Effect of Electron Source to Energy Resolution in Electron Velocity Analysis : Interpretation of Boersch Effect

概要

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The energy broadening of an electron beam depended on the beam currernt, so called "Boersch effect", was examined by an energy analyzer of a cylindrical magnetic type at an beam energy of 50 kV. The energy analysis was carried out by the caustic method. Even in an electron beam of 60 μA and a current density of 10^<-1> A/mm^2, the half width of the energy spread became 0.5 eV by decreasing the divergent angle of the incident beam. This value agrees with the half width deduced from the cathode temperature assuming the energy distribution Maxwellian. Moreover, the line shift S due to the variation of the incident angle α was measured by inclining the electron beam from the optical axis, and dS/dα was 1 volt/1×10^<-4> rad. Thus it is concluded that the energy broadening due to the beam current is to be regarded as an effect of the divergent angle of the incident beam. Characteristics of three cathodes, i.e. usual hair pin cathode of tungsten wire, pointed cathode, and oxide cathode are discussed from a view of line broadening.
社団法人応用物理学会の論文
1969-02-05