[P-CG24] [EJ] Planetary Magnetosphere, Ionosphere, and Atmosphere

[PCG24-P04] Pitch angle scattering due to elastic collisions between magnetospheric keV electrons and neutral H₂O molecules originated from Enceladus

*Hiroyasu Tadokoro¹, Yuto Katoh² (1.Musashino University, 2.Tohoku University)

Keywords:Saturn, Enceladus, Pitch angle scattering

The observations of injected plasmas in the inner magnetosphere suggest that these particles do not survive very long time due to the neutral cloud originated from Enceladus [e.g., Paranicas et al., 2007; 2008]. These neutrals in the inner magnetosphere play the dominant role in a loss process of energetic electrons and ions [e.g., Paranicas et al., 2007; Sittler et al., 2008]. However, little has been reported on a quantitative study of the electron loss process due to electron-neutral collisions. In this study, we focus on the elastic collisional loss process with neutrals. Conducting one dimensional test-particle simulation, Tadokoro et al. [2014] examined the time variations of equatorial pitch angle distribution and electrons within loss cone through 1 keV electron pitch angle scattering due to electron-H₂O elastic collisions around Enceladus when the electron flux tube passes the region of the dense H₂O molecules in the vicinity of Enceladus (~380 sec). The result showed that the electrons of 11.4 % are lost in ~380 sec. Next remaining issue is loss rate of electrons with other energy. In this study, we show a preliminary result of the loss rate of electrons with 500eV-50keV. We also show the comparison of the loss rate between the high H₂O density region (in the vicinity of Enceladus) and the low H₂O density region (in the Enceladus torus).