Electrostatically Focused Radial-Beam Tube

The addition of the electrostatic field between coaxial cylinders to a uniform electrostatic field provides the correct properties for focusing a beam of electrons in the positive direction of the uniform field. In the electrostatically focused radial-beam tube, this combination of fields produces a single radial electron beam which may be rotated by rotating the uniform component of the combined fields. The center coaxial electrode may be either the cathode or a grid surrounding the cathode, and the outer coaxial electrode is broken up into segments to which polyphase potentials are app ied. At any instant these polyphase potentials produce an approximation to a uniform field which rotates at the cyclic frequency of the poly-phase potentials. A number of tubes have been made incorporating these principles. Details are given of such a tube with twelve anodes and twelve associated control grids which is no larger than an ordinary radio receiving tube. The beam current is of the order of 1 ma and the frequency of rotation is limited only by the inductance and capacitance of the elements of the tube. This tube is an inertialess distributor with applications to time-division multiplex, telemetering, remote control, and other high-speed switching functions.