17 research outputs found
Analysis of crosstalk and field coupling to lossy MTL's in a SPICE environment
No full textThis paper proposes a circuit model for lossy multiconductor transmission lines (MTLs) suitable for implementation in modern SPICE simulators, as well as in any simulator supporting differential operators. The model includes the effects of a uniform or nonuniform disturbing field illuminating the line and is especially devised for the transient simulation of electrically long wideband interconnects with frequency dependent per-unit-length parameters. The MTL is characterized by its transient matched scattering responses, which are computed including both dc and skin losses by means of a specific algorithm for the inversion of the Laplace transform. The line characteristics are then represented in terms of differential operators and ideal delays to improve the numerical efficiency and to simplify the coding of the model in existing simulators. The model can be successfully applied to many kinds of interconnects ranging from micrometric high-resistivity metallizations to low-loss PCBs and cables, and can be considered a practical extension of the widely appreciated lossless MTL SPICE model, which maintains the simplicity and efficienc
Lean Blowout Sensing and Plasma Actuation of Non-Premixed Flames
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IEEE Sensors Journal
Volume 16, Issue 10, 15 May 2016, Article number 7426717, Pages 3896-3903
Lean Blowout Sensing and Plasma Actuation of Non-Premixed Flames (Article)
De Giorgi, M.G.a , Sciolti, A.a , Campilongo, S.a , Pescini, E.a , Ficarella, A.a , Lovascio, S.b , Dilecce, G.c
a Department of Engineering for Innovation, University of Salento, Lecce, Italy
b Department of Chemistry, University of Bari, Bari, Italy
c Istituto di Nanotecnologie, Consiglio Nazionale delle Ricerche, University of Bari, Bari, Italy
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Abstract
The aim of this paper is the use of optical sensors to recognize lean blowout in a non-premixed methane/air burner, Bunsen-type, and the use of plasma actuators for flame control and stabilization. The burner is optically accessible to permit the imaging acquisitions of the flame region. The plasma actuation regards alternatively the air flow and the fuel flow. The electric field is generated using a fixed configuration of plasma actuator and the dielectric barrier discharge (DBD) but using two different power supplies: a nanosecond repetitively pulsed high voltage (HV) and a sinusoidal DBD HV. The comparison between the two types of actuation is the core of this paper, together with the analysis of the results obtained when actuation acted on the air or on the fuel. For the analysis, the lean blowout (LBO) limits recorded in the presence and absence of plasma actuation to investigate the plasma actuation success. The flame behavior is acquired using a compact digital camera, an intensified charge-coupled device (CCD) in order to capture the differences between the baseline conditions and the actuated cases. It is shown that the plasma significantly allows stabilizing the flame under lean conditions where it would not exist without plasm
ELECTRON-ENERGY DISTRIBUTION-FUNCTIONS IN HE/N2 MIXTURES IN THE PRESENCE OF METASTABLE STATES
No full textProblems on the experimental determination of the electron energy distribution function in RF discharges
No full textModelling of electron heating in a Penning-Malmberg trap by means of a chaotic map
No full textWe have previously observed the production of an electron plasma in a Penning-Malmberg trap under ultra-high vacuum conditions by means of an original method, namely a radio-frequency excitation of a few Volt amplitude applied on one of the trap electrodes.
We have explained the origin of such plasma formation as a consequence of a Fermi-like heating of free electrons in the residual gas, which in turn can cause gas ionization. The heating of a single electron has been modelled in terms of a two-dimensional, area-preserving map, where the particle bounces within a square potential well and an intermediate, oscillating square barrier represents the RF drive. Similar mappings have been used to describe a variety of physical situations. Even in its simplicity, this model shows a significant predictive power. The low-energy part of the Poincaré plot includes both stable and chaotic regions, where heating up to ionization energies is achievable.
