Mass changes of microparticles in a plasma observed by a phase-resolved resonance method

Carstensen, J.; Jung, Hendrik; Greiner, Franko; Piel, A.

doi:10.1063/1.3556677

Cited by 60 publications

(72 citation statements)

References 17 publications

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“…When analyzing plasma inherent processes like stochastic heating through charge fluctuations 3,4 , the dust radius is important for interpreting the charging mechanism. Other experiments, like the resonance method [5][6][7][8] , investigate the resonant response of the particle to small external forces. The resulting damped oscillation of the particle enables us to determine the coefficient of friction with the neutral gas as well as the particle charge with high accuracy.…”

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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“…First, the plasma parameters drift with time and, second, the dust particles undergo an aging process. 10 On the contrary, molecular dynamics (MD) simulations 11,12 are well suited to study these questions. They allow for systematic parameter scans under well defined conditions for different heating methods.…”

Section: Introductionmentioning

confidence: 99%

Laser heating of finite two-dimensional dust clusters: B. Simulations

et al. 2012

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Laser heating of monolayer dusty plasmas is investigated theoretically by Langevin dynamics simulations. The laser radiation pressure is used to externally control the dust temperature without changing the plasma properties. We show that the laser scanning pattern has a major influence on both the velocity distribution function and the stationary structure of the cluster. Furthermore, the heating effect is found to be enhanced when the laser spots move with slightly higher frequencies than the trap frequency. The simulations confirm that a proper thermodynamic excitation of the dust particles is possible.

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“…12,13 Alternatively the variations of particle oscillation frequencies were also used to estimate particle size changes. 14,15 Experiments in quadrupole traps 16 even revealed that mass loss can occur without the presence of a discharge, through the outgassing of water vapor from the particles.Our new experimental technique consists of two stages. First, after stabilizing the discharge conditions (gas pressure and driving power) the horizontal confining electric field is measured by changing the rotation rate.…”

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confidence: 99%

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confidence: 99%

Simple experiment on the sputtering rate of solids in gas discharges

et al. 2017

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We present a very simple and sensitive method to measure the sputtering rate of solid materials in stationary low-pressure gas discharges. The method is based on the balance of the centrifugal force and the confinement electric force acting on a single electrically charged dust particle in a rotating environment. We demonstrate the use and sensitivity of this method in a capacitively coupled radio frequency argon discharge. We were able to detect a reduction of 10 nm in the diameter of a single dust particle. Published by AIP Publishing. [http://dx.doi.org/10.1063/1.4985080] Low-pressure gas discharges in industrial and laboratory applications are mostly confined in a vacuum chamber made of metallic and/or dielectric solid materials. These surfaces define the boundary conditions (temperature, electric potential, etc.) and provide the most significant loss (and sometimes source) channels for the charged particles by electric conduction, surface recombination, electron emission, etc. As gas discharges are driven-dissipative systems, where the charge production processes (ionization and emission) and loss channels (recombination and absorption) are separated in both space and time, the geometrical properties and the boundary conditions have significant effects on the overall plasma parameters such as the distributions of charged species densities, temperature, and electric potential. To date the effect of solid surfaces at the edges of gas discharge plasmas can only be taken into account by applying overly simplified phenomenological models. 1 The data for the different processes in these models, like secondary electron emission yield, electron reflection probability, sputtering yield, etc., are not available in general for any combination of gas and solid materials. In the rare cases where there are experimental data published, the experiments are mostly performed in a high vacuum environment using mono-energetic beams of electrons or ions and clean surfaces.2,3 These conditions are very different from discharge conditions, where the background gas is able to modify the surface.To advance the field of gas discharge physics, a deeper understanding of the mutual interaction between the discharge plasma and the surfaces is needed. Increasingly, effort is being put into research targeting the combined, self-consistent description of the solid-plasma system, the so called "plasma interface" at the microscopic level of individual atoms and electrons including quantum effects. 4 At some stage of these efforts, any new results will have to be validated against actual phenomenological models and experimental data obtained under real discharge conditions. The aim of this study is to provide a simple and fundamental experimental technique for determination of the sputtering rate of solid materials in gas discharges with high accuracy and sensitivity.5 This method can be used to provide experimental data useful for both present phenomenological models and future fundamental models describing sputtering, one of the important p...

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Mass changes of microparticles in a plasma observed by a phase-resolved resonance method

Cited by 60 publications

References 17 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

Laser heating of finite two-dimensional dust clusters: B. Simulations

Simple experiment on the sputtering rate of solids in gas discharges

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