N. Trushkin - Academia.edu (original) (raw)

Papers by N. Trushkin

Journal of Physics D: Applied Physics, 2014

ABSTRACT Instability waves in the shear layer of turbulent jet are known to be a significant sour... more ABSTRACT Instability waves in the shear layer of turbulent jet are known to be a significant source of jet noise, which makes their suppression important for the aviation industry. In this study we apply plasma actuators in order to control instability waves in the shear layer of turbulent air jet at atmospheric pressure. Three types of plasma actuators are studied: high-frequency dielectric barrier discharge, slipping surface discharge, and barrier corona discharge. PIV measurements of the shear layer demonstrate that the plasma actuators have control authority over instability waves and effectively suppress the instability waves artificially generated in the shear layer. It makes these actuators promising for application in active control systems for jet noise mitigation.

Progress in Flight Physics – Volume 7, 2015

The paper deals with the problem of instability wave control in turbulent jets. Noise of a turbul... more The paper deals with the problem of instability wave control in turbulent jets. Noise of a turbulent jet issuing from a jet engine nozzle still remains an im

Plasma Sources Science and Technology, 2015

Plasma Physics Reports

ABSTRACT

Experimental results and numerical calculations on the detailed search of the properties of noneq... more Experimental results and numerical calculations on the detailed search of the properties of nonequilibrium constricted dc glow discharges in N 2 flow and the pulse-periodical spark are presented. These two types of discharge were used for generation of plasma jets. Different current modes of the constricted dc discharge in N 2 were found. It is established that the generation of a long (≈20 cm) luminous afterglow by constricted dc discharge occurs only in a specific current mode. The mechanism of the discharge generation and the plasma parameters are determined in this current mode. The main active agents of the plasma jet generated by a pulse-periodical spark are established. Conjoint action of different agents provides synergy effect in a modification or bio-inactivation of the surface to be treated. Potential applications of generated plasma jets are discussed.

ABSTRACT Summary form only given. Upon applying of step of high voltage that is over an inception... more ABSTRACT Summary form only given. Upon applying of step of high voltage that is over an inception one, the ignition of a negative corona is accompanied by a sharp splash of discharge current with a pulse duration of about 10-7. As a rule, for electropositive gases (N2 , Ar, etc.) the corona current falls after the splash and goes to the stationary value that is much smaller than the one for initial pulse. For electronegative gases (air, O2, etc.) in which electrons are turned into negative ions, instead of stationary state the pulsed regime of corona with regular splashes of discharge current is established and named as Trichel pulses. The physical condition for existence of regular Trichel pulses lies in the fact that a displacement current of the corona has to approach the conductivity current in this regime. This condition is easily devised for corona in air, O2 in which the negative ions are the main carriers of charge through the interelectrode gap. In the case where the electrons are the major carriers of charge (N2, Ar, etc.) the reduction in the contribution of conductivity current to the total current can be reached only for corona with interelectrode gap more than 15-20 cm

Plasma Physics Reports, 1994

Selected Research Papers on Spectroscopy of Nonequilibrium Plasma at Elevated Pressures, 2002

Dynamics of light emission for the N 2 (A 3  + u ), N 2 (B 3  g ) and N 2 (C 3  u ) electronic... more Dynamics of light emission for the N 2 (A 3  + u ), N 2 (B 3  g ) and N 2 (C 3  u ) electronic excited states was studied spectroscopically in a long pulse glow discharge in pure nitrogen and in afterglow at pressure 50 Torr. An appropriate mathematical processing was made to derive population of excited states from these measurements A rather complete kinetic model was developed for conditions of the experiments. Results of comparison are analyzed.

Selected Research Papers on Spectroscopy of Nonequilibrium Plasma at Elevated Pressures, 2002

