Construction of a Cryogenic Magnet for Quasi-Steady High Magnetic Fields
Grant-in-Aid for Developmental Scientific Research (B).
|Research Institution||Tohoku University|
NAKAGAWA Yasuaki Tohoku Univ. I. M. R. Professor, 金属材料研究所, 教授 (10005944)
高野 広久 (株)東芝, 京浜事業所, 主査
MIURA Shigeto Tohoku Univ. I. M. R. Res. Assoc., 金属材料研究所, 助手 (90005893)
HOSHI Akira Tohoku Univ. I. M. R. Assist. Prof., 金属材料研究所, 講師 (30005889)
KIDO Giyuu Tohoku Univ. I. M. R. Assoc. Prof., 金属材料研究所, 助教授 (10013541)
TAKANO Hirohisa Toshiba Corp. Keihin Branch, Chief. Eng.
|Project Fiscal Year
1989 – 1990
Completed(Fiscal Year 1990)
|Budget Amount *help
¥9,800,000 (Direct Cost : ¥9,800,000)
Fiscal Year 1990 : ¥1,200,000 (Direct Cost : ¥1,200,000)
Fiscal Year 1989 : ¥8,600,000 (Direct Cost : ¥8,600,000)
|Keywords||high magnetic field / quasi-steady field / resistive magnet / cryogenic magnet / long-pulsed magnet / 強磁場 / 準定常磁場 / 常伝導マグネット / クライオジェニック・マグネット / ロング・パルス・マグネット|
1. Design and fabrication of cryogenic magnet
(1) Coil : This magnet is operated at liquid nitrogen temperature, consisting of an outer Bitter coil and an inner polyhelix coil. The electromagnetic force and the Joule heat dissipation were carefully taken into account for designing the magnet.
(2) Power supply : A high-power DC source for steady high field magnets was modified with a pulse operation circuit so as to serve for the quasi-steady cryogenic magnet. The current is increased to 23 KA ror 1 or 2 seconds, and kept at 23 KA for 0-3 seconds.
(3) Cryostat : Liquid nitrogen is supplied from a large reservoir of 9 m_3 capacity, and circulated through the magnet coils in a cryostat.
2. Test of cryogenic magnet
(1) Excitation at room temperature : The resistance of the coils is so large at room temperature that only a small current can be passed through the coils. Under this condition, however, the characteristics of the power supply and the heating of the coils were tested. No unexpected results were obtained.
(2) Cooling down to liquid nitrogen temperature : It took 10 minutes to cool down the coils from 300 K to 77 K.
(3) Excitation at liquid nitrogen temperature : The coil resistance is reduced to about 1/8 of that at room temperature so that a large current is passed through the coils. Although the excitation should be made during the circulation of liquid nitrogen, the circulation was stopped before the excitation in the present test : the coils heated by the excitation was cooled again by circulating liquid nitrogen. The field produced by the magnet was in good agreement with the designed value. The cryogenic magnet has not been applied for the measurement of physical properties at high fields. It should be emphasized, however, that the main purpose of this research is to clarify the characteristics of the quasi-steady cryogenic magnet.
Research Output (7results)