Effects of charged dust grains

Dust grains expelled by radiation pressure of stars are charged to potentials in the range 30–40 V in Hi clouds. These grains may be responsible for the following phenomena which are otherwise hardly explicable. (1) A considerable fraction of electrons knocked-out by charged grains of high speeds have energies around 15 eV and produce singly ionized ions but not doubly ionized ones in accord with an ultraviolet observation of interstellar atoms and ions. (2) Transverse momentum transferred to grains by Coulomb scattering of ambient electrons and protons is greater than that by multiple scattering of cosmic ray protons, thus the former being more effective for the grain alignment than the latter. (3) At a shock front charge separation due to a large inertial mass of grains produces an electric field, thus accelerating charged particles and causing a drift of interstellar matter.