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2. Evolutionary distribution and mode transition in medium frequency from 50 kHz to 5 MHz of argon atmospheric pressure dielectric barrier discharge plasma.

Author

Zhibo Zhao, Yilin Yu, Qiuyue Nie, Zhonglin Zhang, Popoli, Arturo, and Macheret, Sergey

Subjects
ATMOSPHERIC pressure, GLOW discharges, PLASMA physics, PLASMA flow, ATMOSPHERIC pressure plasmas, NONEQUILIBRIUM plasmas, ELECTRON transitions
Abstract

Dielectric barrier discharges (DBDs) provide a promising technology for generating non-equilibrium cold plasmas at atmospheric pressure. For both application-focused and fundamental research, it is important to explore the discharge mode transition and electron heating mechanism to enable effective independent tuning of key plasma parameters in a DBD system. In this work, we report numerical studies of the effects of single-frequency excitation on atmospheric argon DBDs, which are carried out in the medium driving frequency (MF) range from 50 kHz to 5 MHz by using a one-dimensional hydrodynamics coupling model. The spatio-temporal evolution of particle density associated with the discharge mode transition and electron dynamic behavior has been investigated. By tuning different components of a single frequency, we observe the electron heating behaviors of the individual modes and mode transitions from the Townsend discharge to the glow discharge in the low frequency to the Ω mode and the hybrid mode in the medium frequency to the α-mode and the γ-mode in the radio frequency. The physical analysis is understood based on these fundamental insights into the plasma physics. [ABSTRACT FROM AUTHOR]

Published
2024
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18. Duality of Lipschitz classes on compact metric spaces

Author

Popoli, Arturo and Sbordone, Carlo

Abstract

Let (X,d)be a compact metric space and lip(X,d)the closed subspace of the Lipschitz functions space Lip(X,d)whose elements fsatisfy the “vanishing” property limd(x,y)→0|f(x)-f(y)|d(x,y)=0.We consider characterizations of metric spaces (X,d)for which the completion of the space M(X)of Borel measures on (X,d)is isomorphic to lip(X,d)∗.

Published
2024
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26. Numerical Methodologies for Non-Equilibrium Plasma Modelling

Author

Popoli, Arturo <1992> and Cristofolini, Andrea

Subjects
ING-IND/31 Elettrotecnica
Abstract

The development of reliable numerical tools for the simulation of non-equilibrium plasma devices is a fundamental requirement the technological progress. The main challenge in this context is to adequately represent multiple physical phenomena that take place over different temporal and spatial scales, while retaining reasonable computational performances. In the first part of the work, a fluid methodology in which electrons are modelled using the Boltzmann relation is developed as an alternative to Full Drift-Diffusion models. The proposed Boltzmann Drift-Diffusion methodology allows to limit the drift-diffusion approach to the ionic species, granting substantial savings in terms of computational performances. Both methodologies are applied to the 1D/2D simulation of a volumetric Dielectric Barrier Discharge reactor, operating with air at atmospheric pressure. A semi-implicit numerical technique for the integration of plasma kinetic processes is presented and numerically validated against a well established implicit methodology. The Boltzmann Drift-Diffusion and Full Drift-Diffusion approaches are compared. The obtained results are validated against experimental measurements of the deposited surface charge on to the dielectric layers covering the electrodes. In the second part of the work, a hybrid fluid/Particle-In-Cell approach is employed to model a miniaturized annular Hall thruster for space propulsion. The results yielded by two different treatments of the electron transport mechanism inside and outside the thruster channel are compared to macroscopic and microscopic physical information obtained through experimental measurements. These latter are then used to infer the anomalous transport collision frequency along the axis of the thruster. The obtained efficiency of the two chemical kinetic channels for the doubly charged ions production is discussed and correlated with the computed spatial distribution of the species.

