Plasma Physics and Technology Journal
Volume 3 (2016)

Number 1

Investigation of the Arc-Anode Attachment Area by Utilizing a High-Speed Camera

Ondac P.1,2, Maslani A.1, Hrabovsky M.1

1 Institute of Plasma Physics AS CR, Za Slovankou 1782/3, 182 00 Prague 8, Czech Republic
2 Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, V Holesovickach 2, 180 00 Prague 8, Czech Republic

The arc-anode attachment in the DC plasma arc influences power distribution in the plasma, a lifespan of anode and flow structure of plasma jet. A movement of the attachment and the surrounding plasma was directly observed by using a high-speed camera (max. 1,080,000 fps). The observations were compared with cathode-anode voltage measurements (sample rate 80 MHz). We have directly measured the average velocity of the attachments and hydrodynamic waves above them, as well as the characteristic dwell times and dwell frequencies of the attachments.

Keywords: plasma, arc, anode, attachment, camera, wave

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Diagnostics of Plasma Jet Generated in Water/Argon DC Arc Torch

Hurba O.1,2, Hlina M.1, Hrabovsky M.1

1 Institute of Plasma Physics AS CR, Za Slovankou 1782/3, 182 00 Prague 8, Czech Republic
2 Charles University in Prague, Faculty of Mathematics and Physics, Ke Karlovu 3, 121 16 Prague, Czech Republic

Thermal plasma jet generated by the torch with water/argon stabilized arc was investigated. Plasma torches of this type have been used for plasma spraying, waste treatment and gasification of organic materials. Electric probes, enthalpy probe, and schlieren photography were used for diagnostics of the jet in the region downstream of the torch exit. Information about structure and shape of plasma jet was evaluated from the measured data. Large extent of radial plasma spread and high level of turbulence were found from both the schlieren and the probe diagnostics. Plasma temperature corresponding to measured ion saturation currents was determined using calculated composition of plasma assuming ex-istence of local thermodynamic equilibrium.

Keywords: thermal plasma jet, electric probes, schlieren photography, enthalpy probe

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Semiconductor Detectors for Observation of Multi-MeV Protons and Ions Produced by Lasers

J. Krasa1, D. Klir2, M. De Marco1,5, J. Cikhardt2, A. Velyhan1, K. Rezac2,3, M. Pfeifer1, E. Krousky1, L. Ryc4, J. Dostal3, J. Kaufman1, J. Ullschmied3

1Institute of Physics of the CAS, Na Slovance 2, 121 21 Prague, Czech Republic
2Faculty of Electrical Engineering, CTU in Prague, Technicka 2, 166 27 Prague, Czech Republic
3Institute of Plasma Physics of the CAS, Za Slovankou 3, 182 00 Prague, Czech Republic
4Institute of Plasma Physics and Laser Microfusion, EURATOM Association, Warsaw, Poland
5Faculty of Nuclear Sciences and Physical Engineering, CTU in Prague, Brehova 2, 115 19 Prague, Czech Republic

The application of time-of-flight Faraday cups and SiC detectors for the measurement of currents of fast ions emitted by laser-produced plasmas is reported. Presented analysis of signals of ion detectors reflects the design and construction of the detector used. A similarity relation between output signals of ion collectors and semiconductor detectors is established. Optimization of the diagnostic system is discussed with respect to the emission time of electromagnetic pulses interfering with signals induced by the fastest ions accelerated up to velocities of 107 m/s. The experimental campaign on laser-driven ion acceleration was performed at the PALS facility in Prague.

Keywords: laser-accelerated ions, ion collectors, SiC detectors, similarity relations, electromagnetic pulse

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Fast tracking abstracts for volume 3, number 1.

Number 2

Plasma Installation for TiO2 Fine Powder Production:
Mathematical Simulation

Frolov V., Ivanov D., Shibaev M.

