HR: 0800h
AN: SH12A-0855    [Abstracts]
TI: Seeking to improve low energy neutral atom detection in space
AU: * Shappirio, M
EM: mark.d.shappirio@nasa.gov
AF: Goddard Space Flight Center/NASA, 8800 Greenbelt Rd., Greenbelt, MD 20771, United States
AU: Coplan, M
EM: coplan@umd.edu
AF: University of Maryland, IPST, College Park, MD 20742, United States
AU: Chornay, D
EM: dennis.chornay@gsfc.nasa.gov
AF: University of Maryland, IPST, College Park, MD 20742, United States
AU: Collier, M
EM: michael.r.collier@nasa.gov
AF: Goddard Space Flight Center/NASA, 8800 Greenbelt Rd., Greenbelt, MD 20771, United States
AU: Keller, J
EM: John.keller@nasa.gov
AF: Goddard Space Flight Center/NASA, 8800 Greenbelt Rd., Greenbelt, MD 20771, United States
AU: Ogilvie, K
EM: keith.w.ogilvie@gsfc.nasa.gov
AF: Goddard Space Flight Center/NASA, 8800 Greenbelt Rd., Greenbelt, MD 20771, United States
AU: Williams, E
EM: edw@physics.umd.edu
AF: University of Maryland, IPST, College Park, MD 20742, United States
AB: The detection of energetic neutral atoms allows for the remote examination of the interactions between plasmas and neutral populations in space. Before these neutral atoms can be measured, they must first be converted to ions. For the low energy end of this spectrum, interaction with a conversion surface is often the most efficient method to convert neutrals into ions. It is generally thought that the most efficient surfaces are low work functions materials. However, by their very nature, these surfaces are highly reactive and unstable, and therefore are not suitable for space missions where conditions cannot be controlled as they are in a laboratory. We therefore are looking to optimize a stable surface for conversion efficiency. Conversion efficiency can be increased either by changing the incident angle of the neutral particles to be grazing incidence and using stable surfaces with high conversion efficiencies. We have examined how to increase the angle of incidence from ~80 degrees to ~89 degrees, while maintaining or improving the total active conversion surface area without increasing the overall volume of the instrument. We are developing a method to micro-machine silicon, which will reduce the volume to surface area ratio by a factor of 60. We have also examined the material properties that affect the conversion efficiency of the surface for stable surfaces. Some of the parameters we have examined are work function, smoothness, and bond structure. We find that for stable surfaces, the most important property is the smoothness of the surface.
DE: 7514 Energetic particles (2114)
DE: 7837 Neutral particles (2151)
DE: 7894 Instruments and techniques
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2007 Fall Meeting