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A fluid dispersion theory in partially magnetised plasmas is analysed to examine the conditions under which large-wavelength modes develop in Penning-type configurations, that is, where an electric field is imposed perpendicular to a homogeneous magnetic field. The fluid dispersion relation assuming a slab geometry shows that two types of low-frequency, gradient drift instabilities occur in the direction of the $\boldsymbol {E} \times \boldsymbol {B}$ and diamagnetic drifts. One type of instability, observed when the equilibrium electric field and plasma density gradient are in the same direction, is similar to the classic modified Simon–Hoh instability. A second instability is found for conditions in which (i) the diamagnetic drift is in the direction opposite to the $\boldsymbol {E} \times \boldsymbol {B}$ drift and (ii) the magnitude of the diamagnetic drift is sufficiently larger than the electron thermal speed. The present fluid dispersion theory suggests that the rotating spokes driven by such fluid instabilities propagate in the same direction as the diamagnetic drift, which can be in the same direction as or opposite to the $\boldsymbol {E} \times \boldsymbol {B}$ drift, depending on the plasma conditions. This finding may account for the observation, in some plasma devices, of the rotation of large-scale structures in both the $\boldsymbol {E} \times \boldsymbol {B}$ and $-\boldsymbol {E} \times \boldsymbol {B}$ directions.

International audience; This article reports on the characterization of a laboratory model 100 A-class hollow cathode with a sintered lanthanum hexaboride (LaB6) emitter for high-power Hall thrusters. The cathode has been fired up to 70 A with xenon as working gas. The cathode architecture, test setup, ignition procedure, and power consumption are described first. The second part of this contribution comments on the current–voltage characteristics and the discharge modes obtained for discharge currents in the 30–70 A range and flow rates in the 15–30 SCCM range. The cathode operates in a spot mode at high discharge currents and in a plume mode with large oscillations at low currents and low gas flow rate. Spectral analysis shows that most frequencies reside in the 10–200 kHz range with flat and sharp distributions in plume and spot modes, respectively. Finally, we present electron temperatures and densities measured in the cathode plasma plume by means of incoherent Thomson scattering. The two quantities decrease along the axis. The density is large (up to ∼1019m−3) and increases with both the ion current and the gas flow rate. The electron temperature increases with the current and decreases with the gas flow rate. The temperature remains relatively low (

Information on the evolution of electron properties during high-power impulse magnetron sputtering (HiPIMS) operation of planar magnetrons enables the study of fundamental physical processes. In this work, incoherent Thomson scattering is implemented for the non-invasive, spatiotemporally-resolved characterization of electron properties and drifts in the HiPIMS regime of a planar magnetron. In the ionization region of argon and helium plasmas, the azimuthal electron drifts are directly measured perpendicular to the magnetic field and are found to evolve according to a changing balance of E × B and diamagnetic electron drifts, while radial electron drifts, measured parallel to the magnetic field, can be attributed to plasma expansion/contraction and centrifugal forces. The evolutions of electron density and temperature in the afterglow plasma phase show the existence of two time scales for the variation of plasma properties. These characterizations provide detailed information on electron properties and dynamics in regions of the magnetic trap ordinarily inaccessible to invasive diagnostics.

International audience; This paper provides perspectives on recent progress in understanding the physics of devices in which the external magnetic field is applied perpendicular to the discharge current. This configuration generates a strong electric field that acts to accelerate ions. The many applications of this set up include generation of thrust for spacecraft propulsion and separation of species in plasma mass separation devices. These “E × B” plasmas are subject to plasma–wall interaction effects and to various micro- and macroinstabilities. In many devices we also observe the emergence of anomalous transport. This perspective presents the current understanding of the physics of these phenomena and state-of-the-art computational results, identifies critical questions, and suggests directions for future research.

