Generation of multiple toroidal dust vortices by a non-monotonic density gradient in a direct current glow discharge plasma

Kaur, Manjit; Bose, Sayak; Chattopadhyay, P. K.; Sharma, Devendra; Ghosh, Joydeep; Saxena, Y. C.; Thomas, E.

doi:10.1063/1.4929916

Cited by 28 publications

(36 citation statements)

References 23 publications

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“…This analysis further demonstrates the condition for the existence of self-similar multiple co-rotating vortices in a driven-dissipative bounded flow system, of which the characteristic size, numbers, and strength of the multiple vortices depend on the aspect-ratio of the bounded flow domain. In the above whole analysis, the observed scale of dust velocity u ≈ 10 −3 U 0 agree with the experimental observations of u ∼ 0.1 -6 cm/sec in high Reynolds regime while shear ions are streaming with c s ∼ 27 cm/sec in various typical dust vortex flow experiments in both laboratory as well as microgravity space station [6,7,10].…”

Section: Flow Structure Dependence On Aspect-ratio Of the Boundedsupporting

confidence: 85%

Multiple steady state co-rotating dust vortices in streaming plasma

Laishram

Sharma

Zhu

2019

J. Phys. D: Appl. Phys.

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The 2D hydrodynamic model for a dust cloud confined in an axisymmetric toroidal system volumetrically driven by an unbounded streaming plasma is further extended systematically for different aspect-ratio of the bounded dust domain and a wide range of the kinematic viscosity. This work has demonstrated the interplay between inertial and diffusive transport processes for the structural changes of steady dust flow from symmetric into asymmetric nature in higher Reynolds number (Re) regimes where flow streamlines turn more circular and the structural bifurcation takes place through a threshold parameter. In agreement with many experimental observations, the steady vortex structure in highly nonlinear (i.e., high Re) regime is characterized by the critical transition into a new self-similar multiple co-rotating vortices, along with circular core region of single characteristics size and surrounded by strongly sheared layers filled with weak vortices near the boundaries. It is further revealed that the core region persists for a wide range of system parameters in the nonlinear regime and its characteristic size is mainly determined by the smallest distance between the confining boundaries. The threshold parameter, the vortex size, the strength, and the number of the self-similar co-rotating vortices mainly depend on the aspect-ratio of the bounded dust domain. These nonlinear solutions provide insight into the phenomena of the structural transition and coexistence of self-similar steady co-rotating vortices in dusty plasma experiments as well as many relevant complex driven-dissipative natural flow systems.

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Section: Flow Structure Dependence On Aspect-ratio Of the Boundedsupporting

confidence: 85%

Multiple steady state co-rotating dust vortices in streaming plasma

Laishram

Sharma

Zhu

2019

J. Phys. D: Appl. Phys.

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“…The radial modes are determined by the I th root of Bessel function J 0 (α I ) = 0 at the external boundary. The axial mode k z = (π/2L z ) specifies a single vortex along axial direction as in experimental observations [18]. The numerical solution for the stream function ψ(r, z) and its corresponding streamlines ( i.e., the contours of the product rψ) in the linear viscous regime are shown in Fig.…”

Section: A Benchmark Of the Numerical Solutionsmentioning

confidence: 85%

“…In many dusty plasma experiments [18,30], similar multiple dust vortices are observed to correlate with scales of the ion dragging interaction in background. Further, a remarkable property of the present analysis is that the geometry and the dimension of steady driven dust vortex structure in the linear regime are mainly asserted by the confining boundary whereas in the nonlinear regime, the structure is mostly controlled by the dynamical regime rather than the boundary.…”

Section: A Benchmark Of the Numerical Solutionsmentioning

confidence: 88%

“…This suggests that the laboratory dusty plasma may have entered the nonlinear regime of the vortex flow and lends itself to the study of macroscopic nonlinear dynamics in such systems of similar Reynolds number [3]. It motivates us to extend the previous linear analysis to higher Reynolds number flow regime (Re≫ 1), where the nonlinear inertial flow is effective which may explain many new flow characteristics as observed in dusty plasma experiments [18].…”

Section: Introductionmentioning

confidence: 99%

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Structural transition of vortices to nonlinear regimes in a dusty plasma

Laishram

Zhu

2018

Physics of Plasmas

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A 2D hydrodynamical model is developed and analyzed for the steady state of a driven-dissipative dust clouds confined in an azimuthally symmetric toroidal system which is in dynamic equilibrium with background unbounded streaming plasma. Its numerical solution not only confirms the analytical structure of the driven dust vortex flow in linear limit as reported in previous analysis, but also shows how the dust vortices are strongly affected by the nonlinear convection of the flow itself. Effects of various system parameters including external driving field and Reynolds number (Re) are investigated within the linear to nonlinear transition regime 0.001 ≤ Re < 50. In agreement with various relevant experimental observations, the flow structure which is symmetric around center in the linear regime begins to turn asymmetric in the nonlinear regime. The equilibrium structure of dust flow is found to be influenced mainly by the dissipation scales due to kinematic viscosity, ion drag, and neutral collision in the nonlinear regime, whereas in the linear regime, it is mainly controlled by the external driving field and the confining boundaries.

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“…The vortex or rotational motion of dust particles is widely studied in various dusty plasma systems. The spontaneous rotation of dust grains 14 , two-dimensional (2D) dust vortex flow 15 , cluster rotation 16 poloidal rotation of dust grains with toroidal symmetry 17 , and wave a) Electronic mail: mangilal@ipr.res.in motion along with vortex motion [18][19][20] are observed in unmagnetized plasmas world wide. The horizontal and vertical vortex motion of dust grains in the presence of an auxiliary electrode near the levitated dust cloud in capacitive coupled plasma is also reported by Samarian et al 21 and Law et al 22 .…”

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confidence: 99%

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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Generation of multiple toroidal dust vortices by a non-monotonic density gradient in a direct current glow discharge plasma

Cited by 28 publications

References 23 publications

Multiple steady state co-rotating dust vortices in streaming plasma

Multiple steady state co-rotating dust vortices in streaming plasma

Structural transition of vortices to nonlinear regimes in a dusty plasma

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

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