Electromagnetic Field Solver for Fully Kinetic Simulation of Ion-Temperature-Gradient Instabilities in Tokamaks

The feasibility of using full ion kinetics, rather than gyrokinetics, in simulating toroidal Ion-Temperature-Gradient (ITG) instabilities has recently been demonstrated in the electrostatic adiabatic electron case. The present work extends this model to the fully electromagnetic case with drift-kinetic electrons. This model provides an important validation tool for gyrokinetics in applications where higher order terms may be important. We have developed an electromagnetic field solver for this model. The field equations are discretized in the field-line-following coordinates. The solver uses the Fourier spectral method in the toroidal direction and finite differencing in both the radial and field-line following directions. The matrix resulting from the toroidal and radial discretization is directly inverted whereas the variation along the field-line direction is solved by an iterative method. The plasma response enters the field equation via the ion and electron currents and these are calculated by an implicit delta-f method. Numerical results of ITG instabilities obtained from this model will be presented and compared with the gyrokinetic results for the Cyclone base case.