Effective Spot Size in Beam Scanning Tubes

Aurelius Sandor

The Gaussian current distribution does not hold in practical electron beams because of aberrations, space-charge and masking conditions. Only an overall effect of the total current is useful for defining spot size; and thus, the observation of the visible spot boundaries on phosphor screens is adopted (telescope). Because of the prevailing bell-shaped current density distributions, this definition comes closest to a practical measure of spot size based on center peak brightness. Experimental evidence is given for the formation of vertically reduced spot sizes during beam scanning in form of ellipses, manifesting itself in a significant improvement on vertical picture resolution.

Print ISSN
Published
1960-10
Content type
Original Research
DOI
10.5594/J09404