Deflection Distortions Contributed by the Principal Field of a Ring Deflection Yoke

To achieve a more detailed understanding of the factors contributing to deflective distortions, an analysis was made of a simple ring deflection yoke. This type of yoke was selected because its magnetic field can be described by an infinite series whose first term is of principal significance. A practical ring yoke can be wound (with a simple sinusoidal winding distribution) which will establish a magnetic field described completely by this first term. Additional windings can also be added which produce fields corresponding to any of the subsequent terms of the series. This permits a detailed study of the effects of the winding distribution function upon the deflection distortions. Fortunately, these higher order fields are all zero on the yoke axis and are always negligible in the study of small angle deflections.