GEMPIC: Geometric ElectroMagnetic Particle-In-Cell Methods
For computational plasma physics, this provides a general framework ensuring key conservation properties regardless of the finite element basis choice.
This paper presents a novel framework for Finite Element Particle-in-Cell methods that preserves the Hamiltonian structure of the Vlasov-Maxwell system, achieving exact charge conservation, gauge invariance, and excellent long-term energy and momentum behavior.
We present a novel framework for Finite Element Particle-in-Cell methods based on the discretization of the underlying Hamiltonian structure of the Vlasov-Maxwell system. We derive a semi-discrete Poisson bracket, which retains the defining properties of a bracket, anti-symmetry and the Jacobi identity, as well as conservation of its Casimir invariants, implying that the semi-discrete system is still a Hamiltonian system. In order to obtain a fully discrete Poisson integrator, the semi-discrete bracket is used in conjunction with Hamiltonian splitting methods for integration in time. Techniques from Finite Element Exterior Calculus ensure conservation of the divergence of the magnetic field and Gauss' law as well as stability of the field solver. The resulting methods are gauge invariant, feature exact charge conservation and show excellent long-time energy and momentum behaviour. Due to the generality of our framework, these conservation properties are guaranteed independently of a particular choice of the Finite Element basis, as long as the corresponding Finite Element spaces satisfy certain compatibility conditions.