Coupling- and Persistent-Current Magnetizations of $ \hbox{Nb}_{3}\hbox{Sn}$ Rutherford Cables With Cores of Stainless Steel and Woven Glass-Fiber Tape Measured by Pick-Up Coil Magnetometry

Abstract

Coupling- and persistent-current magnetization of $\hbox{Nb}_{3}\hbox{Sn}$ Rutherford cables with cores of stainless steel (SS) and woven glass-fiber tape were measured by pick-up coil magnetometry in transverse magnetic fields of amplitude 400 mT and frequencies of up to 90 mHz applied in the face-on orientation. Analysis of the results yielded the interstrand contact resistances as well as estimates of the face-on coupling magnetizations generated by fields ramping at the LHC-specified 6.5 mT/s. Distinct differences were discovered in the behaviors of the SS-cored and glass-fiber-cored cables. The cable with a wide SS core had suitable coupling properties; that with a narrow off-center SS core provided excessively large coupling magnetization. The glass-fiber-cored cables exhibited anomalous ac-loss frequency dependence indicative of loose Rutherford-like assemblies of strands with relatively few points of low-resistance interstrand contact.