Flux pinning in NbTi/Nb multilayers

McCambridge, J.D.; Rizzo, Nicholas D.; Ling, Xinsheng; Wang, J.Q.; Prober, D. E.; Motowidlo, L. R.; Zeitlin, B. A.

doi:10.1109/77.402903

Cited by 10 publications

(5 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1 A broad pin thickness distribution is believed to be detrimental to J c . 10,11 Thus further significant increases in J c should be possible from more uniform artificial pinning structures, as is suggested by recent multilayer studies by McCambridge et al 16 and Kadyrov et al 17 In conclusion, we have studied the critical current density of Nb 47 wt. % Ti wires with 24 vol.…”

mentioning

confidence: 85%

Increased critical current density in Nb–Ti wires having Nb artificial pinning centers

Heussner

Marquardt

Lee

et al. 1997

Applied Physics Letters

View full text Add to dashboard Cite

Artificial pinning center ͑APC͒ wires containing Nb 47 wt.% Ti with 24 vol.% of round Nb pins have produced very high critical current densities (J c ) which are attributed to a sharply defined, nanometer-scale Nb-pin array. By reducing both the number of warm extrusion steps from four to three and the temperature of the third extrusion from 650°C to 250°C, the degree of pin-matrix interdiffusion has been reduced and J c values at all applied magnetic fields increased by 25-45% over those for a previous composite of almost identical design. The best wire achieved the very high J c ͑5 T, 4.2 K͒ value of 4600 A/mm 2 . These results underscore the importance of the thermomechanical treatment in determining the maximum flux pinning properties of APC Nb-Ti wires. © 1997 American Institute of Physics. ͓S0003-6951͑97͒02407-8͔The critical current density (J c ) of conventionally processed Nb 45-55 wt. % Ti wire is limited by the amount of normal conducting ␣-Ti precipitate that can be developed during thermomechanical treatment of the ␤-Nb-Ti alloy. Optimum flux pinning is achieved when the ␣-Ti precipitates are drawn to 1-2 nm in thickness. 1 J c increases linearly with the volume fraction of ␣-Ti, 2 but there appears to be a kinetic and/or thermodynamic limit of ϳ25 vol. % of ␣-Ti in Nb 47 wt. % Ti. In order to overcome this apparent limit to the conventional process, artificial pinning center ͑APC͒ designs 3 have been implemented which allow, in principle, for complete control over the pinning center composition, spatial arrangement, and volume fraction. Nb has been the most widely studied APC material, primarily because Nb is mechanically similar to Nb-Ti and because Nb-pin composites have produced the highest J c values thus far. Most notably, an APC composite using a multilayer-sandwich design of Nb 50 wt. % Ti matrix and 28 vol. % of Nb pins 4 achieved J c ͑5 T, 4.2 K͒ of 4250 A/mm 2 , distinctly higher than the maximum J c (ϳ3700 A/mm 2 ) achieved conventionally.While the thermomechanical processing steps 5,6 and the resulting flux pinning nanostructures 1,5 of high J c conventional Nb-Ti wire are firmly established, the same is not true for APC wires. Consequently, it is not surprising that a significant range in J c ͑H͒ is found for APC composites of nominally the same composition but manufactured via different processing routes. For instance, three groups have manufactured and characterized APC composites of Nb 47 wt. % Ti with 24-25 vol. % of nominally round 7,8 or planar 9 Nb pins. They produced maximum J c ͑5 T͒ values of 2400, 3200, and 2800 A/mm 2 , respectively. Although hard evidence is lacking, it seems likely that the range in J c originates from differences in the flux pinning nanostructures. As recent work by Jablonski et al. 10,11 has shown the detailed nanostructure of the pins exerts an important effect on the attainable J c , independent of the vol. % of pin and its composition.A very important difference between conventional and APC Nb-Ti lies in the evolution of the flux pinning nanostructure...

show abstract

mentioning

confidence: 85%

Increased critical current density in Nb–Ti wires having Nb artificial pinning centers

Heussner

Marquardt

Lee

et al. 1997

Applied Physics Letters

View full text Add to dashboard Cite

show abstract

“…The best results were obtained using artificial pinning centers (APCs) and ternary alloying with Ta. APC Nb-Ti, where the additional pinning centers are provided by a Nb or Cu structure in the Nb-Ti, has achieved critical current density in excess of 10,000 A/mm 2 at 4.2 K and 5 T [86,87]. The APC samples are in general layered structures, fabricated by sputtering and photolithography, i.e.…”

Section: Challengesmentioning

confidence: 99%

Superconducting Materials and Conductors: Fabrication and Limiting Parameters

Bottura

Godeke

2012

Rev. Accl. Sci. Tech.

View full text Add to dashboard Cite

Superconductivity is the technology that enabled the construction of the most recent generation of high-energy particle accelerators, the largest scientific instruments ever built. In this review we trace the evolution of superconducting materials for particle accelerator magnets, from the first steps in the late 1960s, through the rise and glory of Nb-Ti in the 1970s, till the 2010s, and the promises of Nb 3 Sn for the 2020s. We conclude with a perspective on the opportunities for high-temperature superconductors (HTSs). Many such reviews have been written in the past, as witnessed by the long list of references provided. In this review we put particular emphasis on the practical aspects of wire and tape manufacturing, cabling, engineering performance, and potential for use in accelerator magnets, while leaving in the background matters such as the physics of superconductivity and fundamental material issues.

show abstract

“…Because the ribbonlike pin shape appears to be inevitable, multilayers of Nb-Ti and artificial pins can be used as models for round wire composites. This has been exploited by several research groups, using Nb47Ti superconductor and Nb [8,86,87], Ti [8,87,88] or Cu [9,[89][90][91] pin layers, and pure Nb and Ti layers [92]. Ideal multilayers allow the ultimate limits of J c in APC composites to be probed.…”

Section: Multilayers As Model Systemsmentioning

confidence: 99%

Advances in high-field superconducting composites by addition of artificial pinning centres to niobium-titanium

Cooley

Motowidlo

1999

Supercond. Sci. Technol.

View full text Add to dashboard Cite

Artificial pinning-centre (APC) niobium-titanium composites attain critical current density J c values higher than 4000 A mm −2 at 5 T, 4.2 K, surpassing the barrier reached by the conventional Nb-Ti composite process. At 2 T APC composites achieve more than double the J c of conventional composites, making them particularly well suited for low-field applications. On the other hand, APC composites are inferior to conventional composites at 8 T, due to weak high-field pinning and reduced upper critical field. This review discusses fabrication techniques, microstructural development and superconducting and flux-pinning properties of APC composites. Key elements and underlying issues for achieving higher J c are identified and discussed in terms of the current state of the art.

show abstract

Flux pinning in NbTi/Nb multilayers

Cited by 10 publications

References 20 publications

Increased critical current density in Nb–Ti wires having Nb artificial pinning centers

Increased critical current density in Nb–Ti wires having Nb artificial pinning centers

Superconducting Materials and Conductors: Fabrication and Limiting Parameters

Advances in high-field superconducting composites by addition of artificial pinning centres to niobium-titanium

Contact Info

Product

Resources

About