Topic/Type: 2.5 Adaptative & multi-scale methods, Poster

A new algorithm for the multi-scale and multi-physics modelling of space and laboratory plasmas

Lapo Bettarini, Giovanni Lapenta

Centre for Plasma Astrophysics, K. U. Leuven

A detailed description of space, astrophysical and laboratory plasma structures is a challenging task both from the theoretical and the observational point view. In fact, the complex evolution of the magnetic field (e.g. current-sheet+stream interactions, magnetic reconnection), the possible presence of more than one species of ions, often generated in different conditions and streaming with respect to each other, as well as of small and charged particles of solid matter determine a complex cross-scale dynamics. Since an enormous range of length- and time-scales needs to be considered, numerical simulations of space plasmas are either particle simulations (full kinetic or PIC methods), fluid simulations or hybrids of the two approaches. Yet, any of those approaches sets constrains which limit the possibility to follow the overall cross-scale evolution of plasma phenomena. Several numerical recipes have been used so far to partially overcome the peculiar limitations given by each method, e.g. the implementation of moment-implicit PIC methods for particle simulations or adaptive mesh refinement (AMR hereafter) schemes for the fluid approach. Anyway, it is still lacking a numerical tool bridging the gap between small- and large-scale phenomena evolving according to a large range of time-scales. The algorithm for an adaptive-mesh-refinement implicit (electromagnetic) implicit Particle-In-Cell code to study the nonlinear coupling of electron, ion and fluid scale processes in space and laboratory plasmas is presented. The proper mathematical basis for such robust algorithm in one and two dimensions is discussed as well as the strategy for the implementation of a fully parallelized three-dimensional code, and the introduction of a ?scheme selector? allowing the automatic selection of the best-fitting numerical scheme for any grid resolution level (evolving in time and space). We link also the modelling efforts with ongoing observational efforts, especially with new international projects (e.g. ITER) and space missions. Applications to space plasmas are shown.