A Universal Balance–Feedback Framework (UBFF) Formulation for Magnetically Confined Fusion Plasma Regulation: Model, Minimal State-Space Synthesis, and a Comparative Evaluation Protocol

Abstract This paper formulates the Universal Balance–Feedback Framework (UBFF) as applied to magnetically confined fusion plasma regulation. We derive a minimal state-space control system for the zero-dimensional plasma power and particle balance, replacing non-minimal state representations to eliminate algebraic rank deficiency. We formulate a novel UBFF-native cost functional penalizing the Fusion Balance Index (FBI) and its time derivative, yielding an explicit Algebraic Riccati Equation (ARE) synthesis that mathematically distinguishes UBFF state feedback from standard Linear-Quadratic Regulator (LQR) designs. We evaluate the model using ITER-scale parameters and establish a comparative benchmark protocol—testing UBFF against PID, LQR, and Model Predictive Control (MPC) baselines under matched disturbance scenarios. Criteria are defined for falsifying or validating UBFF's utility as either a distinct control synthesis method or a unifying systems-theoretic reformulation.