46 results on '"Neretti, G"'
Search Results
2. Effect of nanofillers in HVDC insulations on surface partial discharge activity
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Seri, P., primary, Neretti, G., additional, and Diendorfer, C., additional
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- 2022
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- View/download PDF
3. Physical and Chemical Characterization of Plasma Sources for Bio-medical Applications
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Cordaro L., Cavazzana R., De Masi G., Fassina A., Zuin M., Giove A., Neretti G., Tampieri F., and Martines E.
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Plasma Sorces ,Plasma Medicine - Abstract
Plasma medicine is a multidisciplinary field of science that uses cold atmospheric pressure plasmas for biomedical purposes. Several applications have been proposed in the last years, including disinfection of bacteria and fungi, wound healing, dermatological diseases and selective killing of cancer cells. Several plasma production schemes and plasma source designs have been proposed, most of which have obtained interesting therapeutic effects on biological samples. However, an overall understanding of the mechanisms that induce such benefices is still missing. Such an understanding is not trivial, considering the multiplicity of possible interactions between complex systems, such as cold plasmas and biological tissues.
- Published
- 2021
4. Inactivation of Eimeria spp. oocysts in aqueous environment assisted by a gas-liquid dielectric barrier discharge
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Neretti G., Borghi C. A., Taglioli M., Poglayen G., Morandi B., Galuppi G., Tosi G., AA VV, Slobodan Milosevic , Niksa Krstulovic, Neretti G., Borghi C. A., Taglioli M., Poglayen G., Morandi B., Galuppi R., Tosi G., AAVV, and Neretti G., Borghi C.A., Taglioli M., Poglayen G., Morandi B., Galuppi G., Tosi G.
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Plasma, Eimerya, oocysts, treatment - Abstract
Among human and animal diseases agents, parasites are those that show, with very few exceptions, an environmental resistance far superior with respect other pathogens [1]. This is due to the complex structure of the wall of their infective stages, that makes them particularly resistant to almost all physical and chemical agents. In this work, a novel technique to inactivate coccidian parasites in liquid environment has been investigated and implemented. A Petri dish filled with 20 ml of water contaminated by Eimeria spp. oocysts has been placed within a plasma reactor constituted by a lower HV exposed electrode and an upper grounded copper strip electrode covered by a ceramic slab (Fig. 1). The reactor has been supplied with sinusoidal and nanosecond-pulsed voltage waveforms varying the application time. In both cases an atmospheric pressure Dielectric Barrier Discharge (DBD) has been ignited in the air gap above the liquid surface and in contact with it [2]. The temperature of the solution and its pH level were not significantly changed by plasma treatment. The concentration of ozone and hydrogen peroxide increase by increasing treatment time [2]. Plasma treatment efficacy has been detected considering a representative population of 100 oocysts. For both discharges, treatment efficacy has been found to be dose dependent (Fig. 2). After an energy dose treatment of about 100 kJ/l, the number of sporulated oocytes are roughly halved with respect the control sample. Results are statistically significant with a p
- Published
- 2017
5. Effect of nanofillers on surface charge mobility and alternative technique for electrostatic field measurement
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Seri, P., primary, Cristofolini, A., additional, and Neretti, G., additional
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- 2020
- Full Text
- View/download PDF
6. The fourth state of matter chapter II: biocidal effect of plasma against yeast
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Galuppi R., Neretti G., RICCHIUTO, ANNA CHIARA, Borghi C. A., Poglayen G., Morandi B., SoIPa, and Galuppi R., Neretti G., Ricchiuto A.C., Borghi C.A., Poglayen G., Morandi B.
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Annular Plasma Synthetic Jet Actuators (PASJAs), Charged particles, candida guilliermondii - Abstract
INTRODUCTION. The use of plasma for sanitization purpose is of increasing interest. Annular plasma synthetic jet actuators (PSJAs) had demonstrated their ability to produce and induced tubular flow (Neretti et al., 2017, J. Phys. D: Appl. Phys. 50 015210, 9pp) normal to the surface where the dielectric barrier discharge is ignited. This typology of reactor enhances the transport of reactive species toward the treated samples (Taglioli et al., 2016, Plasma sources Sci. Technol., 25 06LT01-5pp.). Long life charged particles are generated within the plasma region and then can be advected together with the induced flow. In this work the effect of free charges into induced flow have been tested against Candida guilliermondii both in agar plates and in water suspension. MATERIALS AND METHODS. Eighty ml suspension of C. guiliiermondii in saline solution (0.5 Mcfarland opacity) was prepared. The CFU of untreated suspension was determined performing multiple dilution that were plated on Sabouraud Dextrose Agar (SDA) petri dishes that were incubated at 26°C for 48 hours. Aliquots of 100 μl of suspension were spread on the surface of 6 SDA plates (9 cm diameter); aliquots of 20 ml of suspension were put into six 9 cm plates. Agar plates were subjected to induced flow for 30 sec, 2 and 5 minutes and suspension plates for 5, 10 and 15 minutes, both with and without blocking the charges by a grounded metallic mesh. After treating, from each suspension CFU was calculated as previous described, while in the agar plates the colonies were directly counted after incubation. RESULTS AND CONCLUSIONS. The untreated yeast suspension contained 5.21 x 105 CFU/100 μl. In treated samples, the reduction of the CFU of the yeast was related to the treatment time and to presence/absence of free charges. The effect was greater on agar plate than on suspension: at the same time of treatment (5 minutes), only 1-log reduction of CFU were observed on suspension, while 4-log reduction was observed in agar plates. Additional 1-log reduction was observed when free charges have been allowed to reach the sample. On suspension, longer treatment time (15 min) was needed to obtain 2-log reduction without free charges and 4-log reduction with free charges.
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- 2018
7. Experimental and Numerical Investigation on the Electric Charge Deposition in a Dielectric Barrier Discharg
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Cristofolini, A., primary, Neretti, G., additional, Popoli, A., additional, Ricchiuto, A. C., additional, and Seri, P., additional
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- 2019
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8. Characterization of a plasma source for biomedical applications by electrical, optical, and chemical measurements
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Neretti, G, Tampieri, F, Borghi, C, Brun, P, Cavazzana, R, Cordaro, L, Marotta, E, Paradisi, C, Seri, P, Taglioli, M, Zaniol, B, Zuin, M, Martines, E, Neretti, Gabriele, Tampieri, Francesco, Borghi, Carlo Angelo, Brun, Paola, Cavazzana, Roberto, Cordaro, Luigi, Marotta, Ester, Paradisi, Cristina, Seri, Paolo, Taglioli, Matteo, Zaniol, Barbara, Zuin, Matteo, Martines, Emilio, Neretti, G, Tampieri, F, Borghi, C, Brun, P, Cavazzana, R, Cordaro, L, Marotta, E, Paradisi, C, Seri, P, Taglioli, M, Zaniol, B, Zuin, M, Martines, E, Neretti, Gabriele, Tampieri, Francesco, Borghi, Carlo Angelo, Brun, Paola, Cavazzana, Roberto, Cordaro, Luigi, Marotta, Ester, Paradisi, Cristina, Seri, Paolo, Taglioli, Matteo, Zaniol, Barbara, Zuin, Matteo, and Martines, Emilio
- Abstract
This paper reports the characterization of a low-power, atmospheric pressure plasma source developed for and successfully tested in applications of plasma medicine. The source produces plasma by ionizing a helium flow containing traces of air. The effluent gas is thus enriched in reactive oxygen and nitrogen species as well as helium metastable excited states. Electrical measurements, Schlieren imaging, OES and various chemical analyses and probes enabled us to fully characterize the plasma source and to determine some fundamental parameters for treating living samples such as the power feeding the discharge, the optimal source to target distance, the maximum exposure time, and to identify the major chemical species responsible for the biological action on exposed living matter.
