Computer Simulation of Ion Beam Extraction from a Free Plasma Surface

A method of computer simulation of an ion beam emitted from a free boundary plasma surface is described for the case of a three-electrode ion extractor. The geometry of the beam and extractor here treated is two dimensional. The case of an asymmetric extractor is simulated and it is shown that the beam is deflected when the saturated ion current density, which can be extracted from the plasma, is nonuniform over the plasma surface and/or the electrodes of the extractor are mutually displaced. Results of the simulation are available for the optimal design of the beam extractor.