A mechanism of current noise reduction in systems of ion beam formation from vacuum arc plasma

Abstract

The influence of a residual gas plasma on the ion beam transport in the drift chamber of an ion source based on the vacuum arc discharge was numerically simulated by the pellet injection method. The plasma formed as a result of ionization of the residual gas causes a change in the potential profile in the drift chamber. This leads to the appearance of an extended slow ion transport zone (occurring at a virtual anode potential) and to a change in the mechanism of suppression of the ion current noise as compared to the well-known mechanism operative in an equipotential vacuum gap. The results of model calculations show that the modified mechanism is related to a spatial redistribution of the density of ions (in the beam characterized by a certain scatter of velocities) in the slow ion transport zone.