Development of an Unstructured Mesh Based Gyro-kinetic Particle-in-cell Code for Exascale Fusion Plasma Simulations

Particle-in-cell (PIC) methods are being widely used for fusion plasma simulations. Unstructured meshes are a natural choice for the domain discretization due to the complexity of the simulation domain. In this poster, we discuss the development of a new distributed unstructured mesh gyro-kinetic PIC code named XGCm, short for x-point included gyrokinetic code mesh-based. The code adopts the physical algorithms from the well-established XGC code. It is developed on top of the Kokkos based PUMIPic library, which is a distributed unstructured mesh infrastructure for PIC simulations. The code is developed to run on current GPU hardware, and is aimed at exascale fusion plasma simulations. First, the numerical algorithms suitable for distributed unstructured mesh and achieving scalability on GPU devices will be presented. Extensive unit tests and integration tests were created for code verification and will be presented. Code validation will be presented using the cyclone base case (case 5 from Burckel, etc. Journal of Physics: Conference Series 260, 2010, 012006). The turbulence growth rate will be compared with existing results to validate the overall code. Additional code validations will be included. Finally, Summit scaling results will be presented.