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

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 dB_θ/dt (Mirnov coils) are analysed using information-geometric measures (information rate Γ and information length L=∫Γdt), together with kurtosis κ and variance σ². In low-density upper single-null plasmas (ne∼1.2×10¹⁹ m⁻³), a∼80 kHz magnetic mode coupling n_e , T_e , and dB_θ/dt 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 generate large spikes in Γ (with smaller changes in κ), signalling ERMP-driven departures from quasi-stationarity. The impact of ERMPs on background fluctuation levels depends on density, radial location, and the fluctuating variable itself (n~ , T~ , B˙ θ), whereas L provides a robust, regime-agnostic measure of cumulative statistical reorganisation and spatial decorrelation. In particular, at low density we observe weaker coupling between n ~ and T ~ , along with a tendency toward decreased radial correlation-most clearly for T ~ -under ERMPs. Overall, information geometry cleanly captures intermittent events, quantifies non-equilibrium PDF evolution, and offers a compact, cross-diagnostic metric for assessing resonant magnetic perturbation effects on edge transport and correlation across densities, radial locations, and confinement states.