Theory of Fast-Wave Parametric Amplification

Abstract

A new type of low‐noise beam‐type parametric amplifier has recently been introduced by Adler, Hrbek, and Wade. This device is characterized by its use of the fast‐cyclotron wave for amplification purposes instead of the conventionally used slow space‐charge wave. The fast‐cyclotron wave is selected because it can be made relatively noiseless by appropriate coupling processes. Since the input beam noise is the principal source of noise in beam‐type tubes, a very great reduction in noise figure is obtained. Amplification of the fast‐cyclotron wave is achieved by use of the parametric principle. An analytical description of the device is presented which includes a discussion of parametric amplification of the fast‐cyclotron wave. A method of coupling to cyclotron waves is investigated, and design procedures for establishing optimum low‐noise characteristics are outlined.