A New Grided Electron Gun Configuration Projected to Operate From Beam Full on to Near Cutoff

Some linear devices can be improve by a control grid providing operation from rated beam current to cut off. This capability is provided by the control grid-cathode combination to be described. Figure 1 shows the structure used which locates the control grid behind the cathode and controls the cathode emission through suitably shaped voids in the directly heated cathode. The cathode voids are shaped to produce strip emitters with voids at either edge. In this -arrangement a single grid controls the emission level from each strip cathode in an identical manner. A simple analysis is used to demonstrate decreasing and cutting off beam current. This analysis is extended to show electron trajectories from an individual cathode as beam current is decreased. The analysis does not include space charge effects or a beam forming electrode (BFE) design. The paper concludes with a specific cathode design and its features as well as minimizing the effects of heater current produced voltages between cathode elements. Considerations for the addition a BFE to the grid-cathode combination are also discussed