ETG turbulence in a tokamak pedestal

This paper explores the fundamental characteristics of electron-temperature-gradient (ETG)-driven turbulence in tokamak pedestal. The extreme gradients pedestal produce linear instabilities and nonlinear that are distinct from corresponding ETG phenomenology core plasma. system exhibits multiple (greater than ten) unstable eigenmodes at each perpendicular wave vector, representing different toroidal slab branches instability. Proper orthogonal decomposition fluctuations reveals no clear one-to-one correspondence between modes for most vectors. Moreover, frequencies deviate strongly those instabilities, with spectra peaking positive frequencies, which is opposite sign picture emerges one properties preserved only a narrow range k-space. Outside this range, processes strong deviations both eigenmode structures. interpreted context critical balance, enforces alignment parallel scales fluctuation frequencies. We also investigate saturation processes. observe direct energy cascade injection scale to smaller directions. However, bi-normal direction, there nonlocal inverse transfer larger scales. Neither streamers nor zonal flows dominate saturation.