- Published
- 2018
9. Measurement of the charge distribution deposited by anannularplasma synthetic jet actuator over a target surface
- Author
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Neretti, G, primary, Ricchiuto, A C, additional, and Borghi, C A, additional
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- 2018
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10. Schlieren imaging in a dielectric barrier discharge actuator for airflow control.
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Cristofolini, A., Neretti, G., Roveda, F., and Borghi, C. A.
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DIELECTRICS research , *ELECTRODES , *ACTUATORS , *ELECTROHYDRODYNAMICS , *BOUNDARY layer (Aerodynamics) - Abstract
The operation of a surface dielectric barrier discharge actuator for airflow control has been experimentally investigated. The actuator is constituted by an electrode pair separated by a dielectric Teflon sheet. Several ac supply conditions have been utilized. An electrohydrodynamics interaction was induced in still air, and several fluid-dynamic regimes were obtained. Visualization of the plasma boundary layer during the discharge ignition phase and during the steady state regime was obtained by utilizing a Schlieren diagnostic technique. The vortex morphology and propagation velocities at all supply conditions utilized have been evaluated. Velocity profiles perpendicular to the actuator surface, obtained from Pitot tube measurements, and line intensity profiles, determined by means of Schlieren imaging, have been determined for the steady regime operation. The integral along a line perpendicular to the actuator surface of the light intensity of the Schlieren image has been calculated. The profile obtained is in good agreement with the Pitot velocity profile in all the supply conditions investigated. Numerical simulations were also performed. The calculations confirm the relation between the flow velocity distribution in the boundary layer and the gas density distribution, which is the cause of the Schlieren image. [ABSTRACT FROM AUTHOR]
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- 2012
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11. Electrohydrodynamic interaction induced by a dielectric barrier discharge.
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Borghi, C. A., Carraro, M. R., Cristofolini, A., and Neretti, G.
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ELECTROHYDRODYNAMICS ,DIELECTRICS ,AIR flow ,SPECTRUM analysis ,TEMPERATURE ,ELECTRIC potential ,PHYSICS - Abstract
In the present work an experimental investigation on the electrohydrodynamic (EHD) interaction effect, induced by means of a dielectric barrier discharge on a 1 atm subsonic air flow, is described. The air flow is obtained in an open circuit blowing wind tunnel at different air speeds. A plane plasma panel equipped with a dielectric discharge barrier system is immersed in the flow. A single phase sinusoidal power supply system, a superposition of a single phase sinusoidal system with a dc voltage supply, and a three phase symmetrical power supply configuration are considered. Electric, fluid dynamic, and spectroscopic diagnostic techniques are utilized. Pitot probe measurements are performed in the boundary layer on the plasma panel surface. Schlieren imaging is done to visualize the plasma sheath. Vibrational and rotational temperatures are evaluated by means of spectroscopic techniques. The force induced on the flow by the dielectric barrier discharge acts on the ions of the non-neutral sheath ahead of the plasma filament when travelling on the panel surface only. This causes a reduction of the time interval during which the force is active. The EHD effect and the momentum transfer to the gas flow in the boundary layer are reduced when the flow speed grows. An increase of the supply frequency and of the supply voltage causes an increase of the momentum transfer. In these experiments no significant increase of the efficiency of EHD effect is observed when utilizing the superposition of a dc voltage to a single phase power supply or a three phase power supply. [ABSTRACT FROM AUTHOR]
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- 2008
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12. Characterization of a dielectric barrier discharge in contact with liquid and producing a plasma activated water
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Neretti, G, primary, Taglioli, M, additional, Colonna, G, additional, and Borghi, C A, additional
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- 2016
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13. Geometry optimization of linear and annular plasma synthetic jet actuators
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Neretti, G, primary, Seri, P, additional, Taglioli, M, additional, Shaw, A, additional, Iza, F, additional, and Borghi, C A, additional
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- 2016
- Full Text
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14. EHD-driven mass transport enhancement in surface dielectric barrier discharges
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Taglioli, M, primary, Shaw, A, additional, Wright, A, additional, FitzPatrick, B, additional, Neretti, G, additional, Seri, P, additional, Borghi, C A, additional, and Iza, F, additional
- Published
- 2016
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15. Experimental Activities on the MHD Interaction in a Hypersonic Air Flow Around a Blunt Body
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Cristofolini, A., Borghi, C. A., Neretti, G., Passaro, A., Baccarella, D., Antonio Schettino, Battista, F., Andrea Cristofolini, Gabriele Neretti, Carlo Angelo Borghi, Andrea Passaro, Damiano Baccarella, Antonio Schettino, and Francesco Battista
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APPLIED MAGNETOFLUID DYNAMICS ,ELECTRODYNAMICS ,HYPERSONIC MHD INTERACTION - Abstract
This paper deals with the design of an experiment devoted to MHD flow control, to be performed in CIRA GHIBLI hypersonic facility. The criteria utilized to define the proper test conditions and to design and realize the model are here described. The expansion in the nozzle has been investigated through numerical simulations in order to have a preliminary estimate of the ionization degree and of the heat fluxes over the test article. Moreover, an MFD code has been used in order to calculate the expected interaction effect, under the assumption of low Rem. The same procedure has been utilized for the design of an MHD test to be performed in the CIRA SCIROCCO facility.
