Critical Current Studies on Fine Filamentary NbTi Accelerator Wires

Abstract

The magnets fov the Superconducting Super Collider, a high energ; proton colliding beam accelerator, require a superconductor with very; high current density (>2400 A/rnm^ at 5 T) and very mall filaments (.r lira in diameter). Previous work has shown that by controlling the formation of Cu^Ti compound particles on the filament surfaces it is possible to make fine filamentary NbTi wire with high critical current density. The performance of multi-filamentary wire is characterited by the current density and the quantity "n" which describes the superconducting-normal transition. Micrographs of wires having high J c and high n shpw smooth, uniform filaments. Recently wires of very high critical current and high n have been produced in experimental quantities by commercial manufacturers.

Thermal stability of oxide superconductors in flux flow state

“…I T IS well known that voltage-current (V-I) characteristics of superconductors are empirically approximated as a power law (1) Typical exponent values had been reported to be 30-50 for conventional metallic superconductors [1], [2], and 5-10 for oxide superconductors [3]. A large value implies that the superconductor should exhibit a sharp transition from superconducting state to normal state.…”

Ab initio theory of the impact of grain boundaries and substitutional defects on superconducting Nb3Sn

“…Conventional niobium-based superconductors dominate industrial superconducting technologies, and while niobiumtitanium alloys are the most widely-used superconductor, Nb 3 Sn offers the potential to operate both at higher fields and temperatures [1][2][3][4]. Yet, many applications have historically avoided Nb 3 Sn, despite its superior critical field and temperature, because of the challenges involved in manufacturing the material in a way that preserves its desirable properties.…”