Nikita Bibinov

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

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Publications (57)94.44 Total impact

  • Journal of Physics D Applied Physics 10/2014; 47:455203. · 2.53 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. · 2.53 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 03/2014; · 3.73 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. · 2.53 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. · 2.53 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.
    Journal of Physics D Applied Physics 02/2013; 46(8):084010. · 2.53 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. · 2.53 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. · 2.53 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. · 2.53 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. · 2.53 Impact Factor
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    Dataset: mypaper2
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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
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    ABSTRACT: Dielectric barrier discharge (DBD) in air is characterized applying current measurement, numerical simulation and optical emission spectroscopy (OES). For OES, a non-calibrated spectrometer is used. This diagnostic method is applicable when cross-sectional area of the active plasma volume and current density can be determined. The nitrogen emission in the spectral range of 380 nm- 406 nm is used for OES diagnostics. Electric field in the active plasma volume is determined applying the measured spectrum, well-known Frank-Condon factors for nitrogen transitions and numerically- simulated electron distribution functions. The measured electric current density is used for determination of electron density in plasma. Using the determined plasma parameters, the dissociation rate of nitrogen and oxygen in active plasma volume are calculated, which can be used by simulation of the chemical kinetics.
    02/2012;
  • Plasma Medicine. 01/2012; 2(1-3):151-168.
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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 01/2012; 23(8). · 1.44 Impact Factor
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    ABSTRACT: form only given. Plasma sterilization is known to be a promising alternative to common sterilization methods. Although lots of effort has been taken to investigate low-pressure plasma sterilization systems, only little effort has been taken to bring plasma sterilization to market. In this contribution we will present a plasma sterilization prototype for use in medical practice. The prototype is a further development of an experimental model. The experimental model was investigated and characterized with absolutely calibrated optical emission spectroscopy among other, in order to obtain the plasma parameters Te and ne, as well as particle fluxes and UV doses for different discharge parameters, such as different process gases and mixtures, and treatment times. In order to improve the plasma sterilization process, a detailed knowledge of the sterilization mechanisms is indispensible. Hence, the impact of plasma was investigated on a macromolecular level. Therefore, the model proteins BSA and AhpF were treated with different process gases and mixtures, namely hydrogen, oxygen, and a mixture of both, as well as different treatment times. Before and after treatment, the samples were investigated with gel electrophoresis. The results obtained with gel electrophoresis help us to understand and to optimize the sterilization process, particularly with regard to process gas and treatment time that should be applied. As a proof of concept sterilization tests were performed with spores of Geobacillus stearothermophilus on glass slides. The glass slides were contaminated with 106 spores. Full spore inactivation could be achieved within 60 s of plasma treatment. Furthermore, 3D objects were tested with similar results.
    Plasma Science (ICOPS), 2012 Abstracts IEEE International Conference on; 01/2012
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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 01/2012; 9(6):619-629. · 3.73 Impact Factor