Continuum Gyrokinetic Simulations of Turbulence in Model Tokamak Scrape-Off Layer Geometry*

We describe results obtained from Gkeyll, a full-F continuum gyrokinetic code, designed to study turbulence in the edge region of fusion devices. The edge region is computationally challenging, requiring robust algorithms that can handle large amplitude fluctuations and stable interactions with material walls. We have designed an energy conserving high-order discontinuous Galerkin scheme that solves the gyrokinetic equations in Hamiltonian form. Efficiency is improved by a careful choice of basis functions and automatically generated computation kernels. Plasma interaction with material walls is handled by model sheath boundary conditions that allow current to flow into/out of the wall, while maintaining overall quasineutrality.  Verification tests have been performed in the straight field-line LAPD machine[1, 2].  Results for turbulence in a scrape-off layer (SOL) for NSTX-type parameters with a model magnetic geometry have been obtained [2]. A version of the code for the full Vlasov-Maxwell equations with applications to solar wind and Hall thrusters will be briefly described.

[1] Shi, E. L., et.al, A. (2017). J. Plasma Phys.
[2] Shi, E.L., Princeton Ph.D. (2017)