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Optical Engineering

Neutral atom imaging mass spectrograph
Author(s): Peter Wurz; Matthias R. Aellig; Peter A. Bochsler; Arthur G. Ghielmetti; Edward G. Shelley; Stephen A. Fuselier; Federico A. Herrero; Mark F. Smith; Thomas S. Stephen
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Paper Abstract

We describe a concept for an instrument to measure 2-D space plasma distributions by remote sensing of neutral atoms. The instrument measures in one dimension, and from a spinning spacecraft one obtains 2-D (line-of-sight) maps of the neutral flux. Because we want to employ this instrument for measurements in the magnetosphere, the main species of interest are neutral H and O atoms with kinetic energies ranging from about 10 eV to 1 keV. The instrument makes use of a low-work-function surface to convert neutral atoms efficiently to negative ions. The ions are then accelerated away from the surface and brought to an intermediate focus by a large aperture lens. After further acceleration, the ions are deflected by a spherical electrostatic analyzer into a time-of-flight mass spectrometer. Mass resolution of the device is sufficient to resolve H, D, He, and O. Energy and azimuth angle information are obtained by position imaging of the secondary electrons produced at the carbon foil. The large geometric factor combined with simultaneous angle-energy-mass measurement eliminates the need for cycling and provides the necessary high sensitivity for imaging at short time intervals. On a spinning spacecraft this instrument is capable of producing 2-D maps of low-energy neutral atom fluxes.

Paper Details

Date Published: 1 August 1995
PDF: 12 pages
Opt. Eng. 34(8) doi: 10.1117/12.205660
Published in: Optical Engineering Volume 34, Issue 8
Show Author Affiliations
Peter Wurz, Univ. Bern (Switzerland)
Matthias R. Aellig, Univ. of Bern (Switzerland)
Peter A. Bochsler, Univ. Bern (Switzerland)
Arthur G. Ghielmetti, Lockheed Palo Alto Research Lab. (United States)
Edward G. Shelley, Lockheed Palo Alto Research Lab. (United States)
Stephen A. Fuselier, Lockheed Palo Alto Research Lab. (United States)
Federico A. Herrero, NASA Goddard Space Flight Ctr. (United States)
Mark F. Smith, NASA Goddard Space Flight Ctr. (United States)
Thomas S. Stephen, Univ. of Denver (United States)

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