Long-range perturbations produced by a localized packet of ion-acoustic waves in a collisionless plasma

A well localized packet of ion-acoustic waves propagating in a collisionless unmagnetized plasma produces long-range second-order perturbations of the moments of the electron distribution function due to those electrons which cross the region where the electric field is present, take a “kick", and carry this information at large distances from the packet itself. An extended “halo" is thus formed around the wave-packet, with an intensity decreasing in space typically according to a power-law. This “halo" contains electrostatic as well as magnetic perturbations.