Comparative measurements of ITER Nb3Sn strands between two laboratories

TL;DR

This study compares measurements of ITER Nb3Sn strands between two laboratories, demonstrating high consistency in critical parameters and discussing sources of minor discrepancies to ensure quality verification.

Contribution

It provides a detailed cross-laboratory comparison of Nb3Sn strand measurements, establishing reliability and identifying sources of measurement discrepancies.

Findings

Very good agreement between labs on critical parameters

Small random discrepancies explained and discussed

Validation of measurement consistency for ITER strand quality

Abstract

ITER Nb3Sn strand quality verification tests require large quantities of precise measurements. Therefore regular cross-checking between testing laboratories is critically important. In this paper, we present results from a cross-checking test of 140 samples between the National High Magnetic Field Laboratory, USA and the University of Twente, the Netherlands. The tests comprise measurements at 4.2 K on critical current, RRR and hysteresis loss, while at room temperature the chromium layer thickness, Cu/nonCu ratio, filament twist pitch, and diameter were determined. Our results show very good agreement between the two labs. The reasons for small random discrepancies are discussed.