Transport and trapping of dust particles in a potential well created by inductively coupled diffused plasmas

Choudhary, Mangilal; Mukherjee, S.; Bandyopadhyay, P.

doi:10.1063/1.4948732

Cited by 11 publications

(19 citation statements)

References 38 publications

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“…They get negatively charged in the plasma and [34,35] To record the dynamics of the confined dust particles, a red laser to illuminate the dust and a CCD camera to record the scattering light from the grains are used. At ground-based experiments, a large volume dusty plasma is possible either in specific discharge configuration [17,37] or discharges with nano to sub-micron sized particles. These stored images are further analysed using MATLAB based code and ImageJ software.…”

Section: Dust Acoustic Waves and Its Characteristics In Absence Of Mamentioning

confidence: 99%

Influence of external magnetic field on dust acoustic waves in a capacitive RF discharge

Choudhary

Bergert²,

Mitic³

et al. 2019

Contributions to Plasma Physics

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This paper reports experiments on self-excited dust acoustic waves (DAWs) andits propagation characteristics in a magnetized rf discharge plasma. The DAWs are spontaneously excited in dusty plasma after adding more particles in the confining potential well and found to propagate in the direction of streaming ions. The spontaneous excitation of such low-frequency modes is possible due to the instabilities associated with streaming ions through the dust grain medium. The background E-field and neutral pressure determine the stability of excited DAWs. The characteristics of DAWs strongly depend on the strength of external magnetic field. The magnetic field of strength B < 0.05 T only modifies the characteristics of propagating waves in dusty plasma at moderate power and pressure, P = 3.5 W and p = 27 Pa, respectively. It is found that DAWs start to be damped with increasing the magnetic field beyond B > 0.05 T and get completely damped at higher magnetic field B ∼ 0.13 T. After lowering the power and pressure to 3 W and 23 Pa respectively, the excited DAWs in the absence of B are slightly unstable. In this case, the magnetic field only stabilizes and modifies the propagation characteristics of DAWs while the strength of B is increased up to 0.1 T or even higher. The modification of the sheath electric field where particles are confined in the presence of the external magnetic field is the main cause of the modification and damping of the DAWs in a magnetized rf discharge plasma. K E Y W O R D Sdust acoustic wave, magnetized dusty plasma, magnetized plasma, RF discharge, superconducting magnet 1The presence of submicron to micrometre-sized particles in a plasma makes it more complex because these particles alter the dynamics of the plasma species (electrons and ions) as well as they exhibit their own dynamics. Such medium, which consists of three charged species namely electrons, ions, and charged solid particles, is termed as a dusty plasma or complex plasma. In the background of a low-temperature plasma, energetic electrons impinge on the surface of the solid particle and charge their surface negatively up to 10 3 -10 5 times of an electron charge [1] to balance the fluxes of electrons and ions. After the density of negatively charged dust particles crosses a critical value, then long-range coulombic interaction among the dust particles turnsThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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Section: Dust Acoustic Waves and Its Characteristics In Absence Of Mamentioning

confidence: 99%

Influence of external magnetic field on dust acoustic waves in a capacitive RF discharge

Choudhary

Bergert²,

Mitic³

et al. 2019

Contributions to Plasma Physics

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“…The experiments are performed in a cylindrical linear device, which is described elsewhere 41 in details. The schematic of the experimental assembly with an operating configuration is depicted in Fig.…”

Section: Experimental Setup and Diagnosticsmentioning

confidence: 99%

“…For injecting the kaolin dust particles (ρ d ∼ 2.6 gm/cm 3 and r d ∼ 0.5 to 5 µm) into the confining potential well, a secondary DC plasma source is used 41 . As these particles come into the plasma volume, they start to flow in the ambipolar electric field of diffused plasma and found to confine in the potential well created by the diffused plasma 41 .…”

Section: Experimental Setup and Diagnosticsmentioning

confidence: 99%

“…The neutrals (either in rest or in motion) affect the motion of the dust particles in the plasma. In the present set of experiments, the direct gas flow inside the chamber is negligible 41 thus neutrals are assumed in thermal equilibrium (or stationary). According to Epstein friction 49 , the neutral friction experienced by the dust particles can be given by…”

