2.2.2 spase://SMWG/Instrument/VenusExpress/ASPERA4/NPI Venus Express ASPERA-4 Neutral Particle Imager 2012-06-13T00:00:00Z The Neutral Particle Imager (NPI) of the ASPERA-4 package flown on Venus Express provides measurements of the integral ENA flux with no mass and energy resolution but with 4.6 deg x 11.5 deg angular resolution. The intrinsic field of view is 9 deg x 344 deg. The sensor utilizes a graphite surface to suppress the UV background. ENAs incident on the surface at a grazing angle of 20 deg are reflected and/or cause ion sputtering. An MCP stack detects the reflected particles and sputtered fragments with a discrete anode. spase://SMWG/Person/Stas.Barabash PrincipalInvestigator PSA ASPERA web page ftp://psa.esac.esa.int/pub/mirror/VENUS-EXPRESS/ASPERA4/VEX-V-SW-ASPERA-2-ELS-V1.0/CATALOG/INST.CAT NeutralAtomImager ASPERA4_NPI spase://SMWG/Observatory/VenusExpress