Resistance-Controlled (RC) Interface With Metal Mesh for Managing Current Bypassing in No-Insulation (NI) Scheme Coils

A simple method is proposed for the establishment of resistance-controlled (RC) interfaces to control bypass resistance inside windings for no-insulation (NI) scheme coils. The method uses stainless steel mesh impregnated with epoxy to create current bypass paths between REBCO tape turns or between a REBCO tape turn and a copper sheet. Short samples for an RC interface are evaluated for bypass resistance using the four-terminal method at 77 K. Each sample is composed of two REBCO tapes between which a 30 μm-thick SS mesh which is impregnated with epoxy to keep the contacts between the surfaces of the REBCO tapes and SS mesh. Most samples show bypass resistances of the order of 100–1000 mΩ·cm²; such high values are of importance from the viewpoint of achieving self-protection of NI scheme coils, via management of both overheating and overstressing. Issues related to variations in bypass resistances must be addressed before the proposed method can be implemented in coils.