Low Energy Neutral Atoms in the Magnetosphere: IMAGE/LENA Observations of
Ionospheric Outflow and Cusp-related Emissions

Hina Khan
NASA Goddard Space Flight Center
Laboratory for Extraterrestrial Physics, Greenbelt, Maryland


The Low-Energy Neutral Atom (LENA) imager on the IMAGE spacecraft was
designed to observe ionospheric outflow events in the energy range,
10-100eV.  The energetic neutrals, created through charge exchange processes
involving superthermal ionospheric ions and atoms in the exosphere, are
imaged by LENA and provide an insight into the dynamics of the topside
ionosphere and interaction of the solar wind with the magnetosphere.  In
this presentation, I wish to provide an overview of the different sources of
neutral atom emissions observed from within the magnetosphere.  The
ionospheric outflow component is principally caused by solar wind
disturbances impacting the magnetopause resulting in pressure variations in
the magnetosphere that cause a surge in ionospheric outflow.  Clear evidence
of this process has been observed and with the IMAGE satellite we are able
to make global ionospheric observations of the ionosphere on short
timescales, investigating the upwelling of plasma during solar wind
disturbances.  Furthermore, IMAGE/LENA observes neutral atom emissions from
the magnetosheath, which can be associated with the cusp-like signatures in
the ionosphere.  Ground-based radar data are presented showing the cusp
features during a time of enhanced neutral atom emission at LENA.  The
analysis shows a clear relationship between these observations indicating
that low energy neutrals are produced as a result of the erosion of the
magnetopause boundary.

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Presented at the Space and Cosmic Ray Physics Seminar, University of 
Maryland, 22 September 2003