The emittance characteristics of a gallium liquid-metal ion source

First measurements have been made of the emittances of momentum-analyzed 69Ga+ ion beams extracted from a liquid-metal ion source. Comparisons of the emittances of beams extracted and postaccelerated with conical and planar geometry electrode systems indicate that the planar geometry system is less aberrant. Space-charge effects and other sources of energy spread lead to increases in the emittances in the energy-dispersion plane of the momentum-analysis system (x direction) over their y-direction counterparts. The energy spread increases rapidly with beam intensity. Brief descriptions are provided of the experimental apparatus and procedures used during these investigations, and emittance and brightness data measured for ion beams accelerated by the two electrode systems are presented.