TY - JOUR
T1 - Thermal runaway of a 1 T cryocooler-cooled oxide superconducting pulsed coil in Ac operation
AU - Miyazaki, H.
AU - Harada, S.
AU - Iwakuma, M.
AU - Funaki, K.
AU - Hayashi, H.
AU - Tomioka, A.
N1 - Funding Information:
Manuscript received October 4, 2004. This work was supported by the 21st Century COE Program “Reconstruction of Social Infrastructure Related to Information Science and Electrical Engineering” in Kyushu University. H. Miyazaki and S. Harada are with the Graduate School of Information Science and Electrical Engineering, Kyushu University, Higashi-ku, Fukuoka 812-8581, Japan (e-mail: miyazaki@sc.kyushu-u.ac.jp). M. Iwakuma and K. Funaki are with Research Institute of Superconductor Science and Systems, Kyushu University, Higashi-ku, Fukuoka 812-8520, Japan. H. Hayashi is with Kyushu Electric Power Co., Inc., Minami-ku Fukuoka 812-8581, Japan. A. Tomioka is with Fuji Electric Advanced Technology Co., Ltd., Yokosuka 240-0194, Japan. Digital Object Identifier 10.1109/TASC.2005.849226 Fig. 1. Set up of pulsed coil and cryocooler. Small circles represent measurement points of temperature.
PY - 2005/6
Y1 - 2005/6
N2 - We designed and fabricated a l T cryocooler-cooled oxide superconducting pulsed coil with Bi2223 multifilamentary flat wires. Previously we studied temperature dependence of the thermal runaway current of the pulsed coil in dc operation. The thermal runaway current was higher than the critical current that was defined as the current where the electric field 10-4 V/m was generated on average over the whole length of the conductor. In this paper, we studied the coil temperature and the ac loss dependence of the thermal runaway current in ac operation. We operated the coil at 0.5 to 5 Hz with a sinusoidal-waveform transport current. The initial coil temperature was set between 30 and 100 K. The thermal runaway current decreased monotonically with increasing temperature in a similar way to dc operation. However, in a low temperature region, the thermal runaway current was restricted to a lower level than that in dc operation due to the ac loss. We discuss the frequency dependence of thermal runaway current in ac operation.
AB - We designed and fabricated a l T cryocooler-cooled oxide superconducting pulsed coil with Bi2223 multifilamentary flat wires. Previously we studied temperature dependence of the thermal runaway current of the pulsed coil in dc operation. The thermal runaway current was higher than the critical current that was defined as the current where the electric field 10-4 V/m was generated on average over the whole length of the conductor. In this paper, we studied the coil temperature and the ac loss dependence of the thermal runaway current in ac operation. We operated the coil at 0.5 to 5 Hz with a sinusoidal-waveform transport current. The initial coil temperature was set between 30 and 100 K. The thermal runaway current decreased monotonically with increasing temperature in a similar way to dc operation. However, in a low temperature region, the thermal runaway current was restricted to a lower level than that in dc operation due to the ac loss. We discuss the frequency dependence of thermal runaway current in ac operation.
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U2 - 10.1109/TASC.2005.849226
DO - 10.1109/TASC.2005.849226
M3 - Article
AN - SCOPUS:22044450071
SN - 1051-8223
VL - 15
SP - 1663
EP - 1666
JO - IEEE Transactions on Applied Superconductivity
JF - IEEE Transactions on Applied Superconductivity
IS - 2 PART II
ER -