Problems of microprobe ion optics

Ion beams with the energy of several megaelectronvolt per a nucleon focused to a micron cross section become consequently a usual device in several acceleration laboratories of the world. They give the widest spectrum of nondestructive methods of qualitative microanalysis with low detection limits (of 10-6 order) for practically all chemical elements and a lot of isotopes. Two the most usable ion-optical flowsheets of a microprobe based on quadrupole lenses: doublet and quartet operating in the quadruplet rotation mode, are compared. Main ion-optical characteristics of the systems compared are calculated taking into account chromatic and geometric abberations; requirements to the focusing devices shaping micron and submicron beams are discussed