| 摘要 |
PURPOSE:To form an electron beam in a desired shape by forming the electron gun with at least one pair of electrode pieces holding the electron beam therebetween and additionally providing the second focusing electrode (quadripole) to which a compensatory focusing voltage synchronizing with a deflection magnetic field is applied. CONSTITUTION:Horizontal electrode pieces 9a are provided to be applied by a focusing voltage higher than that for vertical electrode pieces 9b from a compensatory focusing power supply 20. Accordingly, an electron beam 6 is subjected to attractive force in vertical direction and its cross-sectional shape becomes a longitudial ellipse after passing through the second focusing electrode (quadipole) 9. This electron beam 6 is subjected to focusing in vertical direction and divergency in horizontal direction by means of a deflection magnetic field. Accordingly, a spot 8 very close to an exact circle is formed on a phosphor screen 7.
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