Electron source

Abstract

An electron source comprises cathode means and a permanent magnet. A plurality of channels disposed in the magnet in a two dimensional array of rows and columns and extending between opposite poles of the magnet. The magnet generates, in each channel, a magnetic field which forms electrons received from the cathode means into an electron beam for guidance towards a target. Grid electrode means are disposed between the cathode means and the magnet for controlling flow of electrons from the cathode means into each channel. The grid electrode means comprises a plurality of parallel row conductors and a plurality of parallel column conductors arranged orthogonally to the row conductors. Each channel is located at a different intersection of a row conductor and a column conductor. Electric field isolation means reduces leakage of electric fields from each intersection.

Dependencies are inferred from the claim text.