Electrostatic ion thruster accelerator system, shape and position of plasma sheath prediction

Plasma sheath, as ion injection boundary of accelerator system, has direct effect on ion beam characteristics and consequently on ion thruster performance and lifetime. In most of numerical simulations of accelerator system of electrostatic ion thrusters, the effects of electrons on upstream plasma and plasma sheath's shape are simulated by treating them as fluid (Poisson-Boltzmann method) or charged particles. But in this study, plasma sheath are predicted using particle-in-cell (PIC) method and without any calculation for electrons. Predicted plasma sheath shows good agreement with experimental result and is more accurate; in comparison with numerical models that simulates electrons. Calculation results shows that, for specific beam current, nonconformity between test results and plasma sheath that predicted by Poisson-Boltzmann method, leads to ion beam diverges 3.2 degrees or 18.28 % , in comparison with the method that directly applied electron effect.