Neutral Composition Measurements of the Mesosphere and Lower Thermosphere

摘要

A recently developed rocket-borne mass spectrometer which employs a LN2 cryosorption pump has successfully obtained the first direct measurements of the major and minor neutral constituents of the mesosphere and lower thermosphere. The mass analysis is performed using an rf quadrupole spectrometer with an electron impact ion source. Measurements were obtained from two flights, and the preliminary results from one of these are presented. The constituents measured include N2, O2, Ar, O, CO2, O3, and several other minor constituents. Measurements were obtained from 70 to 120 km. Atomic oxygen measurements were obtained between 85 km and apogee on both up-leg and down-leg of the flight. The atomic oxygen measurements were obtained at lower altitudes by switching the ion source potentials on alternate spectral scans to ionize with 20-eV electrons. The lower ionizing energy reduces that portion of the signal at 16 amu due to dissociative ionization of O2. Number density profiles of individual constituents were obtained by normalizing the relative abundances to a density model. (Author)