2012 Abstracts IEEE International Conference on Plasma Science, 2012

ABSTRACT The subject for plasma sterilization was the bacteria Mycobacterium sp. B-5 (Gram-positi... more ABSTRACT The subject for plasma sterilization was the bacteria Mycobacterium sp. B-5 (Gram-positive) seeded onto the surface of the packing-sheets like paper and polymer. Our standard dose of a liquid suspension with microorganisms deposited onto the aseptic coupons of 10×10 mm2 in sizes was equal to 10 μl. We used white writing paper with density of 80 g/m2 and 20 μm in thickness, brown craft-paper “A” with density of 52 g/m2 and 20 μm in thickness, white filter paper of 20 μm in thickness. As for polymer materials we used white food polystyrene (PS) of 10 μm in thickness, transparence polyethylene (LDPE) of 20 μm in thickness, brown and transparence food polyethylene-terephthalate (PET) of 20 μm in thickness, and transparence food polypropylene (PE) of 250 μm in thickness. Before plasma treatment, the coupons contaminated with the microorganisms were dried over 2-3 hours at room temperature. Non-thermal plasma was generated by plane-to-plane DBD in ambient air at atmospheric pressure. Metallic electrodes were covered by glass of 1 mm in thickness. The length of gas gap between dielectric barriers was varied from 1 to 3 mm. Barrier discharge was activated by sinusoidal voltage with a frequency of 35 kHz and pick-to-pick amplitude varied from 10 to 26 kV. The contaminated coupons were placed in the gap between plane electrodes and exposed to non-thermal plasma over 1-60 s.

2012 Abstracts IEEE International Conference on Plasma Science, 2012

ABSTRACT In general non-thermal plasma generates three main types of bio-active agents: UV radiat... more ABSTRACT In general non-thermal plasma generates three main types of bio-active agents: UV radiation, charged particles and neutral species like radicals and metastables. A role of each agent in bio-inactivation of microorganisms still remains as the subject for discussion. To simplify situation, we used pin-to-plane positive and negative DC coronas in ambient air as a source for generation of bio-active agents. These discharges at atmospheric pressure practically do not produce UV radiation but generate predominantly the charged particles and neutral active species. In the case of humid air the positive and negative charged particles are H3O+, NO+ and OH-, O2-, O3-, O-, NO3-, CO3- for positive and negative corona respectively. As for bio-active neutral species they are O, O2(ά1Δ), O3, OH, HO2 and HNO2, HNO3 as well in small numbers. This study was aimed to evaluate an effect of corona discharge on viability of the pathogenic bacteria Staphylococcus aureus (Gram-positive) and Pseudomonas aeruginosa (Gram-negative) seeded on nutritive agar and to evaluate a role of the charged particles and neutral active species in a total bactericidal effect. To split the effects of the charged particles and neutral species on the microorganisms, we have done the experiments with corona in the rest air and in airflow removing neutral active agents from the agar surface to be treated. Full inactivation of bacteria was observed over the whole agar surface for both Gram-positives and Gram-negatives when the agar surface was exposed to the mixture of charged particles and neutral species for 5 minutes. The obtained results showed that both charged and neutral active particles contribute essentially to the whole bactericidal effect of both positive and negative cor- na discharge. The detailed information will be presented in this report at the conference.

NATO Science for Peace and Security Series A: Chemistry and Biology, 2011

ABSTRACT Non-thermal plasma jet formed by self-running pulsed-periodical high-current spark gener... more ABSTRACT Non-thermal plasma jet formed by self-running pulsed-periodical high-current spark generator (PPSG) was used for atmospheric pressure inactivation of microorganisms including biofilms. A distinctive feature of the PPSG is a formation of transient hot plasma clouds (plasma bullets) periodically flying out to the target. We experimented with model biofilms of E. coli and Bacillus subtilis monocultures which were grown on agar and surfaces of steel and polypropylene coupons. High efficiency of plasma inactivation was demonstrated. This effect is associated primarily with an interaction of transient hot plasma clouds with biofilms. Besides complete or partial degradation of the cell membrane, weakening of the cell wall of E.coli culture by active plasma was found.

Plasma Sources Science and Technology, 2014

Physical properties of the high-current density spots (which are not the hot arc spots) formed on... more Physical properties of the high-current density spots (which are not the hot arc spots) formed on the electrodes due to development of electro-dynamical and ionization instabilities in the near-electrode layers are the subjects of this paper. The influence of these spots on homogeneity of the plasma column between the electrodes due to initiation of the discharge constriction is discussed and illustrated by the proper experimental data. The geometrical and gas-dynamic effects stabilizing the formation of the anode and cathode current spots at higher gas pressures are described.

