Conversion from Gyrokinetic to Full-Orbit Particles for Plasma Sheath Boundary Conditions*

A general issue of gyrokinetic models of magnetized plasmas is handling boundary conditions which can properly account for the full-orbit physics of the  particles in the plasma sheath and magnetic presheath region at the plasma-wall transition. In this work we address the problem of matching a gyrokinetic model to a full-orbit model by enforcing conservation laws at the interface between the two models. We explore a two-region model consisting of a bulk plasma described using gyrokinetics, plus a boundary layer described using a full-orbit model. We enforce the matching conditions by guaranteeing continuity on the moments of the particle distributions up to a given order (density, particle fluxes, energy fluxes, etc.). The approach is general enough that moments up to an arbitrary order can be enforced at the interface. We present preliminary numerical tests implemented using the two codes XGCa (gyrokinetic) and hPIC (full-orbit) as a test bench.