International audience; In this paper, the nonlinear interaction between kinetic instabilities driven by multiple ion beams and magnetized electrons is investigated. Electron diffusion across magnetic field lines is enhanced by the coupling of plasma instabilities. A two-dimensional collisionless particle-in-cell simulation is performed accounting for singly and doubly charged ions in a cross-field configuration. Consistent with prior linear kinetic theory analysis and observations from coherent Thomson scattering experiments, the present simulations identify an ion-ion two-stream instability due to multiply charged ions (flowing in the direction parallel to the applied electric field) which coexists with the electron cyclotron drift instability (propagating perpendicular to the applied electric field and parallel to the E×B drift). Small-scale fluctuations due to the coupling of these naturally driven kinetic modes are found to be a mechanism that can enhance cross-field electron transport and contribute to the broadening of the ion velocity distribution functions

International audience; Emissive cathodes serve a key function as the electron source for Hall plasma thrusters. Development of reliable numerical models for their operation and information on plasma behavior requires the use of sensitive and accurate diagnostics. This paper discusses results from a combined experimental and numerical study of the plasma regimes and properties of a 5 A LaB 6 pellet emitter cathode. Electron properties across a range of currents (2-16 A) are determined for the first time using incoherent Thomson scattering. A 2D axisymmetric fluid code is adapted to the study of the electron properties of this cathode and the nature of regime transitions. Similar trends in the numerical and experimental results are found, such as transitions to plume-like behavior with increasing current; quantitative agreement would require the use of a combined thermal-plasma model for the cathode under study. Comparisons of results from non-invasive Thomson scattering to Langmuir probe measurements reveal limitations of the latter diagnostic for plasma characterization.

International audience; Nonlinear interaction between kinetic instabilities in partially magnetized plasmas in the presence of multiply charged ion streams is investigated using kinetic simulations. It was observed by Hara and Tsikata [Phys. Rev. E 102, 023202 (2020)] that the axial ion–ion two-stream instability due to singly and doubly charged ion streams, coupled with the azimuthal electron cyclotron drift instability (ECDI), enhances cross-field electron transport. In the present study, it is observed that the addition of triply charged ions (as a third ion species) contributes to damping of the excited modes, leading to a reduction in the cross-field electron transport. The net instability-driven electron transport is shown to be a function not only of the azimuthal modes, such as the ECDI, but of the multiple ion species that dictate the development of additional plasma waves. It is found that trapping of the higher ion charge states within the plasma waves results in broadening of the ion velocity distribution functions.

The formation of self-organized standing wave structures is observed due to the electron cyclotron drift instability (ECDI) driven by a time-varying external electric field and a crossed magnetic field. Using a particle-in-cell simulation, two standing wave mechanisms are identified: the linear mode and the beating mode. In the former, a standing wave emerges as a superposition of two counterpropagating ion acoustic waves predicted by the linear theory of ECDI. On the other hand, in the beating mode, the plasma wave is in resonance with the applied frequency. Nonlinear resonance of such standing waves results in a change in the dominant wavenumber and frequency. Such counterpropagating plasma waves are consistent with the experimental observations using coherent Thomson scattering in a crossed-field plasma discharge.The formation of self-organized standing wave structures is observed due to the electron cyclotron drift instability (ECDI) driven by a time-varying external electric field and a crossed magnetic field. Using a particle-in-cell simulation, two standing wave mechanisms are identified: the linear mode and the beating mode. In the former, a standing wave emerges as a superposition of two counterpropagating ion acoustic waves predicted by the linear theory of ECDI. On the other hand, in the beating mode, the plasma wave is in resonance with the applied frequency. Nonlinear resonance of such standing waves results in a change in the dominant wavenumber and frequency. Such counterpropagating plasma waves are consistent with the experimental observations using coherent Thomson scattering in a crossed-field plasma discharge.

National audience; Huge quantities of nanoparticles can strongly modify plasma properties [1, 2] by the trapping of free electrons at their surface [3]. This provokes an increase in the electron temperature [4, 5] and, in return, the entire chemistry is affected. Often plasma instabilities can be observed in nanodusty plasmas, some of them on time scales visible to the human eye [6, 7]. Because instabilities are a tempo-spatial phenomenon that can evolve on short time scales, adequate techniques to examine their nature are rare. In this study laser induced fluorescence [8] and absorption [9] spectroscopy were used to monitor the evolution of argon metastable atoms in a low pressure argon RF plasma. The growth of dense nanoparticle clouds is achieved from sputtering melamine-formaldehyde from the reactor walls and electrodes. The spectroscopic data are correlated with the pressure evolution and discharge current [10] in order to investigate the impact of localized effects, like void formation, on the global process parameters.[1] A. M. Hinz et al., J. Phys. D: Appl. Phys. 48 (2015) 055203[2] M. Mikikian et al., Pure Appl. Chem., 83 (2010) pp. 1273-7282[3] T. Wegner et al., Appl. Phys. Lett. 108 (2016) 063108[4] V. Masserau-Guilbaud et al., IEEE Transactions on Plasma Science 41 (2013) pp. 816[5] A. A. Fridman et al., J. Appl. Phys. 79 (1996) 1303