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- 2010
16. High-voltage high-frequency arbitrary waveform multilevel generator for dielectric barrier discharge
- Author
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Dragonas, F. A., primary, Grandi, G., additional, and Neretti, G., additional
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- 2014
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17. Charge distribution on the surface of a dielectric barrier discharge actuator
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Cristofolini, A., primary, Neretti, G., additional, Roveda, F., additional, and Borghi, C.A., additional
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- 2012
- Full Text
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18. Hypersonic MHD Interaction on a Conical Test Body With a Hall Electrical Connection
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Cristofolini, A., primary, Borghi, C.A., additional, Carraro, M.R., additional, Neretti, G., additional, Passaro, A., additional, Fantoni, G., additional, and Biagioni, L., additional
- Published
- 2008
- Full Text
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19. MHD interaction over an axial symmetric body in a hypersonic flow
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Cristofolini, A., Borghi, C. A., Carraro, M. R., Neretti, G., Passaro, A., Fantoni, G., Biagioni, L., Fabrizio Paganucci, A. Cristofolini, CA. Borghi, M. Carraro, G. Neretti, A. Passaro, G. Fantoni, L. Biagioni, and F. Paganucci
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Physics::Space Physics - Abstract
The MHD interaction around a conical test body in a hypersonic argon flow is experimentally investigated. The hypersonic flow is realized in the high-enthalpy arc-heated wind tunnel of Alta (Pisa-Italy) at Mach 6. The aim of the experiment is to produce a data base to be used for the validation of numerical codes which are utilized to analyze the magneto-fluid dynamics in hypersonic flows. In the present experiment the MHD interaction is obtained in the shock layer of a conical test body placed at the exit of the hypersonic nozzle. The electrical configuration realized, allows to enhance the effect of the MHD interaction on the plasma parameters. This is done by utilizing the Hall field to generate the MHD interaction and by short-circuiting the Faraday current inside the plasma of the shock layer. The magnetic flux density is produced by an array of three magnets located in the test body. Test runs are performed at three different stagnation pressures. Fluid-dynamic, electrical and optical observations have been done. The experiment showed a large effect of the MHD interaction on the values of the measured quantities.
20. Characterization of a new mach 9 nozzle for the heat hypersonic wind tunnel
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Baccarella, D., Passaro, A., Caredda, P., Cristofolini, A., Neretti, G., Granciu, V. M., Schettino, A., Francesco Battista, D Ambrosio, D., D. Baccarella, A. Passaro, P. Caredda, A. Cristofolini, G. Neretti, V.M. Granciu, A. Schettino, F. Battista, and D. D’Ambrosio
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Internal walls ,Pitot pressure ,Heat flux distributions ,Core flow ,Test sections ,Experimental data ,Design phase ,HYPERSONIC FLOWS ,CFD simulations ,PLASMA DIAGNOSTIC ,Engineering codes - Abstract
A new Mach 9 contoured nozzle to use with air was designed and realized at Alta SpA with the aim to produce a uniform core flow with a diameter of at least 80 mm. The design was iteratively carried out using engineering codes and CFD simulations by CIRA. The characterization activity was carried out mapping the complete test section in terms of pitot pressure and total enthalpy and measuring the pressure and heat flux distribution on the nozzle internal walls. The flow before the convergent was characterized by means of total pressure measurements and spectroscopy. A numerical rebuilding of the test was performed by CIRA and PoliTO and compared with experimental data. The paper will briefly describe the design phase and will present all the characterization results.
21. Real Time Power Control in a High Voltage Power Supply for Dielectric Barrier Discharge Reactors: Implementation Strategy and Load Thermal Analysis
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Gabriele Neretti, Arturo Popoli, Silvia Giuditta Scaltriti, Andrea Cristofolini, Neretti G., Popoli A., Scaltriti S.G., and Cristofolini A.
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feedback control ,high voltage ,average power ,Computer Networks and Communications ,Hardware and Architecture ,Control and Systems Engineering ,power supply ,Signal Processing ,Electrical and Electronic Engineering ,dielectric barrier discharge ,plasma - Abstract
Atmospheric-pressure plasma treatments for industrial and biomedical applications are often performed using Dielectric Barrier Discharge reactors. Dedicated power supplies are needed to provide the high voltage frequency waveforms to operate these nonlinear and time-dependent loads. Moreover, there is a growing technical need for reliable and reproducible treatments, which require the discharge parameters to be actively controlled. In this work, we illustrate a low-cost power supply topology based on a push-pull converter. We perform experimental measurements on two different reactor topologies (surface and volumetric), showing that open loop operation of the power supply leads to a temperature and average power increase over time. The temperature increases by Delta T-vol similar to 120 degrees C and Delta T-sup similar to 70 degrees C, while the power increases by Delta P-vol similar to 78% and Delta P-sup similar to 60% for the volumetric (40 s) and superficial reactors (120 s), respectively. We discuss how these changes are often unwanted in practical applications. A simplified circuital model of the power supply-reactor system is used to infer the physical relation between the observed reactor thermal behavior and its electrical characteristics. We then show a control strategy for the power supply voltage to ensure constant average power operation of the device based on real-time power measurements on the high voltage side of the power supply and an empirical expression relating the delivered power to the power supply output voltage. These are performed with an Arduino Due microcontroller unit, also used to control the power supply. In a controlled operation the measured power stays within 5% of the reference value for both configurations, reducing the temperature increments to Delta T-vol similar to 80 degrees C and Delta T-sup similar to 44 degrees C, respectively. The obtained results show that the proposed novel control strategy is capable of following the transient temperature behavior, achieving a constant average power operation and subsequently limiting the reactor thermal stress.
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- 2022
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22. Theoretical and experimental aspects of non-equilibrium plasmas in different regimes: fundamentals and selected applications
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Alix Gicquel, Gabriele Neretti, Gianpiero Colonna, Laura Laguardia, Thomas Bieber, Francesco Pegoraro, Andrea Cristofolini, Arturo Popoli, Carlos D Pintassilgo, Khaled Hassouni, Olivier Duigou, Colonna G., Pintassilgo C.D., Pegoraro F., Cristofolini A., Popoli A., Neretti G., Gicquel A., Duigou O., Bieber T., Hassouni K., and Laguardia L.
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010302 applied physics ,Physics ,Plasma Density ,non-equilibrium plasmas, cold plasmas, non thermal plasmas, plasma modelling, pIC, drift-diffusion models ,Divertor ,Poloidal Flux ,Optical physics ,Plasma ,01 natural sciences ,Divertors (Fusion Reactors) ,Atomic and Molecular Physics, and Optics ,010305 fluids & plasmas ,Computational physics ,Physics::Plasma Physics ,0103 physical sciences ,Nuclear fusion ,Vibrational temperature ,Microwave - Abstract
This paper presents recent activities covering different plasma fields, from both theoretical and experimental point of views. An overview of the present interests of the scientific community is reported here. Starting from a brief description of the role of collisions in astrophysical plasmas, some fundamental aspects of gas discharges modelling, such as superelastic collisions and the basic concept of vibrational temperature, are discussed. Different plasma sources, as DBD and microwave discharges with their own specific applications, are reported. Edge plasmas in nuclear fusion reactors are investigated, focusing on the cooling mechanisms resulting from nitrogen puffing in the divertor region. Graphic abstract: [Figure not available: see fulltext.].
- Published
- 2021
23. Effect of nanofillers on surface charge mobility and alternative technique for electrostatic field measurement
- Author
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Andrea Cristofolini, Paolo Seri, Gabriele Neretti, Seri P., Cristofolini A., and Neretti G.
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surface charge ,010302 applied physics ,chemistry.chemical_classification ,Thermoplastic ,Materials science ,business.industry ,High voltage ,Dielectric ,01 natural sciences ,Electric charge ,010305 fluids & plasmas ,chemistry ,Electric field ,0103 physical sciences ,Electrode ,Optoelectronics ,Surface charge ,Actuator ,business - Abstract
This paper has the main purpose to assess the influence of nanofillers on the mobility of electrostatic surface charge buildup. Electro Hydro Dynamic actuators were produced and tested at a fixed voltage amplitude and frequency, using different thermoplastic dielectrics, some of which belonging to the family of nano-filled materials. The investigation focuses on the mobility of superficial electrostatic buildup, also experimenting the validity of an alternative high voltage potential measurement technique based on monitoring of multiple embedded electrodes. Results show that nanofillers have a profound effect on electrostatic charge buildup, strongly reducing their mobility.
