On the sources of energization of molecular ions at ionospheric altitudes

Details On the sources of energization of molecular ions at ionospheric altitudes On the sources of energization of molecular ions at ionospheric altitudes

Dec 1994

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994jgr....9923257p&link_type=abstract

Journal of Geophysical Research (ISSN 0148-0227), vol. 99, no. A12, p. 23,257-23,274

Physics

14

F Region, Geomagnetism, Ion Recombination, Magnetohydrodynamic Stability, Molecular Ions, Oxygen Ions, Particle Acceleration, Earth Ionosphere, Energy Transfer, Escape Velocity, Exos-D Satellite, Field Aligned Currents, Mass Spectrometers, Ohmic Dissipation

Scientific paper

During geomagnetically active times, the suprathermal mass spectrometer on the Akebono satellite frequency observes upflowing molecular ions (NO(+), N2(+), O2(+)) in the 2-3 Earth radii geocentric distance regions in the auroral zone. Molecular ions originating at ionospheric altitudes must acquire an energy of the order of 10 eV in order to overcome gravitation and reach altitudes greater than 2 R(sub E). This energy must be acquired in a time short compared with the local dissociative recombination lifetime of the ions; the latter is of the order of minutes in the F region ionosphere (300-500 km altitude). Upflowing molecular ions thus provide a test particle probe into the mechanisms responsible for heavy ion escape from the ionosphere. In this paper we analyze the extensive complement of plasma, field, and wave data obtained on the Akebono satellite in a number of upflowing molecular ion events observed at high altitudes (5000-10,000 km). We use these data to investigate the source of energization of the molecular ions at ionospheric altitudes. We show that Joule heating and ion resonance heating do not transfer enough energy or do not transfer it fast enough to account for the observed fluxes of upflowing molecular ions. We found that the observed field-aligned currents were too weak to support large-scale field-aligned current instabilities at ionospheric altitudes. The data suggest but in the absence of high-resolution wave measurements in the 300 to 500 km altitude range cannot ascertain the possibility that a significant fraction of escape energy is transferred to molecular ions in localized regions from intense plasma waves near the lower bybrid frequency. We also compare the energization of molecular ions to that of the geophysically important O(+) ions in the 300 to 500 km altitude range, where the energy trransfer to O(+) is believed to occur via small-scale plasma instabilities, ion resonance, and ion-neutral frictional heating. Direct observation of energy input to the ionosphere from all of these sources in combinations with in situ measurements of the density and temperature of neutral and ionized oxygen in the 300 to 500 km range are required to determine the relative importance of these energy sources in providing O(+) withh sufficient energy to escape the ionosphere.

Affiliated with

Also associated with

No associations

Rating

On the sources of energization of molecular ions at ionospheric altitudes does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with On the sources of energization of molecular ions at ionospheric altitudes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and On the sources of energization of molecular ions at ionospheric altitudes will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1411646