Parallelization of a 3D high-order particle-in-cell method and numerical simulations of a 170 GHz resonator and launcher

Summary form only given. The transient 3D electromagnetic Particle-In-Cell [Birdsall, C. and Langdon, A.; 1991, Jacobs G.B. and Hesthaven, J.S.; 2006] code HALO3D operates on unstructured meshes. It uses a high order discontinuous Galerkin approach to discretize the full set of the Maxwell equations in time domain. HALO3D is designed to be highly scalable, being able to simulate even high frequency particle-wave interactions and field propagation in state-of-the-art gyrotrons. Very recently, this solver was used to simulate the resonant cavity and the large-scale mode converter of a TE_34,19 gyrotron. To enable such computations, the coupled solver had to be optimized to run efficiently on more than 1000 CPU cores. The parallelization of the explicit scheme is base on a domain decomposition approach. The key techniques used for parallelization and load balancing which are required to perform such demanding gyrotron simulations will be presented. Furthermore, the results from scalability studies will be discussed and preliminary results from a coupled gyrotron resonator launcher simulation will be shown.