 |
| Titel |
Theoretical constraints on the cross-tail width of bursty bulk flows |
| VerfasserIn |
C. X. Chen |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
0992-7689
|
| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 31, no. 12 ; Nr. 31, no. 12 (2013-12-11), S.2179-2192 |
| Datensatznummer |
250086160
|
| Publikation (Nr.) |
 copernicus.org/angeo-31-2179-2013.pdf |
|
|
|
|
|
| Zusammenfassung |
| The characteristic cross-tail width of bursty bulk flows (BBFs) in earth's
plasma sheet was investigated at two stages of its life, one at its onset,
the other when it is fully developed. Equilibrium domains with gradient of
magnetic field are constructed. Interchange instability analysis of such
domains yields the most unstable mode with the half wave length comparable
with the observed cross-tail width of a flow burst and the inverse of growth
rate comparable with its duration. The thickness of the plasma sheet for the
most unstable mode is also comparable to the width of BBFs in the
north–south direction. We found that viscosity, the dimension of the
unstable domain, the thickness of the plasma sheet and gradient of the
magnetic field together determine the most unstable mode. The ion Larmor
radius plays an important role in viscosity as half effective mean free path.
For a fully developed flow, however, velocity-caused pressure difference
between the leading and trailing sides of a flow burst also plays a role. The
equatorial cross section of flow is reshaped and its cross-tail width is
changed as well. Representing the surrounding medium with empirical magnetic
field and plasma models, the force balance of the fast flow is analyzed. The
cross-section area of flow burst is estimated to be one to several square
earth radii, and the cross-tail width of fast flow is estimated to be 1 to 3
earth radii, which is consistent with observations of BBFs. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|