Characterisation of Large-Sized REBaCuO Bulks for Application in Flux Modulation Machines

Area of Science:

• Materials Science
• Electrical Engineering
• Aerospace Engineering

Background:

• High temperature superconductors (HTSs) are crucial for aircraft electrification, offering improved power-to-weight ratios in electrical machines.
• The FROST project aims to develop compact, lightweight flux modulation machines using HTS bulks for aircraft propulsion, aligning with decarbonization goals.

Purpose of the Study:

• To characterize the performance and homogeneity of large REBaCuO bulks for the FROST project.
• To identify the causes of trapped field inhomogeneities in HTS bulks used in superconducting electrical machines.

Main Methods:

• Characterization of 11 large REBaCuO bulks, including trapped field mapping and critical current estimation.
• In-depth analysis of a spare bulk using critical current measurement, X-ray diffraction, and scanning electron microscopy.
• Development of a numerical model to simulate the trapped field map based on experimental data.

Main Results:

• Weakly oxygenated regions were identified within the HTS bulks, correlating with local drops in superconducting properties.
• All tested bulks exhibited sufficient current density for use in the proposed flux modulation machine prototype.
• A numerical model successfully reproduced the experimental field map of the spare bulk.

Conclusions:

• Inhomogeneities in trapped magnetic fields are attributed to localized oxygen deficiencies within the HTS bulks.
• Further statistical characterization across multiple bulks is necessary to fully understand the origins of these inhomogeneities.
• The tested HTS bulks are suitable for the development of advanced aircraft electrical machines.