Section: Origin Of Dust Vorticesmentioning

confidence: 99%

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Experimental observation of self excited co-rotating multiple vortices in a dusty plasma with inhomogeneous plasma background

2017

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We report an experimental observation of multiple co-rotating vortices in a extended dust column in the background of non-uniform diffused plasma. Inductively coupled RF discharge is initiated in the background of argon gas in the source region which later found to diffuse in the main experimental chamber. A secondary DC glow discharge plasma is produced to introduce the dust particles into the plasma. These micron sized poly-disperse dust particles get charged in the plasma environment and transported by the ambipolar electric field of the diffused plasma and found to confine in the potential well, where the resultant electric field of the diffused plasma (ambipolar E-field) and glass wall charging (sheath E-field) hold the micron sized particles against the gravity. Multiple co-rotating (anti-clockwise) dust vortices are observed in the dust cloud for a particular discharge condition. The transition from multiple to single dust vortex is observed when input RF power is lowered. Occurrence of these vortices are explained on the basis of the charge gradient of dust particles which is orthogonal to the ion drag force. The charge gradient is a consequence of the plasma inhomogeneity along the dust cloud length. The detailed nature and the reason for multiple vortices are still under investigation through further experiments, however, preliminary qualitative understanding is discussed based on characteristic scale length of dust vortex. There is a characteristic size of the vortex in the dusty plasma so that multiple vortices is possible to form in the extended dusty plasma with inhomogeneous plasma background. The experimental results on the vortex motion of particles are compared with a theoretical model and found some agreement.

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“…In recent studies, the co-rotating vortices are observed in an extended unmagnetized dusty plasma 20 . The charge gradient of dust grains along with the ion drag force, which is due to the plasma inhomogeneity along the dust cloud axis, is considered the source of vortex flow 20,44 . These observed exciting results on the corotating vortices have been created an interest to study the large aspect ratio dusty plasma in inhomogeneous plasma background.…”

Section: Introductionmentioning

confidence: 99%

Collective dynamics of large aspect ratio dusty plasma in an inhomogeneous plasma background: Formation of the co-rotating vortex series

2018

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In this paper, the collective dynamics of the large aspect ratio dusty plasma is studied over a wide range of discharge parameters. An inductively coupled diffused plasma, which creates an electrostatic trap to confine the negatively charged grains, is used to form a large volume (or large aspect ratio) dusty plasma at low pressure. For introducing the dust grains into the potential well, a unique technique using a secondary DC glow discharge plasma is employed. The dust dynamics is recorded in a 2-dimension (2D) plane at a given axial location. The dust fluid exhibits wave like behavior at low pressure (p<0.06 mbar) and high rf power (P>3 W). The mixed motion, waves and vortices, are observed at an intermediate gas pressure(p∼ 0.08 mbar) and low power (P<3 W). Above the threshold value of gas pressure (p>0.1 mbar), the clockwise and anti-clockwise co-rotating vortex series are observed on the edges of the dust cloud, whereas the particles in central region show the random motion. These vortices are only observed above a threshold width of the dust cloud. The streaming ions are considered the available free energy source to excite the waves in dust grain medium. The occurrence of the co-rotating vortices is understood on the basis of the charge gradient of dust particles which is orthogonal to the gravity. The charge gradient is a consequence of the plasma inhomogeneity from the central region to the outer edge of dust fluid. Since, a vortex has the characteristic size in the dissipative medium; therefore, a series of the co-rotating vortex on the both sides of dusty plasma is observed. The experimental results on the vortex formation and its multiplicity are compared to an available theoretical model and are found to be in close agreement.

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Transport and trapping of dust particles in a potential well created by inductively coupled diffused plasmas

Cited by 11 publications

References 38 publications

Influence of external magnetic field on dust acoustic waves in a capacitive RF discharge

Influence of external magnetic field on dust acoustic waves in a capacitive RF discharge

Experimental observation of self excited co-rotating multiple vortices in a dusty plasma with inhomogeneous plasma background

Collective dynamics of large aspect ratio dusty plasma in an inhomogeneous plasma background: Formation of the co-rotating vortex series

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