Vertical dynamics and horizontal transfer of submicron-sized lunar-regolith microparticles levitating in the electrostatic field of the near-surface photoelectron layer

The electrostatic levitation of spherical lunar dust microparticles was modelled, assuming that their surface is covered with a monolayer of hydrogen-rich compounds (or other material with similar photoelectric properties) and that adhesion forces can be neglected. The conditions which result in the levitation of microparticles above the lunar surface due to the electric field generated by the photoelectric layer are derived. The two controlling parameters for the onset of levitation and for the dynamics of the levitating microparticles are the size of the particle and the incidence angle of solar photons. For particles of 0.1 μm, levitation can occur if the solar incidence angle is larger than 76.2°. The role of solar pressure forces in the horizontal motion of levitating particles is also discussed.