An ultra-laminar tetrode gun for high duty cycle applications

This paper describes a high convergence Pierce gun having beam laminarity essentially equal to that of ungridded guns and which is capable of duty cycles well in excess of triode intercepting gridded guns. Since current is drawn more uniformly from 100% of the open area between the grid wires in the tetrode gun, cathode loading is significantly less per total unit area than either standard or contiguous shadow gridded guns. Theoretical and beam analyzer studies, and hot testing of a high power pulsed IJ band helix TWT have confirmed that there is a profound performance improvement as the two control grid voltages in the tetrode gun are trimmed. The adjustable grid wire lens elements enable optimization of beam diameter and laminarity, and account for variations in tolerances. A simple self-biasing network can be included within the tube package for operation by a conventional grid pulse modulator.