Deflection and enhancement of solar energy particle flux at the Moon by structures within the terrestrial magnetosphere

Abstract

The Moon spends 25% of its orbit within the terrestrial magnetosphere. Particle tracking is used to investigate access points of 35 MeV and 760 MeV particles into the magnetosphere for both quiet and disturbed magnetospheric conditions. The results indicate that solar energetic particle (SEP) flux at the Moon can be reduced for storm conditions when the magnitude of the magnetic field in the sheath is enhanced, as particles in the 35 MeV range have limited access to the magnetosphere for storm conditions. Plasmoids are also effective at reducing SEP flux from the tailward direction. The results also indicate that the flux of SEPs from the dawnside of the magnetosphere can be focused into the current sheet, leading to a potential enhancement in SEP flux at the Moon. Particles traveling up the tail for both quiet and storm conditions tended to experience the greatest deflection away from the central tail.