Fully-implicit ultrascale physics solvers and application to ion source modelling

Many problems of interest in plasma modelling are subject to the `tyranny of scales´, specifically, problems that encompass physical processes that operate on timescales that are separated by many orders of magnitude. Investigating such problems therefore requires the use of implicit time-integration schemes, which advance problem solutions on the timescale of interest, while incorporating the physics of the fast-timescales. One promising route to develop these implicit solvers is the combination of Jacobian-Free Newton- Krylov methods (JFNK, [1]), but adapting these methods to work in ultra scale computing environments is a formidable challenge. Here, we describe research on new approaches to adapt Algebraic Mulgrid based solvers (that can be used for provide efficient pre-conditioners for JFNK methods) to ultrascale computing environments, the development and testing of JFNK solvers for coupled plasma-electromagnetics within the USIM framework [2] and the application of these methods to modelling H- ion sources for the Spallation Neutron Source at ORNL.