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Abstract

abstract

Aurorae are optical emissions excited by the collisions of charged particles with the upper atmosphere at about 100 km, the altitude of the ionospheric E-region. In fact, the ionosphere has often been likened to a giant TV screen. For the latter, the electrons are fired from an electron gun, whereas the sources of high energy electrons that cause aurorae are located in the magnetosphere. One of the central problems in space physics is locating the sources and mechanisms causing the acceleration of auroral particles.