Energy distribution measurments of charged particles with a filter lens

A retarding field energy analyzer for the measurement of the energy spread ΔE0 of charged particles with energies up to 10 keV and of an energy resolution of ΔE/E0 = 10-4 is investigated. The resolution of the analyzer, composed of a collimator, a filter lens with a retarding electrode of two plane parallel grids and a Faraday cup, is estimated with the help of known models and is tested with an electron beam from a tungsten hairpin cathode. The measuring method is applied to the ion beam of a duoplasmatron ion source. The energy spread ΔE0 (FWHM) amounts to 2 - 5 eV dependent on source parameters. (author)