Laminar-to-Turbulent Transition of a DC Helium/Oxygen (2%) Plasma Microjet

Zhu, Weidong; Re, Justin Lo; Zhang, Jue; Fang, Jing; López, José L.

doi:10.1109/tps.2011.2139230

Cited by 5 publications

(3 citation statements)

References 3 publications

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“…Further increase in the flow rate leads to the decrease in both emission intensities. This corresponds to the laminar-to-turbulent transition as reported earlier [21], and may be due to the increased entrainment of surrounding air at the exit nozzle, leading to the increase in the oxygen concentration in the gas stream.…”

Section: Optical Emission Spectroscopysupporting

confidence: 68%

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A dc non-thermal atmospheric-pressure plasma microjet

Zhu

López

2012

Plasma Sources Sci. Technol.

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A direct current (dc), non-thermal, atmospheric-pressure plasma microjet is generated with helium/oxygen gas mixture as working gas. The electrical property is characterized as a function of the oxygen concentration and show distinctive regions of operation. Side-on images of the jet were taken to analyze the mode of operation as well as the jet length. A self-pulsed mode is observed before the transition of the discharge to normal glow mode. Optical emission spectroscopy is employed from both end-on and side-on along the jet to analyze the reactive species generated in the plasma. Line emissions from atomic oxygen (at 777.4 nm) and helium (at 706.5 nm) were studied with respect to the oxygen volume percentage in the working gas, flow rate and discharge current. Optical emission intensities of Cu and OH are found to depend heavily on the oxygen concentration in the working gas. Ozone concentration measured in a semi-confined zone in front of the plasma jet is found to be from tens to ∼120 ppm. The results presented here demonstrate potential pathways for the adjustment and tuning of various plasma parameters such as reactive species selectivity and quantities or even ultraviolet emission intensities manipulation in an atmospheric-pressure non-thermal plasma source. The possibilities of fine tuning these plasma species allows for enhanced applications in health and medical related areas.

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Section: Optical Emission Spectroscopysupporting

confidence: 68%

“…Upon further current increase, the plasma jet appears to be turbulent (with a blurry tip). Typically, this is a laminar flow region according to an earlier study conducted with the same device [21].…”

Section: Plasma Images and Jet Lengthmentioning

confidence: 99%

A dc non-thermal atmospheric-pressure plasma microjet

Zhu

López

2012

Plasma Sources Sci. Technol.

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“…Atmospheric pressure non-thermal plasma jets have attracted considerable interests recently due to their various applications, such as surface modification, biological decontamination, combustion and environmental protection [1][2][3]. Many of these plasma jet devices typically use ring-, needle-or plane-electrodes in various geometrical arrangements (often in combination with certain dielectric barriers) [4][5][6][7], and are usually driven by direct current (DC), alternating current (AC), radio frequency (RF) and microwave frequency power supplies [8][9][10][11]. Continuous wave operation often leads to problems such as overheating and low energy efficiency.…”

Section: Introductionmentioning

confidence: 99%

Effect of pulse polarity on the temporal and spatial emission of an atmospheric pressure helium plasma jet

Wang

Zhang

Shen

et al. 2016

Plasma Sources Sci. Technol.

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A single needle-electrode plasma jet driven by a home-made microsecond pulse power supply is studied. The electrical characteristics and optical emissions of the plasma jets driven by positive-and negative-polarity pulses are compared. With the same magnitude of applied voltage, the plasma jet driven by positive pulses shows a higher discharge current, a higher optical emission intensity and travels to a longer distance. The temporal-spatially resolved He (706.5 nm), N 2 (337.1 nm) and + N 2 (391.4 nm) emissions behave differently in the plasma jets driven by different polarity pulses: They appear to be discrete emission packets in the positive plasma jet, but continuous emission in the negative plasma jet (under the time resolution in this study). The emission front propagates at a faster speed in the positive plasma jet than in the negative plasma jet. The different behavior of the plasma jets is attributed to the electric field distribution under different polarity pulses.

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Laminar and turbulent flow modes of cold atmospheric pressure argon plasma jet

Basher

Mohamed

2018

Journal of Applied Physics

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Laminar and turbulent flow modes of a cold atmospheric pressure argon plasma jet are investigated in this work. The effects of the gas flow rate, applied voltage, and frequency on each plasma mode and on intermodal transitions are characterized using photographic, electrical, and spectroscopic techniques. Increasing the gas flow rate increases the plasma jet length in the laminar mode. Upon transition to the turbulent mode, increasing the gas flow rate leads to a decrease in the plasma jet length. The flow rate at which the jet transitions from laminar to turbulent increases with the applied voltage. The presence of nitric oxide (NO) radicals is indicated by the emission spectra of the turbulent plasmas only, while excited Ar, N2, OH, and O excited species are produced in both laminar and turbulent modes. With no distinctive behavior observed upon transition between the two operating modes, the power consumption was found to be insensitive to gas flow rate variation, while the energy density was found to decrease exponentially with the gas flow rate. Rotational and vibrational temperature measurements of the two plasma modes indicated that they are of the non-thermal equilibrium plasma type. Since they offer NO radicals while maintaining the benefits of the laminar plasma jet, the turbulent plasma jet is more useful than its laminar counterpart in biomedical applications.

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Laminar-to-Turbulent Transition of a DC Helium/Oxygen (2%) Plasma Microjet

Cited by 5 publications

References 3 publications

A dc non-thermal atmospheric-pressure plasma microjet

A dc non-thermal atmospheric-pressure plasma microjet

Effect of pulse polarity on the temporal and spatial emission of an atmospheric pressure helium plasma jet

Laminar and turbulent flow modes of cold atmospheric pressure argon plasma jet

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