Published
2021
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27. Numerical Methodologies for Non-Equilibrium Plasma Modelling

Author

Cristofolini, Andrea, Popoli, Arturo <1992>, Cristofolini, Andrea, and Popoli, Arturo <1992>

Abstract

The development of reliable numerical tools for the simulation of non-equilibrium plasma devices is a fundamental requirement the technological progress. The main challenge in this context is to adequately represent multiple physical phenomena that take place over different temporal and spatial scales, while retaining reasonable computational performances. In the first part of the work, a fluid methodology in which electrons are modelled using the Boltzmann relation is developed as an alternative to Full Drift-Diffusion models. The proposed Boltzmann Drift-Diffusion methodology allows to limit the drift-diffusion approach to the ionic species, granting substantial savings in terms of computational performances. Both methodologies are applied to the 1D/2D simulation of a volumetric Dielectric Barrier Discharge reactor, operating with air at atmospheric pressure. A semi-implicit numerical technique for the integration of plasma kinetic processes is presented and numerically validated against a well established implicit methodology. The Boltzmann Drift-Diffusion and Full Drift-Diffusion approaches are compared. The obtained results are validated against experimental measurements of the deposited surface charge on to the dielectric layers covering the electrodes. In the second part of the work, a hybrid fluid/Particle-In-Cell approach is employed to model a miniaturized annular Hall thruster for space propulsion. The results yielded by two different treatments of the electron transport mechanism inside and outside the thruster channel are compared to macroscopic and microscopic physical information obtained through experimental measurements. These latter are then used to infer the anomalous transport collision frequency along the axis of the thruster. The obtained efficiency of the two chemical kinetic channels for the doubly charged ions production is discussed and correlated with the computed spatial distribution of the species.

Published
2021

31. Higher integrability and reverse Hölder inequalities in the limit cases.

Author

Popoli, Arturo

Abstract

We study the higher integrability of weights satisfying a reverse Hölder inequality (⨏ I u β) 1 β ≤ B ⁢ (⨏ I u α) 1 α {\biggl{(}\fint_{I}u^{\beta}\biggr{)}^{\frac{1}{\beta}}}\leq B{\biggl{(}\fint_{I}u^{\alpha}\biggr{)}^{\frac{1}{\alpha}}} for some B > 1 B>1 and given α < β \alpha<\beta , in the limit cases when α ∈ { - ∞ , 0 } \alpha\in\{-\infty,0\} and/or β ∈ { 0 , + ∞ } \beta\in\{0,+\infty\}. The results apply to the Gehring and Muckenhoupt weights and their corresponding limit classes. [ABSTRACT FROM AUTHOR]

Published
2022
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42. Sharp interactions among $$A_\infty $$ -weights on the real line.

Author

Popoli, Arturo, Sbordone, Carlo, and Zecca, Gabriella

Abstract

We prove that any weight $$v\in L^1_{loc}({{\mathbb {R}}})$$ $$v:{{\mathbb {R}}}\rightarrow [0,+\infty )$$ of the Muckenhoupt class $$A_\infty $$ has the form $$v=h^\prime $$ where $$h:{{\mathbb {R}}}\rightarrow {{\mathbb {R}}}$$ is a bi-Sobolev map. As an application we improve the known results on exact continuation and reciprocal imbeddings for Gehring $$G_q$$ and Muckenhoupt $$A_p$$ classes, providing exact bounds in all cases. The method relies on a duality formula due to Johnson and Neugebauer [Rev Mat Iberoam 3(2)249-273, ()] $$\frac{1}{p}+\frac{1}{q}=1$$ . [ABSTRACT FROM AUTHOR]

Published
2015
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43. Sharp interactions among $$A_\infty $$ A∞ -weights on the real line

Author

Popoli, Arturo, Sbordone, Carlo, and Zecca, Gabriella

Abstract

We prove that any weight $$v\in L^1_{loc}({{\mathbb {R}}})$$ v∈Lloc1(R) $$v:{{\mathbb {R}}}\rightarrow [0,+\infty )$$ v:R→[0,+∞) of the Muckenhoupt class $$A_\infty $$ A∞ has the form $$v=h^\prime $$ v=h′ where $$h:{{\mathbb {R}}}\rightarrow {{\mathbb {R}}}$$ h:R→R is a bi-Sobolev map. As an application we improve the known results on exact continuation and reciprocal imbeddings for Gehring $$G_q$$ Gq and Muckenhoupt $$A_p$$ Ap classes, providing exact bounds in all cases. The method relies on a duality formula due to Johnson and Neugebauer [Rev Mat Iberoam 3(2)249–273, (1987)] $$\begin{aligned} A_p((h^{-1} )^\prime ) =G_q(h^\prime ), \end{aligned}$$ Ap((h-1)′)=Gq(h′), $$\frac{1}{p}+\frac{1}{q}=1$$ 1p+1q=1 .

