Observation of electron density by the impedance probe on board the Ohzora (EXOS-C) satellite.

Abstract

Observations of the electron number density have been successfully carried out by the NET instrument on board the Ohzora (EXOS-C) satellite after the launch on February 14, 1984. The NET instrument was designed to measure the effective capacitance of the rod type probe whose length is 45cm with diameter of 2cm in the swept frequency range from 0.1MHz to 16MHz.The results of the initial phase observation show complicated features of the polar ionosphere relating to the auroral particle precipitation and also the large scale movement of the ionospheric plasma. The trough region in the ionospheric level frequently observed in clearly defined form and the remarkable enhancements of the ionization are sometimes observed at the low latitude side of the boundary. Usually the ionosphere around the auroral oval region shows ionization enhancement and the small scale irregularity is predominant. The precipitating low energy particles in the auroral region, excite intense plasma waves. The electrostatic component with large amplitude and also charging of the probe clearly appear in the detected impedance values versus the swept frequency. The polar cap ionosphere which usually shows lower density level than the auroral oval region, indicate sometimes a very large electron density enhancement exceeding auroral oval ionization even in the night side.

Plasma wave observation and sounder experiments(PWS) using the Akebono (EXOS-D) satellite. Instrumentation and initial results including discovery of the high altitude equatorial plasma turbulence.

“…The gyroplasma probe has a long history. After its application to ionospheric sounding rockets (OYA and OBAYASHI, 1967), gyroplasma probes have been used in the Taiyo satellite (OYA and MORIOKA, 1975;OYA et al, 1982), the Hinotori satellite WATANABE and OYA, 1985) and the Ohzora satellite (TAKAHASHI et al, 1985). In addition to the normal mode of the swept frequency impedance probe, fixed frequency (from FIX-1 to FIX-8) impedance probe measurement is also possible in this PWS system.…”

Development of a fast impedance probe for absolute electron density measurements in the ionosphere

“…For ionospheric plasmas this leads to typical frequencies of 0.5-20 MHz. Self-impedance probes were used on ionospheric sounding rockets, for example [5,6] as well as on satellites [7][8][9]. In the present paper the improvements of the self-impedance technique and the application in the DEOS-rocket campaign [10] are described.…”

Sheath capacitance observed by impedance probes onboard sounding rockets: Its application to ionospheric plasma diagnostics

“…Accordingly, the impedance probe made it possible to measure the absolute electron density with a high degree of accuracy. Since then, various types of improved impedance probes have been installed on many sounding rockets (e.g., Yamamoto et al, 1998;Wakabayashi et al, 2005;Barjatya and Swenson, 2006) and scienti c satellites (e.g., Ejiri et al, 1973;Oya and Morioka, 1975;Takahashi et al, 1985;Watanabe and Oya, 1986) for measuring electron density. The observed antenna impedance re ects various physical properties of the ambient plasma as well as the electron density.…”