Inter-Laboratory Comparisons of NbTi Critical Current Measurements

Published

June 22, 2009

Author(s)

Arno Godeke, D. Turrioni, T. Boutboul, Najib Cheggour, A. K. Ghosh, Loren F. Goodrich, M Meinesz, A. den Ouden

Abstract

We report on a multi-institute comparison of critical current data, measured on a modern Large Hadron Collider (LHC) NbTi wire that has shown a standard deviation below 1% in critical current density spread in more than 1500 measurements. Inter-laboratory comparisons on Nb3Sn wires have shown ambiguities that could be attributable to strain related differences in critical current density, originating from differences in sample handling, reaction, and mounting techniques, or also to differences in the magnetic field and current calibrations between the institutes. A round robin test of a well characterized NbTi wire provides a baseline variance in critical current results that is presumed to be only attributable to differences in the characterization systems. Systematic differences on the order of 3.5% are found in the comparison. The most likely cause for the observed differences is a small diameter holder which brings the wire into a strain regime in which strain effects can no longer be ignored. A NbTi round robin test, when performed properly, will separate system differences from sample specific differences and provide laboratories with an opportunity to calibrate equipment against a standard measurement.

Citation

IEEE Transactions on Applied Superconductivity

Volume

19

Issue

3

Pub Type

Journals

Download Paper

Local Download

Keywords

Critical current, NbTi, Round robin, Standardization

Citation

Godeke, A. , Turrioni, D. , Boutboul, T. , Cheggour, N. , Ghosh, A. , Goodrich, L. , Meinesz, M. and den Ouden, A. (2009), Inter-Laboratory Comparisons of NbTi Critical Current Measurements, IEEE Transactions on Applied Superconductivity, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=900166 (Accessed October 14, 2024)