Published
2015
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44. Simulazioni numeriche di plasmi non termici mediante modelli globali

Author

Tamburini, Nicola, thesis supervisor: Popoli, Arturo, Tamburini, Nicola, and thesis supervisor: Popoli, Arturo

Abstract

Questo lavoro si focalizza nella descrizione fisica dei plasmi a bassa temperatura. Si riporta un'introduzione nella quale essi vengono descritti. Viene fornito un elenco di una serie di possibili applicazioni in ambito industriale e in ambito aerospaziale. In questo elaborato sono state descritte le principali lavorazioni al plasma, utilizzate principalmente nell'industria microelettronica, come ad esempio la deposizione e l'incisione. Vengono descritte inoltre le principali tecniche di propulsione elettrica elencando e descrivendo le principali tipologie di propulsori utilizzati. Vengono analizzati i plasmi anche a livello microscopico per studiarne la dinamica; si è visto come essi siano formati da un numero elevato di particelle cariche che si muovono in risposta alla forza elettromagnetica (forza di Lorentz) associata ai campi elettromagnetici e che esse urtano tra di loro, rendendo complesso il loro studio. Viene poi illustrato il processo di ionizzazione di un gas descrivendo la sua struttura atomica ed elencando alcuni dei processi che portano alla ionizzazione. Per lo studio del comportamento di un gas ionizzato le informazioni riguardanti le collisioni atomiche sono molto importanti ma allo stesso tempo difficili da raccogliere e catalogare; sono stati analizzati i diversi tipi di scambio di energia che avvengono tra le particelle (elastico, anelastico, superelastico, radiativo e attachment). Infine sono stati confrontati due diversi modelli cinetici per plasmi di Argon ad alta pressione. Sono state effettuate delle simulazioni numeriche, grazie all'utilizzo del software gratuito ZDPlaskin, per confrontare i risultati dei due diversi modelli cinetici a diversi livelli di campi elettrici ridotti.

45. Simulazioni numeriche di plasmi non termici mediante modelli globali

Author

Tamburini, Nicola, thesis supervisor: Popoli, Arturo, Tamburini, Nicola, and thesis supervisor: Popoli, Arturo

Abstract

Questo lavoro si focalizza nella descrizione fisica dei plasmi a bassa temperatura. Si riporta un'introduzione nella quale essi vengono descritti. Viene fornito un elenco di una serie di possibili applicazioni in ambito industriale e in ambito aerospaziale. In questo elaborato sono state descritte le principali lavorazioni al plasma, utilizzate principalmente nell'industria microelettronica, come ad esempio la deposizione e l'incisione. Vengono descritte inoltre le principali tecniche di propulsione elettrica elencando e descrivendo le principali tipologie di propulsori utilizzati. Vengono analizzati i plasmi anche a livello microscopico per studiarne la dinamica; si è visto come essi siano formati da un numero elevato di particelle cariche che si muovono in risposta alla forza elettromagnetica (forza di Lorentz) associata ai campi elettromagnetici e che esse urtano tra di loro, rendendo complesso il loro studio. Viene poi illustrato il processo di ionizzazione di un gas descrivendo la sua struttura atomica ed elencando alcuni dei processi che portano alla ionizzazione. Per lo studio del comportamento di un gas ionizzato le informazioni riguardanti le collisioni atomiche sono molto importanti ma allo stesso tempo difficili da raccogliere e catalogare; sono stati analizzati i diversi tipi di scambio di energia che avvengono tra le particelle (elastico, anelastico, superelastico, radiativo e attachment). Infine sono stati confrontati due diversi modelli cinetici per plasmi di Argon ad alta pressione. Sono state effettuate delle simulazioni numeriche, grazie all'utilizzo del software gratuito ZDPlaskin, per confrontare i risultati dei due diversi modelli cinetici a diversi livelli di campi elettrici ridotti.

46. Numerical Modelling of Interference from AC Power Lines on Buried Metallic Pipelines in Presence of Mitigation Wires

Author

Andrea Cristofolini, Leonardo Sandrolini, Arturo Popoli, Cristofolini, Andrea, Popoli, Arturo, and Sandrolini, Leonardo

Subjects
Environmental Engineering, Materials science, 020209 energy, Pipeline (computing), Acoustics, finite element method, Energy Engineering and Power Technology, 02 engineering and technology, Industrial and Manufacturing Engineering, low frequency electromagnetic compatibility, Interference (communication), Position (vector), mitigation wire, 0202 electrical engineering, electronic engineering, information engineering, AC interference, Electrical and Electronic Engineering, Electrical conductor, Renewable Energy, Sustainability and the Environment, pipeline, 020206 networking & telecommunications, AC power, Finite element method, Pipeline transport, Electric power transmission, AC corrosion, mesh, Hardware and Architecture
Abstract

This paper presents a numerical approach based on the finite element method for the estimation of AC interference on buried metallic pipelines sharing the same right-of-way of power transmission lines in presence of mitigation wires. The proposed approach relies on a hybrid technique in order to reduce the mesh size and, in turn, the computational time. The feasibility of the method is demonstrated with application to a standard interference configuration. Some tests were performed in order to assess how the position and material of the mitigation wires affect the induced current on a buried metallic pipeline.

