Mass spectrometric measurements of positive ions at altitudes from 64 to 112 kilometers

A quadrupole mass spectrometer system employing a liquid nitrogen chilled zeolite pump has recently been developed for sampling positive ions at altitudes above 50 km. This system was flown successfully on a Nike Cajun rocket on October 31, 1963, at local noon from Eglin Air Force Base, Florida, and has provided the first positive ion composition measurements in the D region. The predominant ions detected within the D region (64 to 82 km) were 19 + , 30 + , and (37±1) + , 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 spectrums, characterized by the rapid disappearance of 19 + and 37 + and instantaneous appearance of six new ion peaks. Five 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 10‐km‐ wide peak with a maximum at 95 km, a minimum at 105 km, and then a continuous increase until apogee at 112 km. Above 82 km the ions 30 + and 32 + appear to be the most predominant, although many other minor constituent ions are present.