[WBP2] Bulk, Assembled Conductors, AC Loss

[WBP2-01] 2D Multiphysics modeling of hole arrangements in relation to growth sectors in REBCO bulks during pulsed-field magnetization

*Santiago Guijosa¹, Kévin Berger¹, Frederic Trillaud^2,1, Melika Hinaje¹ (1. Université de Lorraine (France), 2. Universidad Nacional Autónoma de México (Mexico))

Keywords:

REBCO,Pulsed-field magnetization,Thin-wall bulks,Multiphysics simulation

During pulsed-field magnetization (PFM), high-temperature superconducting (HTS) bulks are subjected to rapid and intense electromagnetic and thermal loads that can limit their performance and mechanical reliability. A key fabrication-induced inhomogeneity arising from the top-seeded melt growth process, are the growth sector regions (GSR) and growth sector boundaries (GSB) resulting in a macroscopic critical current density (J_c) anisotropy due to the different local concentration of pinning centers as the crystal growth evolves. Magnetic flux preferentially invades the GSR, while GSB regions exhibit stronger heating (see Ref. [1]), making the overall trapped field highly dependent on this anisotropy. To mitigate mechanical degradation, holes are often introduced prior to solidification to promote gas escape and reduce porosity (see Ref. [2-4]). In this work, we develop a 2D multiphysics finite element model in COMSOL to investigate how the relative positioning of holes with respect to the GSR/GSB structure influences the electromagnetic, thermal, and mechanical response during PFM (see Fig. 1). Additionally, we demonstrate how different materials can be used to fill holes in order to optimize electromagnetic and thermal diffusion, as well as their impact on mechanical behavior. The results show that optimized hole arrangements can alleviate local stress concentrations and thermal hotspots associated with GSR and GSB inhomogeneities, while maintaining high trapped fields. This study highlights the importance of combining pore-engineering strategies to the intrinsic growth sector structure in order to enhance both performance and the mechanical behavior of REBCO bulks.