Influence of Electrode Structure on Ion Beam Extraction in Cold-cathode Ion Source

In this study, we investigated the influence of electrode structure on ion beam extraction in a cold-cathode ion source. To investigate this influence, we developed a two-dimensional ion ray-tracing code for studying the ion beam extraction. Simulations were performed for three typical structures of cold-cathode ion sources using the developed code. The simulation results show that the potential structure influenced by the electrodes and sheath on the electrodes play an important role in determining the divergence and current of the ion beam. We showed the change of the ion beam according to the electrode structure in terms of current extraction efficiency and ion beam divergence. The results were validated through a series of experiments with a small-sized cold-cathode ion source.