The energy density shown for the mode 16 is the difference from its initial values indicating the fluctuations. As seen in Fig. 4(c), the energy density of the excited wave with k = 30 increases with time roughly exponentially with a modulation of a period of about 120. Correspondingly, as seen in Fig. 4(b), the idler wave with k = —14 shows that the similar periodic change with the same period. The fluctuations shown in Fig. 4(a) is a rather complicated evolution. It consists of three factors. One is a beating component with the pump and oppositely propagating weak O-mode wave with the same k, and a component coming from a nonlinear frequency shift of the large amplitude of the pump wave and finally a slow variation due to the coupling with the idler and excited waves. The details of the last variation is hardly seen. However, a clear exponential damping with a slight modulation with almost the same period of about 120 is seen as the average change of the energy evolution. The present computer simulation could basically reproduce the experimental results obtained in the MINIX experiment. Detailed physics will be discussed in the oral presentation. Acknowledgement — The authors would like to thank members of the MINIX rocket experiment for their discussion. REFERENCES 1. N. Kaya, H. Matsumoto, S. Miyatake, 1. Kimura, M. Nagatomo, and T. Obayashi, Nonlinear Interaction of Strong Microwave Beam with the Ionosphere — MINIX Rocket Experiment Conference, 1985. 2. H. Matsumoto and Y. Omura, Particle Simulation of Electromagnetic Waves and its Application to Space Plasmas. In: Computer Simulation of Space Plasmas. 43, edited by H. Matsumoto and T. Sato. Terra Sci. Pub. Co. and Reidel Pub. Co., 1984.
RkJQdWJsaXNoZXIy MTU5NjU0Mg==