Characteristics of Impregnated Pancake Coils Fabricated Using REBCO Coated Conductors

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

doi:10.1109/tasc.2011.2179691

Cited by 14 publications

(7 citation statements)

References 6 publications

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“…The flux-flow resistivity ρ f and the electric-field criterion E c are set as ρ f = 1×10 −7 Ωm and E c = 1×10 −4 V/m, respectively. In order to take into account the dependence of critical current I c at 77 K on the magnitude B and angle θ of applied magnetic field, the corresponding experimental results for a similar HTS tape [14] are approximated using the equation…”

Section: Modeling and Calculation Methodsmentioning

confidence: 99%

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Numerical reproduction of screening-current-induced fields in HTS tape windings using finite element method

Okabe

Honda

Komori

2017

J. Phys.: Conf. Ser.

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Abstract. The screening-current-induced fields in one of the high temperature superconducting (HTS) coils fabricated previously with coated conductors are evaluated numerically by using a one-dimensional finite element method, in which only the perpendicular component of a current vector potential is considered due to a very thin superconductor layer in the coated conductor. It is assumed that the voltagecurrent characteristics in the superconductor layer can be expressed by the critical state or n-value model, in which the field-dependent critical current density is also taken into account. The numerically calculated results of the screening-current-induced fields are compared with the experimental results carried out previously.

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Section: Modeling and Calculation Methodsmentioning

confidence: 99%

“…where n 0 is the n-value at 77 K in self-field given by n 0 = 35 [14]. On the other hand, the n-value is fixed at n 0 for the case of constant n in the NVM.…”

Section: Modeling and Calculation Methodsmentioning

confidence: 99%

Numerical reproduction of screening-current-induced fields in HTS tape windings using finite element method

Okabe

Honda

Komori

2017

J. Phys.: Conf. Ser.

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“…In the calculation, the I c − B − θ characteristics of the coated conductors are obtained from the fit of the experimental results from 30 K to 77 K under the conduction-cooled conditions, as shown [6]. Fig.…”

Section: A Comparison Of the Calculated And Measured Critical Currenmentioning

confidence: 99%

“…Therefore, we have investigated the thermal behavior of the REBCO cryocooled coils [6], [7]. Although we have fabricated and evaluated a model magnet of the 426 kJ cryocooled magnet with REBCO coated conductors before the fabrication of the 426 kJ cryocooled magnet, the results of the model magnet have not been reported.…”

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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“…Besides improving the single RACC cable current performance, we are also focusing on other equally important aspects: extending the cable length, reducing the AC losses, and assembling coils for possible applications. Pancake coils from coated conductors have been A. Kario, F. Grilli studied by several groups [5][6][7][8][9], but until now only one pancake coil with Roebel cable was successfully made by Jiang et al [10]. That coil was made from a 5 m-long Roebel cable with 9 strands, each 2 mm wide, with a 5.44 mm distance between the turns.…”

Section: Introductionmentioning

confidence: 99%

DC and AC Characterization of Pancake Coils Made From Roebel-Assembled Coated Conductor Cable

Kario¹,

Vojenčiak²,

Grilli³

et al. 2015

IEEE Trans. Appl. Supercond.

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Abstract-Roebel cables made of HTS coated conductors cancarry high currents with a compact design and reduced AC losses. They are therefore good candidates for manufacturing coils for HTS applications such as motors and generators. In this paper we present the experimental DC and AC characterization of several coils assembled from a 5 meter long Roebel cable built at KIT, which differ in the number of turns and turn-to-turn spacing. Our experiments, supported by finiteelement method (FEM) calculations, show that a more tightly wound Roebel coil, despite having a lower critical (and therefore operating) current, can produce a higher magnetic field than a loosely wound one. For a given magnetic field produced at the coil's center, all the coils have similar AC losses, with the exception of the most loosely wound one, which has much higher losses due to the relatively large current needed to produce the desired field. The experiments presented in this paper are carried out on the geometry of pancake coils made of Roebel cables, but they are exemplary of a more general strategy that, coupling experiments and numerical simulations, can be used to optimize the coil design with respect to different parameters, such as tape quantity, size, or AC loss -the relative importance of which is dictated by the specific application.

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Characteristics of Impregnated Pancake Coils Fabricated Using REBCO Coated Conductors

Cited by 14 publications

References 6 publications

Numerical reproduction of screening-current-induced fields in HTS tape windings using finite element method

Numerical reproduction of screening-current-induced fields in HTS tape windings using finite element method

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

DC and AC Characterization of Pancake Coils Made From Roebel-Assembled Coated Conductor Cable

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