Pedestal-to-SOL Transport by Intermittent Fluctuations During RMP ELM-Suppressed Plasmas

Low-wavenumber fluctuation measurements in the outer core (~0.75<rho<0.92) and pedestal (0.95<rho<1) demonstrate that different processes take place in these regions in response to application of Resonant Magnetic Perturbations (RMPs). Inboard of the steep-gradient pedestal region, turbulence is significantly and rapidly (few ms times scale) increased in response to initial application of RMPs, and then further changes (can increase or decrease) when ELMs are fully suppressed. In the pedestal and SOL region, a different phenomenon is observed: “Bursty Wiggles” begin as soon as ELMs are fully suppressed. These intermittent but large amplitude (ñ/n~10%) fluctuation events have a <100 microsecond lifetime and occur at approximately 1 kHz; their frequency band extends to 200 kHz. These events peak in amplitude in the steep gradient pedestal region, and have a poloidal wavenumber k_perp*rho_s=0.05-0.1. These events correlate with bursts of increased density in the near SOL region and have positive skewness. The mechanisms behind this increased particle transport during RMP ELM-suppressed plasmas need to be characterized to accurately predict their impact on confinement.