High temperature superconducting magnet operating above 15 K for ADR cooling

This Phase I program will develop a coil design and deliver a prototype that proves the feasibilty of exceeding the requirements set forth in topic area S.109 for Sub-Kelvin Cooling ADR (Adiabatic Demagnetization Refrigeration) Coils. It will utilize a new type of small diameter wire based on the Bi2212 high temperature superconductor (HTS), that has recently been developed to wind the ac stator coils of compact, lightweight motors for hybrid electric airplane propulsion. These wire types with lt; 0.16 mm diameters now exhibit 3 times higher current density than standard wires and they are in forms that are applicable to ADR magnets. For ADR usage, this wire design will be applied in long insulated lengths to wind coils with the capability to operate at the specified higher operating temperatures, small winding currents, high current densities and with low losses in ramped fields. This wire type is also applicable to Actuators and Other Cryogenic Devices that are described in this topic area. As a first step in Phase I, the capability to produce long lengths of a specific small cross-sectioned 2212 wire design for ADR will be established based on current wire capability, and a demonstration test coil built. The wire design will include axial twisting and unmerged filaments for reducing ramped field loss, thin insulation, and current densities to meet specifications for up to 20K operation at 4T field, as requested for next level ADR coil advances. Coil fabrication techniques will be established, both with the Bi2212 ceramic in its high Jc, reacted form during windings well as in a pre-reacted form.nbsp; A short length, full radial build coil deliverable will be built, tested and provided to NASA for evaluation and validation, attaining a TRL of 4 upon completion. In Phase II a full scale coil system will be developed and delivered.