Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7915676 | Cryogenics | 2018 | 5 Pages |
Abstract
Recently, degradation of a high-field REBCO coil due to strong electromagnetic forces, has been identified. This issue is related to a conductor movement, forming a kink in the conductor body, and hence epoxy impregnation should be effective to prevent it. The purpose of this paper is to examine the effect of epoxy impregnation on the electromagnetic force-induced degradation of a REBCO coil. We made an epoxy impregnated solenoid coil and charged it at 4.2â¯K in an external field of 11â¯T. A notable characteristic behavior, which is different from that of a dry or paraffin impregnated coil, was observed in the coil's performance. The coil did not show any normal voltage below 408â¯A, at 65% on the coil load line, but it showed a sudden voltage jump at 408â¯A, resulted from a sudden fracture of the REBCO conductor. The outward bending, combined with a strong circumferential stress, caused the REBCO layer to fracture. Although epoxy impregnation is effective to suppress a conductor movement inside the winding, avoiding self-supported sites at a coil edge is required to eliminate degradation of the thin and flexible REBCO conductor.
Related Topics
Physical Sciences and Engineering
Materials Science
Electronic, Optical and Magnetic Materials
Authors
T. Matsuda, T. Okamura, M. Hamada, S. Matsumoto, T. Ueno, R. Piao, Y. Yanagisawa, H. Maeda,