Laboratory Measurement of Lunar Regolith Simulant Surface Charging in a Localized Plasma Wake

Laboratory experiments are carried out to measure the charging of Johnson Space Center Number OneA lunar simulant surface in a localized plasma wake similar to that at the lunar terminator. The results show that the floating potential of a regolith surface in a plasma wake may be significantly different from that of a solid dielectric surface because ion collection on a regolith surface is sensitively influenced by the surface collection area of dust grains. The results also suggest that at the same negative charging potential, an isolated dust grain charges 50 times more than a dust grain on the regolith surface.