ショットキー陰極電子銃の電界および電子軌道解析

Abstract

Electric field and electron trajectories of a Schottky emission gun have been studied with the surface charge method, based on the integral form of Laplace equation. The numerical model of the gun consists of four electrodes; the Schottky cathode with the facetted tip, the Schottky shield (suppressor), the 1st anode (extractor) and the 2nd anode. The field distribution on the cathode surface was obtained from the surface charge density. An expression of the field factor β was derived, which gives the field strength (F=βV) on the cathode tip with the radius of curvature of 0.2 - 2 μm. Electron trajectories from the cathode tip were traced by solving an equation of motion directly. The position and size of the virtual source were estimated and the influence of the spherical aberration was discussed.