Dynamics of atomic kinetics in a pulsed positive-column discharge at 100 Pa

Franek, James B.; Nogami, S.H.; Koepke, M. E.; Demidov, V. I.; Barnat, Edward V.

doi:10.1088/0741-3335/59/1/014005

Cited by 4 publications

(13 citation statements)

References 13 publications

(32 reference statements)

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“…The supply is operated in current-limited mode, and experiments were performed for current limits between 2.0 and 10.0 mA. Multiple diagnostics [2,6,13] were employed to sample plasma synchronously at the same position on the cylindrical axis. A hole in the top surface of the microwave resonant cavity was utilized for collection of optical emission and holes in the sides of the cavity provided a line of sight across the plasma column for the diode laser absorption measurement.…”

Section: Methodsmentioning

confidence: 99%

“…The 420.1/419.8 nm emission line ratio is sensitive to stepwise excitation via the 420.1 nm emission and the presence of metastable atoms: initially R = 1, and the ratio will increase when a sufficient number of metastable atoms are present such that the 3p 9 state is populated by both direct and stepwise excitation. The ratio should be less than unity only in the presence of a significant population of high-energy (>30 eV) electrons, as argued in [2,3,6] and shown in [7]. Alternatively, the emission line ratio can be used in combination with the measured metastable atom density (e.g., by tunable diode laser absorption) to determine the EEDF by comparing the measured emission with the predicted emission for different EEDFs.…”

Section: Excitation Of 3p Statesmentioning

confidence: 99%

“…Another option is to use optical emission cross sections that include the branching ratio from selected higher-energy states down into the excited state of interest for the emission line ratio model. The excitation rates used in previous experiments [2,6] were calculated [3] using optical emission cross sections that accounted for the branching ratio as well as cascades into the excited state. The cascade contribution may be accounted for in the high-energy tail of the optical emission cross sections, as a function of pressure, in a procedure outlined in [7].…”

Section: Excitation Of 3p Statesmentioning

confidence: 99%

“…Passive optical diagnostics that are non-invasive and non-perturbative, like the 420.1/419.8 nm argon-emission line-height-ratio technique [2][3][4], are desirable because they can be implemented in real time and can be used to determine metastable-atom density [2,5] and effective electron temperature [4]. Emission spectra have been shown to correlate with high energy electrons [2,3,6,7]. The technique described here represents a computationally assisted argon emission line ratio technique to infer electron energy distribution and determine other plasma parameters in pulsed low-temperature plasma.…”

Section: Introductionmentioning

confidence: 99%

“…While the approximations made to obtain the final form expressed by Equation (1) are particular to the neutral argon transitions of interest, emission line pairs for neon, krypton, and xenon with similar sensitivity to the presence of metastable atoms are presented elsewhere [3] and may be used to expand the emission line ratio technique to other noble gases [8]. The utility of the 420.1/419.8 nm emission line ratio has been demonstrated in previous work [2,6]. The proximity of the two lines is an advantage, but the convenience of using closely spaced emission lines becomes a hindrance when expanding diagnostic capabilities to lower-budget or high-throughput laboratories that lack high-resolution spectrometers.…”

Section: Introductionmentioning

confidence: 99%

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A Computationally Assisted Ar I Emission Line Ratio Technique to Infer Electron Energy Distribution and Determine Other Plasma Parameters in Pulsed Low-Temperature Plasma

Franek

Nogami

Koepke

et al. 2019

Plasma

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In the post-transient stage of a 1-Torr pulsed argon discharge, a computationally assisted diagnostic technique is demonstrated for either inferring the electron energy distribution function (EEDF) if the metastable-atom density is known (i.e., measured) or quantitatively determining the metastable-atom density if the EEDF is known. This technique, which can be extended to be applicable to the initial and transient stages of the discharge, is based on the sensitivity of both emission line ratio values to metastable-atom density, on the EEDF, and on correlating the measurements of metastable-atom density, electron density, reduced electric field, and the ratio of emission line pairs (420.1–419.8 nm or 420.1–425.9 nm) for a given expression of the EEDF, as evidenced by the quantitative agreement between the observed emission line ratio and the predicted emission line ratio. Temporal measurement of electron density, metastable-atom density, and reduced electric field are then used to infer the transient behavior of the excitation rates describing electron-atom collision-induced excitation in the pulsed positive column. The changing nature of the EEDF, as it starts off being Druyvesteyn and becomes more Maxwellian later with the increasing electron density, is key to interpreting the correlation and explaining the temporal behavior of the emission line ratio in all stages of the discharge. Similar inferences of electron density and reduced electric field based on readily available diagnostic signatures may also be afforded by this model.

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Section: Methodsmentioning

confidence: 99%

Section: Excitation Of 3p Statesmentioning

confidence: 99%

Section: Excitation Of 3p Statesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

A Computationally Assisted Ar I Emission Line Ratio Technique to Infer Electron Energy Distribution and Determine Other Plasma Parameters in Pulsed Low-Temperature Plasma

Franek

Nogami

Koepke

et al. 2019

Plasma

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Application of Excitation Cross-Section Measurements to Optical Plasma Diagnostics

Boffard

Lin

Wendt

2018

Advances in Atomic, Molecular, and Optical Physics

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Ultra-high-resolution optical absorption spectroscopy of DC plasmas at low pressure using a supercontinuum laser combined with a laser line tunable filter and a HyperFine spectrometer

Durocher‐Jean

Jean-Ruel

Dion-Bertrand

et al. 2020

J. Phys. D: Appl. Phys.

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Optical absorption spectroscopy of non-equilibrium plasmas using a supercontinuum laser combined with a laser line tunable filter and a HyperFine spectrometer is examined. Owing to the <2 pm spectral resolution of the HyperFine system, details on the absorption line intensity, position and width can be obtained with very high precision using a broadband light emission source. As an example, absorption spectroscopy measurements were recorded in a reduced-pressure, nominally pure argon DC plasma column and allowed for the determination of the neutral gas temperature and the Ar 1s2 and Ar 1s4 (Paschen notation) number densities. At a pressure of 1 Torr, a discharge current of 20 mA, and an absorption length of 18 cm, the analysis of the Ar 2p3-1s2 and Ar 2p8-1s4 absorption lines at respectively 840.8 nm and 842.5 nm resulted in number densities of n 1 s 2 = 5.5 × 1015 m−3 and n 1 s 4 = 1.1 × 1016 m−3 and a neutral gas temperature of T g = 340 K. These values are typical of DC discharges operated under similar experimental conditions. While the fractional absorption of both lines decreased with decreasing optical absorption path, the number densities remained the same, as expected. Finally, the number densities increased with increasing discharge current, a result also coherent with the literature.

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Dynamics of atomic kinetics in a pulsed positive-column discharge at 100 Pa

Cited by 4 publications

References 13 publications

A Computationally Assisted Ar I Emission Line Ratio Technique to Infer Electron Energy Distribution and Determine Other Plasma Parameters in Pulsed Low-Temperature Plasma

A Computationally Assisted Ar I Emission Line Ratio Technique to Infer Electron Energy Distribution and Determine Other Plasma Parameters in Pulsed Low-Temperature Plasma

Application of Excitation Cross-Section Measurements to Optical Plasma Diagnostics

Ultra-high-resolution optical absorption spectroscopy of DC plasmas at low pressure using a supercontinuum laser combined with a laser line tunable filter and a HyperFine spectrometer

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