A Conceptual Assessment of Long-Duration Steady-State Operation in Fusion Systems Through Passive Thermal Decoupling

This paper presents a system-level conceptual assessment of long-duration steady-state operation in fusion energy systems. Unlike conventional approaches that focus on specific materials, geometries, or localized plasma-facing performance, this work emphasizes passive thermal decoupling of peripheral subsystems. By introducing modular, loosely coupled layers acting as thermal buffers, the framework explores the possibility of multi-year continuous operation in a steady-state regime. The analysis relies on aggregated estimates and order-of-magnitude reasoning rather than detailed engineering parameters. Key contributions include a system-level perspective on thermal impedance, peripheral stabilization, and operational persistence, highlighting how distributed damping can reduce coupling between the fusion core and surrounding structures. Conceptual validation within virtual simulation environments is proposed, allowing independent verification without disclosing proprietary or material-specific information.