An electrostatic coaxial probe forming lens suitable for high-energy ion beams

A new class of ion beam lenses is described. The electrostatic coaxial field between a thin central rod and an outer cylinder is used as the focusing element. MeV ion beams may be focused in 100 mm using kilovolts on the lens. Both diverging and converging electrostatic lenses may be made and the two combined to reduce aberrations. An analysis of particle trajectories through these lenses is given and results for a 400 keV proton beam presented. (author)