mercredi 1er mai 2019, par Ulrich Taubenschuss (Department of Space Physics, IAP, Czech Academy of Sciences, Prague, Czech Republic)
Lundi 6 mai 2019 à 11h00 , Lieu : Salle de rĂ©union du bâtiment 16
Unstable particle distributions in the auroral regions of Saturn’s magnetosphere produce a powerful planetary radio emission known as Saturn Kilometric Radiation (SKR). SKR has been continuously monitored by the High Frequency Receiver (built at LESIA) of the RPWS instrument onboard the Cassini spacecraft from 2003 to 2017. While SKR is known to be circularly polarized when observed near the equator, it turned out to be elliptically polarized when observed from high latitudes and fully linearly polarized within its source region. Linear/elliptical wave polarization provide the conditions for the well known “Faraday rotation” effect to occur, which is a rotation of the axis of linear polarization as a function of frequency and the plasma conditions encountered along the ray path. We will present the basic theory of Faraday rotation and comment on the possibility to derive information about the wave propagation medium. Examples of Faraday rotation from Cassini/RPWS will be shown from a preliminary search through the dataset of the first 6 years of the Cassini mission.
