A Study on the Micrometer Ion Beam Focus System

In this paper, the design methods of the focus system for micrometerdiameter ion beam are described. The douplasmatorn ion source of cold ca-thode, the double condenser system of the symmetrical three--aperture elec-trostatic lenses, unsymmetrical electrostatic objective lens, the ion beamscanning system of the double electrostatic deflection type without aberrtion,the magnetical analyzer with 12.6°are discussed. The device provides highbrightness of 4.2×~(10)mA/m~2·str at 20Kv, the lifetime of cathode for 1,000hours or more. The ion beams of 2-200 μm diameter are gotten easily.