| 摘要 |
PURPOSE:To freely control an ion beam current and beam energy by arranging the emitter in such a manner as the edge part is not protruded from a leadout electrode in an ion source of three electrode structure and applying a leadout voltage and a control voltage across said leadout electrode and emitter. CONSTITUTION:The emitter 6 and a leadout electrode 7 are set so that the distance between the tip of the emitter 6 and the center of aperture on the same plane as the surface of leadout electrode 7 facing the side of emitter 6 is ranged from 0-1mm.. A leadout voltage Ve is applied across the emitter 6 and the leadout electrode 7 in order to obtain the required beam current. Moreover, an energy control voltage Vc is applied across the emitter 6 and control electrode 8 and an ion energy can be set to the necessary value by changing such Vc. Introduction of this ion source makes it possible to freely change an acceleration voltage ratio for given focusing relation and acceleration voltage. |
