Dust-acoustic waves in a nonuniform adiabatic dusty plasma in the presence of polarization force
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USTY PLASMA
DustAcoustic Waves in a Nonuniform Adiabatic Dusty Plasma in the Presence of Polarization Force1 M. Asaduzzaman and A. A. Mamun Department of Physics, Jahangirnagar University, Savar, Dhaka1342, Bangladesh Received December 19, 2011
Abstract—The linear propagation of the dustacoustic (DA) waves in a nonuniform adiabatic dusty plasma, which consists of inertialess adiabatic electrons, inertialess adiabatic ions, and inertial negatively charged dust by taking into account the effects of polarization force, is theoretically investigated. It is found that the linear dispersion properties of the DA waves are significantly modified by the dust density nonuniformity, adiaba ticity of electrons and ions, and the effects of the polarization force. It is shown that the phase speed of the DA waves is increased with the increase of adiabaticity of electrons and ions but decreased with the increase of the effects of polarization force. It is also shown that the dust density is enhanced with the increase of adi abatic index but depleted with the increase of polarization force. The scenarios relevant to dustion plasma in space environments are briefly addressed. DOI: 10.1134/S1063780X12090012 1
1. INTRODUCTION
Collective processes in dusty plasmas (a normal electronion plasma with additional extremely mas sive, highly charged particulates), which are found to be common in laboratory plasmas as well as earth’s atmosphere, magnetosphere, planetary rings, cometary tails, asteroid zones, etc. [1–3], have drawn a baronial interest in recent scientific research. Because of unique and novel features of heavier charged dust comparing to usual electronion plasma, a new types of ultralow frequency waves, known as dustacoustic (DA) waves, often called the novel dust acoustic waves [4], was theoretically first introduced by Rao, Yu, and Shukla [4]. After the rudimentary theme of Shukla et al. [4], it has been conclusively ver ified by a series of laboratory experiments [5–7]. In case of such extremely low phase velocity (in compar ison with the electron and ion thermal velocities) of DA waves, the dust mass provides the inertia and the electron and ion thermal pressures give rise to the restoring force. The dispersion properties of the linear novel DA waves are now well established from both theoretical and experimental aspects [4–14]. Effect of adiabaticity on linear propagation of dust acoustic waves has been investigated by Singh and Rao [15] considering isothermal electrons and ions, and nonisothermal dust. It has been found that the damp ing rate of the linear DA waves decreases with increas ing adiabatic dust pressure, whereas in nonlinear case they showed that due to the increase of adiabatic dust plasma pressure soliton (which can be found only in supersonic region) amplitude decreases. Prior to 1 The article is published in the original.
these, most of the authors studied isothermal systems as nonlinear response, for example, twocomponent unmagnetized DA solitary waves (SWs) were studied by Mamun et
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