Numerical Simulation of Ionospheric Wave Interaction Experiments (Digest of NBS Technical Note 325)

Abstract

The need for an improved ground‐based radio technique for probing the lower ionosphere has prompted a number of experiments based on nonlinear radio wave interaction (ionospheric cross modulation or Luxembourg Effect) [Fejer, 1955: Rumi and Little, 1958: Barrington and Thrane, 1962: Ferraro et al., 1963: Smith, 1964]. Their success as accurate and continuous D‐region probes has been somewhat limited by the need for much greater experimental accuracy and sensitivity and an efficient method for interpreting interaction data in terms of electron density and collision frequency profiles. The solution of many of the problems in refining and optimizing this type of experiment and in the development of effective data reduction techniques depends ultimately on the formulation of a more comprehensive model of the interaction mechanism. This note summarizes a recent publication [Georges, 1965] which presents a simple method for simulating the interaction process on a digital computer. The technique is directly applicable to verticalincidence pulse interaction experiments based on the method of Fejer [1955], including cosmic noise interaction [Benson, 1962], phase interaction [Ferraro et al., 1963], and gyrointeraction [Smith, 1964]. By avoiding the explicit formulation and solution of closedform expressions for the interaction effects, many of the limitations and approximations involved in analytical treatments are bypassed. The simulation of many different interaction experiments using various theoretical models yields estimates of the limits of applicability of the simplified analytical theory, and shows that it becomes a poorer approximation as experimental conditions necessary for improved accuracy and sensitivity are approached. The numerical method also provides a basis for the development of an effective technique for the synthesis of ionospheric profiles from interaction data.