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Title: Propagation characteristics of dust–acoustic waves in presence of a floating cylindrical object in the DC discharge plasma

Abstract

The experimental observation of the self–excited dust acoustic waves (DAWs) and its propagation characteristics in the absence and presence of a floating cylindrical object is investigated. The experiments are carried out in a direct current (DC) glow discharge dusty plasma in a background of argon gas. Dust particles are found levitated at the interface of plasma and cathode sheath region. The DAWs are spontaneously excited in the dust medium and found to propagate in the direction of ion drift (along the gravity) above a threshold discharge current at low pressure. Excitation of such a low frequency wave is a result of the ion–dust streaming instability in the dust cloud. Characteristics of the propagating dust acoustic wave get modified in the presence of a floating cylindrical object of radius larger than that of the dust Debye length. Instead of propagation in the vertical direction, the DAWs are found to propagate obliquely in the presence of the floating object (kept either vertically or horizontally). In addition, a horizontally aligned floating object forms a wave structure in the cone shaped dust cloud in the sheath region. Such changes in the propagation characteristics of DAWs are explained on the basis of modified potential (ormore » electric field) distribution, which is a consequence of coupling of sheaths formed around the cylindrical object and the cathode.« less

Authors:
 [1];  [2]; ;  [1]
  1. Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)
  2. (India)
Publication Date:
OSTI Identifier:
22599928
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 23; Journal Issue: 8; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ARGON; CATHODES; CYLINDRICAL CONFIGURATION; DEBYE LENGTH; DIRECT CURRENT; DUSTS; ELECTRIC FIELDS; EXCITATION; GLOW DISCHARGES; ION DRIFT; IONS; PARTICLES; PLASMA; SOUND WAVES

Citation Formats

Choudhary, Mangilal, E-mail: mangilal@ipr.res.in, Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400085, Mukherjee, S., and Bandyopadhyay, P. Propagation characteristics of dust–acoustic waves in presence of a floating cylindrical object in the DC discharge plasma. United States: N. p., 2016. Web. doi:10.1063/1.4960667.
Choudhary, Mangilal, E-mail: mangilal@ipr.res.in, Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400085, Mukherjee, S., & Bandyopadhyay, P. Propagation characteristics of dust–acoustic waves in presence of a floating cylindrical object in the DC discharge plasma. United States. doi:10.1063/1.4960667.
Choudhary, Mangilal, E-mail: mangilal@ipr.res.in, Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400085, Mukherjee, S., and Bandyopadhyay, P. 2016. "Propagation characteristics of dust–acoustic waves in presence of a floating cylindrical object in the DC discharge plasma". United States. doi:10.1063/1.4960667.
@article{osti_22599928,
title = {Propagation characteristics of dust–acoustic waves in presence of a floating cylindrical object in the DC discharge plasma},
author = {Choudhary, Mangilal, E-mail: mangilal@ipr.res.in and Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400085 and Mukherjee, S. and Bandyopadhyay, P.},
abstractNote = {The experimental observation of the self–excited dust acoustic waves (DAWs) and its propagation characteristics in the absence and presence of a floating cylindrical object is investigated. The experiments are carried out in a direct current (DC) glow discharge dusty plasma in a background of argon gas. Dust particles are found levitated at the interface of plasma and cathode sheath region. The DAWs are spontaneously excited in the dust medium and found to propagate in the direction of ion drift (along the gravity) above a threshold discharge current at low pressure. Excitation of such a low frequency wave is a result of the ion–dust streaming instability in the dust cloud. Characteristics of the propagating dust acoustic wave get modified in the presence of a floating cylindrical object of radius larger than that of the dust Debye length. Instead of propagation in the vertical direction, the DAWs are found to propagate obliquely in the presence of the floating object (kept either vertically or horizontally). In addition, a horizontally aligned floating object forms a wave structure in the cone shaped dust cloud in the sheath region. Such changes in the propagation characteristics of DAWs are explained on the basis of modified potential (or electric field) distribution, which is a consequence of coupling of sheaths formed around the cylindrical object and the cathode.},
doi = {10.1063/1.4960667},
journal = {Physics of Plasmas},
number = 8,
volume = 23,
place = {United States},
year = 2016,
month = 8
}
  • The nonlinear propagation of the dust-acoustic waves is studied in a strongly coupled inhomogeneous dusty plasma which consists of the strongly correlated negatively charged dust grains and weakly correlated electrons and ions. The Korteweg-de Vries equation with variable coefficients and an additional term due to the density gradient is deduced, and its solution is found by appropriate transformations. The propagation of two possible modes (fast and slow) and their evolution are investigated. Only the fast rarefactive solitary waves are found to propagate in such plasma with parameter ranges corresponding to the experimental conditions. It is shown that the special patternsmore » of nonlinear DA waves (e.g., amplitude and width) are significantly modified in a way that depends upon the effects of polarization force (which arises due to the interaction between thermal ions and highly negatively charged dust grains), effective dust-temperature (which arises from the electrostatic interactions among highly negatively charged dust and from the dust thermal pressure), equilibrium electron density, and ion temperature. The amplitude of solitary waves also decreases as the wave propagates in the direction of increasing dust concentration.« less
  • Investigation of positive and negative dust charge fluctuations on the propagation of dust-ion acoustic waves (DIAWs) in a weakly inhomogeneous, collisionless, unmagnetized dusty plasmas consisting of cold positive ions, stationary positively and negatively charged dust particles and isothermal electrons. The reductive perturbation method is employed to reduce the basic set of fluid equations to the variable coefficients Korteweg-de Varies (KdV) equation. At the critical ion density, the KdV equation is not appropriate for describing the system. Hence, a new set of stretched coordinates is considered to derive the modified variable coefficients KdV equation. It is found that the presence ofmore » positively charged dust grains does not only significantly modify the basic properties of solitary structure, but also changes the polarity of the solitary profiles. In the vicinity of the critical ion density, neither KdV nor the modified KdV equation is appropriate for describing the DIAWs. Therefore, a further modified KdV equation is derived, which admits both soliton and double layer solutions.« less
  • Dust acoustic waves (DAWs) are spontaneously excited in dusty plasmas produced in dc and rf discharge plasmas over a wide range of plasma and dust conditions. A common feature of these plasmas is the presence of an ion drift relative to the dust, which is driven by an electric field, E{sub o} in the discharge. Using a three fluid model of the DAWs, including the zero order electric field and collisions of all species with the background neutral gas (pressure P{sub o}), DAW stability curves were obtained in the E{sub o}-P{sub o} plane, for various dust and wave parameters. Themore » (E{sub o},P{sub o}) data points from several experiments in which DAWs have been observed are also shown in comparison with the theoretical stability boundaries. This analysis supports the conclusion that the DAWs are excited by an ion-dust streaming instability.« less