An evacuated envelope includes a transparent front panel having a cathodoluminescent screen thereupon and a back panel interconnectably sealed to the front panel. The back has a plurality of cathode stripes thereon. A plurality of vanes, spaced from and parallel to each other, extend between the front and back panels orthogonal to the cathode stripes. Electrodes to control the operation of the device are formed directly on the vanes. Any two adjacent vanes form an electron multiplier in which a self sustaining source of electrons is created only at a location along the vanes which is determined by the proper energizing of the cathode stripe at that location.