- Published
- 2020
24. A multi-stage model for dielectric barrier discharge in atmospheric pressure air
- Author
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Arturo Popoli, Gabriele Neretti, Andrea Cristofolini, Cristofolini A., Popoli A., and Neretti G.
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plasma processing ,Materials science ,Atmospheric pressure ,plasma modelling ,Mechanical Engineering ,Dielectric barrier discharge ,dielectric barrier discharge ,Condensed Matter Physics ,plasma actuator ,Electronic, Optical and Magnetic Materials ,Multi stage ,Mechanics of Materials ,Physics::Plasma Physics ,Electrical and Electronic Engineering ,Composite material ,DBD plasma - Abstract
In this paper, a multi-stage numerical methodology for the description of the Dielectric Barrier Discharge physics in air is discussed. The behavior of the heavy species is computed using drift-diffusion equations. Electrons are taken into account by solving a non-linear formulation of electrostatics. The physical effects of the steamer discharges are modelled by means of a simplified 0D approach. The model also includes a semi-implicit 0D model for the assessment of the elementary chemical processes occurring in air. The developed methodology is employed for the simulation of a volumetric Dielectric Barrier Discharge reactor. The obtained species number density and surface charge deposition rates and are shown and discussed.
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- 2020
25. Electrohydrodynamic interaction induced by a dielectric barrier discharge
- Author
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Neretti, G [Department of Electrical Engineering, University of Bologna, Viale Risorgimento 2, Bologna 40136 (Italy)]
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- 2008
- Full Text
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26. Inactivation of Eimeria Oocysts in Aqueous Solution by a Dielectric Barrier Discharge Plasma in Contact with Liquid
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Gabriele Neretti, Roberta Galuppi, Carlo Angelo Borghi, Matteo Taglioli, Benedetto Morandi, Giovanni Poglayen, G. Tosi, Neretti, G., Morandi, B., Taglioli, M., Poglayen, G., Galuppi, R., Tosi, G., and Borghi, C.A.
- Subjects
Aqueous solution ,Materials science ,biology ,Cold atmospheric-pressure plasma ,Biomedical Engineering ,Coccidian ,General Physics and Astronomy ,Dielectric barrier discharge ,Plasma ,biology.organism_classification ,Biocidal efficacy ,Eimeria ,Parasite ,Physics and Astronomy (all) ,Chemical engineering ,Biological effect - Abstract
This study presents a novel technique to inactivate coccidian oocysts in an aqueous solution. The technique consists of treating the contaminated liquid by using an atmospher- ic-pressure air dielectric barrier discharge (DBD) plasma in contact with it. Many experiments in several operating conditions were performed. The discharge was supplied by sinusoidal and nanosecond-pulsed voltages with a constant average power of ~7 W in both cases. Biological effects due to the plasma were investigated by performing tests with increasing treatment time. A sudden ~40% drop in the number of survived oocysts was reached in 4 min and a two-fold reduction was detected after 12 min of exposure. No significant differences in the biocidal efficacy were detected between the AC-driven and the nanosecond-pulsed discharge. Chi-squared statistical analysis on the treated samples showed significant statistical difference (with a statistical significance P value parameter less than 0.01) and nonrandomness warranty of the results, opening interesting scenarios for fimire developments.
- Published
- 2018
27. Self-Tuning High-Voltage and High-Frequency Sinusoidal Power Supply for Dielectric Barrier Discharge Plasma Generation
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Gabriele Neretti, Mattia Ricco, Neretti G., and Ricco M.
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high-voltage on-board diagnostics ,Materials science ,Computer Networks and Communications ,non-thermal plasma ,High-voltage on-board diagnostic ,lcsh:TK7800-8360 ,Dielectric barrier discharge ,dielectric barrier discharge ,01 natural sciences ,010305 fluids & plasmas ,Generator (circuit theory) ,0103 physical sciences ,Electrical and Electronic Engineering ,010302 applied physics ,business.industry ,lcsh:Electronics ,Electrical engineering ,High voltage ,500 kHz ,Power (physics) ,Lissajous curve ,high-voltage generator ,self-tuning frequency ,Hardware and Architecture ,Control and Systems Engineering ,Modulation ,Signal Processing ,business ,Voltage - Abstract
In this paper a high-voltage sinusoidal power supply controlled by Arduino DUE micro-controller is described. This generator can feed a dielectric barrier discharge (DBD) load with sinusoidal voltages up to 20 kV peak and frequencies in the range 10&ndash, 60 kHz, with a maximum output power of 200 W. Output voltage can be produced either in a continuous mode, or with on/off modulation cycles, according to treatment/application requirements. This power source is equipped with on-board diagnostics used to measure the output voltage and the charge delivered to the load. With a sample frequency of 500 kHz, Arduino DUE allows to evaluate both the high voltage and the average power feeding the discharge without the use of an expensive external measurement setup. Lissajous techniques are utilized to calculate discharge average power in a quasi-real-time manner. When a load is connected to high-voltage terminals, a self-tuning procedure is carried out to obtain the best working frequency. This parameter allows to minimize power-electronic component stress and to maximize generator efficiency.
- Published
- 2019
28. Ozone yield limit in low temperature plasmas based on thermodynamics
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Linsheng Wei, Deng Haizhong, Gabriele Neretti, Yafang Zhang, Wei L., Deng H., Neretti G., and Zhang Y.
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010302 applied physics ,Ozone ,Materials science ,Plasma Physics ,chemistry.chemical_element ,Thermodynamics ,Plasma ,Electron ,010501 environmental sciences ,01 natural sciences ,Oxygen ,Atomic and Molecular Physics, and Optics ,Spectral line ,chemistry.chemical_compound ,Distribution function ,chemistry ,Yield (chemistry) ,0103 physical sciences ,0105 earth and related environmental sciences ,Dimensionless quantity - Abstract
To investigate ozone yield limit in low temperature plasmas, a detailed thermodynamic model is developed to calculate theoretical ozone yield for the first time. Theoretical ozone yield is calculated both from overall reaction and detailed reactions. In the former case, the highest theoretical ozone yield of 1211±2 g kWh−1 is obtained when final gas temperature equals the initial one, and all energy is effectively utilized to synthesize ozone. When final gas temperature is not equal to the initial one, theoretical ozone yield increases with the increase of oxygen admixture ratio and oxygen conversion ratio as well as the decrease of final gas temperature. Theoretical ozone yields are 921.22 g kWh−1 and 487.54 g kWh−1 in pure oxygen and in synthetic air respectively at final gas temperature of 400 K and oxygen conversion ratio of 10%. When detailed reactions and electron energy distribution function is considered, theoretical ozone yield rapidly increases by enhancing reduced field. Oxygen admixture ratio also has non-negligible effects on ozone yield. A higher oxygen admixture ratio leads to higher energy efficiency. The theoretical ozone yields are 238.92 g kWh−1 and 191.14 g kWh−1 in pure oxygen and in synthetic air at reduced field of 300 Td respectively. Graphical abstract: [Figure not available: see fulltext.].
