Applications of Secondary Electron Energy- and Angular-Distributions to Spacecraft Charging

Secondary electron (SE) emission from spacecraft surfaces as a result of energetic electron bombardment is a key process in the electrical charging of spacecraft. It has been suggested that incorporating more complete knowledge of the energyand angular-distributions of secondary electrons is necessary to fully model how SE emission and spacecraft charging are affected by re-adsorption of low energy electrons in the presence of charge-induced electrostatic fields and ambient magnetic fields in the spacecraft environment. We present data for such energyand angular-distributions from sputtered, polycrystalline gold surfaces. The data are compared to empirical SE emission models and found to agree well. We also discuss at what level inclusion of such energyand angular-distributions will affect models of spacecraft charging for both positive and negative surface charging.