A neutral‐atmosphere composition experiment for the Atmosphere Explorer‐C, ‐D, and ‐E

Abstract

The neutral‐atmosphere composition experiment instrumentation is designed to obtain in‐situ measurements of neutral thermosphere composition from Atmosphere Explorer‐C, ‐D, and ‐E. The system is based on previously flown OGO‐6 and San Marco‐3 composition instruments. The mass‐spectrometer sensor includes a gold‐plated thermalizing chamber and ion source, a hyperbolic rod quadrupole analyzer, and an off‐axis electron multiplier. Automatic ion‐source sensitivity control and pulse‐counting techniques provide density measurement capability from approximately 125 to 1000 km altitude. The normal operating mode includes measurement at all masses in the range 1 to 44 amu with emphasis on hydrogen, helium, oxygen, nitrogen, and argon. Additional operational modes are optimized for minor constituent studies of any individual gas in this mass range.