1 February 1994 Fundamentals of low-energy neutral atom imaging
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Imaging of the space plasma environment via low-energy neutral atoms (LENAs) promises to revolutionize the way in which largescale space plasma phenomena are viewed and understood. LENAs are produced by charge exchange between plasma ions (less than tens of kilo-electron-volts) and cold geocoronat neutrals; these LENAs radiate outward in all directions from their points of origin. Previously developed methods for imaging higher energy neutrals are not suitable for observing the majority of the terrestrial magnetosphere, which is comprised primarily of lower energy plasma populations. This paper briefly describes both the direct and indirect techniques that have been suggested for imaging LENAs to date. We then examine in more detail the most advanced of these techniques appropriate for magnetospheric imaging, indirect detection based on ionization of LENAs as they transit ultrathin foils. Such a LENA imager consists of four basic components: (1) a biased collimator to remove the ambient charged particles and set the azimuthal field of view; (2) an ultrathin foil, which ionizes a portion of the incident LENAs; (3) an electrostatic analyzer to reject UV light and set the energy passband; and (4) a coincidence position detector to measure converted LENAs while rejecting noise and penetrating radiation.
David J. McComas, David J. McComas, Herbert O. Funsten, Herbert O. Funsten, John T. Gosling, John T. Gosling, Kurt R. Moore, Kurt R. Moore, Earl E. Scime, Earl E. Scime, Michelle F. Thomsen, Michelle F. Thomsen, "Fundamentals of low-energy neutral atom imaging," Optical Engineering 33(2), (1 February 1994). https://doi.org/10.1117/12.155921 . Submission:

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