無絶縁REBCO パンケーキ・コイルにおける数値解析技術

―解析手法の比較および解析事例―

抄録

A no-insulation (NI) winding technique was proposed by Hahn. This technique drastically improves the thermal stability of REBCO pancake coils. Using the technique, a 45.5-T DC field was achieved at the National High Magnetic Field Laboratory in August 2018. Now, Iwasa, of the Plasma Science and Fusion Center, Massachusetts Institute of Technology, is developing an insert NI REBCO magnet for the 1.3-GHz LTS/HTS NMR magnet. However, since the electromagnetic behavior in NI REBCO pancake coils is complicated, it is desirable to evaluate the magnet stability using simulation. Hence, a few simulation methods for NI REBCO pancake coils have been developed and reported, such as a lumped circuit model, a partial element equivalent circuit (PEEC) model, and a distributed network model. In this review paper, we discuss these simulation methods and describe the specifications for each of them. Finally, we compare the simulation results of each method. Accurate simulation of the lumped circuit model and radially-divided circuit model with a small number of elements was not possible because the magnet coupling between elements or coils was not correctly modeled. As a result, we had to use the PEEC model, distributed network model, or a radially-divided circuit model with many elements in order to accurately express the normal zone propagation.