IEEE Conference Record - Abstracts. 1999 IEEE International Conference on Plasma Science. 26th IEEE International Conference (Cat. No.99CH36297), 1999

ABSTRACT Summary form only given. This paper reports on the conditions when the glow mode of a po... more ABSTRACT Summary form only given. This paper reports on the conditions when the glow mode of a positive corona in nitrogen exists. For the first time, an auto-oscillating regime is observed. Detailed studies on characteristics of corona pulsation in an electrode system of wire (anode) and cylinder (cathode) were carried out. Waveforms for oscillations of current and glow intensity were measured. Voltage-current characteristics, amplitude and repetition frequency for oscillations were measured for a wide range of pressure (10-765 Torr). The repetition frequency of pulses varies in the range 200-500 MHz. Earlier discussed mechanisms for the development of oscillations are critically analyzed and a new one is proposed. A new interpretation of old measurements of preionized electron density in nitrogen and air produced by a positive corona is given. According to Morrow (1997), electrons in gas are produced by UV photons created in positive corona in a small region close to a pin. Direct measurements for these conditions performed by us evidenced that the positive corona generates soft X-rays which we refer to as the process of bremsstrahlung at the anode surface following collisions of fast electrons appearing in the close vicinity of the pin. We believe that these X-rays produced electrons in gas observed by Morrow (1997)

Non-Thermal Plasma Techniques for Pollution Control, 1993

Plasma Physics Reports, 1994

Plasma Sources Science and Technology, 2013

ABSTRACT A surface dielectric barrier discharge (SDBD) exhibits a thin plasma sheet covering a di... more ABSTRACT A surface dielectric barrier discharge (SDBD) exhibits a thin plasma sheet covering a dielectric barrier. Results of the experimental and theoretical studies on the spatial–temporal dynamics of a plasma sheet in a pulsed SDBD are presented. Argon and air were used as plasma-forming gases at pressures of 4 × 104 Pa and 105 Pa, respectively. The SDBD was powered by a single pulse with a relatively long rise time (≤1 µs) and of moderate pulse duration. The chosen pulse parameters allowed us firstly to diminish the contribution of the displacement current to the total discharge current drastically and secondly to avoid the development of ionization instabilities by changing cardinally the spatial configuration of the plasma sheet. After each pulse, the surface charge on the barrier was thoroughly removed by a grounded soft metallic mesh. Instant discharge images were taken at different phases of the current and voltage waveforms. We revealed that the plasma sheet of a pulsed SDBD expands over a barrier not only at the current rise stage but also at the current decay stage. A theoretical interpretation of the obtained results is given. It is shown that the plasma expansion over the barrier surface is similar to an unsteady and non-linear diffusion process.

Journal of Physics D: Applied Physics, 2014

ABSTRACT Instability waves in the shear layer of turbulent jet are known to be a significant sour... more ABSTRACT Instability waves in the shear layer of turbulent jet are known to be a significant source of jet noise, which makes their suppression important for the aviation industry. In this study we apply plasma actuators in order to control instability waves in the shear layer of turbulent air jet at atmospheric pressure. Three types of plasma actuators are studied: high-frequency dielectric barrier discharge, slipping surface discharge, and barrier corona discharge. PIV measurements of the shear layer demonstrate that the plasma actuators have control authority over instability waves and effectively suppress the instability waves artificially generated in the shear layer. It makes these actuators promising for application in active control systems for jet noise mitigation.

Progress in Flight Physics – Volume 7, 2015

The paper deals with the problem of instability wave control in turbulent jets. Noise of a turbul... more The paper deals with the problem of instability wave control in turbulent jets. Noise of a turbulent jet issuing from a jet engine nozzle still remains an im

Plasma Sources Science and Technology, 2015

Plasma Physics Reports

ABSTRACT

Experimental results and numerical calculations on the detailed search of the properties of noneq... more Experimental results and numerical calculations on the detailed search of the properties of nonequilibrium constricted dc glow discharges in N 2 flow and the pulse-periodical spark are presented. These two types of discharge were used for generation of plasma jets. Different current modes of the constricted dc discharge in N 2 were found. It is established that the generation of a long (≈20 cm) luminous afterglow by constricted dc discharge occurs only in a specific current mode. The mechanism of the discharge generation and the plasma parameters are determined in this current mode. The main active agents of the plasma jet generated by a pulse-periodical spark are established. Conjoint action of different agents provides synergy effect in a modification or bio-inactivation of the surface to be treated. Potential applications of generated plasma jets are discussed.

