Summary of JIKIKEN Observation : Preliminary Report of the Initial Observation Result (c. Wave-Particle Interactions in the Magnetosphere) (Proceedings of the Second Symposium on Coordinated Observations of the Ionosphere and Magnetosphere in the Polar Regions : Part I)

• Main Authors: Hiroshi OYA, Nobuki KAWASHIMA, Tatsuzo OBAYASHI
• Format: Article in Journal/Newspaper
• Language: English; Japanese
• Published: National Institute of Polar Research 1980
• Subjects: Geography (General); G1-922; Siple; Antarc*; Antarctica
• Online Access: https://doi.org/10.15094/00008123; https://doaj.org/article/60635345e193403c9d979de87924efe8

JIKIKEN (EXOS-B) was successfully launched on September 16, 1978 into the orbit with initial apogee of 30056 km and perigee of 227 km, with inclination of -31.1°; the orbit is suitable for the investigation of the wave-particle interaction process in the plasmasphere and the magnetosphere near the plasma-pause. The analog data transmission system is used and fine structure of the dynamic spectrum in a swept frequency range from 10 kHz to 3 MHz has been obtained and wide band spectra from several 100 Hz to 10 kHz. The important wave phenomena obtained by current observation of JIKIKEN are. 1) Auroral (Earth) kilometric radio waves 2) Upper hybrid mode emissions 3) (n+l/2)f_c emission where f_c is the electron gyrofrequency 4) Principal phenomena of VLF frequency range, such as whistler, chorus, and hiss 5) Pure tone emissions (narrow band emission) in VLF range, 6) Artificially stimulated plasma waves and observation of plasma parameters 7) Planetary radio waves 8) Solar type III outburst. As a preliminary approach to verify the wave particle interaction processes, investigations of the energy spectra have also been made for the cases of the UHR mode plasma wave and the pure tone (narrow band) emission in ELF and VLF range. UHR resonance with long duration has been triggered by 500 μs pulse in the stimulated plasma wave experiment the resonance persists up to 125 ms,even in VLF range (below 30 kHz) and the electron cyclotron resonances are stimulated at very high harmonics number n, in the maximum case, sometimes n=20. The plasmapause electron density distributions are obtained from these resonance frequencies. The injection of an electron beam from the spacecraft stimulates electrostatic waves and also causes turbulent heating in the surrounding plasma. Bursts of energetic particles of keV energies are frequently encountered outside the plasma-pause Future programs of the EXOS-B experiment include the VLF signal obseivation transmitted from Siple Station, Antarctica, and coordinated observations ...