Peter the Great St. Petersburg Polytechnic University, Polytekhnicheskaya Str. 29, 195251, Saint Petersburg, Russian Federation

The scheme of an evaporator of TiO2 powder based on a plasma torch of combined type is presented. That scheme is characterized by reducing of the equipment cost by decreasing of RF power in comparison to application of usual ICP torches. An analysis of thermo-physical processes of plasma generation as well as heating of fine TiO2 particles is presented. The results were a basis for creating of equipment for the production of fine TiO22 materials and nanostructured TiO2 materials with lower radio frequency (RF) power consumption.

Keywords: fine powder production, inductively coupled plasma torch, arc plasma torch

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Diagnostics of Hybrid Water/Argon Thermal Plasma Jet with Water, Ethanol and Their Mixture Injection to Plasma

Hlina M.1,2, Maslani A.1, Medricky J.1, Kotlan J.1, Musalek R.1, Hrabovsky M.1

1Institute of Plasma Physics AS CR, v.v.i, Za Slovankou 1782/3, CZ-182 00 Prague 8, Czech Republic
2 Charles Univ Prague, Dept Analyt Chem, Albertov 6, CZ-12843 Prague 2, Czech Republic

A plasma torch with the water/argon stabilization of an arc is characterized by extremely hot and high velocity plasma together with the relatively low flow rate of plasma, therefore, the torch might be properly used for plasma suspension spraying. Enthalpy probe and emission spectroscopy measurements were carried out at constant arc power with the combination of the injection of water, ethanol or their mixture to the plasma jet to diagnose the changes in temperature, heat flux and other characteristics.

Keywords: plasma spraying, suspension, enthalpy probe, spectroscopy, air entrainment

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Solutioin of Poisson's Equation in Electrostatic Particle-on-cell Simulation

Kahnfeld D.1, Schneider R.1,2, Matyash K.1,2, Kalentev O.3, Kemnitz S.2,4, Duras J.5,1, Luskow K.1, Bandelow G.1 Hlina M.1,2, Maslani A.1, Medricky J.1, Kotlan J.1, Musalek R.1, Hrabovsky M.1

1Ernst-Moritz-Arndt University Greifswald, Institute of Physics, Felix-Hausdorff-Str. 6, 17487 Greifswald, Germany
2Computing Center, Ernst-Moritz-Arndt University of Greifswald, D-17498 Greifswald, Germany
3Biomedizinische NMR Forschungs GmbH am Max-Planck-Institut fur biophysikalische Chemie, D-37077 Goettingen, Germany
4University Rostock, Institute of Informatics, Albert-Einstein-Str. 22, 18059 Rostock, Germany
5Department of Applied Mathematics, Physics and Humanities, Nurnberger Institute of Technology, D-90489 Nurnberg, Germany

In electrostatic Particle-in-Cell simulations of the HEMP-DM3a ion thruster the role of different solution strategies for Poisson?s equation was investigated. The direct solution method of LU decomposition is compared to a stationary iterative method, the successive over-relaxation solver. Results and runtime of solvers were compared, and an outlook on further improvements and developments is presented.

Keywords: Particle-in-Cell, ion thrusters, Poisson?s equation, LU decomposition, successive overrelaxation

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Fast tracking abstracts for volume 3, number 2.

Number 3

Dominant Physicochemical Properties of SF6/N2 Thermal Plasmas
with a Two-temperature Chemical Kinetic Model

Wang X., Gao Q., Zhong L., Yang A., Rong M.

State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, No. 28 XianNing West Road, 710049, Xi'an, Shaanxi Province , People's Republic of China

It's increasingly clear that the existence of thermodynamic equilibrium is an exception rather than the role in SF6/N2 thermal plasmas. We intended to investigate the dominant physicochemical properties of SF6/N2 thermal plasmas at 4 atm from 12000 K to 1000 K with considering the thermal non-equilibrium. A two-temperature chemical kinetic model containing all the available reactions is developed. The temperature difference between the electron and the heavy species is defined as a function of the electron number density. The molar fractions of species are compared to the equilibrium composition predicted by Gibbs free energy minimization. By analyzing the main reactions in the generation and loss of a dominant species, the chemistry set is simplified and characterized by a few species and reactions. Then, the dominant physicochemical properties are captured and the computing time of complicated chemical kinetic model is dramatically shortened at the same time.

