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8 results on '"Mazières Valentin"'

1. Reflectionless Plasma Ignition via High-Power Virtual Perfect Absorption

Author

Delage, Théo, Sokoloff, Jérôme, Pascal, Olivier, Mazières, Valentin, Krasnok, Alex, and Callegari, Thierry

Subjects
Physics - Plasma Physics, Physics - Applied Physics, Physics - Optics
Abstract

Plasma ignition is critical in various scientific and industrial applications, demanding an efficient and robust execution mechanism. In this work, we present an innovative approach to plasma ignition by incorporating the analysis of fundamental aspects of light scattering in the complex frequency plane. For the first time, we demonstrate the high-power virtual perfect absorption (VPA) regime, a groundbreaking method for perfectly capturing light within a resonator. By carefully designing the temporal profile of the incident wave, we effectively minimize reflections during the ignition stages, thereby significantly enhancing the efficiency and resilience of the process. Through comprehensive experimental investigations, we validate the viability of this approach, establishing VPA as a powerful tool for reflectionless excitation and optimal control of plasma discharge. By addressing the limitations of conventional plasma ignition methods, this research represents a pivotal step towards transformative advancements in plasma technology, with promising implications for improving the performance and sustainability of numerous applications.

Published
2023

2. Experimental demonstration of virtual critical coupling to a single-mode microwave cavity.

Author

Delage, Théo, Pascal, Olivier, Sokoloff, Jérôme, and Mazières, Valentin

Subjects
CAVITY resonators, COMMODITY futures, AMPLITUDE modulation, PLASMA materials processing, MICROWAVE plasmas
Abstract

We present an experimental realization of virtual critical coupling in microwave, i.e., virtual perfect absorption of an incident wave by a resonant cavity, through transient time modulation of its amplitude. The design of a waveform matched to the ignition process of a plasma, characterized in a simplified way by two operating modes over time (plasma off/plasma on), motivates this first step in practical realization of virtual critical coupling in microwaves. We propose a time domain method for extracting necessary parameters for realization of virtual critical coupling, especially the complex frequency called zero of the S-matrix. To this end, we start from the experimental characterization of a single-mode and single-access microwave cavity including metal protrusions for future plasma ignition. Then, the method relies on the analysis of harmonic response of the overcoupled cavity during three time periods: the transient under excitation, the steady state under excitation, and the transient after excitation cutoff. Finally, an experimental demonstration of virtual critical coupling is performed. [ABSTRACT FROM AUTHOR]

Published
2022
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4. Spatio-temporal dynamics of a nanosecond pulsed microwave plasma ignited by time reversal

Author

Luc Stafford, Olivier Pascal, Richard Clergereaux, Romain Pascaud, Mazières Valentin, Laurent Liard, Simon Dap, LAboratoire PLasma et Conversion d'Energie (LAPLACE), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées, Institut Supérieur de l'Aéronautique et de l'Espace (ISAE-SUPAERO), Groupe de Recherche en Electromagnétisme (LAPLACE-GRE), Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Sciences et Ingénierie des Plasmas Réactifs et des Arcs (LAPLACE-ScIPRA), Département de Physique [Montréal], Université de Montréal (UdeM), Groupe de Recherche Energétique, Plasmas et Hors Equilibre (LAPLACE-GREPHE), Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE), Institut Supérieur de l'Aéronautique et de l'Espace - ISAE-SUPAERO (FRANCE), Université de Montréal - UdeM (CANADA), and Université Toulouse III - Paul Sabatier - UT3 (FRANCE)

Subjects
010302 applied physics, Materials science, Argon, Time reversal, chemistry.chemical_element, Plasma, Nanosecond, Condensed Matter Physics, Microwave plasma, 01 natural sciences, Ion source, 010305 fluids & plasmas, [SPI.ELEC]Engineering Sciences [physics]/Electromagnetism, Autre, chemistry, Physics::Plasma Physics, Duty cycle, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], Rise time, Electric field, 0103 physical sciences, Atomic physics, Microwave, ComputingMilieux_MISCELLANEOUS
Abstract

In the present paper, a detailed investigation of the spatio-temporal dynamics of the recently developed time reversal microwave plasma source is presented. This novel source allows to ignite a plasma at a desired location in a reverberant cavity by focusing the electromagnetic energy in time and space. An important feature is the possibility to control the plasma position only by changing the input microwave waveform. The source is operated in a repetitive pulsed mode with very low duty cycle (typically 5 × 10−2%). Nanosecond pulses have rise time lower than 1 ns. The generated plasmas have typical sizes in the millimeter range and are observed using imaging for dozens of nanoseconds. The plasma behavior is investigated for different pressures and repetition frequencies. A strong dependence is observed between each discharge pulse suggesting the existence of an important memory effect. The latter is probably due to argon metastable atoms and/or residual charges remaining in the post-discharge and allowing the next breakdown to occur at a moderate electric field.

