Multiscale Plasma Modeling

Afivo is a framework for adaptive finite volume simulations, with a focus on simplicity. Some of its features are:

• Quadtree (2D) and octree (3D) grids
• OpenMP parallelism
• A geometric multigrid solver for elliptic PDEs
• Output in VTK unstructured and Silo file formats

The framework is described in the this paper. The latest version of the project's code can be found at Github. Several examples are includes in the /examples/ directory, which can help to get started.

A streamer discharge model has been implemented on top of Afivo, with the name a5-streamer¹⁾. The project is still in an alpha stage, but currently features:

• A 2D, cylindrical and 3D version
• A drift-diffusion-reaction plasma fluid model, using the local field approximation
• Modules to read in field-dependent transport data
• A Monte Carlo photoionization model
• A refinement criterion based on the local electric field (i.e., on the ionization length)
• Support for different types of initial conditions

Time stepping is fully explicit, using explicit trapezoidal rule, and the Koren limiter is used to compute advective fluxes. The source code of a5-streamer can also be found on Github.