Turbulence Characteristics from XGC1 simulations of Tokamak Edge.

Strong turbulence near the separatrix is believed to produce filamentary structures (blobs) whose detachment from the bulk impacts the heat flux width and, as a result, the total power deposited at the divertor. Although considerable progress has been made in core research, studies of the edge so far have been mostly confined to reduced models and simplified geometries.

Here, we analyze the results of simulations performed with the full-f, gyrokinetic code XGC1 which includes both turbulence and neoclassical effects in realistic divertor geometries. More specifically, we study the characteristics of turbulence from simulations of two different machines (DIII-D and CMOD): We examine the spatial pattern of turbulent fluxes and the cross-phases between various turbulent quantities. In addition, we perform linear simulations using the gyrokinetic code GENE in order to investigate the effect of driving gradients and the growth rates of dominant modes. Lastly, we identify blobs, measure some of their properties and compare the results with theoretical predictions.