International audience

The low-frequency rotating plasma instability (spoke) in the ISCT200 thruster operating in the wall-less configuration was simulated with a 3 dimensional PIC MCC code. In the simulations an m = 1 spoke rotating with a velocity of 6.5 km/s in the ExB direction was observed. The rotating electron density structure in the spoke is accompanied by a strongly depleted region of the neutral gas, which clearly shows that the spoke instability is of an ionization nature, similar to the axial breathing mode oscillations. In the simulation the electron cross-field transport through the spoke core was caused by diffusion in the high-frequency (4-10 MHz), short-scale (3 mm) electric field oscillations. These short-scale oscillations play a crucial role in the thruster discharge as over 70% of the electron current to the anode originates from the spoke core. The rest of the current originates from the spoke front where the electron cross-field transport toward the anode is due to the ExB drift in the spoke macroscopic azimuthal electric field., Submitted to Plasma Sources Sci. Technol., 2019

International audience

International audience

Planar magnetrons have been applied for decades for low-pressure, plasma-assisted thin film deposition, with applications in sectors such as microelectronics and tribology. Their operation has expanded in recent years to a HiPIMS (High-impulse pulsed magnetron sputtering) regime [1], which can, in some cases, offer superior thin film quality and adhesion than is attainable with DC operation. Modeling of this regime requires an advanced understanding of features such as plasma instabilities [2] and, more fundamentally, particle properties.

Incoherent Thomson scattering (ITS) has a long history of application for the determination of electron density and temperature in dense fusion plasmas, and in recent years, has been increasingly extended to studies in low-temperature plasma environments. In this work, the design and preliminary implementation of a new, sensitive and uniquely compact ITS platform known as Thomson scattering experiments for low temperature ion sources are described. Measurements have been performed on a hollow cathode plasma source, providing access to electron densities as low as 1016 m−3 and electron temperatures of a few eV and below. This achievement has been made possible by the implementation of a narrow volume Bragg grating notch filter for the attenuation of stray light, a feature which guarantees compactness and reduced transmission losses in comparison to standard ITS platforms.

International audience

International audience

In a Hall Thruster (HT), a discharge is ignited inside an annular ceramic chamber between an anode situated at the rear of the device and an electron-emitting hollow cathode downstream of the channel. Xenon gas propellant is injected through the anode plane. A magnetic field is created using internal and external coils to achieve a quasi-radial magnetic field profile. A discharge voltage applied between the anode and the cathode is responsible for the acceleration of the ions and the engine thrust. Nevertheless, a fraction of the energetic ions bombards the ceramic walls, resulting in erosion that reduces the thruster lifetime1.

The electron cyclotron drift instability, implicated in electron heating and anomalous transport, is detected in the plasma of a planar magnetron. Electron density fluctuations associated with the mode are identified via an adapted coherent Thomson scattering diagnostic, under direct current and high-power pulsed magnetron operation. Time-resolved analysis of the mode amplitude reveals that the instability, found at MHz frequencies and millimeter scales, also exhibits a kHz-scale modulation consistent with the observation of larger-scale plasma density nonuniformities, such as the rotating spoke. Sharply collimated axial fluctuations observed at the magnetron axis are consistent with the presence of escaping electrons in a region where the magnetic and electric fields are antiparallel. These results distinguish aspects of magnetron physics from other plasma sources of similar geometry, such as the Hall thruster, and broaden the scope of instabilities which may be considered to dictate magnetron plasma features.

