The Beam Forming Numerical Simulation for High Power Neutral Injector

High power neutral beam injector START-4 for plasma heating has been described in [1]. The distinctive features of the injector are comparatively large initial beam aperture (200 mm) and multi holes grids with the large numbers of the holes (more than 3000). A significant focusing is realized to a beam diameter 50 mm at a length 1.2 m. The disadvantage of the multi holes optic is low transparency, which decreases the efficiency of plasma source and makes worse vacuum conditions in the source. The possible decisions of these problems are using ion-optical systems (IOS) with enlarged diameter of holes and, also, application IOS with the azimuthal-slit holes structure. Numerical simulation and test experiments have been carried out for investigation of the ability such IOS geometries.