Measurement of Inter-Strand Contact Resistance in Epoxy Impregnated Nb3Sn Rutherford Cables

Abstract

An apparatus for the measurement, under transverse pressure, of the inter-strand contact resistance in epoxy-impregnated Nb 3 Sn Rutherford cables has been recently assembled at Fermilab. Procedures have been developed to instrument and measure samples extracted from Nb 3 Sn coils. Samples were extracted from coils fabricated with the Wind-and-React and the React-and-Wind technology, both presently under development at Fermilab. A ceramic binder is used to improve the insulation and to simplify the fabrication of coils using the Wind-and-React technology. Synthetic oil is used to prevent sintering during the heat treatment of coils to be wound after reaction. In order to evaluate the effects of the ceramic binder and of the synthetic oil on the inter-strand resistance, measurements of samples extracted from coils were compared with measurements of cable stacks with varying characteristics. In this paper we describe the apparatus, the sample preparation, the measurement procedure, and the results of the first series of tests.

Common-Coil Dipole for a Very Large Hadron Collider

“…The dependence of the field harmonics on the current ramp rate was very small. The absence of eddy currents in the cable was related to the rather large inter-strand resistance, produced during the cable reaction with synthetic oil without transverse pressure on the cable (Ambrosio et al 2004b).…”

“Mirror” magnet experiment for quench studies, quench analysis techniques development and in support of superconducting magnet modeling

“…It also takes place during quenching and can serve as an indicator of it and possibly as a precursor of it. While the physics of current redistribution is clear and various related processes studied [4[, [5], [12], [32], [33], [34] a significant complication for interpretation in real magnets is the existence of splices (review on splice/joint technology for various superconductors can be found in [35]). Lead splices can be considered in approximation of equal potential for all strands or equal current in all strands with the two giving very different current/power loss distribution outcomes [4].…”

“…The experiment proposed relies partially on instrumenting individual strands with voltage taps. This was successfully done at Fermilab in past [32] and the technology is also implemented elsewhere [6], [7], [8]. However, the configuration of the voltage taps requires access to the narrow cable side instrumenting many strands at close proximity.…”

Field Quality Measurements of Fermilab<tex>$hboxNb_3hboxSn$</tex>Common Coil Dipole Model

“…7. Absence of the eddy currents in the cable is related to the quite high inter-strand resistance, created during the cable reaction with synthetic oil without transverse pressure on the cable [8].…”