Turbulence in lithiated LTX-β plasmas and the discontinuous Galerkin treatment of axisymmetric geometries

The Lithium Tokamak Experiment-β (LTX-β) produces inner-wall-limited plasmas surrounded by a first-wall nearly fully covered with evaporated lithium. Lithium is known to retain hydrogenic ions coming from the plasma and lower recycling, leading to a reduction of the cooling effect that recycling provides and to much higher edge temperatures. It has been shown that this treatment of the first-wall produces shots with flat temperature profiles, which has a number of attractive properties, including the mitigation of temperature-gradient-driven turbulent transport. In this work we present a characterization of transport in LTX-β via 3D gyrokinetic simulations facilitated by the Gkeyll code, handling the closed and open field-line regions with novel, conservative parallel boundary conditions. These limited plasmas are handled with a unique treatment of field-aligned coordinates that preserves the natural properties of the magnetic field (e.g. div B = 0), while at the same time yielding grids and discrete metric coefficients that satisfy the numerical constraints needed for conservation (e.g. of energy). We describe the extension of this treatment to coordinates for plasmas with divertors and an X-point.