Published
2020
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5. Claquage microonde par retournement temporel

Author

Mazières, Valentin and Mazières, Valentin

Abstract

Un des défis auxquels sont confrontées les technologies plasmas est le développement de concepts de sources de plasma qui peuvent être transposés à des dimensions plus importantes, avec pour objectif par exemple le traitement de surface d'objets de grandes dimensions (panneaux solaires, écrans plats, grand wafer...). Cependant, plus la surface à traiter est grande, plus il devient difficile de la traiter. En fait, lorsqu'on augmente la surface, ces technologies se heurtent à des limites physiques et technologiques. Pour les sources plasmas microondes, l'incapacité à contrôler les plasmas vient du caractère multi-mode des grandes cavités, qui rend le contrôle de la distribution spatiale du champ électrique (et donc du plasma) en leur sein très difficile avec les technologies conventionnelles. L'objectif de la thèse est de développer une source plasma micro-onde répondant à ce besoin de contrôle des plasmas dans les grandes cavités (multimodes). Nous avons alors introduit un concept innovant de source de plasma micro-ondes : le "pinceau plasma ondulatoire". Le principe de cette source plasma consiste à contrôler dynamiquement la position du plasma dans une cavité en jouant sur la forme d'onde du signal transmis à la cavité. L'idée est alors d'utiliser le "Retournement Temporel", qui permet de focaliser spatio-temporellement l'énergie électromagnétique dans les cavités de grandes dimensions. Cette thèse propose les premières études théoriques et les premières démonstrations expérimentales du concept de "pinceau plasma ondulatoire"., One of the challenges that face plasma technologies is the development of plasma source concepts that can be scaled to larger dimensions, for example for the surface processing of large objects (solar panels, flat screens, large wafers, etc.). However, the more the area to be processed is large, the more it is difficult to process it. In fact, when increasing the area these technologies face physical and technological limitations. For microwave plasma sources, the inability to control plasmas comes from the multi-mode nature of large cavities, which makes the control of the spatial distribution of the electric field (and thus of the plasma) inside very difficult with conventional technologies. The objective of this thesis is to develop a microwave plasma source addressing this need for plasma control in large cavities (multimode). We then introduced an innovative concept of microwave plasma source: the "wave plasma brush". The principle of this plasma source consists in dynamically controlling the position of the plasma in a cavity by playing on the waveform of the transmitted signal to the cavity. The idea is then to use "Time Reversal", which allows a spatio-temporal focusing of the electromagnetic energy in large cavities.This thesis proposes the first theoretical studies and the first experimental demonstrations of the concept of "wave plasma brush".

Published
2020

8. Microwave plasma source in overmoded cavity: space-time plasma steering source

Author

Mazières, V, Pascaud, R, Pascal, Olivier, Liard, Laurent, Dap, Simon, Stafford, L, Clergereaux, Richard, Groupe de Recherche en Electromagnétisme (LAPLACE-GRE), LAboratoire PLasma et Conversion d'Energie (LAPLACE), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Institut Supérieur de l'Aéronautique et de l'Espace (ISAE-SUPAERO), Groupe de Recherche Energétique, Plasmas et Hors Equilibre (LAPLACE-GREPHE), Sciences et Ingénierie des Plasmas Réactifs et des Arcs (LAPLACE-ScIPRA), Université de Montréal (UdeM), and Mazières, Valentin

Subjects
[SPI]Engineering Sciences [physics], [SPI] Engineering Sciences [physics]
Abstract

International audience; The aim of this communication is first to present the concept of the innovative plasma source we introduced recently, namely the “space-time plasma steering source”. It has been introduced to address the challenge of controlling plasmas in large cavities (overmoded) that has been identified in the literature [1,2]. Contrary to conventional microwave plasma technologies, the idea is not to ignite a plasma occupying the entire volume of a plasma vessel, but rather to ignite a localized plasma whose location in the vessel can be dynamically controlled. This dynamic control is made possible by changing the temporal waveform of the transmitted signal to an overmoded cavity. It is then the behavior of the waves inside the cavity that control the plasma location, hence the name of space-time plasma steering source (see Figure 1). Based on this principle, we successfully managed to control in a pulsed regime the plasma location on several ignitors in an overmoded cavity using time reversal [3] and later using a more elaborated technique [4]. In the present communication, we will focus on the unusual characteristics of this microwave plasma source: plasma dimensions and location are uncorrelated from the cavity design, low rise time (in the order of the nanosecond) and very low duty cycle (in the order of 0.05%). This work is a continuation of our paper [5], in which we proposed a first spatio-temporal description of these original plasmas.

Published
2021

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