Pedestal Turbulence Characteristics in Super H-mode Plasmas on DIII-D*

Two distinct frequency bands of broadband density turbulence are observed in the pedestal of Super H-mode plasmas at DIII-D with a 2D BES array. One is observed between 60 kHz to 250 kHz, while the other is from 300 kHz to 500 kHz and appears to be unique to Super H-mode pedestals. Significant coherence and cross power are found between poloidally adjacent BES channels at these two distinct frequency bands, even though the amplitude of higher frequency band is only 1/10 of the lower frequency band. The lower frequency band is observed in rho=0.9-1.0 and propagates in the ion-diamagnetic direction, while the higher frequency band is located at rho=0.9-0.94 and propagates in the electron-diamagnetic direction. Comprehensive spatial characteristics of these pedestal instabilities, temporal evolution during the Super-H pedestal development, and parametric dependencies will be presented, along with comparisons to theoretically predicted mode features, such as KBM or MTM, that might exist in the pedestal of Super H-mode plasmas. Also, the understanding of the turbulence characteristics and pedestal physics of Super H-mode is critical to achieve high performance successfully.