Coulomb interactions in Ga LMIS

Abstract

For low emission currents from around 1 μ A Ga liquid–metal ion sources (LMIS) produce fine optically bright ion beams that are strongly limited by the Coulomb particle–particle interactions. We present computations of the energy spread, the beam virtual crossover size, and beam brightness based on direct numerical integration of the equation of motion in a numerically calculated field for a number of dimensions of the emission tip. The Coulomb particle–particle interactions are included into the calculation of ion beam evolution. A comparison with experimental data allows to estimate the tip size.