Nanocrystalline soft magnetic alloy (MA) cores are essential magnetic loading components in proton/heavy-ion synchrotron rf cavities. While conventional MA cores fabricated from $16\mathrm{\mu }\mathrm{m}$ ribbons offer reliable performance, further enhancing their shunt impedance and thermal stability to meet the demands of next-generation high-power synchrotrons presents significant challenges. Although the use of thinner ribbons (e.g., $13\mathrm{\mu }\mathrm{m}$) can improve high-frequency magnetic properties, their widespread application is hindered by manufacturing difficulties and reduced packing factor consistency. To address this, we propose an embedded MA core design that strategically integrates $13\mathrm{\mu }\mathrm{m}$ ribbons in specific radial regions alongside normal $16\mathrm{\mu }\mathrm{m}$ ribbons. This approach not only increases shunt impedance but also optimizes the electromagnetic field distribution, thereby reducing peak surface temperature and improving thermal stability. This paper first elucidates the physical mechanism through which the embedded structure improves temperature uniformity. Additionally, a two-dimensional heat transfer numerical model is developed and experimentally validated to assess the thermal performance of the embedded MA core under actual operating conditions. Experiments are conducted and the results demonstrate the embedded core’s peak surface temperature is reduced by $2.5°\mathrm{C}$ compared to a normal MA core. Finally, parameter optimization of the embedded structure is conducted, demonstrating that optimizing the radial position, volume ratio, and thickness of thinner ribbons can achieve a temperature reduction of approximately $6°\mathrm{C}$ and a 12% impedance increase. The findings of this study provide a theoretical foundation for the performance optimization of MA cores in high-power synchrotrons.

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• Electromagnetic field calculations
• Radio frequency calculations
• Radio frequency techniques