The variety of technologies that have been applied in the development of aonded grid cathode are described. These include chemical vapor deposition of tungsten, molybdenum, iridium BN, and Si.sub.3 N.sub.4 on both sides of a sintered tungsten cathode disk. Zirconium and titanium getters have been used to eliminate nitrogen evolution problems. The getter plates are also used as heat shields for the bonded heater. Films of Si.sub.3 N.sub.4 have been added to the insulation to prevent calcium and barium diffusion into the layer and maintain adequate resistivity and breakdown strength. Plasma etching was introduced as a method of removing Si.sub.3 N.sub.4 from the cathode pores.A new method, erosion lithography, is used for making the fine-detail grid structure, combining air erosion and lithographic techniques.