On the apparent diamagnetism of the lunar environment in the geomagnetic tail lobes

The reported investigation presents the magnetic observations averaged in a format that facilitates comparison with models of plasma diamagnetic effects. These models demonstrate that a decreased plasma energy density in the lunar vicinity always causes an induced dipole that increases the external field. Hence, an increased plasma energy density in the lunar environs is required to account for the observed magnetic decrease. There are several different plasma populations in the high-latitude geomagnetic tail lobes, including the lunar ions resulting from photoionization of lunar atmosphere neutrals, possible fluxes of polar-wind protons, low-energy particle events which consist of antisolar directed fluxes of 100-eV protons, photoelectrons from the dayside lunar surface, and a high-energy thermal population.