Helium metastable species generation in atmospheric pressure RF plasma jets driven by tailored voltage waveforms in mixtures of He and N2

I. Korolov; M. Leimkühler; M. Böke; Z. Donkó; V. Schulz-Von Der Gathen; L. Bischoff; G. Hübner; P. Hartmann; T. Gans; Y. Liu; T. Mussenbrock; J. Schulze

doi:10.1088/1361-6463/ab6d97

Helium metastable species generation in atmospheric pressure RF plasma jets driven by tailored voltage waveforms in mixtures of He and N₂

I. Korolov, M. Leimkühler, M. Böke, Z. Donkó, V. Schulz-Von Der Gathen, L. Bischoff, G. Hübner, P. Hartmann, T. Gans, Y. Liu, T. Mussenbrock, J. Schulze

Research output: Contribution to journal › Article › peer-review

Abstract

Spatially resolved tunable diode-laser absorption measurements of the absolute densities of He-I (2³S₁) metastables in a micro atmospheric pressure plasma jet operated in He/N₂ and driven by 'peaks'- and 'valleys'-type tailored voltage waveforms are presented. The measurements are performed at different nitrogen admixture concentrations and peak-to-peak voltages with waveforms that consist of up to four consecutive harmonics of the fundamental frequency of 13.56 MHz. Comparisons of the measured metastable densities with those obtained from particle-in-cell/Monte Carlo collision simulations show a good quantitative agreement. The density of helium metastables is found to be significantly enhanced by increasing the number of consecutive driving harmonics. Their generation can be further optimized by tuning the peak-to-peak voltage amplitude and the concentration of the reactive gas admixture. These findings are understood based on detailed fundamental insights into the spatio-temporal electron dynamics gained from the simulations, which show that voltage waveform tailoring allows to control the electron energy distribution function to optimize the metastable generation. A high degree of correlation between the metastable creation rate and the electron impact excitation rate from the helium ground state into the He-I ((3s)³S₁) level is observed for some conditions which may facilitate an estimation of the metastable densities based on phase resolved optical emission spectroscopy measurements of the 706.5 nm He-I line originating from the above level and metastable density values at proper reference conditions.

Original language	English
Article number	185201
Journal	Journal of Physics D: Applied Physics
Volume	53
Issue number	18
Early online date	25 Feb 2020
DOIs	https://doi.org/10.1088/1361-6463/ab6d97
Publication status	E-pub ahead of print - 25 Feb 2020

Bibliographical note

Keywords

absorption spectroscopy
atmospheric plasma jet
helium metastables
PIC simulations
voltage waveform tailoring

Access to Document

10.1088/1361-6463/ab6d97

Korolov_2020_J._Phys._D__Appl._Phys._53_185201
© 2020 The Author(s).
Final published version, 10.5 MBLicence: CC BY

Cite this

Korolov, I., Leimkühler, M., Böke, M., Donkó, Z., Schulz-Von Der Gathen, V., Bischoff, L., Hübner, G., Hartmann, P., Gans, T., Liu, Y., Mussenbrock, T., & Schulze, J. (2020). Helium metastable species generation in atmospheric pressure RF plasma jets driven by tailored voltage waveforms in mixtures of He and N₂. Journal of Physics D: Applied Physics, 53(18), Article 185201. Advance online publication. https://doi.org/10.1088/1361-6463/ab6d97

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title = "Helium metastable species generation in atmospheric pressure RF plasma jets driven by tailored voltage waveforms in mixtures of He and N2",

abstract = "Spatially resolved tunable diode-laser absorption measurements of the absolute densities of He-I (23S1) metastables in a micro atmospheric pressure plasma jet operated in He/N2 and driven by 'peaks'- and 'valleys'-type tailored voltage waveforms are presented. The measurements are performed at different nitrogen admixture concentrations and peak-to-peak voltages with waveforms that consist of up to four consecutive harmonics of the fundamental frequency of 13.56 MHz. Comparisons of the measured metastable densities with those obtained from particle-in-cell/Monte Carlo collision simulations show a good quantitative agreement. The density of helium metastables is found to be significantly enhanced by increasing the number of consecutive driving harmonics. Their generation can be further optimized by tuning the peak-to-peak voltage amplitude and the concentration of the reactive gas admixture. These findings are understood based on detailed fundamental insights into the spatio-temporal electron dynamics gained from the simulations, which show that voltage waveform tailoring allows to control the electron energy distribution function to optimize the metastable generation. A high degree of correlation between the metastable creation rate and the electron impact excitation rate from the helium ground state into the He-I ((3s)3S1) level is observed for some conditions which may facilitate an estimation of the metastable densities based on phase resolved optical emission spectroscopy measurements of the 706.5 nm He-I line originating from the above level and metastable density values at proper reference conditions.",

