Head-on collision of dust-acoustic solitary waves.

The head-on collision between two dust-acoustic solitary waves in an unmagnetized dusty plasma is investigated, including consideration of the dust charge variation. By using the extended Poincaré-Lighthill-Kuo perturbation method, the analytical phase shifts following the head-on collision are derived. The effects of the ratio of ion temperature to electron temperature, the ratio of the number density of ions to the number density of electrons, and the dust charge variation on the phase shift are studied. It is found that the dust charge variation significantly modifies the phase shift.