Comparison of electron heating and energy loss mechanisms in an RF plasma jet operated in argon and helium

Golda, Judith; Held, Julian; Gathen, Volker Schulz-von der

doi:10.1088/1361-6595/ab6c81

“…This change is induced by a change from the so-called α-mode to the γ-mode as already observed and discussed e.g. for the COST-Jet by Golda et al [12]. A change of the plasma emission from a homogeneous glow in the middle between the electrodes to a bright emission directly at both electrodes is observed in this power region.…”

Section: Power Supply and Power Measurementsupporting

confidence: 71%

Multi-diagnostic approach to energy transport in an atmospheric pressure helium-oxygen plasma jet

Winzer¹,

Blosczyk²,

Benedikt³

et al. 2021

Preprint

0

View full text Add to dashboard Cite

The energy balance of a plasma holds fundamental information not only about basic plasma physics, but it is also important for tailoring plasmas to specific applications. Especially RF-driven atmospheric pressure plasma jets (APPJs) operated in helium with oxygen admixture have high application potential in industry and medicine. Many types of plasma jets have been studied up to now, leading to the challenge how to compare results from various sources. We have developed a method for measuring the power deposited in the plasma as the parameter to compare different sources and gas mixtures with each other. Furthermore, we studied energy transport as a function of this input power and molecular gas admixture in a newly developed APPJ based on the COST-reference jet with a capillary as a dielectric in between the electrodes. The gas temperature, atomic oxygen density, ozone density and absolute emission intensity in the visible wavelength range have been determined. Combining the results gave an energy balance with most of the energy deposited into gas heating. Production of final chemical products made up a small amount of the deposited power while radiation was negligible for all combinations of external parameters studied.

show abstract

“…Similar trends and values are obtained for the RF COST reference microplasma jet operating in the abnormal or α-mode with an inter-electrode gap distance of 1 mm. 60 An independent estimate of T e can be obtained from the power balance. Assuming momentum transfer from electrons to neutrals by elastic collisions as the dominant loss mechanism, the input electrical power density, P/V [W m −3 ] can be written as follows 44…”

Section: Resultsmentioning

confidence: 99%

Characterization of an RF-driven argon plasma at atmospheric pressure using broadband absorption and optical emission spectroscopy

Nayak

¹

,

Simeni

²

,

Rosato

³

et al. 2020

Journal of Applied Physics

View full text Add to dashboard Cite

Atmospheric pressure plasmas in argon are of particular interest due to the production of highly excited and reactive species enabling numerous plasma-aided applications. In this contribution, we report on absolute optical emission and absorption spectroscopy of a radio frequency (RF) driven capacitively coupled argon glow discharge operated in a parallel-plate configuration. This enabled the study of all key parameters including electron density and temperature, gas temperature, and absolute densities of atoms in highly electronically excited states. The space and time-averaged electron density and temperature were determined from the measurement of the absolute intensity of the electron-atom bremsstrahlung in the visible range. Considering the non-Maxwellian electron energy distribution function, an electron temperature (T e ) of 2.1 eV and an electron density (n e ) of 1.1 × 10 19 m −3 were obtained. The time-averaged and spatially resolved absolute densities of atoms in the metastable (1s 5 and 1s 3 ) and resonant (1s 4 and 1s 2 ) states of argon in pure Ar and Ar/He mixture were obtained by broadband absorption spectroscopy. The 1s 5 metastable atoms had the largest density near the sheath region with a maximum value of 8 × 10 17 m −3 , while all other 1s states had densities of at most 2 × 10 17 m −3 . The dominant production and loss mechanisms of these atoms were discussed, in particular, the role of radiation trapping. We conclude with a comparison of the plasma properties of the argon RF glow discharges with the more common He equivalent and highlight their differences.

show abstract

“…The volume-averaged electron density in a He COST-Jet is reported by Golda et al [46]. The plasma is operated at a net mass flow rate of 1000 sccm and a pressure of 99000 Pa.…”

Section: Benchmark Against Measurements and Simulation Resultsmentioning

confidence: 93%

“…The irreproducible experimental results of a µAPPJ are mainly ascribed to the gas impurity and the power uncertainty. Hence, they are minimized by the COST-Jet [46,51] with a large amount of effort [28] (e.g., the sealing improvement and the absorbed power measurements with integrated probes).…”

Section: Setupmentioning

confidence: 99%

Zero-dimensional and pseudo-one-dimensional models of atmospheric-pressure plasma jets in binary and ternary mixtures of oxygen and nitrogen with helium background

He

¹

,

Preissing

²

,

Steuer

³

et al. 2021

Plasma Sources Sci. Technol.

Self Cite

View full text Add to dashboard Cite

A zero-dimensional (volume-averaged) and a pseudo-one-dimensional plug-flow (spatially resolved) model are developed to investigate atmospheric-pressure plasma jets operated with He, He/O2, He/N2 and He/N2/O2 mixtures. The models are coupled with the Boltzmann equation under the two-term approximation to self-consistently calculate the electron energy distribution function. An agreement is obtained between the zero-dimensional model calculations and the spatially averaged values of the plug-flow simulation results. The zero-dimensional model calculations are verified against spatially resolved simulation results and validated against a wide variety of measurement data from the literature. The nitric oxide (NO) concentration is thoroughly characterized for a variation of the gas mixture ratio, helium flow rate and absorbed power. An ‘effective’ and a hypothetical larger rate coefficient value for the reactive quenching N 2 ( A 3 Σ , B 3 Π ) + O ( P 3 ) → N O + N ( D 2 ) are used to estimate the role of the species N2(A3Σ, B3Π; v > 0) and multiple higher N2 electronically excited states instead of only N2(A3Σ, B3Π; v = 0) in this quenching. The NO concentration measurements at low power are better and almost identically captured by the simulations using the ‘effective’ and hypothetical values, respectively. Furthermore, the O ( P 3 ) density measurements under the same operation conditions are also better predicted by the simulations adopting these values. It is found that the contribution of the vibrationally excited nitrogen molecules N2(v ⩾ 13) to the net NO formation rate gains more significance at higher power. The vibrational distribution functions (VDFs) of molecular oxygen O2(v < 41) and nitrogen N2(v < 58) are investigated regarding their formation mechanisms and their responses to the variation of operation parameters. It is observed that the N2 VDF shows a stronger response than the O2 VDF. The sensitivity of the simulation results with respect to a variation of the VDF resolutions, wall reaction probabilities and synthetic air impurity levels is presented. The simulated plasma properties are sensitive to the variation, especially for a feed gas mixture containing nitrogen. The plug-flow model is validated against one-dimensional experimental data in the gas flow direction, and it is only used in case an analysis of the spatially resolved plasma properties inside the jet chamber is of interest. The increasing NO spatial concentration in the gas flow direction is saturated at a relatively high power. A stationary O2 VDF is obtained along the direction of the mass flow, while a continuously growing N2 VDF is observed until the jet nozzle.

show abstract

Comparison of electron heating and energy loss mechanisms in an RF plasma jet operated in argon and helium

Cited by 28 publications

References 52 publications

Multi-diagnostic approach to energy transport in an atmospheric pressure helium-oxygen plasma jet

Multi-diagnostic approach to energy transport in an atmospheric pressure helium-oxygen plasma jet

Characterization of an RF-driven argon plasma at atmospheric pressure using broadband absorption and optical emission spectroscopy

Zero-dimensional and pseudo-one-dimensional models of atmospheric-pressure plasma jets in binary and ternary mixtures of oxygen and nitrogen with helium background

Contact Info

Product

Resources

About