Numerical study of beam extraction phenomena in an ion thruster

Ion beam extraction phenomenon is one of the most important processes in an ion propulsion system because ion beam current and beam accelerating voltage dominate thrust. In order to evaluate the beam extraction capability, which is determined by the interrelation between discharge plasma properties and beam accelerating conditions, there is a need to understand the problems of ion sheath formation. This study has been performed to develop a numerical simulation code which is capable of investigating the ion beam extraction phenomena in the ion thruster. In the calculation, both ions and electrons were treated as particles in a particle-in-cell routine to determine the ion sheath self-consistently. The calculation results of electric potential contours and extracted currents were compared with the experimental ones and they were found to be in good agreement. In addition, it was confirmed that the ion beam extraction capability can be simulated in a wide range of beam accelerating voltage.