International audience; In recent numerical, theoretical, and experimental papers, the short-scale electron cyclotron drift instability (ECDI) has been studied as a possible contributor to the anomalous electron current observed in Hall thrusters. In this work, features of the instability, in the presence of a zero-electron emission material at the thruster exit plane, are analyzed using coherent Thomson scattering. Limiting the electron emission at the exit plane alters the localization of the accelerating electric field and the expected drift velocity profile, which in turn modifies the amplitude and localization of the ECDI. The resulting changes to the standard thruster operation are expected to favor an increased contribution by the ECDI to electron current. Such an operation is associated with a degradation of thruster performance and stability.

In this contribution, we propose an alternative Hall thruster architecture that shifts the ionization and acceleration regions outside the cavity. This unconventional design is here termed a “Wall-Less Hall Thruster”. A 200 W-class prototype with permanent magnets has been developed and tested with two anode variants. Experimental results concerning the thruster operation, discharge oscillations, electric field distribution and ionization zone characteristics are presented and discussed. Preliminary experiments show the magnetized discharge can be moved outside the cavity without drastically disturbing the ion production and acceleration. A wall-less Hall thruster, with an external electric field, could offer significant benefits in terms of integration, operating envelope and lifetime. As the thrust is generated outside, the dielectric channel can be considerably shortened, leading to economies in mass and volume. Furthermore, plasma interaction with the walls will have been significantly reduced. The cavity material will therefore have less influence on the thruster performance, and more importantly, operation at high voltage is presumably possible and lifetime can be extended.

Équipe 107 : Physique des plasmas chauds; International audience; Collective Thomson scattering experiments reveal the presence of high-frequency, axial electron density fluctuations at millimetric wavelengths in the Hall thruster plasma. The properties of these fluctuations are investigated experimentally and via linear kinetic theory. The relative drift of electrons and ions in the axial direction is found to be insufficient to cause excitation of the observed mode. Instead, the mode is determined to be a two-stream instability arising due to the velocity difference between singly and doubly charged ion populations in the plume.

International audience; Dans les plasmas des propulseurs à effet Hall, les électrons montrent une mobilité anormale à travers le champ magnétique présent en sortie de canal. Des modèles linéaires et des simulations PIC ont montré que cette mobilité était liée à la présence d’une fluctuation à l’échelle millimétrique dans la direction azimutale du canal du propulseur. Des observations par diffusion collective ont confirmé la présence de ces instabilités. Ces mêmes observations ont montré la présence d’une autre fluctuation présente aux mêmes échelles, mais principalement dans la direction axiale du propulseur. Les modèles linéaires montrent que cette fluctuation a une nature différente de celle de l’instabilité azimutale.

Turbulence at length scales on the order of the electron Debye length has been shown to be a possible contributor to anomalous electron transport in the Hall thruster. Simulations1 and coherent Thomson scattering experiments2 have identified an azimuthal instability of megahertz frequency and millimeter wavelength which is associated with increased electron current.

Équipe 107 : Physique des plasmas chauds; International audience; Microturbulence has been implicated in anomalous transport at the exit of the Hall thruster, and recent simulations have shown the presence of an azimuthal wave which is believed to contribute to the electron axial mobility. In this paper, the 3D dispersion relation of this E x B electron drift instability is numerically solved. The mode is found to resemble an ion acoustic mode for low values of the magnetic field, as long as a non-vanishing component of the wave vector along the magnetic field is considered, and as long as the drift velocity is small compared to the electron thermal velocity. In these conditions, an analytical model of the dispersion relation for the instability is obtained and is shown to adequately describe the mode obtained numerically. This model is then fitted on the experimental dispersion relation obtained from the plasma of a Hall thruster by the collective light scattering diagnostic. The observed frequency-wave vector dependences are found to be similar to the dispersion relation of linear theory, and the fit provides a non-invasive measurement of the electron temperature and density.

A pseudo-3D modeling approach, based on a particle-in-cell (PIC)-Monte Carlo collisions algorithm, has been developed for the study of large- and short-scale organization of the plasma in a planar magnetron. This extension of conventional PIC modeling permits the observation of spontaneous organization of the magnetron plasma, under the influence of crossed electric and magnetic fields, into the well-known, large-scale regions of enhanced ionization and density known as spokes. The nature of complex three-dimensional electron trajectories around such structures, and non-uniform ionization within them, is revealed. This modeling provides direct numerical evidence for the existence of high-amplitude internal spoke electric fields, proposed in earlier works. A 3D phenomenological model, consistent with numerical results, is proposed. Electron density fluctuations in the megahertz range, with characteristics similar to the electron cyclotron drift instability experimentally identified in a recent Letter, are also found.

