Abstract: In a method for treatment of surfaces of metals or ceramics of machine components by ion irradiation, ions from an ion source (24) are forced to run in an essentially plane helical path inwardly to an inner region. From there the ions are deflected by betatron oscillations and/or by static magnetic and/or electric fields towards a treatment place (34) which is situated in the center inside said inner area, where the surface to be treated is situated. An apparatus for treatment of such surfaces by ion irradiation comprises two annular coaxially disposed magnets (12,20) which are arranged to produce a magnetic field in a vacuum tank. The inner magnet (20) produces a homogeneous field, transversely to the plane in which ions are intended to substantially move and the outer magnet (12) produces an inhomogeneous field which is decreasing outwardly in the radial direction and is also directed substantially transversely to said plane.