Comparative Measurements of ITER Nb₃Sn Strands between Two Laboratories

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, residual resistance ratio, and hysteresis loss, while at room temperature the chromium layer thickness, Cu/non-Cu ratio, filament twist pitch, and diameter were determined. Our results show very good agreement between the two laboratories. The reasons for small random discrepancies are discussed.