Lunar Plasma Environment in Magnetotail Lobe Conditions. First Results
from 3-D Hybrid Kinetic Modeling and Comparison with ARTEMIS Observation
Abstract
The study of lunar plasma environment’s response to the magnetotail lobe
condition is the main subject of our investigation in this report.
Photoionization and charge exchange of protons with the lunar exosphere
arethe ionization processes included in our model. The computational
model includes the dynamics of heavy Na+ pickup and ambient
magnetospheric ions. The electrons are considered as a fluid.The lunar
interior is considered as a weakly conducting body. In this report we
consider for the first time a formation of lunar plasma structures,
wakes, and a generation of low-frequency electromagnetic waves by using
a self-consistent hybrid kinetic modeling. The input parameters were
taken from the ARTEMIS observations. At an early stage the Moon with
exosphere and conducting core excites whistler waves in case of
Sub-Alfvenic/sonic interaction. At a later stage an excitation of the
Alfven wave is observed. The topology of the Alfven waves is
approximately similar to the Alfven wing near the planetary moons (Io,
Europa etc.). The physics of the Moon-magnetotail lobe interaction is
also close to the physics of the interaction between plasma clouds
(expanding and not expanding) and ambient magnetospheric plasma. The
heavy pickup ions create a large structured halo with space scale of
more than 10 R_{E} in the direction of the background field. The
modeling also shows an excitation of the compressional waves due to
expansion of heavy exospheric pickup ions. The lunar model with weaker
interior conductivity excites lower levels of the wave activity. This
work was supported by NASA Award (80NSSC20K0146) from Solar System
Workings Program (NNH18ZDA001N-C.3-SSW2018). Computational resources
were provided by the NASA High-End SupercomputingFacilities
(Aitken-Ames, Project HEC SMD-20-02357875).