Abstract
Space charge effects within the analyser are shown to cause saturation of the output signal for entrance slit widths wider than some value Wentmax, and the variation of Wentmax with ion energy E and charge Z is measured for the ions C6+, C5+ and C4+ in the range 0.75 keV<or=E/Z<or=3 keV. Comparison is made with theory. An ion energy spectrum distorted by space charge effects is contrasted with the same spectrum free of such effects.