This experiment was designed to obtain a description of the concentrations of the ion species in the topside ionosphere (principally atomic hydrogen, helium, nitrogen, and oxygen), as a function of time, location, and solar and geomagnetic activity. The experiment operated nominally. The data were acquired in real time by 13 ground stations and over remote areas by use of a spacecraft tape recorder. The useful satellite lifetime of 10 months permitted a global study of the diurnal variation of the atmosphere during nearly two complete diurnal cycles, since the orbit plane precessed one revolution each 5.5 months. With the data obtained, several studies were undertaken including: (1) the diurnal and seasonal variation of atmospheric ion composition, (2) the effect of atmospheric winds on the atomic hydrogen-atomic oxygen ion transition level, (3) the density and temporal variation of thermospheric atomic hydrogen, and (4) the altitude variation of ion composition in the midlatitude trough region. The instrument flown was similar in design to ion spectrometers flown on the Orbiting Geophysical Observatory (OGO) satellite series. The spectrometer sensor consisted of a 5-3 cycle ceramic tube with 5-mm grid spacing and an external guard ring assembly. Two RF frequencies, 3.7 and 9.0 MHz, were used with a trapezoidal-shaped sweep voltage to cover the ion mass range 12 to 19, and 1 and 4 atomic mass units (u) assuring detection of the primary ionic constituents of the topside ionosphere. An experiment turn-on consisted of one complete mass scan in 208 s followed by recycling of the sweep voltage and a second measurement of the high mass range. The stopping potential and the guard ring potential controlled the sensitivity of the spectrometer, and each voltage was commandable from the ground. The ion current reaching the spectrometer was measured by a series of five-decade amplifiers with a particle sensitivity range of from about 10 to 1.E6 ions/cc. An automatic calibrator functioned once during each turn-on to supply two known signals to the amplifier system and to the sweep monitor. Amplifier characteristics were calculated from the response to these pulses. The spectrometer tube was mounted on the equator of the almost spherically shaped spacecraft. The spacecraft spin period and attitude were magnetically controlled so that the spin axis remained essentially normal to the orbit plane and, consequently, the spectrometer orifice was aligned with the satellite velocity vector once each rotation. The spin rate was 29 plus or minus 1 rpm. Since the mass range was scanned slowly compared with the spin period, each peak in the ion spectrum was modulated at the spin frequency, with the ion current maxima occurring when the angle between the spectrometer axis and velocity vector was a minimum. NSSDC has all the useful data that exist from this investigation.
Version:2.0.0
This experiment was designed to obtain a description of the concentrations of the ion species in the topside ionosphere (principally atomic hydrogen, helium, nitrogen, and oxygen), as a function of time, location, and solar and geomagnetic activity. The experiment operated nominally. The data were acquired in real time by 13 ground stations and over remote areas by use of a spacecraft tape recorder. The useful satellite lifetime of 10 months permitted a global study of the diurnal variation of the atmosphere during nearly two complete diurnal cycles, since the orbit plane precessed one revolution each 5.5 months. With the data obtained, several studies were undertaken including: (1) the diurnal and seasonal variation of atmospheric ion composition, (2) the effect of atmospheric winds on the atomic hydrogen-atomic oxygen ion transition level, (3) the density and temporal variation of thermospheric atomic hydrogen, and (4) the altitude variation of ion composition in the midlatitude trough region. The instrument flown was similar in design to ion spectrometers flown on the Orbiting Geophysical Observatory (OGO) satellite series. The spectrometer sensor consisted of a 5-3 cycle ceramic tube with 5-mm grid spacing and an external guard ring assembly. Two RF frequencies, 3.7 and 9.0 MHz, were used with a trapezoidal-shaped sweep voltage to cover the ion mass range 12 to 19, and 1 and 4 atomic mass units (u) assuring detection of the primary ionic constituents of the topside ionosphere. An experiment turn-on consisted of one complete mass scan in 208 s followed by recycling of the sweep voltage and a second measurement of the high mass range. The stopping potential and the guard ring potential controlled the sensitivity of the spectrometer, and each voltage was commandable from the ground. The ion current reaching the spectrometer was measured by a series of five-decade amplifiers with a particle sensitivity range of from about 10 to 1.E6 ions/cc. An automatic calibrator functioned once during each turn-on to supply two known signals to the amplifier system and to the sweep monitor. Amplifier characteristics were calculated from the response to these pulses. The spectrometer tube was mounted on the equator of the almost spherically shaped spacecraft. The spacecraft spin period and attitude were magnetically controlled so that the spin axis remained essentially normal to the orbit plane and, consequently, the spectrometer orifice was aligned with the satellite velocity vector once each rotation. The spin rate was 29 plus or minus 1 rpm. Since the mass range was scanned slowly compared with the spin period, each peak in the ion spectrum was modulated at the spin frequency, with the ion current maxima occurring when the angle between the spectrometer axis and velocity vector was a minimum. NSSDC has all the useful data that exist from this investigation.
| Role | Person | StartDate | StopDate | Note | |
|---|---|---|---|---|---|
| 1. | PrincipalInvestigator | spase://SMWG/Person/Henry.C.Brinton |
Information about the Ion Mass Spectrometer experiment on the AE-B mission.