Design and Performance Analysis of an Electrostatic Energy Analyzer Based on Multipole-Spherical Fields

Abstract

A design of an electrostatic mirror energy analyzer for the analysis of charged particle beams based on a new ly synthesized field is proposed. The electrostatic field of the analyzer is formed as a superposition of an axi ally symmetric multipole field and a spherical field. The structure of the electrostatic field formed by the su perposition of axially symmetric octupole and spherical fields has been investigated. It is shown that varying the parameters determining the contribution of multipole components allows controlling the aberration prop erties of the electron-optical system. Conditions for compensating for second- and third-order aberrations have been obtained by selecting appropriate values for the weight coefficients of the hexapole and octupole components, which allows for a significant improvement in the focusing properties of the field. Numerical modeling of the electron-optical system and calculation of charged particle trajectories were carried out using the “FOCUS” simulation program. Two regimes of angular focusing were found. The first mode corresponds to second-order angular focusing at a particle input angle of 68°, while the second regime implements third order focusing at an input angle of 90°. The instrumental functions of the device were constructed, and the relative energy resolutions and luminosities of the analyzer were evaluated. The proposed electron-optical schemes can be used in the development of high-resolution spectrometers for analyzing charged particle beams in space research, as well as spectrographs for the energy-angle analysis of solid surfaces.