Keywords: SF6/N2 thermal plasmas, departures from thermal equilibrium, dominant physicochemical properties

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The Increase in Thickness Uniformity of Films Obtained by Magnetron Sputtering with Rotating Substrate

Golosov D.1, Melnikov S.1, Zavadski S.1, Kolos V.2, Okojie J.1

1Belarusian State University of Informatics and Radioelectronics, P. Brovka, 6, 220013, Minsk, Belarus
2JSC "INTEGRAL", I.P. Kazintsa, 121A, 220108 Minsk, Belarus

The titanium thin films obtained by magnetron sputtering with the rotating substrate at different distances between the substrate and magnetron centers were studied with regard to the uniformity of the film thickness distribution. On the basis of the experimental data obtained, the model for the magnetron film deposition during substrate rotation was developed. The analysis of the simulation results shows that the model error is not greater than 10%.

Keywords: magnetron sputtering, deposition rate, film thickness, nonuniformity

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Use of Computer Experiments to Study the Current Collected by Cylindrical Langmuir Probes

Tejero-del-Caz A.1, Diaz-Cabrera J. M.2, Fernandez Palop J. I.1, Ballesteros J.2

1Departamento de Fisica, Universidad de Cordoba, Campus de Rabanales, E-14071, Cordoba, Spain
2Departamento de Ingenieria Electrica, Universidad de Cordoba, Campus de Rabanales, E-14071, Cordoba, Spain

A particle-in-cell simulation has been developed to study the behaviour of ions in~the~surroundings of a negatively biased cylindrical Langmuir probe. Here, we report our findings on~the~transition between radial and orbital behaviour observed by means of the aforementioned code. The influence of the ion to electron temperature ratio on the transition for different dimensionless probe radius is discussed. Two different behaviours have been found for small and large probe radii.

Keywords: computer experiments, particle-in-cell, sheaths, Langmuir probes

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Particle-in-cell Simulation Concerning Heat-flux Mitigation Using Electromagnetic Fields

Lüskow K. F. 1, Kemnitz S.1,3, Bandelow G.1, Duras J.1, Kahnfeld D.1, Schneider R.1, Konigorski D.2

1Ernst-Moritz-Arndt University Greifswald, Institute of Physics, Felix-Hausdorff-Str. 6, 17487 Greifswald, Germany
2Airbus Operations GmbH, Emerging Technologies and Concepts, Kreetslag 10, 21129 Hamburg, Germany
3University Rostock, Institute of Informatics, Albert-Einstein-Str. 22, 18059 Rostock, Germany

The Particle-in-Cell (PIC) method was used to study heat flux mitigation experiments with argon. In the experiment it was shown that a magnetic field allows to reduce the heat flux towards a target. PIC is well-suited for plasma simulation, giving the chance to get a better basic understanding of the underlying physics. The simulation demonstrates the importance of a self-consistent neutral-plasma description to understand the effect of heat flux reduction.

Keywords: Particle-in-Cell, argon, heat-flux mitigation, electromagnetic fields

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Investigation of the Spark channel of Electrical Discharges Near the Minimum Ignition Energy

Essmann S.1, Markus D.1, Maas U.2

1Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig, Germany
2Karlsruhe Institute of Technology (KIT), Institute of Technichal Thermodynamics, Engelbert-Arnold-Str. 4, 76131 Karlsruhe, Germany

In this work, we investigate the expansion of the hot gas kernel and pressure wave induced by electrical discharges near the minimum ignition energy experimentally by means of a schlieren setup and numerically through one-dimensional simulations. The effects of discharge energy and energy density on the expansion are discussed. Via comparison of experimental values with numerical simulations, an estimate of the overall losses of the discharge is presented.

Keywords: electrical discharge, minimum ignition energy, schlieren

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Investigation of Microwave Energy Distribution Character in a Resonator Type Plasmatron

Bordusau S., Madveika S., Dostanko A.

