Nonlinear gyrokinetic particle simulation of dissipative trapped electron mode

Electron turbulence induced by the trapped electron mode has been widely studied. The dissipative trapped electron mode (DTEM) is an important candidate for tokamak edge turbulence. Nonlinear gyrokinetic particle simulations based on edge parameters are carried out to investigate the collisional effects on the nonlinear transport of DTEM turbulence. It is found that the collisions can induce a low level radially inward electron transport for the DTEM turbulence, which is closely related to the phase difference between the radial turbulent motion and perturbed density fluctuation induced by collisional dissipation. We observe an inverse spectral cascade of the turbulence during the nonlinear DTEM saturation, which is caused by quasimode scattering induced by trapped electrons and important for determining the magnitude of turbulent transport. The nonlinear transport of DTEM is found to be inversely proportional to the collisional frequency by gyrokinetic simulation, which is consistent with the prediction ...