Ammar Hakim

From SOL turbulence to planetary magnetospheres: computational plasma physics at (almost) all scales using the Gkeyll code

Ammar Hakim

Princeton Plasma Physics Laboratory

Friday, March 1, 2019



PSFC Seminars

Abstract: Gkeyll is a computational plasma physics package that aims to simulate plasmas at all scales. At present, the code contains solvers for three major equation systems: Vlasov-Maxwell equations, electromagnetic gyrokinetic equations and multi-fluid moment equations. These span the complete range of plasma physics; electromagnetic shocks and turbulence, requiring full kinetic treatment; turbulence in tokamak core and SOL, requiring EM gyrokinetics; and planetary magnetospheres, requiring fluid treatment with proper accounting of kinetic effects to capture reconnection and current sheet dynamics. In this talk I will present algorithmic innovations and physics simulated by the Gkeyll code. In particular, I will focus on recent progress in implementing a  novel algorithm for EM gyrokinetics in the symplectic formulation; and progress in developing a robust semi-implicit algorithm for multi-fluid moment equations. Physics of turbulence in NSTX SOL will be presented, in particular, the statistics of blobs and heat-flux on divertor plates. As an application of the multi-fluid model I will present a study of the magnetosphere of Mercury, showing comparison of simulation data with the MESSENGER mission and the ability of the code to explain observational data hitherto not explained by simulations or theory.

Bio: Dr. Hakim is an expert in computational physics, specially as applied to plasma physics, fluid dynamics, plasma and fluid turbulence and electromagnetism. He has extensive experience developing large-scale (100K+ lines of code) parallel computational software. Dr Hakim's recent interests are in applying state-of-art finite-element and discontinuous Galerkin schemes to solution of the gyrokinetic equations. These equations evolve in 5-dimensional phase space in complex geometries, which makes developing efficient schemes very challenging. He also works on multi-fluid simulations of various plasma problems, with applications to both space and lab plasmas.