Belarusian State University of Informatics and Radioelectronics, P.Brovki 6, 220013 Minsk, Belarus

An investigation of microwave energy distribution character in a plasma of microwave discharge inside a plasmatron based on a rectangular resonator has been carried out. The experiments were done applying the "active probe" method. Microwave discharge was excited in the air and oxygen. It has been found out that the readings of the "active probe" along the discharge chamber are of periodic character. The readings of the "active probe" and data on the local electric conductivity of plasma obtained using electrical probes have been compared.

Keywords: plasma, microwave energy, distribution, resonator, plasmatron

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Influence of Electron Sources on the Near-field Plume in a Multistage Plasma Thruster

Duras J.1,2, Schneider R.1, Kalentev O.4, Kemnitz S.3,5, Matyash K.3, Koch N.2, Lüskow K. 1, Kahnfeld D.1, Bandelow G.1

1Institute of Physics, Ernst-Moritz-Arndt University of Greifswald, D-17498 Greifswald, Germany
2Department of Applied Mathematics, Physics and Humanities, Nurnberger Institute of Technology, D-90489 Nurnberg, Germany
3Computing Center, Ernst-Moritz-Arndt University of Greifswald, D-17498 Greifswald, Germany
4Biomedizinische NMR Forschungs GmbH am Max-Planck-Institut fur biophysikalische Chemie, D-37077 Gottingen, Germany
5University Rostock, Institute of Informatics, D-18059 Rostock, Germany

In order to obtain a better understanding of the near-field plume of a multistage plasma thruster, the influence of an external electron source is investigated by Particle-In-Cell simulations. The variation of the source position showed a strong influence of the magnetic field configuration on the electron distribution and therefore on the plume plasma. In the second part of this work, higher energetic electrons were injected in order to model collision-induced diffusion in the plume. This broadens the electron distribution, which leads to a more pronounced divergence angle in the angular ion distribution.

Keywords: multistage plasma thruster, near-field plume, external electron source, Particle-In-Cell

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Experimental Study of the Liquid Cathode Components Transfer to the DC Discharge Plasma at Atmospheric Pressure

Sirotkin N. A., Titov V. A.

G.A. Krestov Institute of Solution Chemistry RAS, Ivanovo, Russia

The transfer processes of solvent and dissolved substances in gas phase from aqueous solutions used as cathodes under the action of atmospheric pressure DC discharge were investigated.The electric field strength in plasma (E), cathode voltage drop (Uc) and rates of solution evaporation were measured. The transfer coefficients were calculated. The effect of transfer processes on plasma physical properties was experimentally studied. The threshold characteristics of cations transfer process were determined.

Keywords: DC electrical discharge, transfer processes, liquid cathode, cathode voltage drop, electric field strength

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Study of Argon Afterglow with the Air Addition

Mazankova V.1, Trunec D.2, Petrova K.1, Krcma F.1

1Faculty of Chemistry, Brno University of Technology, Purky\v{n}ova 118, 612 00 Brno, Czech Republic
2Faculty of Science, Masaryk University, Kotl\'a\v{r}sk\'a 2, 611 37 Brno, Czech Republic

The reaction kinetics in argon flowing afterglow (post-discharge) with the air addition was studied by optical emission spectroscopy. The optical emission spectra were measured along the~post-discharge flow tube. A zero-dimensional kinetic model for the reactions in the afterglow was developed. This model allows to calculate the time dependencies of particle concentrations.

