A Gyrokinetic Benchmarking of Electron Temperature Gradient Turbulence

A suitable operating point for benchmarking numerical simulations of electron temperature gradient (ETG) turbulence is presented together with a linear analysis of the unstable ETG modes at this operating point. Convergence studies in time step, spatial grid, and velocity-space resolution demonstrate well-converged results from both continuum and particle-in-cell gyrokinetic simulations codes at the chosen benchmark point. Simulation results from four gyrokinetic simulations codes demonstrate excellent agreement ($\pm $10{\%}) in the electron heat flux. Comparison of potential fluctuations between these codes demonstrates similar agreement in the correlation functions, spectral density, and \textit{rms} flow shear due to the self-generated zonal flows. A parameter scan in which the magnetic shear, $s$, is varied reveals dramatic increase in both the ETG turbulent intensity and the transport as the magnetic shear is increased from $s=0.3$ to $s=0.4$.