaries, despite the reduction of their effectiveness at high temperatures.…”

Section: Mgb 2 Columnar Thick Filmsmentioning

confidence: 94%

A review on the understanding and fabrication advancement of MgB₂thin and thick films by HPCVD

Ranot¹,

Duong²,

Bhardwaj³

et al. 2015

Progress in Superconductivity and Cryogenics

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MgB 2 thin films with superior superconducting properties are very promising for superconducting magnets, electronic devices and coated conductor electric power applications. A clear understanding of flux pinning mechanism in MgB 2 films could be a big aid in improving the performance of MgB 2 by the enhancement of J c . The fabrication advancement and the understanding of flux pinning mechanism of MgB 2 thin and thick films fabricated by using hybrid physical-chemical vapor deposition (HPCVD) are reviewed. The distinct kind of MgB 2 films, such as single-crystal like MgB 2 thin films, MgB 2 epitaxial columnar thick films, and a-axis-oriented MgB 2 films are included for flux pinning mechanism investigation. Various attempts made by researchers to improve further the flux pinning property and J c performance by means of doping in MgB 2 thin films by using HPCVD are also summarized.Keywords: MgB2 thin and thick films, HPCVD, flux pinning mechanism * Corresponding author: email: wnkang@skku.edu A review on the understanding and fabrication advancement of MgB2 thin and thick films by HPCVD CCs showed self-field J c values of the order of 10 7 A/cm 2 at 5 K as high as already obtained in MgB 2 thin films, however, J c decreases in response to an applied magnetic field [31,32]. Therefore, a complete understanding of the flux pinning mechanism could be a big aid in improving the performance of MgB 2 by the enhancement of J c , which is most important parameter in practical applications for an operation with low noise and lower power loss. The epitaxial MgB 2 thin films with uniform orientation of grains provide an ideal condition for investigating the vortex dynamics and flux pinning properties, in contrast to MgB 2 bulk system where grains are randomly orientated. In this article, we review the progress made in the last 14 years for the fabrication, understanding of flux pinning mechanism, and for improving the performance by doping in MgB 2 epitaxial thin and thick films by using HPCVD technique.

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Relation between the critical current and the n value of ReBCO thin films: A scaling law for flux pinning of ReBCO thin films

Choi

Lee

et al. 2007

Journal of Applied Physics

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Detailed field and angle dependencies of the critical current and the n value for a SmBCO coated conductor have been measured. It was found that the field dependence of the n value can be fitted by an empirical power law with three parameters including the irreversibility field. We also found that there is a correlation between the critical current and the n value which can be described by the Kramer model including thermal activation. The model fits the field dependence of the empirical critical current data at various angles and temperatures with three fitting parameters, the pinning force maximum, the g factor, and the upper critical field. The upper critical field found from fitting was higher than the irreversibility field, and the angular dependence of the upper critical field is in agreement with the Tinkham model. The pinning force maxima do not show a correlation with the upper critical or the irreversibility fields, which is attributed to the difference in the pinning mechanism with a variation of the angle. It was further shown that the angular dependence of the critical current can be calculated by the Kramer model including thermal activation with empirical angular dependence expressions for each parameter. The critical current data reported by Yamada et al. [Supercond. Sci. Technol. 17, S25 (2004)] for YBCO thin films on various substrates deposited by pulsed laser deposition method can also be described by the Kramer model including thermal activation and the angular dependencies of each parameter were compared with the SmBCO coated conductor fitting results.

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A Consistent Description of Scaling Law for Flux Pinning in<tex>$rm Nb_3rm Sn$</tex>Strands Based on the Kramer Model

Cited by 6 publications

References 11 publications

A general scaling relation for the critical current density in Nb₃Sn

A general scaling relation for the critical current density in Nb₃Sn

A review on the understanding and fabrication advancement of MgB₂thin and thick films by HPCVD

Relation between the critical current and the n value of ReBCO thin films: A scaling law for flux pinning of ReBCO thin films

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A Consistent Description of Scaling Law for Flux Pinning in<tex>$rm Nb_3rm Sn$</tex>Strands Based on the Kramer Model

Cited by 6 publications

References 11 publications

A general scaling relation for the critical current density in Nb3Sn

A general scaling relation for the critical current density in Nb3Sn

A review on the understanding and fabrication advancement of MgB2thin and thick films by HPCVD

Relation between the critical current and the n value of ReBCO thin films: A scaling law for flux pinning of ReBCO thin films

Contact Info

Product

Resources

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A general scaling relation for the critical current density in Nb₃Sn

A general scaling relation for the critical current density in Nb₃Sn

A review on the understanding and fabrication advancement of MgB₂thin and thick films by HPCVD