IEC 61788-17:2021

Overview

IEC 61788-17:2021 - Superconductivity Part 17 specifies an inductive, non‑destructive method to measure the local critical current density (Jc) and its distribution in large‑area high‑temperature superconducting (HTS) films. The method uses third‑harmonic voltages generated by an AC drive coil to determine the local critical sheet current (Jc × film thickness d) at liquid‑nitrogen temperatures. The standard limits its scope to measurements without applied DC magnetic fields and emphasizes determining Jc from an electric‑field criterion and extracting current–voltage characteristics via frequency dependence.

Key topics and requirements

• Measurement principle: Inductive detection of third‑harmonic voltage (U3) as a function of drive current and frequency to infer local Jc and E–J behaviour.
• Electric‑field criterion: Jc must be defined using a specified E‑field threshold; frequency scaling is used to obtain I–V characteristics.
• Apparatus: Sample drive coil configurations, coil‑to‑film positioning, and calibration wafers to determine the experimental coil coefficient (k′).
• Coil coefficients: Procedures to calculate theoretical coil coefficient (k) and determine the experimental k′ used in converting measured voltages to Jc.
• Measurement range & resolution: Reported Jcd (Jc × d) typically from 200 A/m to 32 kA/m, with measurement resolution around 100 A/m (based on experimental results).
• Uncertainty and errors: Guidance on major systematic effects, coil distance sensitivity, edge effects, and an uncertainty budget (Annex C).
• Test reporting: Required specimen identification, measured J values, n‑values, and test conditions for reproducible results.
• Informative annexes: Theory of third‑harmonic generation, induced electric‑field calculations, optional two‑coil/ noise‑reduction systems, and uncertainty evaluation.

Applications

• Quality control and mapping of large‑area HTS films used in microwave filters, superconducting fault current limiters (SFCLs), persistent‑current switches, and other HTS devices.
• R&D and process optimization for thin‑film deposition (YBCO and similar HTS materials) where spatial Jc uniformity affects device performance.
• Acceptance testing and traceable measurement of Jc distributions for product qualification.

Who should use this standard

• Test laboratories and metrology institutes performing nondestructive Jc mapping.
• HTS film manufacturers and production QA teams.
• Researchers and engineers in superconductivity device development.
• Standards committees and compliance assessors working on HTS material characterization.

Related standards

• Other parts of the IEC 61788 series on superconductivity (see IEC catalogue for related measurement and characterization parts).
• Internal references and normative citations within IEC 61788‑17 address measurement practice and uncertainty evaluation.

Keywords: IEC 61788-17:2021, superconductivity, local critical current density, Jc, HTS films, third-harmonic voltages, inductive measurement, coil coefficient, liquid nitrogen, measurement uncertainty.