ABSTRACT Summary form only given. Upon applying of step of high voltage that is over an inception... more ABSTRACT Summary form only given. Upon applying of step of high voltage that is over an inception one, the ignition of a negative corona is accompanied by a sharp splash of discharge current with a pulse duration of about 10-7. As a rule, for electropositive gases (N2 , Ar, etc.) the corona current falls after the splash and goes to the stationary value that is much smaller than the one for initial pulse. For electronegative gases (air, O2, etc.) in which electrons are turned into negative ions, instead of stationary state the pulsed regime of corona with regular splashes of discharge current is established and named as Trichel pulses. The physical condition for existence of regular Trichel pulses lies in the fact that a displacement current of the corona has to approach the conductivity current in this regime. This condition is easily devised for corona in air, O2 in which the negative ions are the main carriers of charge through the interelectrode gap. In the case where the electrons are the major carriers of charge (N2, Ar, etc.) the reduction in the contribution of conductivity current to the total current can be reached only for corona with interelectrode gap more than 15-20 cm

Plasma Physics Reports, 1994

Selected Research Papers on Spectroscopy of Nonequilibrium Plasma at Elevated Pressures, 2002

Dynamics of light emission for the N 2 (A 3  + u ), N 2 (B 3  g ) and N 2 (C 3  u ) electronic... more Dynamics of light emission for the N 2 (A 3  + u ), N 2 (B 3  g ) and N 2 (C 3  u ) electronic excited states was studied spectroscopically in a long pulse glow discharge in pure nitrogen and in afterglow at pressure 50 Torr. An appropriate mathematical processing was made to derive population of excited states from these measurements A rather complete kinetic model was developed for conditions of the experiments. Results of comparison are analyzed.

Selected Research Papers on Spectroscopy of Nonequilibrium Plasma at Elevated Pressures, 2002

2012 Abstracts IEEE International Conference on Plasma Science, 2012

ABSTRACT The subject for plasma sterilization was the bacteria Mycobacterium sp. B-5 (Gram-positi... more ABSTRACT The subject for plasma sterilization was the bacteria Mycobacterium sp. B-5 (Gram-positive) seeded onto the surface of the packing-sheets like paper and polymer. Our standard dose of a liquid suspension with microorganisms deposited onto the aseptic coupons of 10×10 mm2 in sizes was equal to 10 μl. We used white writing paper with density of 80 g/m2 and 20 μm in thickness, brown craft-paper “A” with density of 52 g/m2 and 20 μm in thickness, white filter paper of 20 μm in thickness. As for polymer materials we used white food polystyrene (PS) of 10 μm in thickness, transparence polyethylene (LDPE) of 20 μm in thickness, brown and transparence food polyethylene-terephthalate (PET) of 20 μm in thickness, and transparence food polypropylene (PE) of 250 μm in thickness. Before plasma treatment, the coupons contaminated with the microorganisms were dried over 2-3 hours at room temperature. Non-thermal plasma was generated by plane-to-plane DBD in ambient air at atmospheric pressure. Metallic electrodes were covered by glass of 1 mm in thickness. The length of gas gap between dielectric barriers was varied from 1 to 3 mm. Barrier discharge was activated by sinusoidal voltage with a frequency of 35 kHz and pick-to-pick amplitude varied from 10 to 26 kV. The contaminated coupons were placed in the gap between plane electrodes and exposed to non-thermal plasma over 1-60 s.

2012 Abstracts IEEE International Conference on Plasma Science, 2012

ABSTRACT In general non-thermal plasma generates three main types of bio-active agents: UV radiat... more ABSTRACT In general non-thermal plasma generates three main types of bio-active agents: UV radiation, charged particles and neutral species like radicals and metastables. A role of each agent in bio-inactivation of microorganisms still remains as the subject for discussion. To simplify situation, we used pin-to-plane positive and negative DC coronas in ambient air as a source for generation of bio-active agents. These discharges at atmospheric pressure practically do not produce UV radiation but generate predominantly the charged particles and neutral active species. In the case of humid air the positive and negative charged particles are H3O+, NO+ and OH-, O2-, O3-, O-, NO3-, CO3- for positive and negative corona respectively. As for bio-active neutral species they are O, O2(ά1Δ), O3, OH, HO2 and HNO2, HNO3 as well in small numbers. This study was aimed to evaluate an effect of corona discharge on viability of the pathogenic bacteria Staphylococcus aureus (Gram-positive) and Pseudomonas aeruginosa (Gram-negative) seeded on nutritive agar and to evaluate a role of the charged particles and neutral active species in a total bactericidal effect. To split the effects of the charged particles and neutral species on the microorganisms, we have done the experiments with corona in the rest air and in airflow removing neutral active agents from the agar surface to be treated. Full inactivation of bacteria was observed over the whole agar surface for both Gram-positives and Gram-negatives when the agar surface was exposed to the mixture of charged particles and neutral species for 5 minutes. The obtained results showed that both charged and neutral active particles contribute essentially to the whole bactericidal effect of both positive and negative cor- na discharge. The detailed information will be presented in this report at the conference.

