Probing the Plasma Sheath by the Continuous Mass Loss of Microparticles

Carstensen, J.; Haase, Fabian; Jung, Hendrik; Tadsen, Benjamin; Groth, Sebastian; Greiner, Franko; Piel, A.

doi:10.1109/tps.2012.2224330

Cited by 21 publications

(15 citation statements)

References 29 publications

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“…While the linear loss of mass was known from similar experiments with PMMA particles in rf plasmas 8 , it was assumed to be exclusively a loss of radius with the mass density staying constant. Yet, here we observe a substantial loss of the average mass density in 11 hours to well under half the starting value.…”

Section: Resultsmentioning

confidence: 99%

“…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%

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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: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2017

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“…is the neutral mass (of Argon) and the coefficient accounts for the type of reflection or absorption of the neutral gas particle. For melamine formaldehyde particles in Argon this coefficient was determined to be 1.44 [21,22]. Finally, the thermal speed !…”

Section: A Neutral Drag Forcementioning

confidence: 99%

Analysis of magnetic field plasma interactions using microparticles as probes

et al. 2015

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The interaction between a magnetic field and plasma close to a nonconductive surface is of interest for both science and technology. In space, crustal magnetic fields on celestial bodies without atmosphere can interact with the solar wind. In advanced technologies such as those used in fusion or spaceflight, magnetic fields can be used to either control a plasma or protect surfaces exposed to the high heat loads produced by plasma. In this paper, a method will be discussed for investigating magnetic field plasma interactions close to a nonconductive surface inside a Gaseous Electronics Conference reference cell employing dust particles as probes. To accomplish this, a magnet covered by a glass plate was exposed to a low power argon plasma. The magnetic field was strong enough to magnetize the electrons, while not directly impacting the dynamics of the ions or the dust particles used for diagnostics. In order to investigate the interaction of the plasma with the magnetic field and the nonconductive surface, micron-sized dust particles were introduced into the plasma and their trajectories were recorded with a high-speed camera. Based on the resulting particle trajectories, the accelerations of the dust particles were determined and acceleration maps over the field of view were generated which are representative of the forces acting on the particles. The results show that the magnetic field is responsible for the development of strong electric fields in the plasma, in both horizontal and vertical directions, leading to complex motion of the dust particles.

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“…It yields results that are in good agreement with the Epstein relation. 40 If the size distribution of the dust particles is sufficiently narrow, the obtained damping constant could also be employed for the experiment with many particles.…”

Section: B Analytical Modelmentioning

confidence: 99%