Recent experimental studies on nanocrystalline metals have shown that mechanical strength may decrease with decreasing grain size d for d 7 nm) to localized grain boundary migration (d

Summary form only given. The rotating spoke is a low-frequency azimuthal wave, which has been observed in a variety of cross-field discharges, including linear magnetized plasma devices and Hall thrusters. The spoke can appear in different modes which propagate in the direction perpendicular to electric and magnetic fields with velocities of much lower than E×B velocity1,2. Despite decades of investigation, the origin, dynamics and nature of the spoke are still poorly understood. In recent studies of cylindrical and annular Hall thrusters with segmented anodes, it was demonstrated that the spoke is directly responsible for the enhancement of the electron cross-field transport3,4. A combination of time-resolving plasma measurements with a variety of plasma diagnostic tools suggests that the spoke instability is triggered by the ionization mechanism. This result is supported by recent particle-in-cell simulations5. The advancement in understanding of the spoke mechanism enabled us to develop and demonstrate effective methods of spoke control and spoke suppression. Practical implications of these results open the path to the development of more efficient magnetized plasma thrusters.

International audience; Kinetic models and numerical simulations of E×B plasma discharges predict microfluctuations at the scales of the electron cyclotron drift radius and the ion plasma frequency. With the help of a specially designed collective scattering device, the first experimental observations of small-scale electron density fluctuations inside the plasma volume are obtained, and observed in the expected ranges of spatial and time scales. The anisotropy, dispersion relations, form factor, amplitude, and spatial distribution of these electron density fluctuations are described and compared to theoretical expectations.

International audience; We consider the motion of a finger of low-viscosity fluid as it propagates into a branching network of fluid-filled microchannels - a scenario that arises in many applications, such as microfluidics, biofluid mechanics (e.g. pulmonary airway reopening) and the flow in porous media. We perform experiments to investigate the behaviour of the finger as it reaches a single bifurcation and determine under what conditions the finger branches symmetrically. We find that if the daughter tubes have open ends, the finger branches asymmetrically and will therefore tend to reopen a single path through the branching network. Conversely, if the daughter tubes terminate in elastic chambers, which provide a lumped representation of the airway wall elasticity in the airway reopening problem, the branching is found to be symmetric for sufficiently small propagation speeds. A mathematical model is developed to explain the experimentally observed behaviour. © 2005 Cambridge University Press.

An alternative Hall thruster architecture that shifts the ionization and acceleration regions outside the plasma chamber is demonstrated. This unconventional design is here termed a “wall-less Hall thruster,” as the bulk of the magnetized discharge is no longer limited by solid boundaries. A 200 W prototype with permanent magnets has been developed and characterized. Experimental results concerning the thruster operation, discharge oscillations, electric field distribution, and ionization zone characteristics are presented and discussed. Our first experiments show that the cross-field discharge can be moved outside the cavity without drastically disturbing the ion production and acceleration mechanisms. This design offers the benefit of reduced plasma-wall interaction and lower wall losses, while also greatly facilitating diagnostic access to the entire discharge ionization and acceleration regions.

Collective (or coherent) Thomson scattering has recently emerged as an important tool for identifying and characterizing certain instabilities in Hall thrusters. Plasma instabilities in electric thrusters are implicated in diverse phenomena, including reduced efficiency, lifetime and anomalous particle transport. This work discusses the main features of the collective scattering diagnostic PRAXIS, and recent applications of the diagnostic to study the nature of microturbulence at different thruster operating regimes. Early measurements show the presence of a small-scale azimuthal instability may be linked with regimes of unstable thruster operation.

International audience; The effect of the collective light scattering diagnostic transfer function is considered in the context of the dispersion relation of the unstable E×B mode previously reported. This transfer function is found to have a contribution to the measured frequencies and mode amplitudes which is more or less significant depending on the measurement wavenumbers and angles. After deconvolution, the experimental data are found to be possibly compatible with the idea that the mode frequency in the jet frame (after subtraction of the Doppler effect due to the plasma motion along the thruster axis) is independent of the orientation of the wave vector in the plane orthogonal to the local magnetic field.

