From Hot to Cold: Advanced Materials and Processes for NbSn Based Magnets

We worked out an approach for obtaining “clean” magnets by introducing oxygen during the reaction heat treatment (RHT) of a single glass fiber insulated Nb
₃
Sn Rutherford cable in a channel. A reduction of the RRR by 16% was measured while the glass fiber insulation and support structure was visually clean after the RHT. We developed a filled wax system, consisting of fully refined paraffin wax, carnauba wax and alumina particles, which is compatible with the common glass fiber insulation on Rutherford cables. The filled wax showed a flexural modulus of 19 GPa at −100 °C and a thermal shrinkage of −1.2% from RT to 77 K. We used a commercial glass ceramic coating on stainless steel as primary insulation in single cable in a channel applications or as secondary electrical insulation from the former. The coating survives the RHT and operation temperatures and keeps its electrical insulation properties.