Atomic oxygen densities in a downstream microwave O<sub>2</sub>/Ar plasma source

Ершов, А. П.; Borysow, Jacek

doi:10.1088/0963-0252/16/4/015

Cited by 10 publications

(10 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Since both species are bombarded by the same electron distribution and the concentration of the actinometer is known, the density of the sample can be calculated. To determine the concentration of the ground state oxygen atoms, O (3s 3 P − 3p 3 S) 844 nm and Ar (3p 5 4p (2p 1 ) − 3p 5 4s (1s 2 )) 750.4 nm transitions were chosen and the dissociation fraction can be determined by calculating the ratio 42 45 46 . Here, n l is the number density of ground species l , is the intensity of emission from excited species l for the transition i → j , is the Einstein coefficient, is the spectral response of the system, and is the frequency of the light emission.…”

Section: Resultsmentioning

confidence: 99%

Effect of additive oxygen gas on cellular response of lung cancer cells induced by atmospheric pressure helium plasma jet

Joh

Choi

Kim

et al. 2014

Sci Rep

View full text Add to dashboard Cite

The atmospheric pressure helium plasma jet driven by pulsed dc voltage was utilized to treat human lung cancer cells in vitro. The properties of plasma plume were adjusted by the injection type and flow rate of additive oxygen gas in atmospheric pressure helium plasma jet. The plasma characteristics such as plume length, electric current and optical emission spectra (OES) were measured at different flow rates of additive oxygen to helium. The plasma plume length and total current decreased with an increase in the additive oxygen flow rate. The electron excitation temperature estimated by the Boltzmann plot from several excited helium emission lines increased slightly with the additive oxygen flow. The oxygen atom density in the gas phase estimated by actinometry utilizing argon was observed to increase with the additive oxygen flow. The concentration of intracellular reactive oxygen species (ROS) measured by fluorescence assay was found to be not exactly proportional to that of extracellular ROS (measured by OES), but both correlated considerably. It was also observed that the expression levels of p53 and the phospho-p53 were enhanced in the presence of additive oxygen flow compared with those from the pure helium plasma treatment.

show abstract

Section: Resultsmentioning

confidence: 99%

Effect of additive oxygen gas on cellular response of lung cancer cells induced by atmospheric pressure helium plasma jet

Joh

Choi

Kim

et al. 2014

Sci Rep

View full text Add to dashboard Cite

show abstract

“…One of the most important initial conditions for the numerical simulations was the concentration of atomic oxygen. To find what concentrations existed in the experiments, an NO 2 titration technique was adopted [47]. The NO 2 was added to the plasma afterglow at the same location of NO injection, approximately 5 ms downstream of the plasma.…”

Section: Reactionmentioning

confidence: 99%

Flame propagation enhancement by plasma excitation of oxygen. Part II: Effects of O2(a1Δg)

Ombrello

Won

et al. 2010

Combustion and Flame

207

113

View full text Add to dashboard Cite

a b s t r a c tThe isolated effect of O 2 (a 1 D g ) on the propagation of C 2 H 4 lifted flames was studied at reduced pressures (3.61 kPa and 6.73 kPa). The O 2 (a 1 D g ) was produced in a microwave discharge plasma and was isolated from O and O 3 by NO addition to the plasma afterglow in a flow residence time on the order of 1 s. The concentrations of O 2 (a 1 D g ) and O 3 were measured quantitatively through absorption by sensitive off-axis integrated-cavity-output spectroscopy and one-pass line-of-sight absorption, respectively. Under these conditions, it was found that O 2 (a 1 D g ) enhanced the propagation speed of C 2 H 4 lifted flames. Comparison with the results of enhancement by O 3 found in part I of this investigation provided an estimation of 2-3% of flame speed enhancement for 5500 ppm of O 2 (a 1 D g ) addition from the plasma. Numerical simulation results using the current kinetic model of O 2 (a 1 D g ) over-predicts the flame propagation enhancement found in the experiments. However, the inclusion of collisional quenching rate estimations of O 2 (a 1 D g ) by C 2 H 4 mitigated the over-prediction. The present isolated experimental results of the enhancement of a hydrocarbon fueled flame by O 2 (a 1 D g ), along with kinetic modeling results suggest that further studies of C n H m + O 2 (a 1 D g ) collisional and reactive quenching are required in order to correctly predict combustion enhancement by O 2 (a 1 D g ). The present experimental results will have a direct impact on the development of elementary reaction rates with O 2 (a 1 D g ) at flame conditions to establish detailed plasma-flame kinetic mechanisms.

