 |
 |
Astron. Astrophys. 326, 386-395 (1997)
On elliptical polarization of the decametric radio emission and the linear mode coupling in the Jovian magnetosphere
V.E. Shaposhnikov 1,
Vl.V. Kocharovsky 1,
V.V. Kocharovsky 1,
H.P. Ladreiter 2,
H.O. Rucker 2 and
V.V. Zaitsev 1
1 Institute of Applied Physics, Russian Academy of
Sciences, Uljanov St. 46, 603600 Nizhny Novgorod, Russia
2 Space Research Institute, Austrian Academy of Sciences,
Halbaerthgasse 1, A-8010 Graz, Austria
Received 25 January 1996 / Accepted 15 November 1996
Abstract
We consider the origin of the elliptical polarization of Jupiter's
decametric emission as a consequence of the moderate linear mode
coupling which takes place in the Jovian magnetosphere outside of the
source region. We recognize conditions of emission propagation along
the ray path which are necessary for forming of the observed
polarization characteristic and show that our model explains the main
observed properties of the polarization (value of ellipticity,
independence of polarization on frequency and time, stability of
polarization from storm to storm), does not need low plasma densities
in the emission source and does not contradict the modern knowledge on
the decametric emission origin. We show that there is no strong
correlation between polarization of the emission at the source and the
observed polarization. The observed degrees of (linear and circular)
polarization have to be assumed as limits of possible degrees of the
polarization of the emission escaping the source region. The value of
the ellipticity is defined by the level of the magnetospheric plasma
density ![[FORMULA]](img1.gif)
in the "transitional region", that is in
a part of the ray path where the polarization of the normal waves is
essentially elliptical. The plasma density in this region is quite low
![[FORMULA]](img2.gif)
and is related to the local electron
gyrofrequency as ![[FORMULA]](img3.gif)
where
![[FORMULA]](img4.gif)
.
Key words: planets and satellites:
Jupiter 
radio continuum: solar system
Send offprint requests to: V.E. Shaposhnikov
Contents
- 1. Introduction
- 2. The linear mode coupling of the electromagnetic waves: equations and interaction parameter
- 3. The effect of linear mode coupling of electromagnetic waves: a model of plasma distribution and numerical solution
- 4. Discussion
- Acknowledgements
- References
© European Southern Observatory (ESO) 1997
Online publication: April 20, 1998
helpdesk.link@springer.de