Advances in Low Energy Neutral Atom Imaging

D. J. McComas, H. O. Funsten, and E. E. Scime

Proceedings of the Chapman Conference on Space Plasma Measurement
Techniques, AGU Monograph 103, pp. 275-280, 1998.

In the near-Earth space environment, charge exchange continually occurs
between the magnetospheric ions and very cold (~ eV) neutral atoms in the
geocorona. This process creates both energetic (> tens of keV) and low
energy (< tens of keV) neutral atoms (ENAs and LENAs, respectively) that
radiate from the magnetosphere. Over the past several years, imaging
techniques have been developed for observing these neutrals in space.
Such techniques promise to open a new window onto the magnetosphere,
providing synoptic measurements and a global view of the magnetospheric
plasma and energetic particle environments for the first time. In this
paper we describe recent advances in two of the leading techniques
developed for LENA imaging: thin foil transmission-based imagers and
UV-blocking grating-based imagers. In particular, we will discuss the
development and testing of a flight-quality prototype foil-based imager
and present an advanced design for a grating-based imager that has just
been selected for NASA's IMAGE spacecraft.