INVESTIGATION OF ION BEAM EXTRACTION PHENOMENA USING A PARTICLE SIMULATION CODE

摘要

The beam extraction phenomena in a practical ion thruster were discussed by means of an experimental and computational approach. In the numerical simulation, a Particle-in-Cell method was adopted and electrons are treated as particles as well as ions to investigate the plasma boundary (ion sheath) phenomena in detail. In the experiments, the properties of discharge chamber plasma of the 14-cm diameter cusped ion thruster were measured using an electrostatic probe and its results were used as input parameters of the simulation. As a result, it was found that the beam extraction capability varies drastically depended on radial distance from the thruster center, accelerating voltage and the thickness of screen grid. Each phenomenon was discussed using the ion sheath boundary variation obtained from the particle simulation result.