In this paper, we present results, analytical and experimental, of two dimensionally identical 1.5 T NbTi coils with a 2-T peak field, operated in the 4.2-6 K range, one impregnated with paraffin and the other solid nitrogen (SN2). In the paraffin coil, the paraffin prevents conductor motion and the coil operates stably in the temperature range. In the SN2 coil, although not as strong as...
Improvement of mechanical stability of superconducting cables under high mechanical loads is one of the most important challenges for their industrial application. Provided that impregnation is commonly adopted to protect coil wound by superconducting tapes from mechanical disturbance caused by Lorentz force generated from magnetic field and rotational vibration of machines such as motor, this...
In general, the field coils of a superconducting motor or generator need to be impregnated with epoxy resin to protect the coils from mechanical stress occurring during rotation. Recently, various studies that have been conducted to optimize the epoxy impregnation method revealed that coils impregnated by the vacuum pressure impregnation (VPI) method have superior thermal and electrical...
When a hotspot occurs in a conduction-cooled HTS superconducting winding, decrease of heating at the hotspot and decrease of local temperature rise are necessary. In order to do that, good thermal conduction around the heat-source materials such as an electric-insulation film on the HTS tape and a non-metallic structural material is important. The electric insulation materials are generally...
A major problem of state-of-the-art Nb3Sn accelerator magnets is their long training due to thermo-mechanical perturbations. Increasing the specific heat, Cp, of the Rutherford cable would reduce and/or eliminate training by limiting its temperature rise. This paper studies feasibility of increasing the Cp of Nb3Sn Rutherford-type cables by using composite Cu/Gd2O3 and Cu/Gd2O2S tapes produced...
A major focus of Nb3Sn high field accelerator magnets for HEP is on significantly reducing or eliminating their training. Samples of NbTi and Nb3Sn wires and Rutherford cables were impregnated with organic olefin-based thermosetting dicyclopentadiene (DCP) resin, commercially available as TELENE® by RIMTEC Corporation in Japan, mixed with high heat capacity ceramic powders. The high heat...
Recently, we proposed a novel winding technique, which entails employing grease materials as a turn-to-turn insulator to ameliorate the charging-discharging delay observed in no-insulation (NI) coils. As a result, we obtained coils that possess superior thermal and electrical stabilities without charging-discharging delays. However, because of the higher resistance of these grease materials as...
