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.