- Published
- 2019
29. Influence of the voltage waveform's shape and on-time duration on the dissolved ozone produced by a DBD bubble reactor
- Author
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Carlo Angelo Borghi, Alexander H. Shaw, Alexander R.P. Wright, Felipe Iza, Paolo Seri, H.C. Hemaka Bandulasena, Gabriele Neretti, and Seri, P., Wright, A., Shaw, A., Iza, F., Bandulasena, H., Borghi, C.A., Neretti, G.
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010302 applied physics ,Ozone ,Materials science ,Bubble ,Plasma ,Mechanics ,Sawtooth wave ,Nonthermal plasma ,Condensed Matter Physics ,01 natural sciences ,010305 fluids & plasmas ,chemistry.chemical_compound ,chemistry ,non-thermal plasma, ozone, voltage waveform, water, bubbling reactor ,Duty cycle ,0103 physical sciences ,Waveform ,Voltage - Abstract
In this study we examine both the effect of changing the applied voltage waveform shape and the modulation on-time on the amount of ozone dissolved within a liquid in a dielectric barrier discharges (DBD) bubble reactor. In this device, the discharge forms at the gas–liquid interface allowing for effective transfer of the plasma effluent into the liquid. To produce different voltage waveforms, a multilevel inverter power supply capable of generating arbitrary waveforms without switching-on and switching-off transients has been used. Of the four waveforms used in the study (sinusoidal, sawtooth, square and short-pulse), the square waveform was found to be the most efficient at producing the highest ozone concentration for a fixed peak voltage and average power. To determine the effect of the modulation on-time, the number of cycles during the on-time were increased from 1 up to 1000, adjusting the off-time accordingly to maintain the same duty cycle. Shorter on-time periods were found to be more efficient. Experimental and computational results indicate that the time between subsequent discharges is critical for increased ozone generation efficacy, as this needs to be long enough for ozone produced in one discharge event to diffuse away from the discharge region before the next discharge event occurs, thereby avoiding its partial destruction in the plasma. This insight provides a valuable criterion for the optimization of DBD reactors used in novel biomedical, agricultural and environmental applications.
- Published
- 2019
30. Atmospheric‐pressure plasma actuators: Enhancement of the free charges' transport mechanism
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Gabriele Neretti, Carlo Angelo Borghi, Andrea Cristofolini, A. C. Ricchiuto, and Ricchiuto, A.C., Borghi, C.A., Cristofolini, A., Neretti, G.
- Subjects
Computer Science::Robotics ,Materials science ,Polymers and Plastics ,Chemical physics ,Charged particles, dielectric barrier discharge, electrohydrodynamic interaction, electrostatic simulation, nonthermal plasma ,Atmospheric-pressure plasma ,Dielectric barrier discharge ,Nonthermal plasma ,Condensed Matter Physics ,Actuator ,Charged particle ,Mechanism (sociology) - Abstract
Charge particles can increase the biocidal efficacy of nonthermal plasmas in indirect treatments. The aim of this study is to increase the amount of free charges produced and delivered by a surface dielectric barrier discharge fluid‐ dynamics actuator. Different linear actuators and supplying conditions have been considered. Actuators were utilized to produce an ionic wind impinging an insulating target surface. Charged particles' distribution over the target was measured with and without a metallic mesh between the actuator and target itself. Linear actuators have proven to be more effective in charge delivery with respect to an annular one previously studied by our research team. A two‐ dimensional electrostatic finite‐element analysis has been carried out to get a better insight into this physical behavior.
- Published
- 2021
31. Measurement of the charge distribution deposited on a target surface by an annular plasma synthetic jet actuator: Influence of humidity and electric field
- Author
-
A. C. Ricchiuto, Gabriele Neretti, Carlo Angelo Borghi, Andrea Cristofolini, Ricchiuto A.C., Borghi C.A., Cristofolini A., and Neretti G.
- Subjects
Materials science ,Dielectric barrier discharge ,01 natural sciences ,Electric charge ,010305 fluids & plasmas ,Electric field ,0103 physical sciences ,Charge distribution ,Electrical and Electronic Engineering ,Plasma actuator ,010302 applied physics ,Jet (fluid) ,Non-thermal plasma ,Charge density ,Relative humidity ,Plasma ,Mechanics ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Electro hydro dynamic ,Biotechnology ,Voltage - Abstract
In this paper, an investigation on an annular Plasma Synthetic Jet Actuator (PSJA) utilizing a Surface Dielectric Barrier Discharge (SDBD) is reported. The work is focused at an investigation of the electric charges transported by the jet produced by the actuator and deposited on a target. Particularly, an assessment of the various factors that may affect the charge deposit process has been carried out. Experiments have been performed in a controlled environment with different electric configurations. This allowed to evaluate how the humidity rate affects and the dynamics of the electric charge build-up process. It was observed that humidity rate weakly affects the charge deposition, being the most notable effect an increase of the deposition time for higher humidity rate. Moreover, the performances of two different power supply systems, working at different voltage and frequency conditions, were compared. The two supplies have been set up do feed the actuator with the same power, in order to assess which voltage-frequency condition is more efficient at depositing electric charge on the target. It was observed that a higher applied electric field produces higher charge deposition rates.
- Published
- 2020
32. Characterization of a plasma source for biomedical applications by electrical, optical, and chemical measurements
- Author
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Cristina Paradisi, Roberto Cavazzana, Carlo Angelo Borghi, Emilio Martines, Paolo Seri, Matteo Taglioli, Matteo Zuin, Paola Brun, Gabriele Neretti, L. Cordaro, Ester Marotta, Barbara Zaniol, Francesco Tampieri, Neretti, Gabriele, Tampieri, Francesco, Borghi, Carlo Angelo, Brun, Paola, Cavazzana, Roberto, Cordaro, Luigi, Marotta, Ester, Paradisi, Cristina, Seri, Paolo, Taglioli, Matteo, Zaniol, Barbara, Zuin, Matteo, Martines, Emilio, Neretti, G, Tampieri, F, Borghi, C, Brun, P, Cavazzana, R, Cordaro, L, Marotta, E, Paradisi, C, Seri, P, Taglioli, M, Zaniol, B, Zuin, M, and Martines, E
- Subjects
010302 applied physics ,reactive oxygen species ,Schlieren ,reactive oxygen specie ,Materials science ,Polymers and Plastics ,Chemical measurement ,Analytical chemistry ,Plasma ,Condensed Matter Physic ,plasma medicine ,Condensed Matter Physics ,01 natural sciences ,010305 fluids & plasmas ,Characterization (materials science) ,atmospheric plasma jet ,optical emission spectroscopy ,0103 physical sciences ,Optical emission spectroscopy ,Plasma medicine - Abstract
This paper reports the characterization of a low-power, atmospheric pressure plasma source developed for and successfully tested in applications of plasma medicine. The source produces plasma by ionizing a helium flow containing traces of air. The effluent gas is thus enriched in reactive oxygen and nitrogen species as well as helium metastable excited states. Electrical measurements, Schlieren imaging, OES and various chemical analyses and probes enabled us to fully characterize the plasma source and to determine some fundamental parameters for treating living samples such as the power feeding the discharge, the optimal source to target distance, the maximum exposure time, and to identify the major chemical species responsible for the biological action on exposed living matter.
