【国家标准】 实用超导线　铌-钛(Nb-Ti)与铌三锡(Nb3Sn)复合超导体的扭距测量方法

This document specifies a method of measuring the twist pitch of Nb-Ti and Nb3Sn composite superconductors,including principle,reagent,tool,specimen preparation,measurement procedure,calculation of results,uncertainty of measurement and test report.
This document is applicable to measuring the twist pitch of multifilamentary Nb-Ti and Nb3Sn composite superconductors with the diameter of 0.2 mm to 2.0 mm (or a rectangle with the equivalent cross-sectional area),the superconducting filament(s) diameter of 6 μm to 200 μm,and the twist pitch of 5 mm to 50 mm. The Nb-Ti and Nb3Sn composite superconductors of this document have monolithic structures with a copper matrix.
This document is not applicable to superconductors with coating that cannot be dissolved by nitric acid.
NOTE 1 If the cross-sectional shape,area,filament diameter and twist pitch of composite superconductor are beyond the above range,the uncertainty of measurement will be increased.
NOTE 2 With appro