Keywords: Argon afterglow, optical emission spectroscopy, kinetic model

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Atmospheric Pressure Plasma Generation System Based on Pulsed Volume Discharge for the Biological Decontamination of a Surface

Ponomarev A. V.1, Spyrina A. V.1, Mamontov Y. I.1, Volkhina V. N.2, Zakirov T. V.2, Ioshchenko E. S.2

1Ural Branch of the Russian Academy of Sciences, Institute of Electrophysics, Amundsen Str. 106, Ekaterinburg, Russia
2Ural State Medical University, Repina str. 3, Ekaterinburg, Russia

The research introduces a system for pulsed volume discharges ignition at atmospheric pressure within gaps reaching 125 mm. The corona discharge is used for the volume discharge initiation. A damping oscillations pulse generator is used as a high-voltage power supply. The pulse repetition rate reaches 1 kHz, while the rate of damping high-frequency harmonic oscillations can reach megahertz units. The volume discharge electric and spectral characteristics were analyzed. The study revealed that O2+ emission spectrum dominates in the UV region. The potential of using pulsed volume discharge for cleaning biological surfaces was demonstrated in the research. The survival rate for E. coli under the influence of 15 seconds long pulsed volume discharge has decreased by 30 times.

Keywords: Pulsed volume discharge, corona discharge, damping oscillations pulse generator, optical emission spectrum, bio-decontamination

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Study of the Effect of Low-Temperature Plasma Exposure on Mould Fungi Colonizing Paper

Gontcharova I.1, Arashkova A.1, Bordusau S.2, Madveika S.2, Filatova I.3, Lyushkevich V.3, Brablec A.4

1Institute of Microbiology of the National Academy of Sciences of Belarus, Kuprevich str. 2, 220014 Minsk, Belarus
2Belarusian State University of Informatics and Radioelectronics, P.Brovki 6, 220013 Minsk, Belarus
3B.I. Stepanov Institute of Physics of the National Academy of Sciences of Belarus, Nezavisimosti ave. 70, 220072 Minsk, Belarus
4Masaryk University, Faculty of Science, Department of Physical Electronics, Kotlarska 2, 61137 Brno, Czech Republic

The influence of radiofrequency cold plasma in ambient air at 200 Pa pressure on mould fungi of the genus Aspergillus was studied. It was shown that 20 min plasma treatment of paper with mould and contamination reduced the number of colony forming units but didn't lead to complete suppression of fungal viability. Strains of A. versicolor after plasma treatment lost the ability to excrete pink pigment to the environment. A. niger strains were more resistant and kept acidification ability. One of the possible plasma inactivation factors was formation of reactive hydroxyl (OH) radical.

Keywords: RF cold plasma, mould fungi Aspergillus, emission spectrum

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Three-Dimensional Computations of Free-Burning Arcs and Their Surroundings

Won-Ho Lee1, Jong-Chul Lee2

1Graduate School of Automotive Engineering, Gangneung-Wonju National University, Wonju, Republic of Korea
2School of Mechanical and Automotive Engineering, Gangneung-Wonju National University, Wonju, Republic of Korea

This paper is concerned with developing a capability to model free-burning high-intensity argon arcs and enhancing the accuracy of numerical results according to three-dimensional calculations. It was found that the computed temperatures along the axis between the cathode tip and the anode surface show good agreement with two different measured data. Although the LTE model can reasonably predict the overall arc voltage for free-burning arcs, it fails to account accurately what happens at the regions near electrodes.

Keywords: Free-burning arc, thermal plasma, computational fluid dynamics, LTE model

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Inertial Effects on Tearing Instability

Silveira F. E. M.

Centro de Ciencias Naturais e Humanas, Universidade Federal do ABC, Rua Santa Adelia, 166, Bairro Bangu, CEP 09.210-170, Santo Andre, SP, Brazil

In this work, we explore inertial effects, due to charged species in a resistive plasma, on the tearing instability. The standard theory of tearing modes assumes a long wavelength limit. At shorter wave lengths, inertial effects can become important and the current density flowing in the fluid can acquire a finite relaxation time. The introduction of such a correction into the problem leads to an extension of the standard dispersion relation. In the long wave length limit, we recover the standard scaling of the growth rate γ with the plasma resistivity η, namely γ ≈ η3/5. However, in the short wavelength limit, we find that the scaling of γ with the relevant plasma parameters changes significantly due to the influence of inertia. Notwithstanding, the dependence of γ on the relaxation time of the current density is not determined. In order to achieve such a description, we propose to further rediscuss the problem in the framework of the boundary layer technique.

