30 Years of Conductors for Fusion: A Summary and Perspectives

Bruzzone, Pierluigi

doi:10.1109/tasc.2006.873342

Cited by 35 publications

(32 citation statements)

References 33 publications

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“…Implementing the critical current density of the strands, the two unknown of the model are the cable n-value and the strain of filaments. It was observed that the performances of a conductor worsen with increasing electromechanical load [2], [19], [20]. Complete and accurate models have been developed [21] able to calculate the voltage-temperature characteristics basing on strand scaling law in which the use of several fitting parameters accounts for the mechanical state of the strand (strain), but in which a phenomenological interpretation of the cable performances is not straightforward.…”

Section: A From Strand To Ciccmentioning

confidence: 99%

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Role of the Cross Section Geometry in Rectangular ${\rm Nb}_{3}{\rm Sn}$ CICC Performances

Turtù

Muzzi

Zignani

et al. 2011

IEEE Trans. Appl. Supercond.

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It is now a matter of fact that parameters such as cable twist pitch (TP) and void fraction (VF) have a strong impact on Cable-in-Conduit Conductor performances. A proper choice of their values in the direction of raising the former (TP) and lowering the latter (VF) has been proven to considerably enhance the transport properties, though increasing the AC losses, and to appreciably reduce the conductor degradation with electromagnetic and thermal loading cycles. It has been also demonstrated that a further route for CICCs performance improvement is represented by a suitable optimization of the conductor shape with respect to the electromagnetic force distribution. In this sense, CIC conductors with high aspect ratio rectangular geometry, if properly oriented, have shown a better response to high electromagnetic pressure, as proved by experimental evidences. This paper, where the test results of a large rectangular Nb 3 Sn CIC conductor are interpreted, is intended to clarify the role of the conductor cross-section geometry on the electromagnetic load sharing among the strands and/or on the cable stiffness, and thus on the strain distribution over the cable wires.

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Section: A From Strand To Ciccmentioning

confidence: 99%

“…High field magnets as for example those for fusion reactors, most often are designed to be wound by Cable-In-Conduit Conductors (CICCs) [1], [2]. Yet, one of the principal drawback in employing this material is its brittleness, and this is why the wind&react technique revealed to be the easiest way for manufacturing large CICC magnets.…”

Section: Introductionmentioning

confidence: 99%

Role of the Cross Section Geometry in Rectangular ${\rm Nb}_{3}{\rm Sn}$ CICC Performances

Turtù

Muzzi

Zignani

et al. 2011

IEEE Trans. Appl. Supercond.

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“…The majority of the big magnets, like that in use for the particle accelerators, detectors or fusion machines have been built with NbTi wires and are cooled by Liquid He [2]. The limiting magnetic field of this material, at a reasonable current density, is about 7 T at 4.2 K and 8.5 T at 1.8 K. The NbTi is metallic, so it can be drawn in very thin filaments, can be stranded and does not require any thermal treatment to reach the superconducting state.…”

Section: A Low Critical Temperature Materialsmentioning

confidence: 99%

$\hbox{MgB}_{2}$ Coil Options for Fusion Poloidal Magnets

Giunchi

Coppi

2010

IEEE Trans. Appl. Supercond.

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A hybrid solution is proposed for the IGNITOR research fusion machine by using of superconducting coils for some poloidal magnets, in association with high field copper magnets for the central solenoid and for the toroidal field coils. The choice to be made among the various superconductors is based on the materials performances in high magnetic field, on the mechanical strength of the conductors and on the cost of manufacturing large coils. In this study we analyze a coil based on MgB 2 , a "medium temperature" superconducting material that we expect will avoid, in association with others high temperature superconductors, the use of liquid He in future machines. The external poloidal magnet, 5 m in diameter and subjected to a magnetic field of 5 T, represents a real test bench of the technical issues which should be addressed in the exploitation of the future fusion reactors. To fulfil the technical characteristics of the selected magnet we must optimize the fill factor of the superconducting MgB2 wires, increasing the presently obtained 30% value. Accordingly, the effective current density in the superconducting wire should be of about 1500 A/mm 2 (@10 K, 5 T), a value which is compatible with the present best MgB 2 laboratory short wires, doped by C or SiC.

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“…Figure 2 shows the Ic lines for the strand (strand Ic multiplied by number of strands not including the self field degradation effect) and the cable based on the specified values which were extrapolated to higher temperatures [2] in comparison to the line of the CRPP Ic test data [2,3]. The premature quenches can be explained by the inhomogeneous current distribution caused by different strand contact resistances inside the joints [4], the relative short length of the test sample which did not allow an even current distribution between the strands in the cable [4] and a local superposition of the background field with the self field of the conductor on the high 25th SOFT field side when the current density increases [5]. The W7-X magnet operation is not influenced because the operating current is around 18 kA.…”

Section: Superconductormentioning

confidence: 99%

Experiences from design and production of Wendelstein 7-X magnets

Riße

Team

2009

Fusion Engineering and Design

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The Max-Planck-Institut für Plasmaphysik in Greifswald is building the stellarator fusion experiment Wendelstein 7-X (W7-X). The manufacturing of the W7-X superconducting magnet system, which consists of 50 non-planar and 20 planar coils, was finished in March 2008. The production was a technical challenge for the W7-X design crew as well for the manufacturer due to the complex 3 D shape of the non-planar coils and the stringent requirements for geometrical tolerances. The manufacturers had to solve several technical problems and to consider major design changes even at advanced stages of manufacture. Finally the coils are passing the acceptance tests at cryogenic temperatures at CEA Saclay with a very good performance. Results of the W7-X coil production will be given and critical production steps will be identified. Lessons will be taken from the experiences gained from design, manufacturing and test methods. The reasons for the considerable time delays will be explained.

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30 Years of Conductors for Fusion: A Summary and Perspectives

Cited by 35 publications

References 33 publications

Role of the Cross Section Geometry in Rectangular ${\rm Nb}_{3}{\rm Sn}$ CICC Performances

Role of the Cross Section Geometry in Rectangular ${\rm Nb}_{3}{\rm Sn}$ CICC Performances

$\hbox{MgB}_{2}$ Coil Options for Fusion Poloidal Magnets

Experiences from design and production of Wendelstein 7-X magnets

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