Lécrevisse Thibault, Bascuñán Juan, Hahn Seungyong, Kim Youngjae, Song Jungbin, Iwasa Yukikazu
The authors are with the Magnet Technology Division, Francis Bitter Magnet Laboratory, Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139 USA.
IEEE Trans Appl Supercond. 2015 Jun;25(3). doi: 10.1109/tasc.2014.2372891. Epub 2014 Dec 2.
We present the results of tape-to-tape joint resistances in a 1.3-GHz/54-mm nuclear-magnetic-resonance magnet comprising a 500-MHz low-temperature-superconducting magnet and an 800-MHz high-temperature-superconducting insert (H800), which is currently in the fabrication stage at the Massachusetts Institute of Technology Francis Bitter Magnet Laboratory. The H800, which is a three-coil assembly of double-pancake coils and wound with a 6-mm-wide (RE)BCO tape (rare earth element), requires a total of 94 tape-to-tape joints. Specific results obtained are: 1) an extrapolation technique to predict the resistances of the tape-to-tape curved bridge joints from those of the curved lap joint samples with the same 6-mm-wide tape batch and joint area; 2) increased resistance owing to a small gap (< 0.4 mm) in the outer radii of the two adjacent pancakes, which is mainly caused by the variation in the (RE)BCO tape thickness (on the order of several micrometers); 3) a method to minimize solder-heating influences on the pancake current-carrying capacity; 4) the dependence of resistance on solder materials; and 5) the experience with the 25 joints on Coil 1, which is the first of three coils for our H800 insert (H800 Coil 1).
我们展示了在一个1.3吉赫兹/54毫米的核磁共振磁体中带对带接头电阻的结果，该磁体由一个500兆赫兹的低温超导磁体和一个800兆赫兹的高温超导插入件（H800）组成，目前正在麻省理工学院弗朗西斯·比特磁体实验室制造。H800是一个由双饼式线圈组成的三线圈组件，用6毫米宽的（稀土元素）铼钡铜氧带材缠绕，总共需要94个带对带接头。获得的具体结果如下：1）一种外推技术，用于根据相同6毫米宽带材批次和接头面积的弯曲搭接接头样品的电阻来预测带对带弯曲桥接接头的电阻；2）由于两个相邻饼式线圈外半径的小间隙（<0.4毫米）导致电阻增加，这主要是由铼钡铜氧带材厚度的变化（在几微米量级）引起的；3）一种将焊接加热对饼式线圈载流能力影响最小化的方法；4）电阻对焊接材料的依赖性；5）关于H800插入件三个线圈中的第一个线圈（H800线圈1）上25个接头的经验。
