Electric potential differences across auroral generator interfaces
Strong localized high-altitude auroral electric fields, such as those observed by Cluster, are often associated with magnetospheric interfaces. The type of high-altitude electric field profile (monopolar, bipolar, or more complicated) depends on the properties of the plasmas on either side of the...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2013-02-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/31/251/2013/angeo-31-251-2013.pdf |
| Summary: | Strong localized high-altitude auroral electric fields, such as those
observed by Cluster, are often associated with magnetospheric interfaces.
The type of high-altitude electric field profile (monopolar, bipolar, or more
complicated) depends on the properties of the plasmas on either side of the
interface, as well as on the total electric potential difference across the
structure. The present paper explores the role of this cross-field electric
potential difference in the situation where the interface is a tangential
discontinuity. A self-consistent Vlasov description is used to determine the
equilibrium configuration for different values of the transverse potential
difference. A major observation is that there exist limits to the potential
difference, beyond which no equilibrium configuration of the interface can be
sustained. It is further demonstrated how the plasma densities and
temperatures affect the type of electric field profile in the transition,
with monopolar electric fields appearing primarily when the temperature
contrast is large. These findings strongly support the observed association
of monopolar fields with the plasma sheet boundary. The role of shear flow
tangent to the interface is also examined. |
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| ISSN: | 0992-7689 1432-0576 |