Emittance Measurements on Negative Ion Sources

An automated system has been developed for measuring the emittance of beams from negative ion sources. The data are stored as two-dimensional spectra in a kicksorter and subsequently analysed with a PDP-10 computer. The system was first used to measure the properties of, and assess the value of design changes to, a Middleton sputter source. Subsequently, the emittance of several different types of negative ion source have been compared. A retarding field energy analyzer of high resolution has been used to measure the beam energy spreads from the Middleton sputter source and from other negative ion sources, including a direct extraction duoplasmatron and a sputter Penning source. Typical spectra have a width of a few eV, with a small group of higher energy ions.