Progress with the COGENT Edge Kinetic Code: Implementing the Fokker‐Planck Collision Operator

Abstract

AbstractCOGENT is a continuum gyrokinetic code for edge plasma simulations being developed by the Edge Simulation Laboratory collaboration. The code is distinguished by application of a fourth‐order finite‐volume (conservative) discretization, and mapped multiblock grid technology to handle the geometric complexity of the tokamak edge. The distribution function F is discretized in v‖ – μ (parallel velocity – magnetic moment) velocity coordinates, and the code presently solves an axisymmetric full‐f gyro‐kinetic equation coupled to the long‐wavelength limit of the gyro‐Poisson equation. COGENT capabilities are extended by implementing the fully nonlinear Fokker‐Plank operator to model Coulomb collisions in magnetized edge plasmas. The corresponding Rosenbluth potentials are computed by making use of a finite‐difference scheme and multipole‐expansion boundary conditions. Details of the numerical algorithms and results of the initial verification studies are discussed. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)