Two modes of a plasma jet excited by a direct current voltage

Li, Xuechen; Zhang, Panpan; Bao, Wenting; Jia, Pengying; Chu, Jingdi

doi:10.1088/0963-0252/25/2/025022

Cited by 14 publications

(5 citation statements)

References 50 publications

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“…Many attempts have been implemented to achieve a diffused argon plume. In a needle-to-ring configuration with a ring diameter much larger than that of the tube, a diffuse argon plume is excited by a direct-current voltage [21]. Through utilizing preexisting filamentary discharge excited by a sinusoidal voltage, a diffuse argon plume is produced downstream of the filaments [16].…”

Section: Introductionmentioning

confidence: 99%

Morphology transition from diffuse to diffuse-and-filamentary for an argon plume with varying sinusoidal frequency or voltage amplitude

Chen

Lin

et al. 2020

Plasma Sources Sci. Technol.

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With increasing sinusoidal frequency or its voltage amplitude, a central filament emerges in a diffuse plume downstream of an argon jet with a single-electrode geometry. The plume with a co-existing filament and diffuse part, also referred to as a diffuse-and-filamentary (DAF) plume, is formed after a sudden length increment from a diffuse plume. Only one negative discharge appears per voltage cycle for the diffuse plume. Besides the negative discharge, there is one positive discharge per voltage cycle for the DAF plume. By fast photography, negative discharge behaves as plump plasma bullets propagating along the argon flow, which results in diffuse plume or the diffuse part of the DAF plume. Comparatively, positive discharge behaves as slim bullets, leading to the filament formation. Based on optical emission spectroscopy, it is found that both electron density and electron temperature increase with increasing sinusoidal frequency or voltage amplitude for negative and positive discharges. Moreover, there are abrupt increments in them for negative discharge during the morphology transition. Compared with negative discharge, the positive one has higher electron density and electron temperature. All of the experimental phenomena mentioned above are qualitatively explained through considering the discharge enhancement by residual active species.

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Section: Introductionmentioning

confidence: 99%

Morphology transition from diffuse to diffuse-and-filamentary for an argon plume with varying sinusoidal frequency or voltage amplitude

Chen

Lin

et al. 2020

Plasma Sources Sci. Technol.

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“…With a negative V b , a plume with several swells is generated downstream of the jet nozzle, as presented in the left column of figure 2(a). The plume diameter does not decrease steadily as in a conical plume [24], but fluctuates periodically with increasing distance from the jet nozzle. The zone with a maximal diameter can be defined as a swell, which is marked by the dashed box in figure 2(a).…”

Section: Resultsmentioning

confidence: 82%

Regularly-swelling plumes generated in atmospheric pressure argon plasma jet excited by a biased sinusoidal voltage

Lin

et al. 2019

Plasma Sources Sci. Technol.

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Far different from conical plumes, regularly-swelling plumes are generated in an atmospheric pressure argon plasma jet excited by a biased sinusoidal voltage at low frequency. Depending on the polarity of bias voltage, the plumes with periodic swells can be solid or hollow. Results indicate that discharge initiates once per voltage cycle, which appears in the negative and positive half cycles for the solid and hollow plumes, respectively. By fast photography, it is found that streamers are involved propagating downstream of the argon flow for the two plumes. Transversely, the streamer diffuses for the solid plume, while it propagates only in the flow periphery for the hollow plume. Due to a high field, intense discharges near the nozzle provide the following swell positions with active species, which can remarkably enhance the discharges there and induce the swells. This formation mechanism of periodic swells is verified through investigating the distance of two adjacent swells as a function of gas flow rate and driving frequency. Moreover, spatial distributions of excited electron temperature and streamer propagation velocity are qualitatively explained based on the mechanism.

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“…Unlike the pulsed mode, the applied voltage and the discharge current are invariant with time under higher P d , which is named a continuous mode. [45,46] 085202-2 Plasma plume length as a function of P d is investigated, and the results are shown in Fig. 3.…”

Section: Resultsmentioning

confidence: 99%

Efficient hydrophilicity improvement of titanium surface by plasma jet in micro-hollow cathode discharge geometry

et al. 2023

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The surface hydrophilicity improvement of titanium (Ti) has significant implications to the applications of the important biomaterial. In this paper, efficient hydrophilicity improvement is realized on the Ti surface by an air plasma jet in a micro- hollow cathode discharge (MHCD) geometry. Elementary discharge aspects of the plasma jet and surface characteristics of the Ti surface have been investigated with varying dissipated power (P d ). Results show that the plasma jet operates in a pulsed mode or a continuous mode depending on P d . The plume length increases with increasing P d and air flow rate. By optical emission spectroscopy, plasma parameters are investigated as functions of P d . After plasma treatment, water contact angel (WCA) of the Ti sample decreases until it reaches a minimum of 15° with increasing P d . In addition, surface topography, roughness, and content of chemical compositions are investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) with increasing P d . It is revealed that Ti-O bond and O-H group on the Ti surface are favorable for the improvement of Ti surface hydrophilicity.

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Two modes of a plasma jet excited by a direct current voltage

Cited by 14 publications

References 50 publications

Morphology transition from diffuse to diffuse-and-filamentary for an argon plume with varying sinusoidal frequency or voltage amplitude

Morphology transition from diffuse to diffuse-and-filamentary for an argon plume with varying sinusoidal frequency or voltage amplitude

Regularly-swelling plumes generated in atmospheric pressure argon plasma jet excited by a biased sinusoidal voltage

Efficient hydrophilicity improvement of titanium surface by plasma jet in micro-hollow cathode discharge geometry

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