Applications of the Gkeyll Gyrokinetic Code to Steady-State and Turbulence in Tokamak Edge Plasmas and Mirror Machines

We give examples of recent applications of the gyrokinetic solver in the Gkeyll code to tokamak edge plasmas and mirror machines. We are doing 3X+2V simulations of the turbulence and self-consistent profile evolution in edge plasmas (from r/a ~ 0.8 outward across the last closed flux surface into the scrape-off layer (SOL)), including conducting sheath boundary conditions. This is being used to compare with positive and negative triangularity experiments on DIII-D [1] and TCV. The code is also able to do axisymmetric 2X+2V simulations [2] where turbulence is modelled with radial diffusion. This is similar to fluid codes like SOLPS or UEDGE, but including kinetic effects, though with a simplified treatment of neutrals and particle sources for now. We recently demonstrated the ability to handle X-points in axisymmetric simulations, with general magnetic geometry from EFIT. These capabilities for the open-field lines in a tokamak SOL can also be used to study mirror machines. There is more to improve in the code, but these results are showing the feasibility of comprehensive direct simulations of the plasma edge region.