Excitation dynamics of a kHz driven micro-structured plasma channel device operated in argon

Greb, Arthur; Boettner, Henrik; Winter, J.; Gathen, Volker Schulz-von der

doi:10.1088/0963-0252/20/5/055010

Cited by 15 publications

(19 citation statements)

References 21 publications

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“…As noted above, 15 discharge current pulses having temporal widths of 500 ns were observed during the 400 ns risetime of the voltage waveform. Such behavior is quite similar to the self-pulsing reported in [7] for inverted-pyramid microcavity devices and micro-trenches, and is characteristic of the Townsend mode of operation. As illustrated by the simulations of [8], for example, and the performance of the DBD structure devices of [4], Townsend discharges are known for the presence of several current peaks during one half-cycle of the driving voltage waveform.…”

Section: Experimental Arrangement and Data Acquisitionsupporting

confidence: 82%

“…Differing significantly from the physics of laser-generated filaments [1] and plasma bullets [2] emanating from jet devices, the physical mechanisms responsible for the propagation of ionization waves in and over microchannel and microcavity plasma device arrays has been studied by several groups recently [3][4][5]. Velocities of the ionization waves (also known as plasma wave packets, a term adopted from molecular physics) in such micro-dielectric barrier discharge (DBD) structures [6,7] have been measured to range from a few km/s to ∼20 km s −1 [5]. These values are well below those of streamers produced in needleplate discharges which are capable of reaching velocities of 150 km s −1 [3].…”

Section: Introductionmentioning

confidence: 99%

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Branching, spatial periodicity, and confluence of plasma waves propagating in planar micro-dielectric barrier discharge devices

Wang

Zhou

et al. 2019

Plasma Sources Sci. Technol.

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Self-organization of periodic, streamer-like ionization waves in planar microplasma devices having a dielectric barrier discharge structure is observed. In contrast to plasma propagation in arrays of microchannels or microcavities, the ionization waves originate from a single point but rapidly sub-divide into as many as 10 'branch' plasma wave packets that eventually recombine. In less than 70 ns, the self-organization of the spatially-periodic array of co-propagating branches is complete and two successive sets of waves, separated in distance and time by ∼1.8 mm and ∼50 ns, respectively, are generated. The mean propagation velocity of each plasma packet is greater than 70 km s −1 but values as large as 150 km s −1 have been measured. Because the propagation path for all subsequent streamers is established by the first set of plasma packets, the intensity of the second set is noticeably enhanced. The average length of the primary branches is ∼1.5 mm but reaches a maximum of ∼4.5 mm as the wave packets travel an overall distance of 1 cm. These phenomena are interpreted in terms of photoelectron emission from the floor and walls of the shallow dielectric microcavity, induced by radiation from the advancing packets, and the rapid collapse of the sheath of each microplasma owing to the accumulation of charge on the underlying dielectric. The spatial profiles of the propagating plasmas suggest that generating and probing plasma solitons may now be feasible.

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Section: Experimental Arrangement and Data Acquisitionsupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Branching, spatial periodicity, and confluence of plasma waves propagating in planar micro-dielectric barrier discharge devices

Wang

Zhou

et al. 2019

Plasma Sources Sci. Technol.

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“…Atmospheric-pressure, neon microplasmas generated within such microchannel networks are spatially periodic, and the propagation of the plasma packet array in several microchannel designs reveals both plasma-wall and electrostatic plasma-plasma interactions. The first reports of microplasma propagation in microfabricated cavity arrays observed an ionization wave propagating with a velocity of 3 km s −1 [15,16], and subsequent experiments and simulations suggested that the surface streamer head is directed and sustained by photoelectron emission driven by rare gas dimer fluorescence [6]. A similar mechanism appears to be partially responsible for the propagation of plasma 'bullets' [17], microplasmas traveling within microchannels [18], and the experiments described in detail below.…”

Section: Introductionmentioning

confidence: 89%

“…Before discussing the images of figures 1 and 3 further, it should also be mentioned that time-resolved studies of the channel fluorescence patterns with a gated ICCD camera showed the intensity maps of figures 1(c)-(e) to be stationary. That is, the propagation phenomena reported in [6,15,16,18], for example, were absent but we hasten to add that the possible existence of transient effects early in the voltage waveform was not investigated.…”

Section: Spatially-periodic Microplasmas In Nanoporous Alumina Channe...mentioning

confidence: 99%

Spatially-periodic microplasmas in complex microchannel networks: wall-plasma interactions and dynamic behavior

