Numerical Simulation Of Charge-Exchange Propagation In The Plume Of Ion Thruster

In recent years, ion thruster has been widely used in many commercial and deep-space missions as propulsion system. The interaction between charge-exchange ions and spacecraft will influence solar panels and other instruments. It is very important to evaluate the distribution character of charge-exchange ions for the application and development of ion thruster. Ground and flight tests are very expensive and time-consuming for plume research. Numerical simulation gets more details of propagation character under different conditions for a short time. Particle-in-cell with Monte Carlo collision (PIC-MCC) method and Direct Simulation Monte Carlo (DSMC) method has been used as main approach in most analysises. The efficiency of central processing unit (CPU) is very low, and the use and maintenance costs of parallel cluster system is very expensive.With performances rapidly increasing, general computation ability of graphic processor unit (GPU) has transcended CUP's for its parallel hardware architecture and obvious advantages such as higher efficiency, higher arithmetic intensity and lower energy consumption. For all of these, the large-scale parallel computing can be practiced on personal computer to improve the efficiency of scientific research.PIC-MCC method is used to simulate the charge-exchange ions to study its distribution. Two-dimensional axisymmetric and three-dimensional Cartesian coordinate models are established. The alternating direction implicit (ADI) method and full approximation storage-algebraic multigrid (FAS-AMG) method are used to update the electric field. Random numbers are generated by the parallel MT19937 algorithm in the process of MCC collision sampling. A particle simulation code based on CPU and a parallel one, which base on GPU by using the Compute Unified Device Architecture (CUDA), has been developed. The result shows that the chage-exchange ions driven by the electrostatic force will move out of the beam zone, and an expansion structure of electric formed in the grid downstream. A part of ions will move to the upstream of thruster with a velocity about 7 kilometers per second. These high speed ions can impact spacecraft surface. The ion number density is 1×1010~5×1010/cm3 in a 0.4m upstream distance from the grid. And GPU's result agrees well with CPU's and foreign related reports. Compared with a single CPU, 16-processor GPU represents 4.5~10 speedup.