Performance of an HTS Persistent Current System for REBCO Pancake Coil

Takahashi, Kohki; Hase, Tomoya; Awaji, Satoshi; Nakai, A.; Yamano, Satoshi; Mukoyama, S.; Sakamoto, H.

doi:10.1109/tasc.2017.2773826

Cited by 24 publications

(15 citation statements)

References 8 publications

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“…To reduce the heat leakage of the cryostat from external environment in work status, the HTS magnet generally adopts the closed-loop method to maintain persistent operation and to output stable magnetic field for magnetic levitation, magnetic resonance imaging (MRI), and other special application conditions, considering the flexibility of the utilization of power equipment and device space. Although the current will gradually decrease in the closed-loop circuit under the static condition due to the joint resistance, the decay rate is within the permitted range [7]. Furthermore, with the development of the technology of superconducting joint, the HTS magnet in persistent current mode will present superior performance [8].…”

Section: Introductionmentioning

confidence: 99%

The Underlying Mechanism of Faster Current Attenuation of HTS Magnet in Persistent Current Mode Subject to the Traveling Magnetic Fields

Wang

Wang²,

Deng

et al. 2020

J Supercond Nov Magn

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High-temperature superconducting (HTS) magnet, due to its greater performance of magnetic field at higher temperature (20-40 K), better thermal stability, smaller volume and weight under the same requirements, and lower refrigeration costs, has attracted growing attention in the ultra-high-speed maglev system, high field magnet, and some other applications. Considering the practical requirements, closed-loop method is generally adopted in HTS magnet to maintain the persistent operation and to output the stable magnetic fields. But the accelerated current attenuation occurs when the HTS magnet is subjected to traveling magnetic fields, which is not conducive to the long-term operation. Therefore, this paper aims to investigate the essence of current attenuation of HTS magnet in persistent current mode under traveling magnetic fields and to further suppress this adverse behavior. In this study, to calculate the current distribution and dynamic resistance, a two-dimensional (2-D) finite element model (FEM) was established and verified by comparing with the experimental results. It can be seen from the simulation results that the dissipative losses caused by dynamic resistance present a non-negligible effect on the current attenuation of the magnet. And the mechanism of faster current attenuation was well explained by the variation of the dynamic resistance under the traveling magnetic fields.

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Section: Introductionmentioning

confidence: 99%

The Underlying Mechanism of Faster Current Attenuation of HTS Magnet in Persistent Current Mode Subject to the Traveling Magnetic Fields

Wang

Wang²,

Deng

et al. 2020

J Supercond Nov Magn

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“…The PCS usually achieve above features through the transitions of the superconductor between the superconducting state (zero-resistance state) and the normal state. Thermally-controlled switches trigger the transition though heating the superconductor above its critical temperature [2][3][4][5][6]. This type of PCS can achieve a high resistance, but it usually takes several seconds or even longer to transfer between the two states.…”

Section: Introductionmentioning

confidence: 99%

Persistent Current Switch for HTS Superconducting Magnets: Design, Control Strategy, and Test Results

Geng

Shen

et al. 2019

IEEE Trans. Appl. Supercond.

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High temperature superconductor (HTS) is becoming more and more attractive for the application in high field magnets which can be utilized in the magnetic resonance imaging (MRI) and rotating machines. To charge the HTS magnets and operate them in persistent current mode, a persistent current switch (PCS) is very necessary. This paper will focus on how to build a fast persistent current switch controlled by AC magnetic field. The PCS can present a large resistance rapidly compared with conventional PCS and recover to zero-resistance in a short recovery time. Impacting factors and strategy to control the proposed PCS are discussed. An experimental system is built and tests are carried out to verify the practicality of the proposed PCS.

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“…6. 28) In general, the current dependence of voltage (V-I) can be approximated by the power law model with an exponent n ( µ V I n ). It is known that this approximation is applicable to V-I dominated by flux creep.…”

mentioning

confidence: 99%

Interpretation of time-dependent current and resistance of HTS closed loop with superconducting joint considering flux creep

Takeda,

Tsuchiya,

Nishijima

2023

Appl. Phys. Express

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A low circuit resistance is required for a superconducting magnet operated in persistent mode using superconducting joints. We performed current decay measurements on a high-temperature superconducting (HTS) closed loop with a superconducting joint to evaluate the time dependence of the current and resistance. The results have been quantitatively explained by considering current sharing and flux creep. After the elapse of 105 s, current sharing was suppressed and a circuit resistance of less than 10−13 Ω was observed. The main finding is that joint resistance of an HTS closed loop is inversely proportional to time, contributing to low circuit resistance.

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Performance of an HTS Persistent Current System for REBCO Pancake Coil

Cited by 24 publications

References 8 publications

The Underlying Mechanism of Faster Current Attenuation of HTS Magnet in Persistent Current Mode Subject to the Traveling Magnetic Fields

The Underlying Mechanism of Faster Current Attenuation of HTS Magnet in Persistent Current Mode Subject to the Traveling Magnetic Fields

Persistent Current Switch for HTS Superconducting Magnets: Design, Control Strategy, and Test Results

Interpretation of time-dependent current and resistance of HTS closed loop with superconducting joint considering flux creep

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