BEAM ANALYZER. 2. CHROMATIC AND SPACE CHARGE ABERRATIONS IN CIRCULARLY DEFLECTED ELECTRON BEAMS
ILLINOIS UNIV AT URBANA ELECTRICAL ENGINEERING RESEARCH LAB
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An analysis is presented of aberration effects on a circularly deflected electron beam used as the phase writer element in a beam analyzer designed to five an accurate picture of the space charge and velocity distribution of an electron beam. Three kinds of aberrations are considered 1 the radial spread of the beam during its path from the deflecting system to its observation plane 2 an angular displacement which allows some electrons to occur at a phase differing from that to which they originally belonged and 3 an undesired velocity modulation which may be caused by axial fields, even in continuos uniform circularly deflected beams. Several approximations were made to reduce almost insolugle situations to workable ones. It was believed that a more accurate study would not reveal more essential features than a rather rough treatment. The effect is considered of the extension of the deflection system the distance of he 2 pairs of the Lecher wires which provide deflections in 2 rectangular coordinates on electrons with different velocities polychromatic electro beam. Means are discussed for determining the current and velocity distribution functions at a point of interest when measurements are obtained at other than the point of interest when measurements are obtained at other than the point of interest.
- Electricity and Magnetism