Published
2018

47. Assessment of AC interference caused by transmission lines on buried metallic pipelines using F.E.M

Author

Adisa A. Jimoh, Leonardo Sandrolini, Andrea Cristofolini, Arturo Popoli, Bolanle Tolulope Abe, Popoli, Arturo, Cristofolini, Andrea, Sandrolini, Leonardo, Abe, Bolanle T., and Jimoh, Adisa

Subjects
Finite element method, Engineering, 02 engineering and technology, Interference (communication), Pipeline, 0202 electrical engineering, electronic engineering, information engineering, Electronic engineering, AC interference, Instrumentation, Electrical conductor, Mesh, Signal processing, Radiation, business.industry, Electromagnetic compatibility, Computational mathematics, 020206 networking & telecommunications, 021001 nanoscience & nanotechnology, Electric power transmission, AC corrosion, Signal Processing, Computational Mathematic, 0210 nano-technology, business, Focus (optics)
Abstract

The focus of this paper is on the implementation and subsequent improvement of a technique for computing AC interference on buried metallic pipelines due to nearby power transmission lines. In order to perform this task, the finite element method (F.E.M.) is employed. After performing a description of the implementation of the classic F.E.M. approach, a hybrid technique designed to reduce the size of the mesh and therefore the computational time is presented. The results obtained with the two approaches are finally compared.

Published
2017

48. A comparison between Carson’s formulae and a 2D FEM approach for the evaluation of AC interference caused by overhead power lines on buried metallic pipelines

Author

Leonardo Sandrolini, Arturo Popoli, Andrea Cristofolini, Cristofolini, Andrea, Popoli, Arturo, and Sandrolini, Leonardo

Subjects
Pipeline transport, Electric power transmission, Materials science, Interference (communication), business.industry, 020209 energy, 0202 electrical engineering, electronic engineering, information engineering, Electrical engineering, Overhead (computing), 02 engineering and technology, business, Finite element method, Electronic, Optical and Magnetic Materials
Abstract

In this paper, the AC interference produced by an overhead power transmission line on a buried metallic pipeline is estimated using a circuital method based on the well-known Carson’s formulae and a two-dimensional finite element numerical code. The finite element formulation used in this paper implicitly takes into account the mutual inductive coupling between all the considered conductors, and it allows a more detailed analysis in cases where a nonhomogeneous soil is present. The FEM approach includes a procedure which has been developed to enforce that the sum of the currents flowing through the soil, pipeline and eventual overhead ground wire is equal to zero. A case study has been identified, and the results obtained by the two approaches have been compared and discussed.

Published
2017

49. Sharp interactions among $A_\infty$- weights on the real line

Author

Arturo Popoli, Carlo Sbordone, Gabriella Zecca, Popoli, Arturo, Sbordone, Carlo, and Zecca, Gabriella

Subjects
Discrete mathematics, Applied Mathematics, General Mathematics, Duality (order theory), Muckenhoupt weights, Algebra over a field, Real line, Prime (order theory), Mathematics
Abstract

We prove that any weight $$v\in L^1_{loc}({{\mathbb {R}}})$$ $$v:{{\mathbb {R}}}\rightarrow [0,+\infty )$$ of the Muckenhoupt class $$A_\infty $$ has the form $$v=h^\prime $$ where $$h:{{\mathbb {R}}}\rightarrow {{\mathbb {R}}}$$ is a bi-Sobolev map. As an application we improve the known results on exact continuation and reciprocal imbeddings for Gehring $$G_q$$ and Muckenhoupt $$A_p$$ classes, providing exact bounds in all cases. The method relies on a duality formula due to Johnson and Neugebauer [Rev Mat Iberoam 3(2)249–273, (1987)] $$\begin{aligned} A_p((h^{-1} )^\prime ) =G_q(h^\prime ), \end{aligned}$$ $$\frac{1}{p}+\frac{1}{q}=1$$ .

Published
2015

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