Development of a 5T 2G HTS Magnet With a 20-cm-Diameter Bore

Daibo, M.; Fujita, Shin; Haraguchi, M.; Iijima, Y.; Itoh, Masahiko; Saitoh, Takashi

doi:10.1109/tasc.2013.2246758

Cited by 14 publications

(8 citation statements)

References 10 publications

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“…In this section, we apply our numerical model in order to predict several features of an example of magnet-size coil consisting on a stack of pancake coils, such as those in solenoidal SMES [56][57][58][59], high-field magnets [60,61] or other solenoidal magnets [62][63][64]. As a generic example of any of these applications, we study a stack of pancake coils consisting on 20 pancakes with 200 turns per pancake (see table 1 and figure 10).…”

Section: Magnet-size Coilsmentioning

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

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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

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Section: Magnet-size Coilsmentioning

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

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“…5. These results indicates that the 426 kJ cryocooled magnet with a dump resistor can be shut down without degradation after the detected normal transition, in the case where the maximum voltage (V m = I t · R d ) of the 426 kJ cryocooled magnet is greater than 333 V with a 0.3-mmthick copper stabilizer as in [4].…”

Section: B Thermal Runaway Testmentioning

confidence: 81%

“…Manuscript In 2012, we succeeded in developing a 5 T cryocooled REBCO magnet with a 20-cm-diameter room temperature bore with a stored energy of 426 kJ [4]. The magnet is composed of 24 impregnated pancake coils with an inner diameter of 260 mm, and the total length of the REBCO coated conductors is approximately 7.2 km.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of a 426 kJ Cryocooled Magnet and a Model Magnet With REBCO Coated Conductors

Daibo

Fujita

Haraguchi

et al. 2014

IEEE Trans. Appl. Supercond.

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REBa 2 Cu 3 O x (REBCO, RE = rare earth) coated conductors are expected to show high performance for superconducting applications because of their high current density and high mechanical strength. Fujikura has developed REBCO coated conductor over 570 A/cm width at 77 K, self field with over 800 m length. In addition, we have succeeded in developing a 5 T cryocooled REBCO magnet with a stored energy of 426 kJ. The magnet is composed of 24 pancake coils with an inner diameter of 260 mm, and the total length of the REBCO coated conductors is approximately 7.2 km. We confirmed that the REBCO magnet could be excited up to 5 T for 720 min 9 months after the fabrication of the magnet. It is important to validate the long-term operation test results of the REBCO magnets with larger diameters in order to use these conductors in practical superconducting applications. On the other hand, we have fabricated and evaluated a model magnet before we fabricated a 426 kJ cryocooled magnet. The model magnet is composed of 6 REBCO pancake coils and 18 "dummy coils" with an inner diameter of 260 mm and an outer diameter of 515 mm. The model magnet is about the same size and shape as the 426 kJ cryocooled magnet. We have confirmed that the calculated critical current (I c ) of the top pancake coil of the model magnet was in good agreement with the measured coil I c from 30 to 77 K under the conduction-cooled conditions. In addition, we have evaluated the thermal runaway behavior of the model magnet under the conduction-cooled conditions. As a result, we have confirmed that the model magnet with a 0.3-mm-thick copper stabilizer had sufficient time to ramp down without degradation at 361 A transport current after the detected normal transition.

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“…The coated conductor manufacturing by IBAD-PLD method by Fujikura Ltd [21] has been progressing and a successful application of 5 T magnet operating at 24 K with a cryocooler [22] has been demonstrated. Fujikara's commercial coated conductor had been first laminated by copper stabilization layer only on one side, making the superconducting layer close to the neutral line, but lately the architecture was changed to a folding-type stabilizer [23] in order to improve on the weak delamination strength, and this new conductor became commercially available very recently.…”

Section: Coated Conductormentioning

confidence: 99%