Patent Number: 041918886
Section: abstract

An ion extraction system utilizing small hole accel grid (SHAG) optics is disclosed. A screen grid, an accel grid and a decel grid are positioned downstream of a neutral, highly ionized plasma source, and each of these grids have apertures in axial alignment. The accel grid has a relatively small aperture in the range of less than 50% to approximately 10% the size of the aperture of the screen grid. The electric field set up by the screen grid and the accel grid serve to extract an ion beam from the plasma source and focus the ion beam through the accel grid aperture. The small aperture in the accel grid is formed by drilling a relatively large aperture in the accel grid and then securing a thin metallic foil on at least the downstream face of the accel grid to cover the large, drilled aperture.The relatively small aperture is etched in the thin metallic foil by the ion beam.