Study of Nonlinear Wave-wave Interaction in the Ionospheric Plasma

Research Project

Project/Area Number	60580007
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	プラズマ理工学
Research Institution	Research Institute of Atmospherics, Nagoya University
Principal Investigator	HAYAKAWA Masashi Research Institute of Atmospherics, Nagoya University , Associate Prof., 空電研究所, 助教授 (80023688)
Co-Investigator(Kenkyū-buntansha)	SHIMAKURA Shin Faculty of Enigeering, Chiba University, Assistant Prof., 工学部電気科, 講師 (00009721) OKADA Toshimi Research Institute of Atmospherics,Nagoya University,Research Associate, 空電研究所, 助手 (90008566) TANAKA Yoshihito Research Institute of Atmospherics, Nagoya University,Associate Prof., 空電研究所, 助教授 (30023675)
Project Period (FY)	1985 – 1986
Project Status	Completed (Fiscal Year 1986)
Budget Amount *help	¥2,100,000 (Direct Cost: ¥2,100,000) Fiscal Year 1986: ¥400,000 (Direct Cost: ¥400,000) Fiscal Year 1985: ¥1,700,000 (Direct Cost: ¥1,700,000)
Keywords	Ionospheric plasma / The nonlinear wave-wave interaction / VLF transmitter signal / バイスペクトル解析
Research Abstract	Among many wide-band(0-16kHz) VLF data observed on Aureol 3 satellite and telemetered onto the ground station of Sagadaira,we have found out an interesting new phenomenon which has never been reported so far. This phenomenon is associated with the high-power (500kwatts) VLF transmitter (called "Alpha station") signals from the eastern USSR. On the satellite, we have observed Doppler broadening of the spectrum on some occasions,and on other occasions, we have detected the side-band structures above and below the transmitter signal. The former phenomenon was already discovered by Stanford group a few years ago,but the latter phenomenon is a newly-found wave phenomenon. Based on the detailed spectral analysis and on the sophisticated bi-spectrum analysis,it is concluded that those side-band structures are the consequence of the nonlinear wave-wave interaction(three-wave process) between the very intense VLF transmitter signal and the ion wave(such as ion cyclotron harmonic wave) existing near the satellite.