2017/07/05 by Joseph Guadagni, Antoine Cerfon, Guadagni, Joseph +1 · 1 citation
Materials Science · Computer Science · Physics and Astronomy · #Magnetic Properties and Applications #Matrix Theory and Algorithms #Scientific Research and Discoveries
paper · pdf · doi:10.48550/arxiv.1707.01260
We present a fast and spectrally accurate numerical scheme for the evaluation\nof the gyroaveraged electrostatic potential in non-periodic gyrokinetic-Poisson\nsimulations. Our method relies on a reformulation of the gyrokinetic-Poisson\nsystem in which the gyroaverage in Poisson's equation is computed for the\ncompactly supported charge density instead of the non-periodic, non-compactly\nsupported potential itself. We calculate this gyroaverage with a combination of\ntwo Fourier transforms and a Hankel transform, which has the near optimal run\ntime complexity O(N\ρ(P+\P)\log(P+\P)), where P is the\nnumber of spatial grid points, \P the number of grid points in Fourier\nspace, and N\ρ the number of grid points in velocity space. We present\nnumerical examples illustrating the performance of our code and demonstrating\ngeometric convergence of the error.\n