Mirror Modes observed in the Saturnian Middle Magnetosphere

Mirror Modes Waves (MMW) have been observed by the Cassini spacecraft in the Saturnian middle magnetosphere. These compressive waves are characterized by strong dips in magnetic field magnitude which are anti-correlated with the density. As with Ion Cyclotron Waves (ICW), MMW requires high anisotropy in the plasma temperature (pressure) (T⊥/T‖>>1). In this work we analyze four Cassini orbits from 2005 that had a low inclination angle, <0.5°. The data were obtained from the MAG and CAPS instruments. We analyze wave properties and study their region of occurrence. We have observed that the MMW can appear between 6RS and 6.9RS (1RS=60268 km), with respect to Saturn’s center. Additionally, we use linear kinetic theory to determine conditions for wave growth in a plasma resembling the regions where these waves and modes were observed.