Patent ID: 6407399
Filing Date: 2002-06-18
Classification: H01J

Abstract:
An electron emission apparatus, comprising:(a) a vacuum chamber; (b) a large surface area cathode in the vacuum chamber; (c) means for applying a negative voltage to the cathode and causing the cathode to issue electrons toward a target in the vacuum chamber; (d) an anode spaced apart from the cathode and positioned between the cathode and the target; said anode comprising an electrically conductive grid having an array of spaced apart apertures therethrough extending from a center of the grid to an edge of the grid; said apertures having progressively increasing area from the center of the grid to the edge of the grid, and said grid having a progressively decreasing thickness from a center of a grid to an edge of the grid; and (e) means for applying a voltage to the anode which is positive relative to the voltage applied to the cathode.