Nikita Bibinov

Ruhr-Universität Bochum, Bochum, North Rhine-Westphalia, Germany

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Publications (61)100.53 Total impact

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    ABSTRACT: Cold atmospheric pressure plasmas are a promising alternative therapy for treatment of chronic wounds, as they have already shown in clinical trials. In this study an air dielectric barrier discharge (DBD) developed for therapeutic use in dermatology is characterized with respect to the plasma produced reactive oxygen species, namely atomic oxygen and ozone, which are known to be of great importance to wound healing. To understand the plasma chemistry of the applied DBD, xenon-calibrated two-photon laser-induced fluorescence spectroscopy and optical absorption spectroscopy are applied. The measured spatial distributions are shown and compared to each other. A model of the afterglow chemistry based on optical emission spectroscopy is developed to cross-check the measurement results and obtain insight into the dynamics of the considered reactive oxygen species. The atomic oxygen density is found to be located mostly between the electrodes with a maximum density of &${{n}_{\text{O}}}=6\times {{10}^{16}}$ ; cm&$^{-3}$ ;. Time resolved measurements reveal a constant atomic oxygen density between two high voltage pulses. The ozone is measured up to 3 mm outside the active plasma volume, reaching a maximum value of &${{n}_{{{\text{O}}_{3}}}}=3\times {{10}^{16}}$ ; cm&$^{-3}$ ; between the electrodes.
    Journal of Physics D Applied Physics 06/2015; 48(27). DOI:10.1088/0022-3727/48/27/275203 · 2.52 Impact Factor
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    ABSTRACT: A capacitively coupled plasma driven at a frequency of 81.36 MHz from the VHF-band is investigated by means of optical emission spectroscopy (OES) and multipole resonance probe (MRP). The discharge is operated with hydrogen, yielding an electropositive discharge, as well as oxygen, yielding an electronegative discharge, and mixtures of both. Pressure is varied from &$p=5$ ; Pa to &$p=25$ ; Pa. Homogeneity of the discharge is investigated by CCD camera recordings as well as spatially resolved multipole resonance probe measurements. The results indicate the presence of electromagnetic edge effects as well as standing wave effects. Furthermore, a largely homogeneous discharge can be achieved with hydrogen as process gas at a pressure of &$p=5$ ;–10 Pa. With increasing pressure as well as with increasing oxygen content, the discharge appears less homogeneously. The transition from an electropositive to an electronegative discharge leads to a change in electron heating mechanisms, with pronounced local maxima of electron density at the sheath edges. A comparison of OES and MRP results reveal a significant difference in electron density, which can be explained by a non-Maxwellian distribution function of electrons.
    Plasma Sources Science and Technology 05/2015; 24(3). DOI:10.1088/0963-0252/24/3/034014 · 3.06 Impact Factor
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    ABSTRACT: Plasmoids are produced in the argon filamentary discharge. By going through hydrocarbon gas, the plasmoids collect carbon material. These plasmoids produce diamond single micro-crystals upon contact on the inner surface of cavity in air atmosphere. When the plasmoid's contact point on the substrate is in inert atmosphere, they deposit their material as micro-balls with a graphite core. The dimension and nature of the micro-materials deposited by the plasmoids are analysed using scanning electron microscopy and Raman microspectroscopy. The compressive residual stress in the deposited micro-diamonds varies in the range??7 to??21?GPa.
    Journal of Physics D Applied Physics 02/2015; 48(11):115201. DOI:10.1088/0022-3727/48/11/115201 · 2.52 Impact Factor
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    ABSTRACT: In this manuscript we show fascinating properties of plasmoids, which are known to be self-sustained plasma entities, and can exist without being in contact with any power supply. Plasmoids are produced in a filamentary discharge in a Ar/CH4 mixture with a high production rate of about 10(5) s(-1). It is observed that plasmoids etch the solid amorphous hydrocarbon film with high efficiency. Energy density of the plasmoid, which is estimated on the basis of glowing area of plasmoids in the photographic image and sublimation enthalpy of the etched hydrocarbon film, amounts to about 90 J m(-3). This value is much lower than the energy density of observed ball lightning (natural plasmoid). A very surprising property is an attraction between plasmoids, and the formation of plasmoid-groups. Because of this attractive force, carbon material, which is collected in plasmoids by etching of the hydrocarbon film or by propagation through a methane/argon gas mixture, is compressed into crystals.
