Development of an electron gun operated at intermediate-high energies for electron energy-loss spectrometer

Abstract Background: In an electron energy-loss spectroscopy (EELS) experiment, the electron emitted by the electron gun collides with atoms and molecules, and the momentum and energy of the scattered electron are analyzed by EELS, then the information of electronic structure and collision dynamics of the target can be deduced. Purpose:A well designed intermediate-high energy electron gun with small beam size and divergence angle is needed to satisfy the requirement of EELS. Methods: To obtain the optimal beam condition, the electron optics software SIMION was utilized to simulate the space size and divergence angle of the electron beam at target position, the electron gun has a simple structure, i.e., consisting of thermionic cathode, grid electrode, anode electrode, focus electrode and deflection plates. The tuning range of electron energy is wide (1-3 keV) and easy to operate. Results: The beam size of 0.95 mm, divergence angel of 0.93 °, and beam current of 6.27 μA of the constructed electron gun was obtained at 27 mm from the exit of electron gun at a beam energy of 1.5 keV. Conclusion: An electron gun which satisfies the requirements of EELS has been developed. (authors)