keywords = "absorption spectroscopy, atmospheric plasma jet, helium metastables, PIC simulations, voltage waveform tailoring",

author = "I. Korolov and M. Leimk{\"u}hler and M. B{\"o}ke and Z. Donk{\'o} and {Schulz-Von Der Gathen}, V. and L. Bischoff and G. H{\"u}bner and P. Hartmann and T. Gans and Y. Liu and T. Mussenbrock and J. Schulze",

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Korolov, I, Leimkühler, M, Böke, M, Donkó, Z, Schulz-Von Der Gathen, V, Bischoff, L, Hübner, G, Hartmann, P, Gans, T, Liu, Y, Mussenbrock, T & Schulze, J 2020, 'Helium metastable species generation in atmospheric pressure RF plasma jets driven by tailored voltage waveforms in mixtures of He and N₂', Journal of Physics D: Applied Physics, vol. 53, no. 18, 185201. https://doi.org/10.1088/1361-6463/ab6d97

TY - JOUR

T1 - Helium metastable species generation in atmospheric pressure RF plasma jets driven by tailored voltage waveforms in mixtures of He and N2

AU - Korolov, I.

AU - Leimkühler, M.

AU - Böke, M.

AU - Donkó, Z.

AU - Schulz-Von Der Gathen, V.

AU - Bischoff, L.

AU - Hübner, G.

AU - Hartmann, P.

AU - Gans, T.

AU - Liu, Y.

AU - Mussenbrock, T.

AU - Schulze, J.

PY - 2020/2/25

Y1 - 2020/2/25

N2 - Spatially resolved tunable diode-laser absorption measurements of the absolute densities of He-I (23S1) metastables in a micro atmospheric pressure plasma jet operated in He/N2 and driven by 'peaks'- and 'valleys'-type tailored voltage waveforms are presented. The measurements are performed at different nitrogen admixture concentrations and peak-to-peak voltages with waveforms that consist of up to four consecutive harmonics of the fundamental frequency of 13.56 MHz. Comparisons of the measured metastable densities with those obtained from particle-in-cell/Monte Carlo collision simulations show a good quantitative agreement. The density of helium metastables is found to be significantly enhanced by increasing the number of consecutive driving harmonics. Their generation can be further optimized by tuning the peak-to-peak voltage amplitude and the concentration of the reactive gas admixture. These findings are understood based on detailed fundamental insights into the spatio-temporal electron dynamics gained from the simulations, which show that voltage waveform tailoring allows to control the electron energy distribution function to optimize the metastable generation. A high degree of correlation between the metastable creation rate and the electron impact excitation rate from the helium ground state into the He-I ((3s)3S1) level is observed for some conditions which may facilitate an estimation of the metastable densities based on phase resolved optical emission spectroscopy measurements of the 706.5 nm He-I line originating from the above level and metastable density values at proper reference conditions.

AB - Spatially resolved tunable diode-laser absorption measurements of the absolute densities of He-I (23S1) metastables in a micro atmospheric pressure plasma jet operated in He/N2 and driven by 'peaks'- and 'valleys'-type tailored voltage waveforms are presented. The measurements are performed at different nitrogen admixture concentrations and peak-to-peak voltages with waveforms that consist of up to four consecutive harmonics of the fundamental frequency of 13.56 MHz. Comparisons of the measured metastable densities with those obtained from particle-in-cell/Monte Carlo collision simulations show a good quantitative agreement. The density of helium metastables is found to be significantly enhanced by increasing the number of consecutive driving harmonics. Their generation can be further optimized by tuning the peak-to-peak voltage amplitude and the concentration of the reactive gas admixture. These findings are understood based on detailed fundamental insights into the spatio-temporal electron dynamics gained from the simulations, which show that voltage waveform tailoring allows to control the electron energy distribution function to optimize the metastable generation. A high degree of correlation between the metastable creation rate and the electron impact excitation rate from the helium ground state into the He-I ((3s)3S1) level is observed for some conditions which may facilitate an estimation of the metastable densities based on phase resolved optical emission spectroscopy measurements of the 706.5 nm He-I line originating from the above level and metastable density values at proper reference conditions.

KW - absorption spectroscopy

KW - atmospheric plasma jet

KW - helium metastables

KW - PIC simulations

KW - voltage waveform tailoring

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