Resonant interactions between ultra low frequency waves and reflected ions in the lunar plasma environment

The Moon lacks a global magnetic field and an atmosphere to protect it from the solar wind. Instead, the Moon has smaller magnetic fields that are embedded in the lunar surface. These crustal fields can reflect some of the incoming solar wind ions. The ions that are reflected can then interact with the plasma around the Moon and generate plasma waves. In particular, these reflected ions are thought to generate plasma waves with a frequency around 0.01 Hz. The purpose of this research is to study such ultra low frequency plasma waves, and the interaction between those waves and the reflected ions.

We start by studying one case of ultra low frequency waves and reflected ions using both spacecraft observations and simulated data. From this case study, we are able to develop a technique to determine the intrinsic polarization and propagation direction of the waves. To gain a broader understanding of these waves and interactions, we next look at the statistics of a set of events similar to the event in the case study. When we examine the ambient plasma conditions during the events, we conclude that there are some conditions in which these events are more likely to be observed. From simulated data based on the ambient plasma conditions, we conclude that most of the waves are intrinsically right-hand polarized.