Low Energy Neutral Atoms in the Magnetosphere

T. E. Moore (1), M. R. Collier (1), J. L. Burch (2), D. J. Chornay (1,3), 
S. A. Fuselier (4), A. G. Ghielmetti (4), B. L. Giles (1), D. C. Hamilton (3), 
F. A. Herrero (1), J. W. Keller (1), K. W. Ogilvie (1), B. L. Peko (5), 
J. M. Quinn (6), T. M. Stephen (5), G. R. Wilson (7), and P. Wurz (8) 

1 NASA Goddard Space Flight Center, Greenbelt, MD
2 Southwest Research Institute, San Antonio, TX
3 Department of Physics, University of MD, College Park
4 Lockheed Martin ATC, Palo Alto, California
5 Department of Physics, University of Denver
6 Institute for EOS, University of New Hampshire, Durham
7 Mission Research Corporation, Nashua, New Hampshire
8 Physikalisches Institut, University of Bern, Switzerland

We report observations of low energy neutral atoms (LENA) from the solar wind and the 
ionosphere, obtained by the LENA Imager on the IMAGE spacecraft.  The LENA Imager 
detects and images LENAs arriving at the spacecraft from within a 90 degree field of 
view (8 degree x 8 degree pixels), swept through 360 degree every two minutes by 
spacecraft spin. Neutral atoms arriving at the sensor are converted to negative ions 
by a conversion surface. The resulting negative ions are separated in energy (3 bins, 
10 - 250 eV) and arrival direction ( ±45 degrees). They are then accelerated, detected, 
and time-of-flight mass analyzed. The solar wind and the ionosphere both emit 
measurable neutral atom fluxes, the latter responding rapidly to to variations of the 
former. 

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Geophysical Research Letters, Vol. 28, No. 6, pp. 1143-1146, March 15, 2001