Unveiling space plasma environments by electromagnetic wave observations
Assoc. Prof. Mitsunori Ozaki
Faculty of Electrical, Information and Communication Engineering, Institute of Science and Engineering
Speciality: Instrument Engineering, Communication and Network Engineering
Radio wave Engineering Group
Protecting satellites from radioactive rays generated in the space surrounding the Earth
In the space surrounding the Earth, natural electromagnetic waves are radiated due to the fluctuation of plasma consisting of electrons and ions. High energy plasma becomes radioactive rays in space up to the geostationary orbit altitude, called geospace, where satellites for communication, broadcasting, metrology and GPS, essential to our daily lives are located. Those rays can induce deterioration and malfunction of the electronic circuits of satellites. Thus, elucidation of the radioactive ray environment of the geospace through investigation of electromagnetic waves generated there is of great importance to the safe and secure operation of satellites.
Visualization of the electromagnetic environment of geospace by cooperation between a scientific satellite and a ground-based observation network
It is known that radioactive rays are generated by resonant interaction between the “chorus wave,” an electromagnetic wave accompanying cyclotron movements of electrons along magnetic field lines of the Earth, and plasmas generated in the geospace. This phenomenon is called the wave-particle interaction, causing acceleration of plasma to relativistic energies and subsequent scattering. However, the spatial development and temporary changes of the magnetosphere where the wave-particle interactions take place have so far not been elucidated in detail. Here we focused on the special transient auroral flashes generated when chorus waves precipitate energetic electrons into the Earth’s atmosphere. We were successful in the scientific satellite Arase’s capturing chorus waves and in simultaneously observing transient auroral flashes by the ground-based observation network (PWING) of 8 bases at the Far North. We thus found that the intensity change of the chorus wave and the shape variations of a flash auroral intensity corresponded. It was shown for the first time that the development of spatial variations of the magnetosphere, where wave-particle interactions take place, confirms the geomagnetic north-south asymmetry on the time-scale of tens of milliseconds.
Microsatellites produced by Kanazawa University for further development of the space industry
We are developing our observations using scientific satellites and the ground-based observation network combined with theoretical research to contribute to development of the space industry by fully utilizing satellites. Furthermore, we are accelerating research on the development of microsatellites by Kanazawa University.
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