科学衛星 JIKIKEN における電子ビーム放出実験

概要

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Beam-plasma interaction experiment in the magnetosphere by emitting controlled electron beam has been performed by JIKIKEN (EXOS-B). Several types of waves in both ranges of VLF and LF/HF were strongly excited by the electron beam. In LF/HF range in low altitude ragion (hight 10000km) several types of plasma waves are clearly identified such as the plasma frequency, the upper hybrid frequency, the electron cyclotron frequency and its harmonics, the half-cyclotron frequency and f_<Q2>. It is observed that the amplitude of these waves strongly depends on f_<pe>/f_<ce> of the ambient plasma. In VLF range the spectrum changes clearly when the satellite goes through the plasmapause. Inside the plasmapause the excited wave has a broad spectrum up to several kHz, whereas outside the plasmaspause the excited wave has narrow band width and the frequency changes rapidly. The effect of beam modulation is strong especially far into the magnetospere. The nonlinear coupling of the beam modulation and the plasma wave is also observed. Furthermore the density profile of the magnetosperic plasma is obtained by the electron beam experiment.
宇宙航空研究開発機構の論文