    Journal of Physics D Applied Physics 10/2014; 47:455203. DOI:10.1088/0022-3727/47/45/455203 · 2.52 Impact Factor
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    ABSTRACT: Thin plasma filaments are produced by the propagation of ionization waves from a spiked driven electrode in a quartz tube in an argon/methane gas mixture (2400 sccm/2 sccm) at atmospheric pressure. The position of the touch point of filaments on the substrate surface is controlled in our experiment by applying various suitable substrate configurations and geometries of the grounded electrode. The gas conditions at the touch point are varied from argon to ambient air. Based on microphotography and discharge current waveforms, the duration of the filament touching the substrate is estimated to be about one microsecond. Carbon-based materials are deposited during this time at the touch points on the substrate surface. Micro-balls are produced if the filament touch points are saved from ambient air by the argon flow. Under an air admixture, micro-crystals are formed. The dimension of both materials is approximately one micrometre (0.5–2 µm) and corresponds to about 1010–1012 carbon atoms. Neither the diffusion of neutral species nor drift of ions can be reason for the formation of such a big micro-material during this short period of filament–substrate interaction. It is possible that charged carbon-based materials are formed in the plasma channel and transported to the surface of the substrate. The mechanism of this transport and characterization of micro-materials, which are formed under different gas conditions in our experiment, will be studied in the future.
    Journal of Physics D Applied Physics 07/2014; 47:315203. DOI:10.1088/0022-3727/47/31/315203 · 2.52 Impact Factor
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    ABSTRACT: The adhesion of thin CVD films on polyolefins is often critical due to the low surface free energy of the polymers. In this study, injection moulded PP samples are produced and investigated. The samples are treated in very well-characterized pulsed plasmas before a HMDSO-based coating is applied. The resulting bond strength is analyzed using pull-off tests. The fractured interfaces are characterized with XPS. Oxygen and argon plasma pre-treatments of the PP samples result in a bond strength improvement by a factor of about 2. Comparing oxygen and argon pre-treatments at equal ion fluences to the surface, it can be shown that the bond strength between CVD-coating and polymer is similar.
    Plasma Processes and Polymers 05/2014; 11(5). DOI:10.1002/ppap.201300128 · 2.96 Impact Factor
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    ABSTRACT: An argon/nitrogen (0.999/0.001) filamentary pulsed discharge operated at atmospheric pressure in a quartz tube is characterized using voltage-current measurements, microphotography, optical emission spectroscopy (OES) and absorption spectroscopy. Nitrogen is applied as a sensor gas for the purpose of OES diagnostic. The density of argon metastable atoms Ar(3P2) is determined using tunable diode laser absorption spectroscopy (TDLAS). Using a plasma chemical model the measured OES data are applied for the characterization of the plasma conditions. Between intense positive pulses the discharge current oscillates with a damped amplitude. It is established that an electric current flows in this discharge not only through a thin plasma filament that is observed in the discharge image but also through the whole cross section of the quartz tube. A diffuse plasma fills the quartz tube during a time between intense current pulses. Ionization waves are propagating in this plasma between the spike and the grounded area of the tube producing thin plasma channels. The diameter of these channels increases during the pause between the propagation of ionization waves probably because of thermal expansion and diffusion. Inside the channels electron densities are ~21013 cm-3 , argon metastable densities ~1014 cm-3 and a reduced electric field about 10 Td are determined.
    Journal of Physics D Applied Physics 11/2013; 46(46):464009. DOI:10.1088/0022-3727/46/46/464009 · 2.52 Impact Factor
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    ABSTRACT: An AC discharge is ignited with the frequency of 170 kHz at the tip of a sharpened electrode in He-N2 gas mixture under atmospheric pressure. Plasma parameters (electron density and reduced electric field) are determined using phase resolved optical emission spectroscopy. An absolutely calibrated ICCD camera with an appropriate filter is used for the time and space resolved measurement of N2(C-B,0-2) as well as N2 +(B-X,0-0) emissions. From the temporal and spatial distributions of these emission bands, time and space resolved plasma parameters are determined. Limits of time and space resolutions of this diagnostic method are discussed.
    Journal of Physics D Applied Physics 11/2013; 46(46):464012. DOI:10.1088/0022-3727/46/46/464012 · 2.52 Impact Factor
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    ABSTRACT: A widely used plastic for packaging, polyethylene terephtalate (PET) offers limited barrier properties against gas permeation. For many applications of PET (from food packaging to micro electronics) improved barrier properties are essential. A silicon oxide barrier coating of PET foils is applied by means of a pulsed microwave driven low-pressure plasma. While the adjustment of the microwave power allows for a control of the ion production during the plasma pulse, a substrate bias controls the energy of ions impinging on the substrate. Detailed analysis of deposited films applying oxygen permeation measurements, x-ray photoelectron spectroscopy and atomic force microscopy are correlated with results from plasma diagnostics describing the deposition process. The influence of a change in process parameters such as gas mixture and substrate bias on the gas temperature, electron density, mean electron energy, ion energy and the atomic oxygen density is studied. An additional substrate bias results in an increase in atomic oxygen density up to a factor of 6, although plasma parameter such as electron density of ne = 3.8 ± 0.8 × 1017 m−3 and electron temperature of kBTe = 1.7 ± 0.1 eV are unmodified. It is shown that atomic oxygen densities measured during deposition process higher than nO = 1.8 × 1021 m−3 yield in barrier films with a barrier improvement factor up to 150. Good barrier films are highly cross-linked and show a smooth morphology.
