IEC 61788-9:2005

Overview

IEC 61788-9:2005 Superconductivity – Part 9 outlines a standardized test method for measuring the trapped field (trapped flux density) in bulk high temperature superconductors (BHTSCs), specifically those made from large grain oxide materials. The standard applies to samples with well-defined shapes, such as round discs and rectangular or hexagonal pellets. Measurements can be taken over a broad temperature range (4.2 K to 90 K), but for consistency and global comparability, results are reported at liquid nitrogen temperature.

This international standard was developed to meet the growing need for consistent and reliable measurement practices in both the manufacturing and application of bulk superconductors, ensuring accurate characterization for research, industry, and advanced engineering use.

Key Topics

• Trapped Flux Density Measurement:

  • Defines trapped flux density as the magnetic field retained in a BHTSC at a set temperature and sample gap.
  • Specifies a standardized measurement procedure using a Hall sensor to scan the superconductor’s surface after field cooling.
  • Emphasizes that measurements must be taken after a stabilization period (minimum 15 minutes post field removal) to account for initial flux relaxation.

• Sample and Equipment Requirements:

  • Applicable to large grain oxide superconductors with clearly defined geometric shapes.
  • Utilizes a cryostat for temperature control and a superconducting or equivalent magnet for sample magnetization.

• Precision and Reporting:

  • Ensures that coefficients of variation in repeat measurements within one month do not exceed 5%, supporting the reliability of inter-laboratory comparisons.
  • Test reports are to detail measurement conditions, results, and methodology for transparency and repeatability.

• Safety Considerations:

  • Highlights the need for careful handling of intense magnetic fields, cryogenic liquids, and the associated risk of rapid thermal energy release.

Applications

IEC 61788-9:2005 is essential for anyone designing, manufacturing, or utilizing bulk high temperature superconductors in various high-tech and industrial applications, such as:

• Magnetic Bearings & Levitation Devices: The trapped flux density measurement allows engineers to determine suitability for applications requiring sustained magnetic fields, like frictionless bearings or maglev systems.
• Energy Storage Systems: Flywheel energy storage relies on accurately characterized BHTSCs for efficient performance.
• Trapped Field Magnets: High-performance magnets utilizing trapped flux density serve in MRI systems, scientific instruments, and particle accelerators.
• Load Transportation Technologies: Design and verification of devices that use bulk superconductors for non-contact load support or movement.

Reliable and repeatable measurement of trapped flux density is crucial in these areas to optimize device performance and guarantee safety. Manufacturers and users benefit from harmonized international methods to ensure product quality and device interoperability.

Related Standards

The IEC 61788 series addresses various measurements and properties pertinent to superconductivity, providing a comprehensive framework for the field. Closely related standards include:

• IEC 61788-1 to 61788-8: Cover critical current, residual resistance ratio, matrix to superconductor volume ratio, and AC loss measurements for different superconducting materials and configurations.
• IEC 60050(815):2000: Offers essential definitions and terminology linked to superconductivity for ensuring consistent language in measurement and reporting.
• IEC 61788-10, 11, 12, 13: Extend the range of standardization to aspects such as critical temperature measurement and further loss and ratio measurements.

For researchers, manufacturers, and users, referencing IEC 61788-9 in conjunction with these related standards enables a holistic approach to the characterization of superconducting materials, improving credibility and facilitating international trade and cooperation in advanced technological sectors.