Massively parallel code named NEPTUNE for 3D fully electromagnetic and PIC simulations

A massively parallel code named NEPTUNE for 3D fully electromagnetic and particle-in-cell (PIC) simulations is introduced, which can run on the Linux system with hundreds or even thousands of CPUs. NEPTUNE is capable of three-dimensional simulation of various typical high power microwave (HPM) devices. In NEPTUNE code, electromagnetic fields are updated by using finite-difference time-domain (FDTD) method to solve Maxwell equations and particles are moved by using Buneman-Boris method to solve the relativistic Newton-Lorentz equation. The electromagnetic fields and particles are coupled by using linear weighing interpolation PIC method, and the electric field components are corrected by using Boris method to solve the Poisson equation in order to ensure charge-conservation. NEPTUNE code ca