On electron-optical spatial and temporal aberrations in a bi-electrode spherical concentric system with electrostatic focusing

Abstract

For a concentric spherical system composed of two electrodes with electrostatic focusing, the electrostatic potential distribution and the spatial-temporal trajectory of electron motion can be expressed by analytical forms. It is naturally to take such system as an ideal model to investigate the imaging properties, as well as the spatial-temporal aberrations, to analyze its particularity and to find the clue of universalities and regularities. Research on this problem can afford academic foundation not only in studying the static imaging for the night vision tube, but also in studying the dynamic imaging for high speed image converter tube. In the present paper, based on the practical electron ray equation and electron motion equation for a bi-electrode concentric spherical system with electrostatic focusing, the spatial-temporal trajectory of moving electron emitted from the photocathode is solved, the exact and approximate formulae for image position and arriving time, have been deduced. From the solution of spatial-temporal trajectory the electron optical spatial and temporal properties of this system are then discussed, the paraxial and geometrical lateral aberrations with different orders, as well as the paraxial and geometrical temporal aberrations with different orders, are defined and deduced, that are classified by the order of (e z /Φ ac ) 1/2 and (e r /Φ ac ) 1/2