Off-axis electron gun

Abstract

The purpose of the off-axis electron gun is to generate a beam of electrons and to deflect the beam onto the axis of a device which utilizes the beam. The off-axis electron gun includes an arcuate wire electron emitting source subtending an azimuthal angle of up to 125.degree., a non-intercepting azimuthally asymmetric focussing and deflecting electrode located at and around the electron source, and an anode plate with a beam exit hole. The non-intercepting electrode has an arcuate slot subtending a predetermined angle at a predetermined radius from the beam axis in which the arcuate wire electron source is mounted in electrical isolation from the electrode. The deflecting section of the electrode is azimuthally asymmetric in shape such that when selected voltages are applied between the wire source, the focussing and deflecting sections of the non-intercepting electrode and the anode, an electric field is produced which directs the electrons towards the axis, focusses the beam and deflects it onto the axis.

Dependencies are inferred from the claim text.