Numerical analysis of plasma spatial uniformity in negative ion sources by a fluid model

A fluid plasma model of negative ion sources is developed to analyze a spatial nonuniformity of plasma profile in the extraction region. According to a preliminary two-dimensional (2D) analysis in the direction perpendicular to the magnetic-filter field, the E×B and diamagnetic drifts of electrons are shown to be almost cancelled. On the other hand, ion flow arises from the synergic effect of Lorentz force and the electric field force. This ion flow is one of the possible causes of the plasma nonuniformity in the extraction region.