[PEM13-08] Causality for formation of electromagnetic channel from Polar to Equatorial Ionosphere
キーワード：磁気圏電離圏結合、電磁結合、プラズマダイナミクス、極域ー磁気赤道域結合
Formation of global ionospheric current system and it’s associated plasma dynamics are frequently discussed under the electrostatic approximation of plasma electrodynamics. Since the Poynting flux never across the equipotential line, it is impossible to provide electromagnetic energy from source region to loading region across the magnetic field line. And hence, to discuss causality for evolution of ionospheric current system, we need to take into account an electromagnetic process of coupled system. To resolve this problem, we propose electromagnetic coupling model from polar to equatorial ionosphere. In this model, ionospheric current produces Ampere force and generates motion of plasma. The motion of plasma and associated mechanical process excite electromotive force and resultant electric field. Curl of electric field causes magnetic field disturbances and evolution of ionospheric current. Therefore, causality for evolution of electromagnetic energy and plasmas acceleration for expanding of ionospheric current system has occurred at the wave front region and/or conductivity gradient region. In this talk, we will discuss about what type of plasma motion induces electric field in the ionosphere, and how and whrere they produce magnetic field disturbances (hence the Ampere force) for acceleration of plasma as wave propagation process. Furthermore, we also discuss what kind of mechanical and electromagnetic process have occurred at the conductivity gradient region, which become very important for establishment of geometrical structure of ionospheric current system.