show abstract

“…Work done by previous authors has shown that application of the actinometry method does not always yield results that reflect the true atomic oxygen number density in the plasma. The validity of actinometry for atomic oxygen has been investigated for various plasma sources: RF capacitive plasma [14,15,16], ECR source [17], DC glow discharge [18], microwave source [19,20], helicon source [21], inductive source [22], and micro-scale atmospheric pressure jet source [23]. Walkrup et al [14] investigated the validity of actinometry for atomic oxygen in RF capacitive plasmas containing both pure O 2 and O 2 /CF 2 mixtures by examining line emission intensity ratios.…”

Section: Introductionmentioning

confidence: 99%

“…Again they found that the method works best for the O * (844)/Ar * (811.5) emission ratio particularly if the dissociation fraction was greater than a few per cent. Ershov et al [20] investigated atomic oxygen actinometry in an Ar/O 2 , 2.45 GHz microwave source and used downstream NO 2 gas titration to measure [O] for comparison. They concluded that actinometry using the O * (844)/Ar * (750) emission ratio was valid for modest Ar/O 2 flow ratios (smaller than 2) when the total pressure in their system exceeded 1 Torr while the O * (777)/Ar * (750) ratio gave misleading results.…”

Section: Introductionmentioning

confidence: 99%

Use of particle-in-cell simulations to improve the actinometry technique for determination of absolute atomic oxygen density

Conway

Kechkar

Connor

et al. 2013

Plasma Sources Sci. Technol.

View full text Add to dashboard Cite

Actinometry is a non-invasive optical technique that can be used to quantitatively monitor atomic oxygen number densities [O] in gas discharges under certain operating conditions. However, careless application of the technique can lead to erroneous conclusions regarding the behaviour of atomic oxygen in plasma. One limitation on this technique is an accurate knowledge of the various rate constants required, which in turn is hampered by an insufficiently precise knowledge of the Electron Energy Distribution Function (EEDF) in the plasma. In this work Particle in Cell (PIC) simulations have been used to generate theoretical EEDFs. To validate a simulation the electron density n e produced by the PIC code is compared to experimental n e values measured using a hairpin probe. The PIC input parameters are adjusted to optimise agreement between the PIC and experimental n e results. This approach should in principle yield an EEDF that more accurately reflects the true EEDF in the plasma. The PIC EEDF is then used to generate rate constants for the actinometry model which should improve the accuracy of the quantitative [O] result for that particular set of plasma conditions. The actinometry [O] results are then compared to [O] results obtained using Two-photon Absorption Laser Induced Fluorescence (TALIF) to validate the approach.

show abstract

Atomic oxygen densities in a downstream microwave O₂/Ar plasma source

Cited by 10 publications

References 19 publications

Effect of additive oxygen gas on cellular response of lung cancer cells induced by atmospheric pressure helium plasma jet

Effect of additive oxygen gas on cellular response of lung cancer cells induced by atmospheric pressure helium plasma jet

Flame propagation enhancement by plasma excitation of oxygen. Part II: Effects of O2(a1Δg)

Use of particle-in-cell simulations to improve the actinometry technique for determination of absolute atomic oxygen density

Contact Info

Product

Resources

About

Atomic oxygen densities in a downstream microwave O2/Ar plasma source

Cited by 10 publications

References 19 publications

Effect of additive oxygen gas on cellular response of lung cancer cells induced by atmospheric pressure helium plasma jet

Effect of additive oxygen gas on cellular response of lung cancer cells induced by atmospheric pressure helium plasma jet

Flame propagation enhancement by plasma excitation of oxygen. Part II: Effects of O2(a1Δg)

Use of particle-in-cell simulations to improve the actinometry technique for determination of absolute atomic oxygen density

Contact Info

Product

Resources

About

Atomic oxygen densities in a downstream microwave O₂/Ar plasma source