Experimental Study of Photoemission from Glass Dust

Solar radiation, especially its UV part, is considered as a main contributor to the space dust charging. On the other hand, the study of photoemission from a majority of space-related materials is difficult because the surface of insulators is quickly charged. We present experimental observations of photoemission charging of glass dust grains that could serve for example as a lunar regolith substitute. A single grain is kept in a 3D electrodynamic trap and a temporal evolution of the grain charge and other quantities are determined. Differentially pumped (He or Ar) discharge lamp is employed as a source of the UV radiation. Besides dynamic observations, we estimate the glass grain work function to be about 4.7 eV.