Impurity intrusion in radio-frequency micro-plasma jets operated in ambient air

Niermann, Benedikt; Kanitz, Alexander; Böke, Marc; Winter, J.

doi:10.1088/0022-3727/44/32/325201

Cited by 22 publications

(39 citation statements)

References 14 publications

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“…As measured in [20], (He(2 3 S)) is still present few microsecond after the discharge. The lifetime of He(23S) (5.7 μs) in pure helium is longer than our half period (3.3 μs) [21]. So, in our experiment, in pure helium He(2 3 S) are probably present between two discharges.…”

Section: Importance Of the Helium Excited Speciescontrasting

confidence: 48%

“…N 2 consumes the He * and reduces their lifetimes. For example, at a nitrogen concentration of 1%, the lifetime of the helium metastable He(2 3 S) is reduced to 50 ns (same calculation as [21]), which is shorter than the time between two discharges. Considering this low lifetime and the periodicity of the discharge, it could be surprising to observe a Penning effect.…”

Section: Importance Of the Helium Excited Speciesmentioning

confidence: 89%

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Transition from diffuse to self-organized discharge in a high frequency dielectric barrier discharge

Belinger

Naudé

Ghérardi

2017

Eur. Phys. J. Appl. Phys.

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Abstract. Depending on the operating conditions, different regimes can be obtained in a dielectric barrier discharge (DBD): filamentary, diffuse (also called homogeneous) or self-organized. For a plane-to-plane DBD operated at high frequency (160 kHz) and at atmospheric pressure in helium gas, we show that the addition of a small amount of nitrogen induces a transition from the diffuse regime to a self-organized regime characterized by the appearance of filaments at the exit of the discharge. In this paper, we detail mechanisms that could be responsible of the transition from diffuse mode to this self-organized mode. We point out the critical role of the power supply and the importance of the gas memory effect from one discharge to the following one on the transition to the self-organised mode. The self-organized mode is usually attributed to a surface memory effect. In this work, we show an additional involvement of the gas memory effect on the self-organized mode.

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Section: Importance Of the Helium Excited Speciescontrasting

confidence: 48%

Section: Importance Of the Helium Excited Speciesmentioning

confidence: 89%

Transition from diffuse to self-organized discharge in a high frequency dielectric barrier discharge

Belinger

Naudé

Ghérardi

2017

Eur. Phys. J. Appl. Phys.

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“…The significant effect of gas impurities on the plasma neutral chemistry could already be demonstrated by absorption spectroscopy showing a reduction of the lifetime of Helium metastables with increasing impurity concentration [24]. Similarly in APPs driven in argon gas, it was shown that water impurities change the reactive species composition and cell viability [25].…”

Section: Introductionmentioning

confidence: 93%

Methods of gas purification and effect on the ion composition in an RF atmospheric pressure plasma jet investigated by mass spectrometry

et al. 2016

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The analysis of the ion chemistry of atmospheric pressure plasmas is essential to evaluate ionic reaction pathways during plasma-surface or plasma-analyte interactions. In this contribution, the ion chemistry of a radio-frequency atmospheric pressure plasma jet (μ-APPJ) operated in helium is investigated by mass spectrometry (MS). It is found, that the ion composition is extremely sensitive to impurities such as N 2 , O 2 and H 2 O. Without gas purification, protonated water cluster ions of the form H + (H 2 O) n are dominating downstream the positive ion mass spectrum. However, even after careful feed gas purification to the sub-ppm level using a molecular sieve trap and a liquid nitrogen trap as well as operation of the plasma in a controlled atmosphere, the positive ion mass spectrum is strongly influenced by residual trace gases. The observations support the idea that species with a low ionization energy serve as a major source of electrons in atmospheric pressure helium plasmas. Similarly, the neutral density of atomic nitrogen measured by MS in a He/N 2 mixture is varying up to a factor 3, demonstrating the significant influence of impurities on the neutral species chemistry as well.

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“…Inside the filaments, both electron and metastable densities become high enough to show significant impact on metastable quenching by superelastic collisions and pooling reactions. Additionally, nitrogen, oxygen as well as water molecules are desorbing from the gas supply system or the chamber walls and intermix with the working gas, so that the ambient atmosphere is estimated to contain at least some dozens of ppm of air [21]. All these effects make a theoretical estimation of the different factors that limit the metastable lifetime unfeasible.…”

Section: Density Approximations and Experimental Uncertaintiesmentioning

confidence: 99%

Argon metastable dynamics in a filamentary jet micro-discharge at atmospheric pressure

Niermann¹,

Reuter²,

Kuschel³

et al. 2012

Plasma Sources Sci. Technol.

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Abstract.Space and time resolved concentrations of Ar ( 3 P 2 ) metastable atoms at the exit of an atmospheric pressure radio-frequency micro-plasma jet were measured using tunable diode laser absorption spectroscopy. The discharge features a coaxial geometry with a hollow capillary as an inner electrode and a ceramic tube with metal ring as outer electrode. Absorption profiles of metastable atoms as well as optical emission measurements reveal the dynamics and the filamentary structure of the discharge. The average spatial distribution of Ar metastables is characterized with and without a target in front of the jet, showing that the target potential and therewith the electric field distribution substantially changes the filaments' expansion. Together with the detailed analysis of the ignition phase and the discharge's behavior under pulsed operation, the results give an insight into the excitation and de-excitation mechanisms.

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Impurity intrusion in radio-frequency micro-plasma jets operated in ambient air

Cited by 22 publications

References 14 publications

Transition from diffuse to self-organized discharge in a high frequency dielectric barrier discharge

Transition from diffuse to self-organized discharge in a high frequency dielectric barrier discharge

Methods of gas purification and effect on the ion composition in an RF atmospheric pressure plasma jet investigated by mass spectrometry

Argon metastable dynamics in a filamentary jet micro-discharge at atmospheric pressure

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