Turbulence statistical analysis of the L-H transition and RMPs in KSTAR

Abstract We investigate the turbulence statistics associated with low-to-high confinement (L-H) transitions and externally applied resonant magnetic perturbations (RMPs) in KSTAR. Time-series fluctuations of electron density n e , electron temperature T e , and the time derivative of the poloidal magnetic field d B θ / d t (Mirnov coils) are analysed using information-geometric measures (information rate Γ and information length L = ∫ Γ d t ), together with kurtosis κ and variance σ 2. In low-density upper single-null plasmas ( n e ∼ 1.2 × 10 19 m − 3 ), a ∼ 80 kHz magnetic mode coupling n e , T e , and d B θ / d t emerges prior to the L-H transition and persists into the edge-localised modes H-mode. Edge-localised RMPs (ERMPs) suppress this coherent mode but enhance intermittency, producing frequent bursts that abruptly reshape the time-dependent probability density functions (PDFs) and…