Weak dust ion-acoustic and dust-acoustic solitons with absorption of ions, ionization, and ion drag

The novelty of the approach lies in a self-consistent treatment of the ion density depletion due to absorption on dust grains, of dust charge variations, ionization, and the ion-dust drag friction. For dust ion-acoustic solitons, it is shown that the validity of the Korteweg-de Vries (KdV) equation which is usually used is restricted to some range of amplitudes (which does not always exist). For dust-acoustic solitons, an additional dispersion term responsible both for the ion-dust drag friction and the ion density depletion due to absorption of ions is derived. It is found that two types of dust-acoustic solitons are possible, namely, when the new dispersion term is small and when the new dispersion term dominates. For the second type of solitons, the equation is not the KdV equation. Solitary wave solutions are represented in analytical form and discussed. Weak dust-acoustic solitons of both types are found to be compressive with the same range of amplitudes but with different ranges of spatial width. Estimates are made to see the possibility of experimental observation of the calculated soliton structures.