GRIDDED ELECTRON TUBE EMPLOYING COOLED CERAMIC INSULATOR FOR MOUNTING CONTROL GRID

The gridded gun of an electron tube includes an annular high voltage beryllia insulator body having good thermal conductivity. The thermionic cathode emitter is mounted within the central bore in the annular beryllia insulator in thermally insulative relation relative to the insulator body. The control grid and focus electrode for the gun are mounted from the surface of the annular insulator facing the anode. The outer periphery of the annular insulator is mounted to the body of the electron tube in heat exchanging relation therewith, such that the control grid is cooled by thermal conduction through the beryllia insulator body to the cooled main body of the electron tube.