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FAST Sheds Light on Auroral Particle Acceleration
New FAST observations show that the auroral acceleration region is composed of a hot low density plasma devoid of cold plasma, contrary to previous reports by the Viking satellite investigators.
The controversy over how electric fields parallel to the magnetic field can exist in the auroral plasma may now be settled since the absence of cold plasma eliminates the need to postulate "anomalous resistivity".
The lower boundary of the acceleration region contains a strong parallel electric field because this boundary acts as an interface between the hot,tenuous magnetospheric plasma and cold, dense ionospheric plasma.
Understanding the basic properties of the interface between different density and temperature plasmas has applications to other astrophysical boundaries such as the interface between the hot solar corona and cooler dense photosphere.
Contact: J. McFadden, mcfadden@ssl.berkeley.edu