Research and development of fundamental technologies for accelerator magnets using high Tc superconductors

Amemiya, Naoyuki; Takahashi, Katsutoshi; Otake, Hiroko; Nakamura, Taketsune; Mori, Y.; Ogitsu, T.; Koyanagi, K.; Osanai, Akihiro; Yoshiyuki, T.; Noda, K.; Yoshimoto, Masahiro

doi:10.1016/j.physc.2012.05.017

Cited by 25 publications

(20 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…That is, the relative error of the generated magnetic field compared to the design value. Often, the design value is taken as the magnetic field created by the winding, ignoring magnetization currents [72][73][74][75] (B ideal ), and therefore the magnetic field distortion is |B c,mag |/B ideal . For our example, this magnetic field distortion at the bore center and the initial curve ranges between 0.13 and 0.018, decreasing with the current ( figure 17).…”

Section: Magnetic Field Distortion Due To Magnetization Currentsmentioning

confidence: 99%

“…For our example, this magnetic field distortion at the bore center and the initial curve ranges between 0.13 and 0.018, decreasing with the current ( figure 17). These values are very high for NMR and accelerator magnets [36,75], although a decrease of this quality factor could be obtained by optimizing the winding geometry. However, magnets with small bores are likely to present low quality factors, since the magnetic field created by magnetization currents increases with decreasing the distance from the winding.…”

Section: Magnetic Field Distortion Due To Magnetization Currentsmentioning

confidence: 99%

See 1 more Smart Citation

Electromagnetic modelling of superconductors with a smooth current–voltage relation: variational principle and coils from a few turns to large magnets

Pardo

Šouc

Frolek

2015

Supercond. Sci. Technol.

121

View full text Add to dashboard Cite

Many large-scale applications require electromagnetic modelling with extensive numerical computations, such as magnets or 3-dimensional (3D) objects like transposed conductors or motors and generators. Therefore, it is necessary to develop computationally time-efficient but still accurate numerical methods. This article develops a general variational formalism for any E(J) relation and applies it to model coated-conductor coils containing up to thousands of turns, taking magnetization currents fully into account. The variational principle, valid for any 3D situation, restricts the computations to the sample volume, reducing the computation time. However, no additional magnetic materials interacting with the superconductor are taken directly into account. Regarding the coil modelling, we use a power law E(J) relation with magnetic field-dependent critical current density, Jc, and power law exponent, n. We test the numerical model by comparing the results to analytical formulas for thin strips and experiments for stacks of pancake coils, finding a very good agreement. Afterwards, we model a magnet-size coil of 4000 turns (stack of 20 pancake coils of 200 turns each). We found that the AC loss is mainly due to magnetization currents. We also found that for an n exponent of 20, the magnetization currents are greatly suppressed after 1 hour relaxation. In addition, in coated conductor coils magnetization currents have an important impact on the generated magnetic field; which should be taken into account for magnet design. In conclusion, the presented numerical method fulfills the requirements for electromagnetic design of coated conductor windings. * Final version published as E Pardo, JŠouc and L Frolek 2015 Supercond. Sci. Technol. 28 044003, doi:10.1088/0953-2048/28/4/044003. Several minor typos have been corrected in the published version. 1 ReBCO stands for ReBa 2 Cu 3 O 7−x , where Re is a rare earth, typically Y, Gd or Sm. the flux creep exponent and the AC loss. Critial current density and flux-creep exponentIn this article, we use a ReBCO coated conductor tape from SuperPower [49] for all experiments. This tape is 4 mm wide, with a total of 40 µm copper stabilizer layers, a 1 µm thick superconducting layer, and a self-field critical current at 77 K of 128 A.We measured the dependence of the critical current density J c on the magnetic field magnitude |B| ≡ B and its orientation θ (see sketch in figure 3) at 77 K, as detailed in [50]. In order to extract J c from measurements of the tape critical current, I c , we corrected the spurious effects of the self-field, following the method in [50]. The reader can find the I c measurements and extracted J c for the tape used in this article in [30]. For completeness, we include the extracted J c (B, θ) relation, being J c (B, θ, J) = [J c,ab (B, θ, J) m + J c,c (B) m ] 1/m (60) with J c,ab (B, θ, J) = J 0,ab 1 + Bf (θ,J) B 0,ab β ab ,J c,c (B) = J 0,c

show abstract

Section: Magnetic Field Distortion Due To Magnetization Currentsmentioning

confidence: 99%

Section: Magnetic Field Distortion Due To Magnetization Currentsmentioning

confidence: 99%

Electromagnetic modelling of superconductors with a smooth current–voltage relation: variational principle and coils from a few turns to large magnets

Pardo

Šouc

Frolek

2015

Supercond. Sci. Technol.

121

View full text Add to dashboard Cite

show abstract

“…Therefore, the first question addresses the design and fabrication of magnets. Although racetrack and cos θ-type magnets using single REBCO tapes have been demonstrated [88,[97][98][99], developing magnets with multi-tape REBCO conductors is in its early stage.…”

Section: How To Make High-field Accelerator Magnets Using Multi-tape mentioning

confidence: 99%

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

2019

View full text Add to dashboard Cite

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.

show abstract

“…This project is supported by Japan Science and Technology Agency under Strategic Promotion of Innovative Research and Development Program, and conducted by a research consortium of Kyoto University, KEK and other institutes [16]. While current targets are set to an accelerator system for cancer therapy and an accelerator driven sub-critical reactor which only requires fields below 6 T, there are same critical issues anticipated in the high field accelerator magnets.…”

Section: B Hts Accelerator Magnet Randdmentioning

confidence: 99%

R&D Efforts Towards High Field Accelerator Magnets at KEK

Nakamoto

Jin

et al. 2012

IEEE Trans. Appl. Supercond.

View full text Add to dashboard Cite

KEK has emphasized efforts to develop the RHQsuperconductor and a 13 T sub-scale magnet towards the LHC upgrade in last years. In addition, relevant R&D regarding radiation resistance has been carried out. For realization of higher field magnets beyond 15 T, thorough understanding of strain behavior of HTS and A15 superconductors is truly desired. KEK has launched a new research subject on stress/strain sensitivity of HTS and A15 superconductors in collaboration with the neutron diffraction facility at J-PARC and the High Field Laboratory in Tohoku University.

show abstract

Research and development of fundamental technologies for accelerator magnets using high Tc superconductors

Cited by 25 publications

References 24 publications

Electromagnetic modelling of superconductors with a smooth current–voltage relation: variational principle and coils from a few turns to large magnets

Electromagnetic modelling of superconductors with a smooth current–voltage relation: variational principle and coils from a few turns to large magnets

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

R&D Efforts Towards High Field Accelerator Magnets at KEK

Contact Info

Product

Resources

About