NATO Science for Peace and Security Series A: Chemistry and Biology, 2011

ABSTRACT Non-thermal plasma jet formed by self-running pulsed-periodical high-current spark gener... more ABSTRACT Non-thermal plasma jet formed by self-running pulsed-periodical high-current spark generator (PPSG) was used for atmospheric pressure inactivation of microorganisms including biofilms. A distinctive feature of the PPSG is a formation of transient hot plasma clouds (plasma bullets) periodically flying out to the target. We experimented with model biofilms of E. coli and Bacillus subtilis monocultures which were grown on agar and surfaces of steel and polypropylene coupons. High efficiency of plasma inactivation was demonstrated. This effect is associated primarily with an interaction of transient hot plasma clouds with biofilms. Besides complete or partial degradation of the cell membrane, weakening of the cell wall of E.coli culture by active plasma was found.

Plasma Sources Science and Technology, 2014

Physical properties of the high-current density spots (which are not the hot arc spots) formed on... more Physical properties of the high-current density spots (which are not the hot arc spots) formed on the electrodes due to development of electro-dynamical and ionization instabilities in the near-electrode layers are the subjects of this paper. The influence of these spots on homogeneity of the plasma column between the electrodes due to initiation of the discharge constriction is discussed and illustrated by the proper experimental data. The geometrical and gas-dynamic effects stabilizing the formation of the anode and cathode current spots at higher gas pressures are described.

IEEE Conference Record - Abstracts. 1999 IEEE International Conference on Plasma Science. 26th IEEE International Conference (Cat. No.99CH36297), 1999

ABSTRACT Summary form only given. This paper reports on the conditions when the glow mode of a po... more ABSTRACT Summary form only given. This paper reports on the conditions when the glow mode of a positive corona in nitrogen exists. For the first time, an auto-oscillating regime is observed. Detailed studies on characteristics of corona pulsation in an electrode system of wire (anode) and cylinder (cathode) were carried out. Waveforms for oscillations of current and glow intensity were measured. Voltage-current characteristics, amplitude and repetition frequency for oscillations were measured for a wide range of pressure (10-765 Torr). The repetition frequency of pulses varies in the range 200-500 MHz. Earlier discussed mechanisms for the development of oscillations are critically analyzed and a new one is proposed. A new interpretation of old measurements of preionized electron density in nitrogen and air produced by a positive corona is given. According to Morrow (1997), electrons in gas are produced by UV photons created in positive corona in a small region close to a pin. Direct measurements for these conditions performed by us evidenced that the positive corona generates soft X-rays which we refer to as the process of bremsstrahlung at the anode surface following collisions of fast electrons appearing in the close vicinity of the pin. We believe that these X-rays produced electrons in gas observed by Morrow (1997)

Non-Thermal Plasma Techniques for Pollution Control, 1993

Plasma Physics Reports, 1994

Plasma Sources Science and Technology, 2013

ABSTRACT A surface dielectric barrier discharge (SDBD) exhibits a thin plasma sheet covering a di... more ABSTRACT A surface dielectric barrier discharge (SDBD) exhibits a thin plasma sheet covering a dielectric barrier. Results of the experimental and theoretical studies on the spatial–temporal dynamics of a plasma sheet in a pulsed SDBD are presented. Argon and air were used as plasma-forming gases at pressures of 4 × 104 Pa and 105 Pa, respectively. The SDBD was powered by a single pulse with a relatively long rise time (≤1 µs) and of moderate pulse duration. The chosen pulse parameters allowed us firstly to diminish the contribution of the displacement current to the total discharge current drastically and secondly to avoid the development of ionization instabilities by changing cardinally the spatial configuration of the plasma sheet. After each pulse, the surface charge on the barrier was thoroughly removed by a grounded soft metallic mesh. Instant discharge images were taken at different phases of the current and voltage waveforms. We revealed that the plasma sheet of a pulsed SDBD expands over a barrier not only at the current rise stage but also at the current decay stage. A theoretical interpretation of the obtained results is given. It is shown that the plasma expansion over the barrier surface is similar to an unsteady and non-linear diffusion process.