    Journal of Physics D Applied Physics 02/2013; 46(8):084013. DOI:10.1088/0022-3727/46/8/084013 · 2.52 Impact Factor
  • S Bienholz, N Bibinov, P Awakowicz
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    ABSTRACT: A novel large area multiple frequency coupled plasma is introduced for sputter deposition purposes. The discharge is driven by three different excitation frequencies (13.56, 27.12 and 60 MHz) simultaneously for advanced control of Ar ion flux and energy at the target by applying the electrical asymmetry effect during sputter processes. Optical emission spectroscopy is performed to characterize the sputter plasma with respect to plasma parameters as well as the Al transport through the plasma. The spectroscopic data are compared with TRIDYN calculation in combination with a simulation of the transport of atoms through the plasma volume.
    Journal of Physics D Applied Physics 02/2013; 46(8):084010. DOI:10.1088/0022-3727/46/8/084010 · 2.52 Impact Factor
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    ABSTRACT: Low-pressure plasmas offer a rapid and efficient option for sterilization of pharmaceutical and medical objects. First commercial plasma sterilization reactors are approved by European Medicines Agency (EMA).1 On short time scales UV/VUV radiation was shown to be the main sterilization mechanism. In order to inactive heterogeneous contamination of microorganisms (i.e., multilayer arrangements of vegetative cells and bacterial endospores) sufficient etching is needed for plasma sterilization.
    Plasma Science (ICOPS), 2013 Abstracts IEEE International Conference on; 01/2013
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    ABSTRACT: form only given. As Plasma is known to be very effective against bacteria, spores, fungi and macromolecules, a setup was developed to meet commercial needs. In order to keep sterilized goods sterile after plasma treatment, the discharge chamber can serve as sterile container. This required using a polymer discharge chamber. Since polymer and plasma interact, the plasma composition is strongly influenced by contaminated chamber walls. To study the effects and characterize the plasma, absolutely calibrated optical emission spectroscopy, Langmuir probe measurements, multipole resonance probe measurements and mass spectrometry were performed. The results were linked to biological experiments proving the effectiveness of the setup and improving understanding of sterilization and decontamination mechanisms. The experiments revealed some drawbacks due to plasma-wall interaction, but also possibilities to use the contamination for optimization of the sterilization process.
    Plasma Science (ICOPS), 2013 Abstracts IEEE International Conference on; 01/2013
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    ABSTRACT: For electrosurgical procedures, the argon plasma coagulation (APC) discharge is a well-established atmospheric-pressure plasma tool for thermal haemostasis and devitalization of biological tissue. To characterize this plasma source, voltage–current measurements, microphotography, optical emission spectroscopy and numerical simulation are applied. Two discharge modes are established during the operation of the APC plasma source. A short transient spark discharge is ignited within the positive half period of the applied high voltage after a streamer channel connects the APC probe and the counter-electrode. During the second phase, which continues under negative high voltage, a glow discharge is stabilized in the plasma channel.
