Ultrashort pulsed barrier discharges and applications

Okazaki, Ken; Nozaki, Tomohiro

doi:10.1351/pac200274030447

Cited by 63 publications

(30 citation statements)

References 12 publications

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“…By comparison with the classical low pressure plasma processing, the DBD technique has several advantages, as working at atmospheric pressure in various geometries, inducing homogenous and efficient treatment due to the chemical active species present in the volume of plasma and near the surface, exposure of the sample to minimum thermal stress, low cost and easy to implement in industrial processing [7,8].…”

Section: Introductionmentioning

confidence: 99%

Influence of Plasma Treatments on the Hemocompatibility of PET and PET + TiO2 Films

Topală

Dumitrascu

Pohoaţǎ

2006

Plasma Chem Plasma Process

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A dielectric barrier discharge (DBD) in helium was used to ameliorate the interface between the blood and the surface of polymeric implants: polyethylene terephthalate (PET) and PET with titanium oxide (PET + TiO 2 ).A higher crystallinity degree was found for the DBD treated samples. The wettability of polymers was improved after the treatment. The chemical composition, analyzed by infrared spectroscopy was preserved during the DBD treatment. The surface modifications have been correlated with polymers hemocompatibility. Concerning the polymer surface-blood interaction, the treatment induced a decrease of the interfacial tension between the blood components and the treated surfaces. The in vitro tests of hemocompatibility showed no perturbation in the blood composition when the polymer samples are present in the blood volume. An interesting result is related to the whole blood clotting time that shows a dramatic increase on the treated surfaces. Moreover, the coagulation kinetics on the treated surfaces is modified.

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Section: Introductionmentioning

confidence: 99%

Influence of Plasma Treatments on the Hemocompatibility of PET and PET + TiO2 Films

Topală

Dumitrascu

Pohoaţǎ

2006

Plasma Chem Plasma Process

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“…Among them are the dielectric-barrier discharges (DBD) and alternatingcurrent corona discharges, which are known to achieve highly nonequilibrium conditions [12]- [19]. A DBD is an ac-driven discharge that, in most conditions, produces pulsed microstreamers.…”

Section: Introductionmentioning

confidence: 99%

“…A DBD is an ac-driven discharge that, in most conditions, produces pulsed microstreamers. Okazaki and Nozaki [12] and Cha et al [16] used a DBD to reduce the concentration of NO X , SO X , and soot produced by combustion. Starikovskii [15], Mintoussov et al [17], and Starikovskaia et al [18] implemented the nanosecond pulsed streamer discharge characteristic of the DBD to increase flame stability.…”

Section: Introductionmentioning

confidence: 99%

Plasma-Discharge Stabilization of Jet Diffusion Flames

Kim

Mungal

et al. 2006

IEEE Trans. Plasma Sci.

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Abstract-The authors examine three different types of plasma discharges in their ability to stabilize a lifted jet diffusion flame in coflow. The three discharges include a single-electrode corona discharge, an asymmetric dielectric-barrier discharge (DBD), and a repetitive ultrashort-pulsed discharge. The degree of nonequilibrium of this pulsed discharge is found to be higher than that for the DBD. Furthermore, this pulsed discharge causes the most significant improvement in the flame stability. The optimal placement of the discharge electrodes is investigated, and it is found that there is a close relation between this placement and the emission spectra, suggesting use of the emission spectra as a possible indicator of fuel/air mixture fraction. The optimal placement is mapped into mixture-fraction space by use of a fully premixed flame experiment of known mixture fraction. The result shows that the mixture fraction, which corresponds to the optimal placement, is much leaner than that of a conventional lifted jet flame.

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“…Among these are the dielectric barrier discharges (DBD), which are known to achieve highly nonequilibrium conditions. [12][13][14][15][16][17][18] Nonequilibrium corona discharges have also been implemented with a fair degree of success. 19 These types of discharges have the advantages of being relatively simple to integrate into a combustion experiment, are of relatively low cost, and introduce minimal electromagnetic interference.…”

Section: Introductionmentioning

confidence: 99%

Flame Stabilization Enhancement and NOx Production using Ultra Short Repetitively Pulsed Plasma Discharges

Kim

2006

44th AIAA Aerospace Sciences Meeting and Exhibit

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This paper examines the use of plasma discharges in flame stabilization. Three different types of plasma discharges are applied to a lifted jet diffusion flame in a coflow configuration, and evaluated for their abilities to enhance flame stabilization. A single electrode corona discharge (SECD) between a platinum electrode and the flame base is found to maintain the flame at a 20% higher coflow speed than that without the discharge. An asymmetric dielectric barrier discharge (DBD) results in flame stabilization at up to 50% higher coflow speed. The nonequilibrium properties of the DBD are characterized by a spectral line analysis and simulation of the nitrogen 2 nd positive system. Finally, an ultra short repetitively-pulsed discharge (USRD, pulse width of ~10ns) is used in an opposed platinum electrode configuration and found to increase in the stability limit by nearly tenfold. The degree of nonequilibrium of this pulsed discharge is found to be higher than that of the DBD. The stabilization process is sensitive to the positioning of the discharge in the flame flow field, and the optimal position of the discharge is mapped into mixture fraction space by comparing the emission spectra from the plasma-stabilized flame to that in a fully premixed reference flame. The result shows that the local mixture fraction at the optimal position is much leaner than that of a conventional lifted jet flame. In a second part of this study, the USRD is used to stabilize lean premixed methane flames. Nitric Oxide (NO) production is measured using probe sampling and chemiluminescence analysis. While the discharge is a potential source of NO, it is found that the flame partially consumes NO in a reburn mode. The NO production is modeled by use of PLASMAREACTOR followed by the standard PREMIX code. The modeling results show some promise in its ability to predict NO concentration. The flame structure of plasma assisted premixed combustion is also discussed. Under certain conditions, we observe a cold inner flame that has an abundance of OH radicals which have an unusually high vibrational temperature with low rotational temperature when compared to the OH found in a conventional lean premixed flame. While the role of the OH in this inner flame is not fully understood, we believe it may be important in igniting the surrounding combustible mixture.

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Ultrashort pulsed barrier discharges and applications

Cited by 63 publications

References 12 publications

Influence of Plasma Treatments on the Hemocompatibility of PET and PET + TiO2 Films

Influence of Plasma Treatments on the Hemocompatibility of PET and PET + TiO2 Films

Plasma-Discharge Stabilization of Jet Diffusion Flames

Flame Stabilization Enhancement and NOx Production using Ultra Short Repetitively Pulsed Plasma Discharges

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