Transport of Noise at Microwave Frequencies through a Space‐Charge‐Limited Diode

Abstract

Several analyses of the transport of cathode shot noise through a space‐charge‐limited diode at microwave frequencies have been published to date. Each of these analyses has been beset by inconsistencies arising from assumptions of monovelocity perturbation flow, direct or reflected. A new method of analysis of diode flow eliminating this problem has been developed. Numerical results based on this method are presented here. Attention is restricted to the now classical problem of one‐dimensional longitudinal confined flow.The magnitude and variation with distance of the so‐called beam noise invariants is shown for a range of diode operating conditions. These calculated results, based for economy on an approximate static flow model, essentially substantiate the qualitative expectations suggested by prior analyses, and fit what little experimental data are available.The method of analysis employed in the calculation of the numerical results comprises a linear multistream formulation, based on representation or approximation of the perturbation particle density for the noise flow as a composite of singular impulse streams, N in number, along characteristic trajectories in the velocity‐distance phase space. The set of N coupled first‐order linear differential equations resulting is solved by simultaneous numerical extrapolation.