Optical properties of magnetized transient low-pressure plasma

Bergert, Roman; Mitic, Slobodan

doi:10.1088/1361-6595/ab497e

Cited by 9 publications

(13 citation statements)

References 29 publications

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“…The evaluated 1s 4 and 1s 5 multiplet densities for all together eight different gas mixtures are presented in figures 4 and 5 respectively. As already found in [8], both 1s 4 and 1s 5 multiplets have symmetric positive and negative alignment respectively. This fact does allow to reduce the number of variables in modeling of fluorescence by using identical densities for sub-states with opposite signs in magnetic quantum numbers (n m j = n −m j ).…”

Section: Resultssupporting

confidence: 78%

“…Further, radial TDLAS measurements were done in magnetized conditions, targeting 1s 4 and 1s 5 multiplets, providing information about the 1s sub-state absolute densities for each gas mixture. The absorption measurements under similar conditions were already described in our previous work [8], where detailed description of the measurement procedure and evaluation were explained. The evaluated 1s 4 and 1s 5 sub-state densities for each condition are further used in the modeling of measured fluorescence in order to reduce the number of unknowns and increase the accuracy of the estimated disalignment effect driven by nitrogen collisions.…”

Section: Resultsmentioning

confidence: 99%

“…In absorption mode, the laser scan was set for a wide frequency range scanning through all possible sub-levels of the measured 1s multiplet as described in [8]. As a result, the absolute state density of each targeted 1s multiplet could be reconstructed providing additionally the alignment of the multiplet.…”

Section: Methodsmentioning

confidence: 99%

“…In our case < ∆E >= 11.83 eV which is the energy of argon 1s 2 state. According to [15], the expression < v 3/5 > < v > = 0.9314 µ 2k B T 1 5 (8) depends on the reduced mass µ = M 1 M 2 M 1 +M 2 , the neutral gas temperature T and the Boltzmann constant k B . Finally, the disalignment rate constant can be calculated as…”

Section: Theoretical Estimation Of the Disalignment Rate Coefficientmentioning

confidence: 99%

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Disalignment rate coefficient of argon $\mathrm{2p_8}$ due to nitrogen collision

Bergert,

Isberner,

Mitic

et al. 2020

Preprint

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Tunable diode laser induced fluorescence (TDLIF) measurements are discussed and quantitatively evaluated for nitrogen admixtures in argon plasma under the influence of a strong magnetic field. TDLIF measurements were used to evaluate lighttransport properties in a strongly magnetized optically thick argon/nitrogen plasma under different pressure conditions. Therefore, a coupled system of rate balance equations was constructed to describe laser pumping of individual magnetic sub-levels of 2p 8 state through frequency-separated sub-transitions originating from 1s 4 magnetic sub-levels. The density distribution (alignment) of 2p 8 multiplet was described by balancing laser pumping with losses including radiative decay, transfer of excitation between the neighboring sub-levels in the 2p 8 multiplet driven by neutral collisions (argon and nitrogen) and quenching due to electron and neutral collisions. Resulting 2p 8 magnetic sub-level densities were then used to model polarization dependent fluorescence, considering self-absorption, which could be directly compared with polarization-resolved TDLIF measurements. This enables to estimate the disalignment rate constant for the 2p 8 state due to collisions by molecular nitrogen. A comparison to molecular theory description is given providing satisfactory agreement. The presented measurement method and model can help to describe optical emission of argon and argon-nitrogen admixtures in magnetized conditions and provides a basis for further description of optical emission spectra in magnetized plasmas.

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Section: Resultssupporting

confidence: 78%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Theoretical Estimation Of the Disalignment Rate Coefficientmentioning

confidence: 99%

See 2 more Smart Citations

Disalignment rate coefficient of argon $\mathrm{2p_8}$ due to nitrogen collision

Bergert,

Isberner,

Mitic

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…On the contrary, the Lorentz force on electrons induced by a relatively small magnetic field (mT range) can increase the plasma density, when magnetic fields were applied to the low‐pressure plasma. [ 19,20 ] Although the mean free path of ions at atmospheric pressure plasma is much smaller, the axial magnetic field with the intensity of 1.4 T increased the confinement and electron density of plasma in an atmospheric pressure dielectric barrier discharges.…”

Section: Introductionmentioning

confidence: 99%

Deposition of charged aerosols by E × B enhanced low‐temperature plasma jet array

Chen

Huang

Liu

2021

Plasma Processes & Polymers

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In this paper, an efficient plasma jet array based on the E × B enhancement was developed. The direction of the magnetic field was the same as the propagation direction of the plasma jet, and the direction of the electric field was perpendicular to the plasma jet. The E × B enhancement increased the length of the plasma jet from 0.5 to 1.8 cm, the discharge current peak by 37.8%, and the plasma power by 11.1%, compared with the control case. Three‐dimensional simulation of electrons movement indicates that the confinement of electrons in the high argon concentration region was the main reason for the E × B enhancement. The stronger discharge based on the E × B enhancement increased the ion density in the open air significantly. The charged aerosols were generated through the diffusion charging mechanism. The image charge electric force between charged and neutral aerosols increased the collision rate between aerosols, therefore, the larger aerosols were generated, and 108% more deposition of aerosols than the natural settlement case were achieved.

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Quantitative evaluation of laser-induced fluorescence in magnetized low-pressure argon plasma

et al. 2021

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A new quantitative evaluation of tunable diode laser induced fluorescence (TDLIF) measurements in magnetized plasma is presented in this article, taking into account Zeeman splitting of energetic levels as well as inter- and intra-multiplet mixing, defining the density distribution (alignment) of the excited 2p8 multiplet of argon. TDLIF measurements were used to evaluate light-transport properties in a strongly magnetized optically thick argon plasma under different pressure conditions. Therefore, a coupled system of rate balance equations was constructed to describe laser pumping of individual magnetic sub-levels of the 2p8 state through frequency-separated sub-transitions originating from 1s4 magnetic sub-levels. The density distribution of the 2p8 multiplet was described by balancing laser pumping with losses, including radiative decay, transfer of excitation between the neighboring levels within the 2p8 multiplet driven by neutral collisions, and quenching due to electron and neutral collisions. Resulting 2p8 magnetic sub-level densities were then used to model polarization dependent fluorescence, considering self-absorption, which could be directly compared with measured polarization-resolved TDLIF measurements. The achieved results enable to obtain unique solutions for the 1s4 and 1s5 magnetic sub-level densities which were found to be in good agreement with the densities obtained by laser absorption measurements. It is shown that polarization resolved TDLIF measurements in magnetized plasma conditions have strong pressure dependence. The effective disalignment rate constant which redistributes the 2p8 sub-levels among each other has to be considered for a correct description of the TDLIF. This rate is dependent on the neutral gas density and a specific rate coefficient. With the presented method, 1s state densities involved in the TDLIF can be determined without any absolute intensity calibration in an optically thick plasma. Additionally, the presented measurement method and model can help to further understand and improve the description of optical emission of argon based on individual sub-transition descriptions under magnetized conditions.

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Optical properties of magnetized transient low-pressure plasma

Cited by 9 publications

References 29 publications

Disalignment rate coefficient of argon $\mathrm{2p_8}$ due to nitrogen collision

Disalignment rate coefficient of argon $\mathrm{2p_8}$ due to nitrogen collision

Deposition of charged aerosols by E × B enhanced low‐temperature plasma jet array

Quantitative evaluation of laser-induced fluorescence in magnetized low-pressure argon plasma

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