Energieverteilungen in thermisch ausgel�sten Elektronenstrahlen

Abstract

In contrast with the original Maxwellian distribution of thermionically emitted electrons, there appear in electron beams so-called anomalous shirtings and broadenings as well as symmetrizations of the energy distribution (BOERSCH t954). These anomalies are ascribed to a phenomenon of relaxation with the energy distribution changing to a new equilibrium. A relation is given to connect beginning relaxation with cathode temperature, accelerating voltage and beam current density ~'s" The relative energy broadening is found to be proportional to js ~. This is verified experimentally. It is shown that strong relaxation is already acting in the accelerating region. The influence of source geometry, especially source aperture, is discussed. The mechanism of relaxation is derived from general principles. Therefore it could turn out to be of importance for other corpuscular beams also.

Simultaneous measurements of the brightness and the energy distribution of electrons emitted from a triode gun

“…These results support the space-charge oscillation theory. We conclude that energy distribution measurements obtained with systems as shown in figure l(a) using total energy analysers always give an E exp (-E/kT) distribution when no anomalous broadening occurs, This is in agreement with all the reported experimental results (Boersch 1954, Dietrich 1958, Kunze 1959, Hartwig and Ulmer 1963, Rehmet 1965, Beck and Maloney 1967 assuming that the analysers used were total-energy analysers not directional analysers. Little attention has been given to this point, but the operating conditions of the different analysers appear to be such that they were most likely to perform as total-energy analysers.…”

“…The energy analyser is placed behind an aperture which selects part of the electron beam emitted from the triode gun. As reported by several authors (Boersch 1954, Kunze 1959, Hartwig and Ulmer 1963 W. H. J. Andersen and A .…”