0883-6272/86 $3.00 + .00 Copyright ® 1986 SUNSAT Energy Council NONLINEAR EXCITATION OF ELECTRON CYCLOTRON WAVES BY A MONOCHROMATIC STRONG MICROWAVE Computer Simulation Analysis of the MINIX Results H. MATSUMOTO AND T. KIMURA RASC Kyoto University Uji. Kyoto. Japan Abstract — Triggered by the experimental results of the MINIX, a computer simulation study was initiated on the nonlinear excitation of electrostatic electron cyclotron waves by a monochromatic electromagnetic wave such as the transmitted microwave in the MINIX. The model we used assumes that both of the excited waves and exciting (pumping) electromagnetic wave as well as the idler electromagnetic wave propagate in the direction perpendicular to the external magnetic field. The simulation code used for the present study is one-and-two-half dimensional electromagnetic particle code named KEMPO. The simulation result shows the high power electromagnetic wave produces both the back-scattered electromagnetic wave and electrostatic electron cyclotron waves as a result of nonlinear parametric instability. Detailed nonlinear micro-physics related to the wave excitation is discussed in terms of the nonlinear wave-wave couplings and associated ponderomotive force produced by the high power electromagnetic waves. 1. INTRODUCTION A rocket experiment named MINIX was carried out to study nonlinear effects of a high power microwave beam on the ionosphere. The results of the MINIX showed that electron cyclotron harmonic waves and electron plasma waves are excited by the transmitted microwave from the rocket. The excitation of the electron plasma waves may be due to the well-known Raman scattering process. However, the excitation mechanism of electrostatic electron cyclotron harmonic waves is not well-understood and needs to be clarified. The results are highly nonlinear so that no analytic theory is effective while yet the experimental data are not sufficient to understand the micro-physics in the nonlinear process of the wave excitation. We, therefore, carried out a computer simulation to understand the micro-physics underlying the phenomenon. In Section 2, a brief review of the MINIX results on the plasma wave spectra. Section 3 presents a model and a code hired in the present computer simulation. Section 4 describes the results of the computer simulation. 2. PLASMA WAVE SPECTRUM EXCITED BY THE MINIX MICROWAVE As discussed in the companion paper (Kaya et al., this conference), a clear difference was seen in the plasma wave spectra by on and off of the transmission of the microwave. Figure 1 shows the plasma wave spectra for both periods of microwave
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