We perform an analysis of the map in order to define the conditions for an efficient heating. Chaotic properties and scaling laws are studied as a function of the control parameters, e.g. width of the potential well, barrier amplitude, frequency and position. These define a series of different cases that are evaluated and compared: RF drive with zero and non-zero static potential barrier; Different oscillation functions; Creation of one, two and three trapping regions. The effects on the ionization of a background gas, introducing a weak dissipation in the map, are also investigated using a Monte Carlo scheme
On the Influence of a target on OH density distribution in the Plasma Gun plume: Quantification by LIF and estimation of water and air penetration in the jet
No full textInternational audienceAmong Reactive oxygen and nitrogen Species produced by plasma jets, hydroxyl radical is of main interest for biomedical applications. The in-air expending jet produced by the Plasma Gun (PG) developed at GREMI [1] (Orléans) has been studied at CNR-IMIP (Bari) by Laser Induced Fluorescence (LIF). This technique [2-3] allows spatially resolved identification of OH density together with estimation of air and water partial pressures.As biomedical applications are target-dependant, the system under study is constituted of the PG in interaction with targets of different nature: a grounded metal surface and Petri dishes filled with aqueous solution of different conductivity in relation with in vivo and in vitro antitumor plasma jet assays respectively [4-5].Spatial distributions obtained during this STSM evidence the key role of target conductivity on OH production through plasma propagation modification confirming rare gas flow structuration by plasma as already observed by Schlieren photography [6]. Moreover good correlation has been observed between plasma emission and OH ground state distribution allowing for convenient and easy diagnostic of the PG plume.OH spatial distribution characterization opens up strategies to control its delivery on diverse biological targets and to match the application requirements.References [1] E. Robert, V. Sarron, D. Riès, S. Dozias, M. Vandamme, J.-M. Pouvesle " Characterization of pulsed atmospheric-pressure plasma streams (PAPS) generated by a plasma gun ", Plasma Sources Sci. Technol. Vol 21 Issue 3. [2] G. Dilecce, S. De Benedictis " Laser diagnostics of high-pressure discharges : laser induced fluorescence detection of OH in He/Ar-H2O dielectric barrier discharges ", Plasma Phys. Control. Fusion Vol 53 Issue 12[3] G. Dilecce, P.F. Ambrico, M. Simek, S. De Benedictis " LIF diagnostics of hydroxyl radical in atmospheric pressure He-H2O dielectric barrier discharges ", Chemical Physics Vol 398 (2012).[4] M. Vandamme, E. Robert, S. Lerondel, V. Sarron, D. Ries, S. Dozias, J. Sobilo, D. Gosset, C. Kieda, B. Legrain, J.-M. Pouvesle, A. Le Pape " ROS implication in a new antitumor strategy based on non-thermal plasma ", Int J Canc (2011)[5] L. Brullé, M. Vandamme, D. Riès, E. Martel, E.Robert, S. Lerondel, V.Trichet, S. Richard, J.-M. Pouvesle, A. Le Pape, " Effects of a Non Thermal Plasma Treatment Alone or in Combination with Gemcitabine in a MIA PaCa2-luc Orthotopic Pancreatic Carcinoma Model ", Plos one Vol 7 (2012) Issue 12[6] E. Robert, V. Sarron, T. Darny, D. Riès, S. Dozias, J. Fontane, L. Joly and J.-M. Pouvesle " Rare gas flow structuration in plasma jet experiments ",Plasma Sources Sci. Technol.100012.R1 (in press
Exploring Factors Influencing the Inhibitory Effect of Volume Dielectric Barrier Discharge on Phytopathogenic Fungi
No full textThe application of Low-Temperature Plasmas has shown great potential as an effective and alternative tool for microbial inactivation in recent years. Nevertheless, further investigations are required to fully understand the possible factors influencing these processes. The present study aims to investigate the effectiveness of square wave modulated Volume Dielectric Barrier Discharge on the direct inhibition of conidial germination in five different fungal species, various discharge conditions, and medium composition. The five different fungal species used were Botrytis cinerea, Monilinia fructicola, Aspergillus carbonarius, Fusarium graminearum, and Alternaria alternata. On water agar, the inhibition of Botrytis cinerea was influenced by the applied voltage, which mainly reflects the uniformity of the treatment. Under the selected voltage condition, the inhibition increased with treatment duration and decreased with fungal spore complexity. B. cinerea and M. fructicola, with unicellular conidia and low melanin content, showed similar behaviour and high sensitivity to the treatment. F. graminearum and A. alternata, both having multicellular conidia, were more resistant to the plasma treatment and showed different sensitivity likely due to different content in melanin. However, after 1 min of treatment, complete inhibition of conidial germination was achieved for all the tested species. Inhibition of A. carbonarius conidia on different agarized media containing dextrose or malt extract was influenced by the complexity and composition of the medium, being potato dextrose agar that more hindered the plasma efficacy. Each medium exhibited a different electrical response studied by Electrical Impedance Spectroscopy and morphology observed by Scanning Electron Microscopy images. These differences translated into a different response to the applied electrical field, influencing plasma generation and uniformity
Evaluating the inhibitory effect of low-temperature volume barrier discharge against phytopathogenic fungi
No full textThe inhibitory effect of a square wave modulated plasma (duty cycle 20%) Volume Dielectric Barrier Discharge (VDBD) at atmospheric pressure in ambient air was evaluated on conidial germination of different fungal species (Botrytis cinerea, Monilinia fructicola, Aspergillus carbonarius, Fusarium graminearum and Alternaria alternata). Several factors potentially influencing the efficacy of plasma treatment were considered, including total treatment time, applied voltage, and agarized medium composition. As previously observed, the inhibitory effect of the treatments progressively increased with the total time of exposure to VDBD and decreased with the complexity of cellular structures of the analyzed fungal species. Another main factor influencing efficacy is the uniformity of the distribution of the plasma microdischarges. In in vitro experiments, one crucial point is the response
of agarized media (Water Agar (WA), Glucose Agar (AG), Malt Extract Agar (MEA), and Potato Dextrose Agar (PDA)) to the electrical applied field that could strongly influence plasma generation. To better understand this point, agarized media structure was analyzed through cryo-scanning electron microscopy (cryo-SEM) images and correlated to the different plasma electrical responses in terms of electrical impedance and charge transfer characteristics in the plasma phase. In the tested experimental conditions, complete inhibition of conidial germination was achieved with different treatment times. For instance, 5 s total treatment time, inhibited completely the conidial germination of B. cinerea, while 20 s were required for both M. fructicola and F. graminearum instead, the total inhibition of conidial germination was shown after 60 and 180 s of treatment for A. alternata and A. carbonarius, respectively
