Influence of dust particles on the bulk electron density in radio frequency plasmas measured by microwave interferometry

Killer, C.; Wegner, Thomas; Melzer, A.; Meichsner, Jürgen

doi:10.1063/1.4937793

Cited by 7 publications

(6 citation statements)

References 31 publications

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“…Another approach in using the microwaves for sensing the free electron density in plasmas is the interferometry. [136,137] Unlike MCRS, it does not require any modification inside the chamber and only requires optical (e.g., through glass window) access to the plasma. Emitter and receiver antennas are placed in front of opposite windows of the chamber.…”

Section: Interferometrymentioning

confidence: 99%

“…[141][142][143][144] However, the importance of qualitative information delivered by the OES should not be underestimated. Spatial profiles of the intensities of the spectral lines [55,99,137,145,146] or change of the ratio of the spectral lines between the dusty and dust-free conditions [147] may contain very important signs for the understanding of the physics of dust-plasma interactions. So-called branching ratio methods [148] can be used to determine the densities of metastable states.…”

Section: Optical Emission Spectroscopymentioning

confidence: 99%

“…The microwave interferometry measurements [ 137 ] performed above the microparticle layer showed the modification of the electron density. Larger microparticles were found to cause its increase, and smaller microparticles—its decrease.…”

Section: Basic Phenomenamentioning

confidence: 99%

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Physical aspects of dust–plasma interactions

Pustylnik

Pikalev

Zobnin

et al. 2021

Contributions to Plasma Physics

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Low‐pressure gas discharge plasmas are known to be strongly affected by the presence of small dust particles. This issue plays a role in the investigations of dust particle‐forming plasmas, where the dust‐induced instabilities may affect the properties of synthesized dust particles. Also, gas discharges with large amounts of microparticles are used in microgravity experiments, where strongly coupled subsystems of charged microparticles represent particle‐resolved models of liquids and solids. In this field, deep understanding of dust–plasma interactions is required to construct the discharge configurations which would be able to model the desired generic condensed matter physics as well as, in the interpretation of experiments, to distinguish the plasma phenomena from the generic condensed matter physics phenomena. In this review, we address only physical aspects of dust–plasma interactions, that is, we always imply constant chemical composition of the plasma as well as constant size of the dust particles. We also restrict the review to two discharge types: dc discharge and capacitively coupled rf discharge. We describe the experimental methods used in the investigations of dust–plasma interactions and show the approaches to numerical modelling of the gas discharge plasmas with large amounts of dust. Starting from the basic physical principles governing the dust–plasma interactions, we discuss the state‐of‐the‐art understanding of such complicated, discharge‐type‐specific phenomena as dust‐induced stratification and transverse instability in a dc discharge or void formation and heartbeat instability in an rf discharge.

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Section: Interferometrymentioning

confidence: 99%

Section: Optical Emission Spectroscopymentioning

confidence: 99%

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Physical aspects of dust–plasma interactions

Pustylnik

Pikalev

Zobnin

et al. 2021

Contributions to Plasma Physics

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“…The active methods are used to measure some parameters in both weakly and strongly ionized plasma (the electron concentration, the collision frequency, and others), as well as in a high-temperature plasma in experiments dealing with controlled thermonuclear fusion. Recently, the application scope of active microwave methods was somewhat extended owing to their usage in the diagnostics of a dusty plasma [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

“…As was already mentioned, the development of microwave methods for the dusty plasma diagnostics has received an impetus in recent years [5][6][7][8]. There are several approaches aimed at the consideration of the interaction between electromagnetic waves and a dusty plasma [23,24].…”

Section: Introductionmentioning

confidence: 99%

Specific Features of Microwave Methods for Dusty Plasma Diagnostics. I. Dielectric Permittivity, Refractive and Absorption Indices

Kovtun

Skibenko

et al. 2019

Ukr. J. Phys.

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Two widely used approaches for the determination of the refractive, n, and absorption, ϰ, indices of a dusty plasma have been analyzed. In one of them, the expressions for n and ϰ obtained for a dust-free plasma are used, but the collisions of plasma ions with dust particles are taken into account by means of the collision frequency parameter. In the other approach, the characteristic charging frequency for dust particles is additionally introduced.

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Influence of nanoparticle formation on discharge properties in argon-acetylene capacitively coupled radio frequency plasmas

Wegner

Hinz²,

Faupel³

et al. 2016

Applied Physics Letters

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This contribution presents experimental results regarding the influence of nanoparticle formation in capacitively coupled radio frequency (13.56 MHz) argon-acetylene plasmas. The discharge is studied using non-invasive 160 GHz Gaussian beam microwave interferometry and optical emission spectroscopy. Particularly, the temporal behavior of the electron density from microwave interferometry is analyzed and compared with the changing plasma emission and self-bias voltage caused by nanoparticle formation. The periodic particle formation with a cycle duration between 30 s and 140 s starts with an electron density drop over more than one order of magnitude below the detection limit (8 × 1014 m−3). The electron density reduction is the result of electron attachment processes due to negative ions and nanoparticle formation. The onset time constant of nanoparticle formation is five times faster compared to the expulsion of the particles from the plasma due to multi-disperse size distribution. Moreover, the intensity of the argon transition lines increases and implies a rising effective electron temperature. The cycle duration of the particle formation is affected by the total gas flow rate and exhibits an inverse proportionality to the square of the total gas flow rate. The variation in the total gas flow rate influences the force balance, which determines the confinement time of the nanoparticles. As a further result, the cycle duration is dependent on the axial position of the powered electrode, which also corresponds to different distances relative to the fixed optical axis of the microwave interferometer.

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Influence of dust particles on the bulk electron density in radio frequency plasmas measured by microwave interferometry

Cited by 7 publications

References 31 publications

Physical aspects of dust–plasma interactions

Physical aspects of dust–plasma interactions

Specific Features of Microwave Methods for Dusty Plasma Diagnostics. I. Dielectric Permittivity, Refractive and Absorption Indices

Influence of nanoparticle formation on discharge properties in argon-acetylene capacitively coupled radio frequency plasmas

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