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The magnetic ion‐mass spectrometer on Atmosphere Explorer
Author(s) -
Hoffman J. H.,
Hanson W. B.,
Lippincott C. R.,
Ferguson E. E.
Publication year - 1973
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/rs008i004p00315
Subject(s) - ion , mass spectrometry , range (aeronautics) , atmosphere (unit) , atomic physics , polar , spectrum analyzer , physics , spectrometer , analytical chemistry (journal) , computational physics , materials science , chemistry , optics , meteorology , chromatography , quantum mechanics , astronomy , composite material
The magnetic ion‐mass spectrometer is designed to measure the abundances of the ambient positive ions in the ionosphere. It will be calibrated in flight against the retarding‐potential analyzer and the cylindrical electrostatic probe to give absolute concentration data for the ion species detected. These parameters can be measured to approximately ±10% in well‐behaved regions where concentrations are above 10 3 cm −3 . However, in highly structured polar regions, some degradation in accuracy may be expected. Three mass ranges, covered simultaneously by the scan of the instrument, 1 to 4, 4 to 16, and 16 to 64 amu, permit measurement of the entire mass range, 1 to 64 amu, in 1 sec in the main (peaks) mode. An alternate mode, analog‐long, will extend the mass range to 90 amu with a 9‐sec period. Capability is provided to lock onto any set of mass numbers in the ratio 1:4:16 to give very high spatial resolution, e.g., 500, 250, and 125 m in the low‐, mid‐, and high‐mass ranges, respectively. This mode will be most useful in the despun satellite orientation to provide fine‐structure data on ion concentrations. In the spinning mode the phase shifts between roll modulation maxima of heavy and light ions determine the vertical component of the individual ion‐drift velocities. Values from a few km sec −1 to over 20 km sec −1 can be determined. Such data are applicable to the study of polar wind phenomena.