Bi-2212 Structured Cable for High-Field Solenoid Inserts

A structured cable has been developed and tested for use in insert windings for high-field solenoids. The cable utilizes a design developed earlier, in which six strands of multi-filament Bi-2212/Ag round wire are cabled around a thin-wall spring tube and jacketed in a high-strength Inconel sheath. The cable provides stress management within each winding so that coil stress cannot degrade the fragile superconducting filaments. The cable-based coil accommodates inward pre-load, giving the potential for twice the achievable field increment per shell. Prototype lengths of cable have been prepared and a heat treatment schedule has been optimized. Test results are presented for the performance of small test windings.