Synchronization of dust density waves in anodic plasmas

Pilch, Iris; Reichstein, Torben; Piel, A.

doi:10.1063/1.3274928

Cited by 41 publications

(26 citation statements)

References 22 publications

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“…Another effect of nonlinearity is wavefront merging, as was reported in [2]. This is observed in Fig.…”

supporting

confidence: 64%

“…1(c), applying an f dr = 8-Hz modulation caused the wave's frequency to change to f w = 24 Hz. The frequency usually changes by a rational fraction, which in this case was 3:1.Another effect of nonlinearity is wavefront merging, as was reported in [2]. This is observed in Fig.…”

supporting

confidence: 50%

“…We observed wave synchronization where the wave's frequency changes in response to an external modulation of the plasma conditions [2]- [4]. We study the same synchronization phenomenon as in [4], but here we rely on space-time diagrams, prepared as in [5], as our analysis method.…”

Section: Imaging Of the Dust Acoustic Wave To Explore Synchronizationmentioning

confidence: 99%

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Imaging of the Dust Acoustic Wave to Explore Synchronization

Ruhunusiri

Goree

2014

IEEE Trans. Plasma Sci.

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Abstract-A self-excited dust acoustic wave is synchronized by sinusoidal modulation of the ion density, and the wave is imaged by planar laser-light scattering. Space-time diagrams based on the images reveal how the nonlinearity of the plasma's response causes the wave's frequency to be synchronized to a multiple of 0.5, 1, 2, or 3 of the modulation frequency. Space-time diagrams also reveal wave front merging as is observed for a wide range of modulation frequencies.Index Terms-Dusty plasmas, plasma waves. T HE dust acoustic wave (DAW) is a plasma wave that an experimenter can observe with the naked eye. This wave is analogous to an ion acoustic wave and propagates in a dusty plasma containing highly charged particles of solid matter (dust) in addition to electrons, ions, and neutral gas atoms. Compressions and rarefactions of the dust particles have such a high amplitude, and they propagate so slowly, that they are easy to view and image by laser light scattering. Due to the low charge-to-mass ratio of the dust particles, the wave frequency is typically only a few tens of hertz. The wave is self-excited by an ion-streaming instability [1].We performed an experiment to observe nonlinear phenomena, which occur because the wave grows to a large amplitude. We observed wave synchronization where the wave's frequency changes in response to an external modulation of the plasma conditions [2]- [4]. We study the same synchronization phenomenon as in [4], but here we rely on space-time diagrams, prepared as in [5], as our analysis method.An argon glow discharge plasma was ignited by applying a 13.56-MHz radio frequency voltage with 57 V peak-to-peak amplitude to a horizontal lower electrode [ Fig. 1(a)]. Dust particles, which were 4.8-µm melamine formaldehyde spheres, were dropped into the plasma using a dispenser with a single hole. The dust particles were negatively charged by collecting more electrons than ions, and they levitated under the action of naturally occurring electric fields. To vertically elongate the dust cloud, we used a glass box that enhanced the horizontal component of the electric field. The vertical component of this electric field drove a downward ion flow, which was the energy source for exciting the DAW. The 120-mTorr gas pressure was low enough that gas damping did not prevent the DAW from growing to large amplitudes with significant nonlinearities. The natural frequency of the wave, meaning its frequency without any modulation present, was 20.5 Hz. Our primary diagnostic was planar laser-light scattering for imaging the dust cloud [6]. The intensity of the scattered light was proportional to the dust number density n d , because the dust cloud was optically thin. A vertical cross section of the cloud was illuminated with a sheet of 532-nm laser light. A movie was recorded at 256 frames/s using a Phantom v5.2 camera. A still image is shown in Fig. 1(b). We analyzed the intensity within a region of interest (ROI) [ Fig. 1(b)]. The wavefronts were planar in the ROI, so that we can average the int...

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“…Another effect of nonlinearity is wavefront merging, as was reported in [2]. This is observed in Fig.…”

supporting

confidence: 64%

supporting

confidence: 50%

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Imaging of the Dust Acoustic Wave to Explore Synchronization

Ruhunusiri

Goree

2014

IEEE Trans. Plasma Sci.

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“…2 A DDW is often self-excited naturally in dusty plasma due to an instability driven by ion flow. 3,4 This has been observed in several experiments, both in the laboratory [5][6][7][8][9][10][11][12][13][14] and under microgravity conditions. 15,16 In laboratory experiments dust particles are often levitated in the plasma sheath, where ion flows can be strong enough to couple their energy to dust particles and drive the wave.…”

Section: Introductionmentioning

confidence: 75%

Development of nonlinearity in a growing self-excited dust-density wave

Flanagan

Goree

2011

Physics of Plasmas

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The development of nonlinearity is observed in a naturally occurring planar dust-density wave. As it propagates through a dusty plasma, the wave grows and harmonics are generated. The amplitudes, wave numbers, and growth rates are measured for the fundamental and its harmonics. The energy in the harmonic modes exhibits a strong exponential increase with diminishing gas pressure, until it levels off at lower gas pressures. The wave numbers and growth rates for the harmonics are near integer multiples of those for the fundamental.

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“…Since being initially predicted in 1990 1 and identified experimentally in 1995, 2 the DAW has been a topic of great experimental, [3][4][5][6][7][8][9][10] and theoretical, [11][12][13][14] interest within the dusty plasma community. While the majority of the experimental studies of this wave mode have been restricted to measurements in a two-dimensional plane (i.e., the slice of the dust cloud illuminated by a thin laser sheet) and a number of these studies have hinted that the wave motion associated the dust acoustic wave is three-dimensional, there have been relatively few studies that have examined the potential three-dimensional wave motion associated with this wave mode.…”

Section: Introductionmentioning

confidence: 99%

Volumetric measurements of a spatially growing dust acoustic wave

Williams

2012

Physics of Plasmas

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In this study, tomographic particle image velocimetry (tomo-PIV) techniques are used to make volumetric measurements of the dust acoustic wave (DAW) in a weakly coupled dusty plasma system in an argon, dc glow discharge plasma. These tomo-PIV measurements provide the first instantaneous volumetric measurement of a naturally occurring propagating DAW. These measurements reveal over the measured volume that the measured wave mode propagates in all three spatial dimensional and exhibits the same spatial growth rate and wavelength in each spatial direction.

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Synchronization of dust density waves in anodic plasmas

Cited by 41 publications

References 22 publications

Imaging of the Dust Acoustic Wave to Explore Synchronization

Imaging of the Dust Acoustic Wave to Explore Synchronization

Development of nonlinearity in a growing self-excited dust-density wave

Volumetric measurements of a spatially growing dust acoustic wave

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