Design Optimization of Round Strands Made by Twisted Stacks of HTS Tapes

Bykovsky, Nikolay; Uglietti, D.; Wesche, R.; Bruzzone, Pierluigi

doi:10.1109/tasc.2016.2517187

Cited by 37 publications

(20 citation statements)

References 13 publications

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“…Given the strain dependence of I c , the presented approach allows to determine the expected I c of the REBCO tape after bending [45][46][47][48]. Considering the I c dependence on both strain and magnetic field, one can determine the expected cable and magnet performance in order to assess if the fabrication process has introduced any conductor degradation [49].…”

Section: Discussionmentioning

confidence: 99%

Strain Distribution in REBCO-Coated Conductors Bent With the Constant-Perimeter Geometry

Wang

Arbelaez

Caspi

et al. 2017

IEEE Trans. Appl. Supercond.

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Abstract-Cable and magnet applications require bending REBa2Cu3O 7−δ (REBCO, RE = Rare Earth) tapes around a former to carry high current or generate specific magnetic fields. With a high aspect ratio, REBCO tapes favor the bending along their broad surfaces (easy way) than their thin edges (hard way). The easy-way bending forms can be effectively determined by the constant-perimeter method that was developed in the 1970s to fabricate accelerator magnets with flat thin conductors. The method, however, does not consider the strain distribution in the REBCO layer that can result from bending. Therefore, the REBCO layer can be over-strained and damaged even if it is bent in an easy way as determined by the constant-perimeter method.To address this issue, we developed a numerical approach to determine the strain in the REBCO layer using the local curvatures of the tape neutral plane. Two orthogonal strain components are determined: the axial component along the tape length and the transverse component along the tape width. These two components can be used to determine the conductor critical current after bending. The approach is demonstrated with four examples relevant for applications: a helical form for cables, forms for canted cos θ dipole and quadrupole magnets, and a form for the coil end design. The approach allows to optimize the design of REBCO cables and magnets based on the constantperimeter geometry and to reduce the strain-induced critical current degradation.

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Section: Discussionmentioning

confidence: 99%

Strain Distribution in REBCO-Coated Conductors Bent With the Constant-Perimeter Geometry

Wang

Arbelaez

Caspi

et al. 2017

IEEE Trans. Appl. Supercond.

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“…An effective approach to understanding the long-term behavior of REBCO magnets is to measure the transport behavior of the conductors and coils under large and cycling Lorentz load relevant to the conditions of magnet operation as is done for fusion conductors [133,137,146]. The HTS/LTS hybrid approach (Section 2) not only motivates but also provides a natural test bed for this study.…”

Section: What Is the Long-term Performance Of Rebco Magnets Under Lormentioning

confidence: 99%

Dipole Magnets above 20 Tesla: Research Needs for a Path via High-Temperature Superconducting REBCO Conductors

2019

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To enable the physics research that continues to deepen our understanding of the Universe, future circular colliders will require a critical and unique instrument—magnets that can generate a dipole field of 20 T and above. However, today’s maturing magnet technology for low-temperature superconductors (Nb-Ti and Nb 3 Sn) can lead to a maximum dipole field of around 16 T. High-temperature superconductors such as REBCO can, in principle, generate higher dipole fields but significant challenges exist for both conductor and magnet technology. To address these challenges, several critical research needs, including direct needs on instrumentation and measurements, are identified to push for the maximum dipole fields a REBCO accelerator magnet can generate. We discuss the research needs by reviewing the current results and outlining the perspectives for future technology development, followed by a brief update on the status of the technology development at Lawrence Berkeley National Laboratory. We present a roadmap for the next decade to develop 20 T-class REBCO accelerator magnets as an enabling instrument for future energy-frontier accelerator complex.

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“…Discussion of this phenomenon for various HTS strands is published recently in [4]. According to the Lorentz force:…”

Section: Transverse Load During the Cable Operationmentioning

confidence: 99%

“…Summary of the conductors parameters and properties together with a sketch of the cross section are given in Table II. Geometry of the copper profiles of the strand (see the sketch of the cables' cross section in Table II) was chosen according to the results recently presented in [4]. These profile geometry is stronger against transverse Lorentz force than the one first introduced.…”

Section: Design Proposalsmentioning

confidence: 99%

“…At the same time, two issues were discovered: around 3% degradation of I c for the both cables after the cycling test (1000 cycles of the current from 0 to 50 kA at 12 T) and relatively high AC loss-from 2 to 10 times larger than in the ITER TF conductors-which was mainly related to inter-strand currents. In order to further optimize the strand design and investigate reasons of the degradation during the cycling test, various electromechanical tests (twisting, bending and transverse pressure) were performed with the strands of various tapes and profile geometry [4]. Higher current density of the strand, lower AC loss and improved mechanical strength against transverse pressure can be achieved with a square stack of 3 mm-width tapes.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Design of the HTS Fusion Conductors for TF and CS Coils

Bykovsky

Uglietti

Wesche

et al. 2016

IEEE Trans. Appl. Supercond.

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Abstract-The main electrical and mechanical requirements for the LTS fusion conductors of DEMO are retained as a starting point for the development of HTS fusion cables. Based on the HTS coated conductor technology, a flat cable design was proposed by CRPP Swiss Plasma Center (SPC) using the strands made of twisted stack of tapes soldered into copper profiles. Analytical modeling of the cable geometry is developed and presented in this work. The model was used to estimate various properties of cable. Addressing the issue of bending strain and related performance degradation, an optimization model of the cable properties was built, which allows to best fulfill the cable requirements. Design options are developed for both toroidal field (TF) coils operating at 63 kA and central solenoid (CS) coils operating at 50 kA. Paying attention to the DC and pulsed operation of the TF and CS coils, proposals for the design of the forced-flow HTS conductors are reported and discussed for each type of the coils.

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Design Optimization of Round Strands Made by Twisted Stacks of HTS Tapes

Cited by 37 publications

References 13 publications

Strain Distribution in REBCO-Coated Conductors Bent With the Constant-Perimeter Geometry

Strain Distribution in REBCO-Coated Conductors Bent With the Constant-Perimeter Geometry

Dipole Magnets above 20 Tesla: Research Needs for a Path via High-Temperature Superconducting REBCO Conductors

Design of the HTS Fusion Conductors for TF and CS Coils

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