Development of radio frequency ion sources and their applications

In this paper a review is made of the main developments of RF ion sources. These developments are directed towards intensifying the plasma, improving the ion beam quality and increasing the extent of the highly charged ion species in the ion beam. In the radial extraction type, the proper position for ion beam extraction is made as near as possible to the highest plasma intensity in the discharge bottle to allow for extraction of high ion current in order to intensify the plasma and increase the extracted ion current from the discharge, the discharge bottle was made with: a mechanical constriction, immersed in the axial magnetic field and a simple electron gun is sealed with it to inject electrons (with sufficient energy /spl sim/150 eV) into the plasma. Improving the beam uniformity is achieved in the broad beam RF ion source through the use of a multi-aperture graphite cathode with exit apertures distributed to perform perveance matching. On the other hand, the insertion of the RF antenna in the vacuum arc ion source (cold cathode type) reduces the ignition voltage and allows for extraction of higher ion currents at lower extraction voltages (50 up to 300 V). Also in this article a brief review is given of the main industrial processes in which RF ion sources have already been used or are potentially fitted. These processes are used for removal, deposition as well as modification of material.