High Current Positive Hydrogen Ion Source with Mass Analysis

A high current positive ion source with an extraction electrode, focusing system and mass analysis is described. The results of experiments on the apparatus for different geometries are presented. The difficulties involved in extracting and containing ion beams under space-charge forces are explored and a practical method which reduced the space-charge effects is described. It is shown that when space-charge densities of ∼30 ma/in2. are reached the optimum Einzel lens geometry is a function of beam current and beam diameter at the position of measurement.