Received: 31 January 2017 Revised: 9 March 2017 Accepted: 3 April 2017 DOI: 10.1002/ctpp.201700008 ORIGINAL ARTICLE Weakly dissipative dust acoustic solitons in the presence of superthermal particles Saadat Khan 1,2 Ata-ur- Rahman 3 * F. Hadi 4 Aurang Zeb 3 M.Z. Khan 5 1 Department of Physics, Gomal University, D. I. Khan, Pakistan 2 National Centre for Physics, QAU Campus, Islamabad, Pakistan 3 Department of Physics, Islamia College Peshawar (Public Sector University), Peshawar, Pakistan 4 Department of Applied Physical and Material Sciences, University of Swat, Swat, Pakistan 5 Applied Physics Department, Federal Urdu University of Arts, Science and Technology, Islamabad, Pakistan *Correspondence Ata-ur-Rahman, Department of Physics, Islamia College Peshawar (Public Sector University), Peshawar 25120 Pakistan. Email: ata797@yahoo.com An investigation of the linear and non-linear properties of low-frequency electro- static (dust acoustic) waves in a collisional dusty plasma with negative dust grains, Maxwellian electrons, and  -distributed ions is carried out. Low dust–neutral col- lisions accounting for dissipation (wave damping effect) is considered. The linear properties of dust acoustic excitations are discussed for varying values of relevant plasma parameters. It is shown that large wavelengths (beyond a critical value) are overdamped. In the limit of low dust–neutral collision rate, we have derived a damped Korteweg de Vries (KdV) equation by using the reductive perturbation tech- nique. Supplemented by vanishing boundary conditions, the time-varying solution of damped KdV equation leads to a weakly dissipative negative potential soliton. The soliton evolution with the damping parameter and other physical plasma parameters (superthermality, dust concentration, ion temperature) is delineated. KEYWORDS damped KdV equation, dust acoustic solitons, superthermal plasmas 1 INTRODUCTION The investigation of the physical processes in dusty plasmas has been of much interest in the recent past owing to their direct link to space and astrophysical environments, as well as industrial applications. [1,2,3] The presence of highly negatively charged and massive dust grains in an electron–ion plasma introduces new types of waves and instabilities. Low-frequency dust acoustic (DA) wave is one of these possible modes whose existence in an unmagnetized dusty plasma was first reported theoretically by Rao et al. [1] and was later on conclusively verified in a laboratory experiment. [2] Extensive work has been devoted to the study of dust acoustic waves (DAWs) in unmagnetized dusty plasmas. For example, Mamun et al. [4] reported the existence of only negative-potential structures associated with non-linear DAWs in a two-component plasma consisting of ions and dust particles. Xie et al. [5] looked at the DA solitary waves and double layers in dusty plasma with variable dust charge and two-temperature ions. They showed that both compressive and rarefactive solitons, as well as double layers, exist. Moreover, it was shown that the amplitude of the DA solitary waves diminishes while the Mach number regime becomes wider for the variable dust charge situation compared to the constant dust charge situation. Most treatments of the DAWs were limited to a simple plasma model, that is, they have not taken into account the effect of neutrals and paid little attention in this direction. Although neutral gas has more relevance to stellar material in galactic dynamics, [6] and also most laboratory dusty magnetoplasmas are partially ionized, the effects of dust–neutral collisions cannot be ignored. Moreover, dusty plasmas observed in laboratory devices [2] are of finite size and also contain a large number density of neutrals. It was found that the effects of charged–neutral particle collisions could significantly affect the wave characteristics. [7] Besides, it has also been reported that under some experimental conditions, the mean free paths in case of dust–neutral collisions were roughly equal to the ordinary wavelengths for the excited waves. [7] The collisional effects on the characteristics of DAWs have been a focus of many researchers in the last few years. In this context, Nakamura et al. [8] examined the effects of collisions on ion acoustic waves and showed that the non-linear dynamics of the ion acoustic waves is significantly affected by the presence Contrib. Plasma Phys. 2017;57:223–232 www.cpp-journal.org © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 223