Keywords: Resistive instabilities, Ohm's law, current relaxation

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The Penning Discharge Experimental Study and Its Simulation

Mamedov N. V., Schitov N. N., Lobok M. G., Kanshin I. A.

All-Russia Research Institute of Automatics (VNIIA), Moscow, 127055, Russia

The influence of the demountable Penning ion source electrodes geometry on the discharge characteristics and extracted ion current is investigated. The extracted currents, ignition potentials and the operational pressure ranges are compared at different anode heights and its arrangement relative to the discharge cell. The use of ring and mesh anodes has allowed to visualize the discharge burning areas and their structure versus the pressure, anode potential and cell geometry. Some PIC simulations of Penning discharge are made in the Vorpal code. The good correspondence between the simulated electron density and plasma glow areas on the photos is shown. The other one-particle simulation has shown that the magnetic field nonuniformity significantly affects the ignition and combustion discharge potentials.

Keywords: Penning discharge, Penning source, current-voltage characteristic, PIC simulation

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The Influence of CO2 Admixtures on Process in Titan's Atmospheric Chemistry

Torokova L.1, Mazankova V.1, Mason N. J.2, Krcma F.1, Morgan G.2, Matejcik S.3

1Faculty of Chemistry, Brno University of Technology, Purkynova 118, 612 00 Brno, Czech Republic
2Department of Physical Sciences, Open University, Milton Keynes MK7 6AA, United Kingdom
3Faculty of Mathematics, Physics and Informatics, Comenius University, 842 48 Bratislava, Slovakia

The exploration of planetary atmosphere is being advanced by the exciting results of the Cassin-Huygens mission to Titan. The complex chemistry revealed in such atmospheres leading to the synthesis of bigger molecules is providing new insights into our understanding of how life on Earth developed. In our experiments Titan's atmosphere is simulated in a glow discharge formed from a mixture of N2:CH4:CO2 gas. Samples of the discharge gas were analysed by GC-MS and FTIR. The major products identified in spectra were: hydrogen cyanide, acetylene and acetonitrile. The same compounds were detected in the FTIR: hydrogen cyanide, acetylene and ammonia. Whilst many of these compounds have been predicted and/or observed in the Titan atmosphere, the present plasma experiments provide evidence of both the chemical complexity of Titan atmospheric processes and the mechanisms by which larger species grow prior to form the dust that should cover much of the Titan's surface.

Keywords: Atmosphere of Titan, glow discharge, GC-MS analysis and FTIR spectroscopy

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Hydrolysis of PLA-like Plasma Polymer Films with Varying Degree of Crosslinking

Kolarova Raskova Z.1, Kousal J.2, Stloukal P.1, Krtous Z.2

1Centre of Polymer Systems, Tomas Bata University in Zlin, Trida Tomase Bati 5678, 76001 Zlin, Czech Republic
2Department of Macromolecular Physics, Faculty of Mathematics and Physics, Charles University in Prague, V Holesovickach 2, 18200 Prague, Czech Republic

Poly-lactide acid (PLA) based biodegradable films are of interest for packaging materials or bioapplications. Plasma-assisted vacuum evaporation technique uses oligomers released during thermal decomposition of source polymer as precursors for plasma polymerization. Conventionally prepared PLA with mw = 10000 g/mol was used as a source polymer. Films were prepared at various RF (13.56 MHz) plasma powers (0-20 W) in order to vary the amount of crosslinking in the film.
Swelling and hydrolysis of films were monitored in real time using spectroscopic ellipsometry. The concentration profile of products of hydrolysis was measured by liquid-chromatography (LC-MS). FTIR, XPS and SEM analyses were used for monitoring of film composition and surface characterization. Molecular weights of source polymer and of the plasma polymer were determined by gel-permeation chromatography (GPC).
Possibility to prepare PLA-like plasma polymer films with controlled degradability by hydrolysis was demonstrated.

Keywords: polylactide, plasma polymer, biodegradability, hydrolysis

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