Cos- &lt;inline-formula&gt; &lt;tex-math notation="TeX"&gt;$\theta$&lt;/tex-math&gt;&lt;/inline-formula&gt; Design of Dipole Inserts Made of REBCO-Roebel or BSCCO-Rutherford Cables

To study the influence of coated-conductor magnetization on the field quality of accelerator magnets, we made a small dipole magnet consisting of four racetrack coils wound with GdBCO coated conductors and measured its magnetic field in liquid nitrogen by using rotating pick-up coils. We focused on the dipole and sextupole components (coefficients) of the magnetic field, which vary with time owing to the decay of the magnetization of the coated conductors. About 50 min (3055 s) after the current was ramped up to 50 A, the dipole coefficient normalized by the design value of the dipole component, i.e., the value calculated with the designed coil shape and the uniform current distribution in the coated conductors, increased by 7.4 × 10 −4 , and the sextupole coefficient normalized by the design value of the dipole component increased by 1.8 × 10 −4 . The magnitudes of the dipole and sextupole components depended on the excitation history of the magnet. Electromagnetic field analyses were carried out to calculate the current distributions in coated conductors, considering their superconducting properties; the dipole and sextupole coefficients were then determined from the calculated current distributions. Although the analyses were based on the two-dimensional approximation of the cross-section of the magnet, the temporal behaviours as well as the hysteretic characteristics of the calculated dipole and sextupole coefficients agree qualitatively with those of the dipole and sextupole coefficients measured in the magnet.

Section: Multipole Components Of Two-dimensional Magnetic Fieldsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Temporal behaviour of multipole components of the magnetic field in a small dipole magnet wound with coated conductors

Amemiya

Otake

Sano

et al. 2015

“…As part of the EuCARD-2 project [1,2], two types of demonstrator dipole magnets are developed which make use of REBCO Roebel cables developed at the Karlsruhe Institute of Technology [3]. One dipole magnet is developed at CEA Saclay, and is based on a classical cos-theta layout [4]. In a recent paper, winding tests of such a magnet using stainless steel dummy Roebel cables are discussed [5].…”

Section: Introductionmentioning

confidence: 99%

Bending properties of different REBCO coated conductor tapes and Roebel cables atT= 77 K

Otten

Kario

Kling

et al. 2016

Application of REBCO coated conductors in coils or cables involves deformation of the conductor in different modes, such as in-plane bending, out-of-plane bending and torsion. For example, the dipole magnet designs in the EuCARD-2 project require bending radii as low as 7.5 mm, inducing significant bending strain in the REBCO layer. In this paper, we investigate the effect of out-of-plane bending on the current-carrying properties of coated conductors from different manufacturers. The samples are manipulated by means of a Goldacker-type bending rig, which allows continuous bending at T = 77 K. By reversal to after each bending step, the reversible strain effect is separated from irreversible degradation. All tested conductors are found to tolerate compressive bending to a radius of 6 mm with less than 5% irreversible degradation of the critical current. The magnitude of the reversible strain effect shows a large variation among the samples. The effect of out-of-plane bending on Roebel cables is investigated as well, and the results are compared to the bending characteristic of single conductors. The results show no detrimental effect of the cable assembly on the bending properties within the constraints of the test.

“…The cable is the same that is being used at CERN for the aligned block type. Mechanical analysis on a preliminary dipole design [93] has shown peak transverse stresses as high as 600…”

Section: Cos-theta Dipole (Cea)mentioning

confidence: 99%

A review of commercial high temperature superconducting materials for large magnets: from wires and tapes to cables and conductors

Uglietti

2019

197

123

High Temperature Superconducting (HTS) materials have the potential to generate magnetic field beyond the level obtainable with Low Temperature Superconducting (LTS). This review reports the past and present R&D on HTS cables and conductors for high field tokamaks, accelerator dipoles and large solenoids. Among the HTS wires and tapes available commercially, coated conductor tapes are the most appealing because of the outstanding critical strength and large improvement margin. Limitations are the weakness against peeling and shearing and the short piece length. The prices for technical superconductors are reviewed because they play an important role in large projects; moreover the perspective of industrial production of HTS wires and tapes is discussed considering the historical development of the LTS wire market. Various designs have been proposed for HTS cables and conductors: some are better suited for soft materials, while others can exploit the anisotropy of coated conductors (by aligning the tape with the field), providing the highest current density. The last decade has seen an increase in the size and complexity of the prototypes; however some peculiar features of HTS, such as high stability margin and high mechanical limits, have not yet been fully incorporated in the designs: for example the transposition requirements for HTS have not yet been studied in detail. Several facts indicate that tapes (even if anisotropic) can be used for manufacturing cables and magnets of any size and have advantages with respect to round wires.