Verification and RW Validation of Collision Models for the Edge Gyrokinetic Code COGENT

Understanding the edge of tokamak plasmas is an important problem in fusion studies. The edge presents a number of simulation challenges, with its complex geometry, large amplitude turbulent fluctuations, and the fact that it spans both collisionless and collisional regions. COGENT is a full-f continuum gyrokinetic code being developed to tackle these problems, using a fourth-order conservative finite volume discretization and mapped multiblock grid technology to handle tokamak edge geometry. COGENT implements a number of collision models containing various levels of physics, such as a simple Krook operator, Lorenz collisions, and a linearized-model Fokker-Planck operator. Here we present preliminary verification and validation results for these collision models.