- Published
- 2018
33. Measurement of the charge distribution deposited by an annular plasma synthetic jet actuator over a target surface
- Author
-
Carlo Angelo Borghi, A. C. Ricchiuto, Gabriele Neretti, Neretti, G., Ricchiuto, A.C., and Borghi, C.A.
- Subjects
010302 applied physics ,Materials science ,Acoustics and Ultrasonics ,Target surface ,Electronic, Optical and Magnetic Material ,Non-thermal plasma ,Charge density ,Plasma ,Dielectric barrier discharge ,Condensed Matter Physic ,Nonthermal plasma ,Condensed Matter Physics ,Acoustics and Ultrasonic ,01 natural sciences ,Synthetic jet actuator ,010305 fluids & plasmas ,Electronic, Optical and Magnetic Materials ,Surfaces, Coatings and Films ,Electro hydro dynamic ,0103 physical sciences ,Charge distribution ,Atomic physics ,Plasma actuator - Abstract
Annular plasma synthetic jet actuators demonstrated their ability to produce a tubular flow normal to the surface where the dielectric barrier discharge (DBD) is ignited. These fluid-dynamic actuators enhance the delivery of reactive species towards the target to be treated. In these actuators, long life charged particles are generated within the plasma region and then carried on by the induced flow. In this work, the potential distribution induced by charges deposited over an insulating target has been measured. Surface DBD actuators, made with different dielectric materials, have been supplied by different sinusoidal voltages at a constant average power supplying the discharge. Actuators with the exposed electrode connected to both the high voltage potential and grounded have been tested. The charge distribution accumulated on a target surface perpendicular to the flow has been measured at different time intervals with the plasma on. Charges advected by the flow are always positive. The potential distribution on the target surface generated by the charges has been measured. For both configurations, firstly an M-shaped distribution develops and, later on, it becomes bell-shaped. A charge build-up mechanism has been found to be faster when the exposed electrode is connected to the high voltage terminal. The target has been placed at a variable distance from 1 to 5 cm from the actuator surface. At a distance of 5 cm, induced potentials are two times smaller than those with the target at 1 cm. Measurements allow us to estimate a charge flux toward the target on the order of 1011 particles (cm2 s)−1. The results presented in this work show that the presence of charged particles in the jet flow outside the plasma could be an important factor to be accounted for when these plasma actuators are used for treatment purposes (indirect plasma treatment).
- Published
- 2018
34. Geometry optimization of linear and annular plasma synthetic jet actuators
- Author
-
Gabriele Neretti, Paolo Seri, Matteo Taglioli, Alexander H. Shaw, Carlo Angelo Borghi, Felipe Iza, Neretti, G, Seri, P., Taglioli, M., Shaw, A., Iza, F., and Borghi, C.A.
- Subjects
Materials science ,Acoustics and Ultrasonics ,Pitot tube ,02 engineering and technology ,Dielectric barrier discharge ,Condensed Matter Physic ,Acoustics and Ultrasonic ,01 natural sciences ,Schlieren imaging ,010305 fluids & plasmas ,law.invention ,Flow separation ,Optics ,law ,0103 physical sciences ,Plasma actuator ,Plasma processing ,business.industry ,Electronic, Optical and Magnetic Material ,Non-thermal plasma ,Laminar flow ,Mechanics ,Electrohydrodynamic ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Plasma actuator geometry ,Electronic, Optical and Magnetic Materials ,Surfaces, Coatings and Films ,Synthetic jet ,0210 nano-technology ,business - Abstract
The electrohydrodynamic (EHD) interaction induced in atmospheric air pressure by a surface dielectric barrier discharge (DBD) actuator has been experimentally investigated. Plasma synthetic jet actuators (PSJAs) are DBD actuators able to induce an air stream perpendicular to the actuator surface. These devices can be used in the field of aerodynamics to prevent or induce flow separation, modify the laminar to turbulent transition inside the boundary layer, and stabilize or mix air flows. They can also be used to enhance indirect plasma treatment effects, increasing the reactive species delivery rate onto surfaces and liquids. This can play a major role in plasma processing and chemical kinetics modelling, where often only diffusive mechanisms are considered. This paper reports on the importance that different electrode geometries can have on the performance of different PSJAs. A series of DBD aerodynamic actuators designed to produce perpendicular jets has been fabricated on two-layer printed circuit boards (PCBs). Both linear and annular geometries were considered, testing different upper electrode distances in the linear case and different diameters in the annular one. An AC voltage supplied at a peak of 11.5 kV and a frequency of 5 kHz was used. Lower electrodes were connected to the ground and buried in epoxy resin to avoid undesired plasma generation on the lower actuator surface. Voltage and current measurements were carried out to evaluate the active power delivered to the discharges. Schlieren imaging allowed the induced jets to be visualized and gave an estimate of their evolution and geometry. Pitot tube measurements were performed to obtain the velocity profiles of the PSJAs and to estimate the mechanical power delivered to the fluid. The optimal values of the inter-electrode distance and diameter were found in order to maximize jet velocity, mechanical power or efficiency. Annular geometries were found to achieve the best performance.
- Published
- 2017
35. Geometry optimization of linear and annular Plasma Synthetic Jet Actuators for enhanced transport of reactive species
- Author
-
BORGHI, CARLO ANGELO, NERETTI, GABRIELE, SERI, PAOLO, TAGLIOLI, MATTEO, Shaw, A., Wright, A., FitzPatrick, A., Iza, F., Borghi, C. A., Neretti, G., Seri, P., Taglioli, M., Shaw, A., Wright, A., FitzPatrick, A., and Iza, F.
- Subjects
non-thermal plasma, DBD, EHD interaction, chemical species - Published
- 2016
36. The fourth State of Matter and its biocidal effect: Plasma vs Coccidia
- Author
-
MORANDI, BENEDETTO, POGLAYEN, GIOVANNI, BORGHI, CARLO ANGELO, GALUPPI, ROBERTA, NERETTI, GABRIELE, TAGLIOLI, MATTEO, Tosi, G., AAVV, SOIPA, Morandi, B., Poglayen, G., Borghi, C.A., Galuppi, R., Neretti, G., Taglioli, M., and Tosi, G.
