A SIMPLE-MODEL TO DESCRIBE ION-SOURCE EXTRACTION OPTICS - SIMULATIONSAND EXPERIMENTAL TEST

The main goal of this work was to experimentally check the value of th e ''cos+lin'' method previously developed by the authors. The design a nd optimization of the beam extraction optics for a hollow-cathode ion source have been carried out. Starting from an existing electrode arr angement the optical system (e.g., the shape and potential of the elec trodes) was gradually fitted to the requirements of the model. The fin al optimization of the optics was carried out by the SIMION computer c ode. We tested the extraction and focusing optics with H+ and Ar+ ions at different energies up to 30 keV. The electrode potentials, optimiz ed for the best beam parameters (the largest intensity and smallest di ameter), are in good agreement with the calculated values. (C) 1996 Am erican Institute of Physics.