Temporal Stability via Phase Decorrelation in Plasma and Fluid Systems

This technical note introduces a conservative temporal robustness metric for shear-regulated plasma and fluid systems, with primary application to tokamak pedestal stability in ITER-relevant regimes. The proposed dimensionless ratioR = ω_shear,eff / γ_effcompares shear-induced decorrelation rates with effective instability growth rates and serves as a diagnostic overlay for existing pedestal models (e.g. EPED-based workflows). The framework highlights operational time margins and fragility in metastable regimes where suppression relies on shear rather than intrinsic stability. No new stability criterion or governing physics is introduced; the contribution is strictly diagnostic and intended for scenario ranking and early-warning assessment.