New possibilities for the design of Plumbicon tubes

The design to be described is based on an electrostatically focused gun, which, in contrast to the one used in the miniature Plumbicon tube, contains an accelerating lens. As a consequence the triode part, which contains a limiting aperture, can be biased at a low voltage, thus leading to a reduction in beam discharge lag. Such a gun could be placed in a normal straight pickup tube envelope, but it may also be combined with an enlarged head carrying the target, such that the outer diameter of the head is equal to that of the deflection coils. In this way the useful scan diagonal of the target can be made equal to the inner diameter of the envelope of the gun. A version with such an enlarged head has been realized in the research laboratory.