Toward HTS-Ready Axial-Flux Motors: Interface-Limited Heat Transfer to an MCE-Active Core via AlN Thermal Pathways

—This paper presents a decoupled, layered axial-flux architecture aimed at mitigating the severe thermal-magnetic coupling challenges in future high-temperature superconducting (HTS) rotating machines. By shifting from a highly coupled radial monolithic motor to a weakly coupled coaxial sub-motor array, the system enables layered hierarchical torque allocation under thermal constraints. A multi-node parametric thermal resistance-capacitance (RC) network analysis reveals a critical bottleneck transition: the dominant thermal limitation shifts from bulk material resistance to interfacial contact resistance. Within the adopted lumped thermal network, replacing standard alumina-class insulation with Aluminum Nitride (AlN) reduces the total winding-to-core thermal resistance by roughly a factor of three. However, downstream vapor chamber (VC) utilization remains severely limited unless the longitudinal heat path to the Magnetocaloric Effect (MCE) active core is resolved. To address this, a selective thermal interface optimization strategy is evaluated. The model suggests that targeted lapping/polishing and controlled compression can reduce contact thermal resistance on the primary conduction path while retaining electrical insu lation on secondary surfaces. These findings outline a plausible engineering pathway for HTS-ready motor thermal management, pending interface-level fabrication and experimental validation. Index Terms—HTS-Ready Motors, Axial Flux, Thermal Re sistance Network, Aluminum Nitride (AlN), Contact Thermal Resistance, Magnetocaloric Effect (MCE)