MASS SPECTROMETRY IN THE D-REGION IONOSPHERE, APPARATUS, TECHNIQUES, AND FIRST MEASUREMENTS,
AIR FORCE CAMBRIDGE RESEARCH LABS L G HANSCOM FIELD MASS
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A quadrupole mass spectrometer system employing a liquid nitrogen chilled zeolite pump has recently been developed for sampling positive ions at altitudes above 50 kilometers. This system was flown successfully on a Nike-Cajun rocket on 31 October 1963, and has provided the first positive ion composition measurements in the D-region. For simultaneous environmental measurements of ion and electron densities, two spherical electrostatic analyzers were included in the rocket payload. Supplemental information on ionospheric conditions was provided by a ground-based ionosonde. Due to the high sensitivity of the system approximately twenty 20 positive ion peaks were detected in the mass range 10 to 45 amu within the altitude range of 64 to 112 km. The predominant ions detected within the D-region 64 to 82 km were 18, 30 and 371, with 32 rapidly rising above 75 km approaching the abundance of 30 at 83 km. At 82.5 km a sharp transition occurred in the spectra, characterized by the rapid disappearance of 18 and 37 and instantaneous appearance of six 6 new ion peaks. Five 5 of these ion peaks are suggested to be the metallic ions of sodium 23, magnesium 24, 25, 26 and calcium 40. The metallic ions all exhibited an identical altitude profile, a ten 10 km-wide peak with a maximum at 95 km, a minimum at 105 km, and then continuously increasing until apogee at 112 km.