Rocket Measurements of Electron Energy Spectra From Earth's Photoelectron Production Layer

Abstract

When sunlight shines upon planetary atmospheres, energetic photoelectrons are excited and ejected from neutral atoms by the absorption of extreme ultraviolet solar radiation. Photoelectrons play a key role in many aspects of atmospheric physics; they are an important source of heat for the ionosphere and upper thermosphere (Shea et al., 1968); they strengthen the ambipolar electric potential drop generated by planetary ionospheres (Khazanov et al., 1997;Lemaire, 1972) which is critical to understanding the quiet time polar wind (Banks & Holzer, 1968) and its global structure (Glocer et al., 2017); photoelectrons are also important in magnetospheric physics, enabling field line tracing (