Nonlinear acoustic mode at high dust density

Abstract

Small but finite amplitude nonlinear acoustic mode at high dust density, i.e., the nonlinear dust electro acoustic (DEA) wave mode has been studied by reductive perturbation technique. The effect of dispersion is introduced to saturate the nonlinear steepening effect leading to Korteweg–de Vries (KdV) equation for the description of its propagation. It is found that the dispersive effect of DEA wave is more pronounced than that of dust acoustic (DA) wave for hydrogen plasma with equal electron, ion temperatures T_e and T_i. For lower values of T_i/T_e, the DEA soliton flattens out more and more as the dust space charge density |q_dn_d| increases but after maximum flattening the soliton width decreases and the soliton becomes more sharply peaked as |q_dn_d| comes closer to that of ions. In this respect and also in respect of soliton amplitude the behaviours of the DEA wave and DA wave differ qualitatively.