An Electron Oscillator with Plane Electrodes

This paper describes a new type of thermionic tube capable of producing ultra-high frequencies by means of electron oscillations. Tubes of this type are characterized by having parallel plane electrodes, instead of cylindrical electrodes as in the conventional Barkhausen-Kurz tubes, and a fourth element called a backing plate. The relations between wavelength and amplitude of oscillation and the various electrode potentials are shown by measurements on a typical tube. It is found that in these tubes the filament voltage is not critical, space-charge-limited operation being satisfactory, and that only one mode of oscillation is obtained. Both of these factors appear to give these tubes an advantage in stability over cylindrical Barkhausen-Kurz tubes. A tube of the flat type is described which has produced oscillations at a wavelength of less than 10 centimeters in the fundamental mode with a positive grid potential of 150 volts.