Stability Evaluation of No-Insulation REBCO Pancake Coils – Comparison of Different NI Winding Techniques –

Abstract

The no-insulation (NI) winding technique proposed by Hahn on 2011 drastically improves the thermal stability of REBCO pancake coils. Thereafter, several different kinds of NI winding techniques have been proposed, such as the partial-insulation, the metal-as-insulation (MI), the conductive-epoxy-resin-covering (CERC), and the intra-layer NI winding techniques. Recently, we have reported the thermal stability comparison of REBCO coils which these NI winding techniques are applied to. The reduction of contact resistance improves the thermal stability even more.

In addition, the multiple REBCO tape bundled (MB) technique was recently proposed. REBCO tapes may have a few defects before winding. When the MB technique applies to REBCO coils, the current can avoid the defect region to transfer into the neighboring REBCO tapes. That is why the technique can improve the charging delay. The MB winding technique is getting attention. We have also evaluated REBCO pancake coils with the MB winding technique comparing them with a conventional NI REBCO pancake coil.