Persistent Current HTS Magnet Cooled by Cryocooler (4)—Persistent Current Switch Characteristics

Tosaka, Taizo; Tasaki, Kenji; Marukawa, K.; Kuriyama, T.; Nakao, Hiroyuki; Yamaji, M.; Kuwano, K.; Igarashi, M.; Nemoto, Kaoru; Terai, Motoaki

doi:10.1109/tasc.2005.849634

Cited by 35 publications

(16 citation statements)

References 7 publications

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“…Since the PCS in the Mini-RT is made of a small coil with a few turns of the Bi-2223 tape, it takes ∼10 min for the switchover. In contrast, in the MAGLEV project, a PCS made of a YBCO thin film has been developed [16]. Since this PCS is a thin film, the switchover time is quite short, typically 2 min.…”

Section: Excitation Methods Of the Internal Coilmentioning

confidence: 99%

Construction and Operation of an Internal Coil Device, RT-1, with a High-Temperature Superconductor

Ogawa

Yoshida

Morikawa

et al. 2009

Plasma and Fusion Research

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An internal coil device called Ring Trap-1 (RT-1) has been constructed to explore an innovative concept for a high-beta plasma based on a new relaxation theory. A high-temperature superconductor (HTS) Bi-2223 tape is employed for the internal coil of RT-1. The coil is cooled to 20 K with helium gas supplied by G-M refrigerators, and charged to a magnetomotive force of 250 kA using an external power supply. For these cooling and charging methods, we have developed several innovative techniques such as a demountable transfer tube system, persistent current switch, detachable electrode, and others. In addition, we have paid much attention to the deterioration of the HTS tape during the fabrication of the internal coil. As a result, we have demonstrated that the decay of the persistent current of the internal coil is ∼1% during 8 h. The internal coil is lifted with a levitation coil located at the upper region of the vacuum vessel. The coil position monitored with laser sensors is feedback controlled through the regulation of the levitation coil current. Stable levitation for a few hours has been demonstrated for various plasma experiments.

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Section: Excitation Methods Of the Internal Coilmentioning

confidence: 99%

Construction and Operation of an Internal Coil Device, RT-1, with a High-Temperature Superconductor

Ogawa

Yoshida

Morikawa

et al. 2009

Plasma and Fusion Research

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“…We applied a PCS that was developed in the project for maglev trains [8], [9]. The specifications of the PCS are summarized in Table II.…”

Section: B Persistent-current Switchmentioning

confidence: 99%

“…The other reason is that a good performance of a persistent-current HTS magnet with low current-decay rate was recently shown in the maglev train project. This HTS magnet consists of an HTS coil wound with Ag-sheathed Bi2223 tapes and a persistent-current switch (PCS) made by YBCO thin films [5]- [8]. This paper describes the design, manufacture and test results of the persistent-current HTS coil for the floating magnet.…”

Section: Introductionmentioning

confidence: 99%

Development of Persistent-Current Mode HTS Coil for the RT-1 Plasma Device

Tosaka

Ohtani

Ono

et al. 2006

IEEE Trans. Appl. Supercond.

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The plasma confinement device "RT-1" which had a high temperature superconducting (HTS) floating magnet was constructed for advanced high-beta plasma and fusion research at the University of Tokyo. The high temperature superconducting (HTS) floating magnet is magnetically levitated inside the plasma vacuum vessel. Plasma is confined by a magnetic dipole field around the HTS floating magnet. The HTS floating magnet is operated in persistent-current mode and it consists of an HTS coil, an HTS persistent-current switch (PCS), a pair of demountable joints of current leads, detachable joints of a cooling tube, a thermal shield and a vacuum vessel. The HTS coil and the PCS and the thermal shield are cooled below 20 K by a flow of helium gas through the cooling tube. The floating HTS magnet is designed to operate in the temperature range from 20 K to 30 K without being cooled while it is levitated. We fabricated a persistent-current HTS coil that consists of the HTS coil and the PCS. Persistent-current operations and protection tests were conducted with the persistent-current HTS coil before it was mounted in the floating magnet cryostat. The current-decay rate was 0.9% in an 8 hour operation. The coil energy was safely discharged by inducing PCS quench in a protection test.

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“…It is impossible to energize a superconducting loop, e.g., a coil or magnet, using only a power supply connected across the loop [2]; to energize such a shorted coil, a persistent-current switch (PCS) is also required. The HTS PCS has been developed for magnets of Bi2212 [3], Bi2223 [4]–[6], YBCO [7], [8], and MgB 2 [9]. Note that YBCO is the first so-called coated conductor now generally designated as REBCO.…”

Section: Introductionmentioning

confidence: 99%

A REBCO Persistent-Current Switch (PCS): Test Results and Switch Heater Performance

Michael

Voccio

et al. 2017

IEEE Trans. Appl. Supercond.

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In this paper, we report preliminary results of our on-going effort to develop a superconducting persistent-current switch (PCS) for REBCO pancake coils that will be operated in liquid helium. In the first part of this paper, we briefly describe experimental results of our PCS operated in the temperature range 77–57 K, i.e., liquid-and solid-nitrogen environments. The rest we devote to a new PCS heater design in which we target a heating power of < 1 W in liquid helium.

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Persistent Current HTS Magnet Cooled by Cryocooler (4)—Persistent Current Switch Characteristics

Cited by 35 publications

References 7 publications

Construction and Operation of an Internal Coil Device, RT-1, with a High-Temperature Superconductor

Construction and Operation of an Internal Coil Device, RT-1, with a High-Temperature Superconductor

Development of Persistent-Current Mode HTS Coil for the RT-1 Plasma Device

A REBCO Persistent-Current Switch (PCS): Test Results and Switch Heater Performance

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