For example, Cr, Fe, and Ni ions sputter from stainless steel surfaces within a duoplasmatron. Without a primary beam mass filter, these metal contaminants deposit onto the sample surface, raising the detection limits for stainless steel elements. In the figure above, the electromagnetically active components are shown in blue. The electrostatic lenses and the apertures control the intensity and width of the primary ion beam. Several aperture diameters are usually available at each aperture location.
Electrostatic deflectors steer the primary beam in a raster pattern onto the sample.
A finely focused and rastered primary ion beam delivers uniform primary beam intensity to an area on the sample. This leads to flat bottom sputter craters. The best depth resolution in a depth profile results when the secondary ions are sampled from the flat bottom of such a crater without contributions from the crater edges. They help tune the primary beam through the middle of the electrostatic lenses .