- Subjects
Plasma ,Coccidia - Published
- 2016
37. The effect of plasma surface modification on biodegradation rate and biocompatibility of a poly(butylene succinate)-based copolymer
- Author
-
SERI, PAOLO, BORGHI, CARLO ANGELO, GIORDANO, EMANUELE DOMENICO, NERETTI, GABRIELE, TAGLIOLI, MATTEO, FABBRI, MARTINA, GAMBERINI, RITA, GIGLI, MATTEO, GOVONI, MARCO, LOTTI, NADIA, MUNARI, ANDREA, Rimini, B., Seri, P., Borghi, C.A., Giordano, E., Neretti, G., Taglioli, M., Fabbri, M., Gamberini, R., Rimini, B., Gigli, M., Govoni, M., Lotti, N., and Munari, A.
- Published
- 2015
38. Characterization of hybrid gas-liquid Dielectric Barrier Discharge plasma reactors for water treatment
- Author
-
BORGHI, CARLO ANGELO, NERETTI, GABRIELE, TAGLIOLI, MATTEO, Borghi, C.A., Neretti, G., and Taglioli, M.
- Published
- 2015
39. Hybrid gas-liquid dielectric barrier discharge plasma reactor driven by sinusoidal and nanosecond supply systems
- Author
-
NERETTI, GABRIELE, BORGHI, CARLO ANGELO, TAGLIOLI, MATTEO, Neretti, G., Borghi, C.A., and Taglioli, M.
- Published
- 2015
40. Inactivation of Eimeria spp. oocysts in aqueous environment assisted by dielectric barrier discharge plasma reactor
- Author
-
TAGLIOLI, MATTEO, BORGHI, CARLO ANGELO, NERETTI, GABRIELE, POGLAYEN, GIOVANNI, MORANDI, BENEDETTO, GALUPPI, ROBERTA, Tosi, G., Taglioli, M., Borghi, C.A., Neretti, G., Poglayen, G., Morandi, B., Galuppi, R., and Tosi, G.
- Published
- 2015
41. Wind tunnel experiments on a NACA0015 airfoil equipped with vectorizable dielectric barrier discharge plasma actuators
- Author
-
Gabriele Neretti, Seri Paolo, Carlo Angelo Borghi, Alessandro Talamelli, Alessandro Rossetti, Andrea Cristofolini, AIAA, Borghi C.A, Cristofolini A., Neretti G., Seri P., Talamelli A., and Rossetti A.
- Subjects
Airfoil ,Leading edge ,Lift coefficient ,Materials science ,PLASMA ,business.industry ,Stall (fluid mechanics) ,Dielectric barrier discharge ,Mechanics ,FLOW CONTROL ,Flow control (fluid) ,Aerospace engineering ,business ,Plasma actuator ,Wind tunnel - Abstract
This work reports an experimental investigation performed in wind tunnel facility on a NACA0015 airfoil equipped with a set of vectorizable fluid-dynamic DBD plasma actuators. The ability of the actuators to recover the stall condition with free stream velocities in the range 5-23 m/s has been investigated. The discharge has been generated by feeding the actuators with a sinusoidal voltage waveform with a frequency of 15 kHz and voltages up to 7.5 kV peak. The actuator positioned on the leading edge exhibits highest ability in the stall recovery. Unsteady actuation obtained by alternatively switching on and off the discharge is more effective in the stall recovery when compared with a steady actuation. The frequency that optimizes the stall recovery has been found to be a function of the velocity with the power of 1.5. This result leads to the determination of a constant Strouhal number if the boundary layer thickness is used as characteristic length. Finally the lift coefficient, obtained when the plasma actuator has been turned on, has been found to be a linear function of the applied voltage.
- Published
- 2014
42. Characterization of a dielectric barrier discharge in contact with liquid and producing a plasma activated water
- Author
-
Gianpiero Colonna, Carlo Angelo Borghi, Gabriele Neretti, Matteo Taglioli, Neretti, G., Taglioli, M., Colonna, G., and Borghi, C.A.
- Subjects
010302 applied physics ,Free electron model ,spectroscopy ,Electron density ,plasma activated water ,Atmospheric pressure ,Plasma cleaning ,Chemistry ,Analytical chemistry ,Plasma ,Dielectric barrier discharge ,dielectric barrier discharge ,electrical engineering ,Condensed Matter Physics ,01 natural sciences ,010305 fluids & plasmas ,plasma engineering ,numerical simulation ,0103 physical sciences ,plasma physic ,Electron temperature ,Electrical measurements ,Atomic physics - Abstract
In this work a low-temperature plasma source for the generation of plasma activated water (PAW) is developed and characterized. The plasma reactor was operated by means of an atmospheric-pressure air dielectric barrier discharge (DBD). The plasma generated is in contact with the water surface and is able to chemically activate the liquid medium. Electrodes were supplied by both sinusoidal and nanosecond-pulsed voltage waveforms. Treatment times were varied from 2 to 12 min to increase the energy dose released to the water by the DBD plasma. The physics of the discharge was studied by means of electrical, spectroscopic and imaging diagnostics. The interaction between the plasma and the liquid was investigated as well. Temperature and composition of the treated water were detected. Images of the discharges showed a filamentary behaviour in the sinusoidal case and a more homogeneous behaviour in the nanosecond-pulsed one. The images and the electrical measurements allowed to evaluate an average electron number density of about 4 × 1019 and 6 × 1017 m-3 for the sinusoidal and nanosecond-pulsed discharges respectively. Electron temperatures in the range of 2.1÷2.6 eV were measured by using spectroscopic diagnostics. Rotational temperatures in the range of 318-475 K were estimated by fitting synthetic spectra with the measured ones. Water temperature and pH level did not change significantly after the exposure to the DBD plasma. The production of ozone and hydrogen peroxide within the water was enhanced by increasing the plasma treatment time and the energy dose. Numerical simulations of the nanosecond-pulsed discharge were performed by using a self-consistent coupling of state-to-state kinetics of the air mixture with the Boltzmann equation of free electron kinetics. Temporal evolution of the electron energy distribution function shows departure from the Maxwellian distribution especially during the afterglow phase of the discharge. When limited deviations from Maxwellian distribution were observed, calculated electron temperature is in good agreement with the one measured by means of spectroscopic diagnostics. Computed temporal evolution of the energy delivered to the discharge is comparable with the one obtained from electrical measurements. The electrical discharges supplied by both voltage waveforms produce plasma activated water with negligible thermal effects and pH variations.
- Published
- 2016
43. Mhd flow control experiment in air: Test article design
- Author
-
Eduardo Trifoni, Carlo Angelo Borghi, Damiano Baccarella, Andrea Passaro, Andrea Cristofolini, Gabriele Neretti, Baccarella, D., Passaro, A., Cristofolini, A., Neretti, G., and Trifoni, E.
