Dust ion-acoustic solitons with trapped q -non-extensive electrons, dissipative processes, and streaming ions (original) (raw)

Contributions to Plasma Physics

The characteristics of dust ion-acoustic waves (DIAWs) that are excited because of streaming ions and hot q-non-extensive electrons obeying a vortex-like distribution are investigated. By exploiting a pseudo-potential technique, we have derived an energy integral equation. The presence of non-extensive q-distributed hot trapped electrons and a streaming ion beam has been shown to influence soliton structure quite significantly. The evolution of the soliton-like perturbations in complex plasmas, taking into account the dissipation processes, are also investigated, obtained by numerically solving the modified Schamel, equation whose widths are dependant on electron trapping efficiency. Our illustrations indicate that compressive DIAWs develop in this plasma. As the plasmas in reality have a relative flow, such an analysis can be used to understand the DIA solitary structures observed in the mesospheric noctilucent clouds. KEYWORDS dissipative solitons, dust ion acoustic solitons, electron trapping 1 INTRODUCTION An ionized gas (either fully or partially) laden with heavier charged particles is defined as dusty plasma. These heavier charged particles with a mass in the micron or submicron range are called dust particles or grains. [1] Dust-containing plasmas can be found anywhere, including plasmas in laboratories, near the earth, in the environments of planets, interplanetary space, cometary tails, interstellar clouds, mesospheric noctilucent clouds, rings of giant planets (e.g., Saturn's F rings), and various Earth-bound plasmas. [2,3] These dust particles make analysis more difficult as it requires additional coordinates of space and time. [4,5] Langmuir et al. [6] carried out a theoretical investigation to study the impact of dust particles on plasma characteristics. Later, their findings (or conclusions) were confirmed experimentally. [7,8] These dust particles can have a negative or positive charge on it, depending on which ionization or excitation processes are dominant in the dusty plasma environments. [9,10] Owing to lighter mass, the electrons are more mobile compared to ions, and hence, they (electrons) have a greater chance to become attached to comparatively heavier dust. They (electrons) attach to the dust particle's surfaces in large quantity, making these particles' charge frequently negative in experiments of laboratories as well as in space environments observed in nature. However, in the case of dominant secondary electron production and photoionization, these dust particles may acquire positive charge, but negatively charged dust is prevalent in dusty plasmas of laboratories at low temperatures. [11] The existence of such heavier species can give rise to various types of collective processes, which consequently help the plasma sustain some new, very low-frequency modes. The dust ion-acoustic (DIA) mode is one of these novel modes that can develop in unmagnetized dust plasmas. Under the equilibrium quasi-neutrality condition, that is, n e0 + n d0 Z d = n i0 for n e0 ≪ n i0 , a dusty plasma can sustain low-frequency DIA waves. [12] Here, n d0 , n i0 , and n e0 represent the number densities of dusty particles, ions, and electrons, respectively. The DIAWs' phase speed is much higher/lower than the thermal speeds of ions/electrons. For longer wavelengths, the DIA waves' dispersion relations become analogous to the ion-acoustic (IA) waves' dispersion relation,