    Journal of Physics D Applied Physics 12/2012; 46(2):025402. DOI:10.1088/0022-3727/46/2/025402 · 2.52 Impact Factor
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    ABSTRACT: A hard hydrocarbon film is deposited on the inner surface of glass tubes using a filamentary discharge at atmospheric pressure in Ar–C 2 H 2 –H 2 and Ar–CH 4 mixtures. Under similar conditions, a soft film is deposited with a high deposition rate in an Ar–C 2 H 2 mixture. These differences in film hardness and deposition rate are interpreted on the basis of carbon and hydrogen elemental composition in the plasma. The deposition rate is varied along the axis of the tubes in the Ar–C 2 H 2 –H 2 plasma. This can be controlled by controlling the substrate (tube) temperature. Chemical erosion of the deposited film by hydrogen atoms is the probable reason for this effect. The plasma conditions (gas temperature, electron distribution function and electron density) are characterized by applying optical emission spectroscopy (OES), microphotography and numerical simulation for all three gas mixtures. The density of hydrogen atoms in the inter-electrode region of the tube is determined by applying OES in all gas mixtures. The rates of precursor molecule excitation and follow-up plasma-chemical reactions are calculated on the basis of the determined plasma parameters. Correlations between plasma conditions and film properties are discussed. (Some figures may appear in colour only in the online journal)
    Journal of Physics D Applied Physics 08/2012; 45(45):335202-11. DOI:10.1088/0022-3727/45/33/335202 · 2.52 Impact Factor
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    ABSTRACT: A hard hydrocarbon film is deposited on the inner surface of glass tubes using a filamentary discharge at atmospheric pressure in Ar–C 2 H 2 –H 2 and Ar–CH 4 mixtures. Under similar conditions, a soft film is deposited with a high deposition rate in an Ar–C 2 H 2 mixture. These differences in film hardness and deposition rate are interpreted on the basis of carbon and hydrogen elemental composition in the plasma. The deposition rate is varied along the axis of the tubes in the Ar–C 2 H 2 –H 2 plasma. This can be controlled by controlling the substrate (tube) temperature. Chemical erosion of the deposited film by hydrogen atoms is the probable reason for this effect. The plasma conditions (gas temperature, electron distribution function and electron density) are characterized by applying optical emission spectroscopy (OES), microphotography and numerical simulation for all three gas mixtures. The density of hydrogen atoms in the inter-electrode region of the tube is determined by applying OES in all gas mixtures. The rates of precursor molecule excitation and follow-up plasma-chemical reactions are calculated on the basis of the determined plasma parameters. Correlations between plasma conditions and film properties are discussed. (Some figures may appear in colour only in the online journal)
    Journal of Physics D Applied Physics 08/2012; 45(45):335202-11. · 2.52 Impact Factor
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    Dataset: mypaper2
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    ABSTRACT: A non-calibrated spectrometer is used for quantitative characterization of a dielectric barrier discharge (DBD) in air wherein optical emission spectroscopy (OES) is completed by current measurement and numerical simulation. This diagnostic method is applicable when the cross-sectional area of the active plasma volume and the current density can be determined. The nitrogen emission in the spectral range of 330–406 nm is used for OES diagnostics. The electric field in the active plasma volume is determined by applying the measured spectrum, well-known Franck–Condon factors for nitrogen transitions and numerically simulated electron distribution functions. The measured electric current density is used for the determination of electron density in plasma. Using the determined plasma parameters, the dissociation rates of nitrogen and oxygen in active plasma volume are calculated, which can be used for the simulation of chemical kinetics.
    Measurement Science and Technology 08/2012; 23(8). DOI:10.1088/0957-0233/23/8/085605 · 1.35 Impact Factor
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    ABSTRACT: For the first time, a commercial low pressure plasma sterilization system integrated in a pharmaceutical filling line is presented. The route from a laboratory plasma reactor to an industry scale plasma sterilization reactor is shown. Absolutely calibrated measurements (e.g. OES and Langmuir probe) yield to a knowledge transfer from an experimental set-up to an industrial reactor. Spore count reduction of 4 log in 10 s of Geobacillus stearothermophilus and Bacillus subtilis spores prove the applicability of an industrial grade plasma sterilization reactor for transfer isolators typically used in pharmaceutical filling and packaging lines.
    Plasma Processes and Polymers 06/2012; 9(6-6):619-629. DOI:10.1002/ppap.201100211 · 2.96 Impact Factor
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    ABSTRACT: Microplasma jet for the generation of pulsed fi lamentary discharge at atmospheric pressure has been devised for biological decontamination as well as for modifi cation of surface properties. Long plasma-fi lament is generated inside a quartz tube and characterized using optical emission spectroscopy, current voltage measurements, numerical simulations and microphotography. Effi ciency of our plasma source for the decontamination on inner surface of the tube as well as on objects placed in proximity of plasma effl uent is studied. Escherichia coli (Gram-negative bacteria) and spores of Bacillus atrophaeus (Gram-positive bacteria) are used for the decontamination studies. Decontamination of Bacillus atrophaeus endospores, which are layered on PET polymer material, and placed in the proximity of plasma effl uent, shows the mean logarithmic bacterial reduction of 3.67 for the treatment time of 120 s. Inactivation of Escherichia coli coated on inner surface of the tube shows the mean logarithmic bacterial reduction of about 5 for the treatment time of 30 s. In addition to this, inhibition studies of bacteria coated on agar plate are also carried out. It shows plasma effl uent generated in our plasma source is very effective for the inhibition of bacterial colonization.
    Plasma for Bio-Decontamination, Medicine and Food Security, 04/2012: chapter 4: pages 45-55; Springer., ISBN: 978-94-007--2851-6
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    Chemical Kinetics, 02/2012; , ISBN: 978-953-51-0132-1