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

Yuichi OGAWA; Zensho YOSHIDA; Junji MORIKAWA; Haruhiko SAITO; Sho WATANABE; Yoshihisa YANO; Shoichi MIZUMAKI; Taizo TOSAKA

doi:10.1585/pfr.4.020

Regular Articles

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

Yuichi OGAWA, Zensho YOSHIDA, Junji MORIKAWA, Haruhiko SAITO, Sho WATANABE, Yoshihisa YANO, Shoichi MIZUMAKI, Taizo TOSAKA

Author information

Yuichi OGAWA
Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8568, Japan
Zensho YOSHIDA
Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8568, Japan
Junji MORIKAWA
Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8568, Japan
Haruhiko SAITO
Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8568, Japan
Sho WATANABE
Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8568, Japan
Yoshihisa YANO
Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8568, Japan
Shoichi MIZUMAKI
TOSHIBA corporation, Yokohama 230-0045, Japan
Taizo TOSAKA
TOSHIBA corporation, Yokohama 230-0045, Japan

Keywords: internal coil device, high temperature superconductor, persistent current switch, magnetic levitation, relaxation theory, high-beta plasma

JOURNAL FREE ACCESS

2009 Volume 4 Pages 020

DOI https://doi.org/10.1585/pfr.4.020

Details

Abstract

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.

Corresponding author

Register with J-STAGE for free!