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A dynamo excitation mechanism for the electroglow on uranus
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Yung, Yuk L. |
| Organization | The National Aeronautics and Space Administration (NASA) |
| Copyright Year | 1990 |
| Abstract | The fundamental problem in the thermospheres of the giant planets is the enormous UV airglow and high heating rates to sustain the observed high temperatures. Preliminary results are reported. It is proposed that the diffuse FUV emissions of H and H2 in excess of photoelectron excitation observed from the sunlit atmospheres of Uranus, Saturn, and Jupiter are produced by electric field acceleration of photoelectrons and ions locally in the upper atmospheres. This in situ acceleration is required to satisfy the many observational constraints on the altitude distribution, exciting particle energy, and total input energy requirements of the electroglow mechanism. The calculated altitude of charge separation by the neutral wind drag on ions across magnetic field lines is consistent with the observed peaks in electroglow-emissions from the Voyager ultraviolet spectrometer limb scan data on both Saturn (near the homopause) and Uranus (just above the homopause). This dynamo action therefore appears to initiate the acceleration process, which must have the form of field-aligned potentials are due to anomalous resistivity, which results from sufficiently high field-aligned currents in the ionosphere to generate plasma instabilities and therefore runaway electrons and ions above some critical lower initial energy. Work will be continued along this line in order to establish the existence of suprathermal electrons (E is greater than 100 eV) and their energy distributions. |
| File Size | 72183 |
| File Format | |
| Alternate Webpage(s) | http://www.archive.org/details/nasa_techdoc_19930075229 |
| Archival Resource Key | ark:/13960/t2m628m9g |
| Language | English |
| Publisher Date | 1990-05-11 |
| Access Restriction | Open |
| Subject Keyword | Space Missions Spacecraft Instruments Surveys Flight Instruments Measuring Instruments Onboard Equipment Space Exploration Spacecraft Equipment Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
