On the Design of Magnetic Spectrometers for Electron Energy Loss Spectroscopy

Abstract

In designing an energy loss spectrometer, one can avoid the need for a highly regulated high voltage supply by decelerating the electrons prior to the energy analysis.1,2 However, with present technology it is equally feasible to regulate the high voltage to a few parts per million and to use a magnetic spectrometer to analyze the fast electrons.3 With that approach one requires a magnetic analyzer which will perform optimally in a given application. Specific cases have been treated, notably that of constant angular magnification4, and theoretical calculations sufficient for most design problems have been performed5-9 Even so, it is not always clear how to formulate design criteria which can be used to determine values of the various parameters which describe a magnetic spectrometer. Moreover, the ideal focusing case has not been treated for any but constant angular magnification instruments.