Pedestal stability and broadband turbulence spectrum analysis of wide pedestal quiescent H-mode scenario*

Wide pedestal QH-mode discovered on DIII-D in recent years is characterized by a stationary and quiescent H-mode with a pedestal width exceeding EPED prediction by 25{\%}. Simulations carried out by BOUT$++$ six-fields reduced MHD model demonstrate that two fluid effects may be key to understanding the physics of the wide pedestal QH-mode, which drive two kinds of MHD-scale instabilities in different radial locations: one is a peeling-ballooning mode modified by two fluid effects at the peak pedestal gradient position; the other is a drift Alfveìn wave (DAW) at the pedestal top which is driven unstable when electron dynamics is included, and therefore imposes a limit on the pedestal height. Detailed turbulence $\omega $-k power spectrum analyses in different radial locations show a reasonable agreement among BES/MIR experimental measurements on directions of multiple-modes rotation, frequency range and wave number. In order to study micro-scale turbulence transport dynamics, simulations using gyro-kinetic code CGYRO find trapped-electron mode (TEM) unstable inside the pedestal region, which may be regulating the density and temperature gradients of wide pedestal QH-mode. This work presents improved physics understanding of the pedestal stability and turbulence dynamics for wide pedestal QH-mode.