Bochum 2015 – scientific programme
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P: Fachverband Plasmaphysik
P 12: Helmholtz Graduate School for Plasma Physics I
P 12.6: Talk
Tuesday, March 3, 2015, 15:55–16:10, HZO 50
A Particle in Fourier Method for Field Aligned Gyrokinetic Models — •Jakob Ameres1,2, Roman Hatzky1, and Eric Sonnendrücker1,2 — 1Max Planck Institut für Plasmaphysik, Garching, Germany — 2Technische Universität München, Lehrstuhl für Numerische Methoden der Plasmaphysik, Garching, Germany
The gyrokinetic model, which approximates the Vlasov-Maxwell equations by averaging over the gyro-motion, is well suited for the study of turbulent transport in tokamaks and stellarators. Gyrokinetic PIC codes using a finite element field description are known to conserve energy but not momentum. Using the Vlasov-Poisson equations in periodic domains with a purely Fourier based field solver yields a Monte Carlo particle method, Particle in Fourier (PIF), conserving both energy and momentum. Similiar to Fourier filtering techniques on finite elements this also reduces the statistical noise. However, the computational costs per particle are high. But for many problems the total number of physically relevant Fourier modes remains small thus reducing the overall computational effort. In the scope of a field aligned description we derive a field solver, which couples a two dimensional Fourier transform in the torus' angular directions to B-splines over the radial coordinate yielding a hybrid PIC/PIF scheme. We study our solver for a guiding center approximation in polar and cylindrical coordinates, in particular to quantify the stochastical error.