Development of gyrokinetic simulation code for the study of electrostatic drift wave turbulence

Abstract

Global drift wave map equations that allow the integration of particle orbits on long time scales are implemented to describe transport. Ensembles of test particles are tracked to simulate the Low-confinement mode/Reversed Shear/Enhanced Reversed Shear plasmas in Tokamak Fusion Test Reactor(TFTR) tokamak and the Optimized Shear plasma in Joint European Torus(JET) tokamak. The simulations incorporate a radial electric field, $\overline{E}_r$, obtained from a neoclassical calculation, and a model for drift wave fluctuations that takes into account change in the mode structure due to $\overline{E}_r$. Steady state particle density profiles along with two different measures of transport, the diffusion coefficient based on a running time average of the particle displacement and that calculated from the mean exit time, are obtained. For either weak or reversed magnetic shear and highly sheared $\overline{E}_r$, particle transport barriers are observed to be established. In the presence of such a transport barrier, it is shown that there is, in general, a difference between the two measures of transport. The difference is explained by a simple model of the transport barrier. To investigate the physical properties of the electrostatic ion temperature gradient turbulence occurred in toroidal plasmas and associated ion energy and particle transports, we developed a numerical simulation program. The program was designed to solve the gyrokinetic Vlasov Poisson system by using the δ f particle in cell simulation scheme in 3-dimensional toroidal geometry in fully parallel ways. Its performance was tested varying number of processing elements used in calculation and we could confirm a good scalability. For the validation of the simulation program, we compared the simulation results with known analytical solutions and local analysis. The linear simulation results showed a good agreement with the solutions of the local dispersion relation and reproduced the well known characte...