A potential future muon collider requires high field solenoids of 30T or more in the final cooling section. The Magnet Division at Brookhaven National Laboratory has an active research programme to realize this using high temperature superconductors. A two coil system is presently being build which is designed to produce 20T or more. The coil design uses a commercially available YBaCuO superconductor from SuperPower.
It is common practice to co-wind the HTS tape with stainless steel tape. This is done to provide additional reinforcement to counterbalance the high Lorentz forces at high fields. In addition, the steel tape can be seen as an insulation due to the high resistivity.
The steel/HTS structure is not impregnated with epoxy resin, which means that it is not clear if classical composite theory applies in this case. Bulk parameters, obtained using the rule of mixtures or the Halphin-Tsai equations, are potentially incorrect. A further question is that of mechanical slippage: the friction coefficient between the steel and HTS tape can be assumed to be very small (metal to metal), so it is not unreasonable to assume that the pancake may unwind under load and thus withstand much smaller forces and fields.
To investigate this an existing experimental setup was used, which is named exploding pressure vessel test. This material test is ideally suited to investigate this, as it allows to subject materials to loading conditions very similar to that experienced in solenoids in a controlled way. This report describes the experimental setup and initial results obtained in June 2012.