Microparticles as Plasma Diagnostic Tools

Maurer, H. R.; Schneider, Viktor; Wolter, Matthias; Basner, R.; Trottenberg, Thomas; Kersten, Holger

doi:10.1002/ctpp.201000091

Cited by 13 publications

(6 citation statements)

References 25 publications

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“…One goal of these methods is to use dust particles as small, reliable probes for determining different plasma properties. 1 The strength of the interaction forces in these systems scales differently with the particle dimensions and -for spherical particles -can be described by the dependency on the particle radius a p .…”

Section: Introductionmentioning

confidence: 99%

Size and density evolution of a single microparticle embedded in a plasma

et al. 2017

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This article presents two measurement techniques to determine the diameter of a single dust particle during plasma operation. Using long-distance microscopy (LDM), the particle is imaged from outside the plasma chamber. In combination with phase-resolved resonance measurements the development of the volumeaveraged particle mass density is measured over several hours. The measurements show a significant decrease of mass density for polymethyl methacrylate (PMMA) particles due to a plasma etching process on the surface. This is explained by a core-shell model and is supported by a surface roughness effect seen in the LDM images, an out-of-focus imaging of the angular Mie scattering pattern and ex-situ laser scattering microscopy measurements.

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Section: Introductionmentioning

confidence: 99%

Size and density evolution of a single microparticle embedded in a plasma

et al. 2017

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“…2011; Maurer et al. 2011). The following methods are not only simple to carry out, but use only standard dusty plasma experimental equipment such as dust, cameras and lasers already present in dusty plasma laboratories.…”

Section: Introductionmentioning

confidence: 99%

“…The small size of the dust grain allows for minimal perturbation of the plasma parameters within the sheath, providing more accurate information regarding its extent and structure. Other experimental methods have been employed to investigate the plasma sheath, but often require additional equipment (Beckers et al 2011;Maurer et al 2011). The following methods are not only simple to carry out, but use only standard dusty plasma experimental equipment such as dust, cameras and lasers already present in dusty plasma laboratories.…”

Section: Introductionmentioning

confidence: 99%

Using dust as probes to determine sheath extent and structure

et al. 2016

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Two in situ experimental methods are presented in which dust particles are used to determine the extent of the sheath and gain information about the time-averaged electric force profile within a radio frequency (RF) plasma sheath. These methods are advantageous because they are not only simple and quick to carry out, but they also can be performed using standard dusty plasma experimental equipment. In the first method, dust particles are tracked as they fall through the plasma towards the lower electrode. These trajectories are then used to determine the electric force on the particle as a function of height as well as the extent of the sheath. In the second method, dust particle levitation height is measured across a wide range of RF voltages. Similarities were observed between the two experiments, but in order to understand the underlying physics behind these observations, the same conditions were replicated using a self-consistent fluid model. Through comparison of the fluid model and experimental results, it is shown that the particles exhibiting a levitation height that is independent of RF voltage indicate the sheath edge -the boundary between the quasineutral bulk plasma and the sheath. Therefore, both of these simple and inexpensive, yet effective, methods can be applied across a wide range of experimental parameters in any ground-based RF plasma chamber to gain useful information regarding the sheath, which is needed for interpretation of dusty plasma experiments.

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“…This correlation analysis of the dust equilibrium position combined with the spatial electric field profile is applicable as a diagnostic tool to estimate plasma parameters, i.e. the dust particles can serve as electrostatic probes [38,39,[92][93][94]. The correlation analysis yields the maximum sheath extension as the only free fitting parameter, which depends on electron temperature and density (s max,p ∝ λ De /T ).…”

Section: Adiabatic Phase Changementioning

confidence: 99%

Transport control of dust particles via the electrical asymmetry effect: experiment, simulation and modelling

Iwashita¹,

Schüngel²,

Schulze³

et al. 2013

J. Phys. D: Appl. Phys.

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Abstract.The control of the spatial distribution of micrometer-sized dust particles in capacitively coupled radio frequency discharges is relevant for research and applications. Typically, dust particles in plasmas form a layer located at the sheath edge adjacent to the bottom electrode. Here, a method of manipulating this distribution by the application of a specific excitation waveform, i.e. two consecutive harmonics, is discussed. Tuning the phase angle θ between the two harmonics allows to adjust the discharge symmetry via the Electrical Asymmetry Effect (EAE). An adiabatic (continuous) phase shift leaves the dust particles at an equilibrium position close to the lower sheath edge. Their levitation can be correlated with the electric field profile. By applying an abrupt phase shift the dust particles are transported between both sheaths through the plasma bulk and partially reside at an equilibium position close to the upper sheath edge. Hence, the potential profile in the bulk region is probed by the dust particles providing indirect information on plasma properties. The respective motion is understood by an analytical model, showing both the limitations and possible ways of optimizing this sheath-to-sheath transport. A classification of the transport depending on the change in the dc self bias is provided, and the pressure dependence is discussed.

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Microparticles as Plasma Diagnostic Tools

Cited by 13 publications

References 25 publications

Size and density evolution of a single microparticle embedded in a plasma

Size and density evolution of a single microparticle embedded in a plasma

Using dust as probes to determine sheath extent and structure

Transport control of dust particles via the electrical asymmetry effect: experiment, simulation and modelling

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