- Subjects
Engineering ,Electromagnet ,business.industry ,Airflow ,Mechanical engineering ,Aerospace Engineering ,Plasma ,Computational fluid dynamics ,law.invention ,Magnetic field ,Flow control (fluid) ,law ,Space and Planetary Science ,Control and Systems Engineering ,Aerospace engineering ,Magnetohydrodynamics ,business ,Wind tunnel - Abstract
An advanced flow control experiment, concerning magnetohydrodynamics (MHD) interaction over a blunt body, has been designed by Alta, CIRA and Department of Electrical Engineering (DIE) of University of Bologna and to be realized in CIRA's plasma wind tunnel "Scirocco" under a technology research program (TRP) funded by the European Space Agency (ESA). This work is a further step of the researches performed during the last decade by Alta and DIE in the field of MHD interaction. This experimental campaign foresees the employment of a 50 kW electromagnet, enclosed into an insulated blunt-shaped metallic TPS convectively cooled and electrically insulated by a ceramic coating. The test article has been designed for an air flow with nominal stagnation conditions of p0=2 bar and h0=22 MJ/kg, but several other conditions are planned to be investigated. The aim of the experimental campaign, along with a better understanding of the physical phenomena occurring within an highly ionized shock layer with an applied magnetic field, is the comparison of the collected data with the numerical predictions of CFD codes developed by CIRA. © 2011 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
- Published
- 2011
44. Experimental investigation on a vectorized aerodynamic dielectric barrier discharge plasma actuator array
- Author
-
Carlo Angelo Borghi, Gabriele Neretti, Andrea Cristofolini, Neretti G., Cristofolini A., and Borghi C.A.
- Subjects
Materials science ,Analytical chemistry ,General Physics and Astronomy ,Pitot tube ,Plasma Aerodynamics ,Mechanics ,Plasma ,Dielectric barrier discharge ,Schlieren imaging ,law.invention ,law ,Surface Dielectric Barrier Discharge Actuator ,Plasma diagnostics ,Plasma Physic ,Actuator ,Electro-hydro-dynamic Interaction ,Plasma actuator ,Schlieren Diagnostic ,Voltage - Abstract
The Electro-Hydro-Dynamics (EHD) interaction, induced in atmospheric pressure still air by a surface dielectric barrier discharge (DBD) actuator, had been experimentally studied. A plasma aerodynamic actuator array, able to produce a vectorized jet, with the induced airflow oriented toward the desired direction, had been developed. The array was constituted by a sequence of single surface DBD actuators with kapton as dielectric material. An ac voltage in the range of 0–6 kV peak at 15 kHz had been used. The vectorization had been obtained by feeding the upper electrodes with different voltages and by varying the electrical connections. The lower electrodes had been connected either to ground or to the high voltage source, to produce the desired jet orientation and to avoid plasma formation acting in an undesired direction. Voltage and current measurements had been carried out to evaluate waveforms and to estimate the active power delivered to the discharge. Schlieren imaging allowed to visualize the induced jet and to estimate its orientation. Pitot measurements had been performed to obtain velocity profiles for all jet configurations. A proportional relation between the jet deflection angle and the applied voltage had been found. Moreover, a linear relation had been obtained between the maximum speed in the jet direction and the applied voltage. The active power of the discharge is approximated by both a power law function and an exponential function of the applied voltage.
- Published
- 2014
45. Experimental investigation of dielectric barrier discharge plasma actuators driven by repetitive high-voltage nanosecond pulses with dc or low frequency sinusoidal bias
- Author
-
Dmitry Opaits, Alexandre Likhanskii, Richard B. Miles, Sergey Macheret, Sohail Zaidi, Mikhail N. Shneider, Gabriele Neretti, DMITRI F. OPAITS, ALEXANDER V. LIKHANSKII, NERETTI G, SOHALI ZAIDI, MIKHAIL N. SHNEIDER, and RICHARD B. MILES AND SERGEY MACHERET
- Subjects
DIELECTRIC BARRIER DISCHARGE ,Physics ,Electro Hydro Dynamic Interaction ,Analytical chemistry ,General Physics and Astronomy ,Biasing ,High voltage ,Mechanics ,Dielectric barrier discharge ,Plasma ,Nanosecond ,Physics::Fluid Dynamics ,Nano pulses ,Physics::Plasma Physics ,AERODYNAMIC ,Plasma diagnostics ,Electrical impedance ,Plasma actuator - Abstract
Experimental studies were conducted of a flow induced in an initially quiescent room air by a single asymmetric dielectric barrier discharge driven by voltage waveforms consisting of repetitive nanosecond high-voltage pulses superimposed on dc or alternating sinusoidal or square-wave bias voltage. To characterize the pulses and to optimize their matching to the plasma, a numerical code for short pulse calculations with an arbitrary impedance load was developed. A new approach for nonintrusive diagnostics of plasma actuator induced flows in quiescent gas was proposed, consisting of three elements coupled together: the schlieren technique, burst mode of plasma actuator operation, and two-dimensional numerical fluid modeling. The force and heating rate calculated by a plasma model was used as an input to two-dimensional viscous flow solver to predict the time-dependent dielectric barrier discharge induced flow field. This approach allowed us to restore the entire two-dimensional unsteady plasma induced flow pattern as well as characteristics of the plasma induced force. Both the experiments and computations showed the same vortex flow structures induced by the actuator. Parametric studies of the vortices at different bias voltages, pulse polarities, peak pulse voltages, and pulse repetition rates were conducted experimentally. The significance of charge buildup on the dielectric surface was demonstrated. The charge buildup decreases the effective electric field in the plasma and reduces the plasma actuator performance. The accumulated surface charge can be removed by switching the bias polarity, which leads to a newly proposed voltage waveform consisting of high-voltage nanosecond repetitive pulses superimposed on a high-voltage low frequency sinusoidal voltage. Advantages of the new voltage waveform were demonstrated experimentally.
- Published
- 2008
46. Development of a multilevel plasma generator for Dielectric Barrier Discharge actuators
- Author
-
Carlo Angelo Borghi, Filopimin A. Dragonas, Gabriele Grandi, Andrea Cristofolini, Gabriele Neretti, AIAA, Borghi C.A., Cristofolini A., Dragonas F.A., Grandi G., and Neretti G.
- Subjects
Materials science ,business.industry ,Electro Hydro Dynamic Interaction ,Acoustics ,POWER ELECTRONICS ,Electrical engineering ,Impedance matching ,Aerodynamics ,Dielectric barrier discharge ,FLOW CONTROL ,Generator (circuit theory) ,Waveform ,business ,Actuator ,Plasma actuator ,Voltage ,DBD ACTUATORS - Abstract
In this work the development and the testing of a high voltage - high frequency plasma generator to supply Dielectric Barrier Discharge (DBD) actuators for the aerodynamic control, is reported. The generator can produce a wide set of different voltage wave¬forms. The peak-to-peak electrical tension is 30 kV at a frequency up to 20 kHz. The operating frequency are independent of the load char¬acter¬istics and are not subject to require¬ments on impedance matching. The generator has been tested when supplying a DBD actuator for aerodynamic control based on the Electro-Hydro-Dynamic (EHD) interaction. The tests have been performed in still air. The flow induced in the region above the surface of the actuator has been investigated and the EHD efficiency has been evaluated. The sinusoidal voltage waveform, simulated by the multilevel generator, and the sinusoidal voltage waveform of a conventional generator obtain comparable EHD effects and efficiencies. The sinusoidal and the inverse saw-tooth voltage waveforms show the best efficiencies with regard to the EHD interaction.
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