Cho¹,

Yang²,

Park³

et al. 2019

J. Phys. D: Appl. Phys.

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Wall-plasma interactions have been observed for spatially-periodic microplasmas generated in 300-700 µm wide channels fabricated in nanoporous alumina. Examination of Ne microplasma discs produced in a standing-wave pattern in Al 2 O 3 channels illustrates the competition between electron production at the sheath-wall interface and loss by recombination in an atmospheric pressure background. Two topologies of the microplasma arrays are observed. For channel widths (d) less than 450 µm, the microplasmas are generally centered in the channel and sustained by electron generation at both plasma sheath/channel wall interfaces, presumably including the release of charge residing in the hexagonal alumina pores. As d is progressively increased from 300 to 450 µm, the microchannel plasma crosssection is gradually transformed from circular to elliptical, and its surface area declines by as much as 50% so as to minimize e − losses to the background gas. Increasing d above ~450 µm abruptly switches the topology to one in which plasmas having a triangular crosssection attach to one of the channel walls in a pattern that alternates along the channel axis. Microfabricating trapezoidal cross-section channels into complex geometries, including the Cornu spiral and intersecting linear arrays, also reveals dynamic behavior in the propagation of microplasmas. For a common spiral structure, observations of plasma expansion show the wavefront propagates over the corrugated surface or within the channel with radial and azimuthal velocities of 3 ± 1 km s −1 and 8 ± 1.5 km s −1 , respectively. Plasma formation is initiated in each ring of the spiral through electron seeding by streamers propagating radially outward at velocities approaching 200 km s −1 . In addition to electrostatic charge-mediated variations in the mean separation between adjacent microplasmas, the time-dependent interference between two 1D microplasma arrays has been observed during plasma expansion. Reproducible ignition of a microplasma ensemble along ridges micromachined into channels near the intersections of two linear arrays has also been realized. The results reported here demonstrate that microchannels with the walls overcoated with any of a variety of materials provide a promising platform for examining in detail the interaction of low temperature plasma with a surface of arbitrary composition and topography.

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“…Meanwhile, the ion space charge gradually builds up, which is attributed to the relatively small ion mobility compared with electron mobility, but the primary electrons have been rapidly accumulated on the glass surface. And the important thing is that part of the long-lived excited particles generated in the previous discharge, as shown in figure 6(a), can survive until the following negative half period [30]. The sequential discharge is managed by the total electric field between the gas gap.…”

Section: Formation Mechanism Of the 'Center-emission' Andmentioning

confidence: 99%

Co-effect of dielectric layer material and driving pulse polarity on the spatial emission intensity distributions of micro dielectric barrier discharge

Wang

Chen

et al. 2021

J. Phys. D: Appl. Phys.

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A micro concentric ring device with asymmetric dielectrics (glass and n-silicon) is driven by a bipolar pulse generator with 20 kHz frequency, 1 µs pulse width, 50 ns rising/falling time, and 3.6 kV peak-to-peak voltage, and the spatial emission intensity distributions in the device are investigated. The experiments are operated at 133 mbar pure argon. The spatial-temporal microplasma evolution recorded by intensified charge-coupled device illustrates that 'edge emission' arises in the microchannels when the electrode (indium tin oxide) on which the glass dielectric is located acts as the cathode. However, when the electrode (conductive silver paste) adjacent to the n-silicon acts as the cathode, 'center emission' is induced. The dielectric materials' properties (relative permittivity and secondary electron emission coefficient), synergistically with the pulse polarity, which determines the influence of the residual long-living particles generated by previous discharge on the subsequent discharge, are inferred to be responsible for the distinct spatial emission intensity distributions at different pulse polarities. When the n-silicon is situated on the cathode, the high permittivity of n-silicon repels the electric field into plasma, which means that the electrons can obtain more energy in the first half of their journey. Furthermore, the high secondary electron yield of n-silicon makes it possible to provide more seed electrons for microdischarge. This mechanism of electrons dynamics leads to the occurrence of 'center emission'. When the positive half period of the bipolar pulse arrives at the n-silicon, the residual charged particles generated by the previous discharge will induce a reversed electric field in the channel center to impair the applied electric field and bring about the 'edge emission', but this cannot emerge in the microdischarge powered by the unipolar pulse. Investigation of spatial emission intensity distributions of microplasmas is important for the comprehension of devices based on micro-structure techniques.

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Excitation dynamics of a kHz driven micro-structured plasma channel device operated in argon

Cited by 15 publications

References 21 publications

Branching, spatial periodicity, and confluence of plasma waves propagating in planar micro-dielectric barrier discharge devices

Branching, spatial periodicity, and confluence of plasma waves propagating in planar micro-dielectric barrier discharge devices

Spatially-periodic microplasmas in complex microchannel networks: wall-plasma interactions and dynamic behavior

Co-effect of dielectric layer material and driving pulse polarity on the spatial emission intensity distributions of micro dielectric barrier discharge

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