Bi : 2212/Ag-based Rutherford cables: production, processing and properties

The fabrication of Bi:2212/Ag-based Rutherford-type accelerator cables, the ir transport critical current (I-c) testing and ac loss measurement are des cribed. Multifilamentary strands were used to form several cables with 18-1 9 strands and a lay pitch, L-p (half the transposition pitch) of 27.5 mm. T he inclusion of a metallic alloy core was proposed for mechanical strength, the limiting of cable winding damage and ac loss/residual magnetization mi tigation. Single-strand measurements of 'poisoning' from several candidate core materials are reported, as well as the influences of winding pitch and thermal shock degradation on I-c. Nichrome 80 was selected as a core mater ial on the basis of ready availability in strip form and its initially obse rved inertness from a poisoning standpoint. In-cable single-strand studies indicated that winding damage could degrade edge-measured I-c by about 16%. Full cable I-c measurements demonstrated that core-induced poisoning could reduce I-c by a further 35-40%. Ac loss measurements on a series of specia lly designed cables showed that the core (either bare or coated) effectivel y insulated the strands against crossover contact. This, together with the fact that the cable had been only lightly compacted (thereby ensuring moder ate but not strong side-by-side contact) allowed the effective interstrand contact resistance of a projected Bi:2212/Ag-wound core-type LHC Rutherford cable to fall close to the acceptability range for the windings of acceler ator magnets.