Quantification of Systematic Error in Ic Testing

Abstract

Critical current (Ic) testing of the superconducting wire for the Superconducting Super Collider (SSC) is an important Quality Assurance concern due to its significance in magnet variability. Established industrial QA procedures to quantify measurement variability have been adapted to Ic measurements. To implement these ideas, a round robin experiment was developed and six test sites were invited to participate in the evaluation of Ic measurement uncertainty. An SSCL Quality Assurance representative witnessed all measurements performed in this program. The definition of each component of variability, the test plan procedure that quantified each component, preliminary findings, and future plans are reported. Preliminary results show that four of the six round robin participants achieved accuracy within +/- 2% of the National Institute of Standards and Technology critical current Standard Reference Material value. Reproducibility results show that five of six test sites have a 2% or less uncertainty, with one test site as high as 6.5%. In addition, the repeatability results show that only one participant has less than 2% uncertainty; the remaining labs falling within 2-5%. Cumulative uncertainty is determined to be 3-10% depending on the method used to calculate repeatability.