International audience; Collective scattering measurements have been conducted on the plasma of a Hall thruster, in which the electron density fluctuations are fully characterized by the dynamic form factor. The dynamic form factor amplitude distribution has been measured depending on the k-vector spatial and frequency components at different locations. Fluctuations are seen as propagating waves. The largest amplitude mode propagates nearly along the cross-field direction but at a phase velocity that is much smaller than the E×B drift velocity. Refined directional analysis of this largest amplitude mode shows a thin angular emission diagram with a mean direction that is not strictly along the E×B direction but at small angles near it. The deviation is oriented toward the anode in the (E,E×B) plane and toward the exterior of the thruster channel in the (B,E×B) plane. The density fluctuation rate is on the order of 1%. These experimentally determined directional fluctuation characteristics are discussed with regard to the linear kinetic theory model and particle-in-cell simulation results.

International audience

Incoherent Thomson Scattering (ITS) is one of the most reliable techniques for determining electron properties inside a plasma. Key information (electron density, temperature (more generally, the EEDF), and drift velocity) can be determined from the analysis of the intensity and spectral distribution of light of a laser pulse scattered by free electrons. In contrast to many conventional techniques, it is non-perturbative, gives access to spatiotemporally-resolved information, and can be applied in magnetized plasma regions. Yet ITS implementation in low-temperature plasmas poses a particular challenge due to the low plasma densities involved.This thesis focuses on the development and application of a new ITS diagnostic.Traditional diagnostics have commonly used triple grating spectrometers to filter the stray light signal (from Rayleigh scattering and laser reflections) in order to allow detection of the Thomson-scattered signal from electrons. Instead, this work uses a recently-commercialized notch filter for stray light reduction. This approach enabled the development of a diagnostic with notable sensitivity and compactness.This diagnostic, named THETIS, was used to gain insights into three low-temperature, magnetized plasmas sources operating at low pressure.A planar magnetron was studied in continuous (DCMS) and pulsed (HiPIMS) regimes, with these investigations allowing the extraction of spatial and temporal profiles of electron properties. This study focused on the influence of the gas type, repetition rate, and magnetic field intensity.A ECR ion source was also studied in pulsed and continuous regimes. The influence of the gas type, pressure and power were investigated. In addition to the study of the dynamics of electron properties in pulsed operation, insights into species excitation and ionization were gained from the analysis of the plasma emission.Lastly, electron properties along radial and azimuthal directions in Hall thrusters in “standard” and “magnetic shielding” configurations were investigated. The influence of the magnetic field intensity, configuration, and direction were investigated, as well as the discharge power and voltage. This work revealed not only the presence of anisotropies in electron properties, but also high electron temperatures in magnetized regions of the thruster plasma and the presence of strongly non-Maxwellian EEDFs in such regions.The information on electron properties, and the accompanying physical insights obtained in this work, contribute to current understanding of these plasmas and provides a new path forward for their modeling and development., La diffusion Thomson incohérente (DTI) est l’une des techniques les plus fiables pour sonder les propriétés électroniques d’un plasma. Des informations clés (densité, température, vitesse de dérive et FDEE) peuvent être obtenues par analyse de l’intensité et de la distribution spectrale de la lumière diffusée sur les électrons libres. Cette technique est non perturbative, permet de bonnes résolutions spatiotemporelles et peut être appliquée dans des régions magnétisées du plasma. Pourtant, l’implémentation de diagnostiques de DTI dans les plasmas bas températures pose un défi en raison des faibles densités plasma.Cette thèse se concentre sur le développement et l’application d’un nouveau diagnostic DTI. Un nouveau type de filtre notch est utilisé pour atténuer la lumière parasite (provenant de la diffusion de Rayleigh et des réflexions laser) et faciliter la détection du signal de diffusion Thomson. Ce composant a permis le développement d’un diagnostic, nommé THETIS, à la fois sensible et compact pour étudier trois sources plasmas magnétisés basse température fonctionnant à basse pression.Un magnétron plan a été étudié en régime continu (DCMS) et pulsé (HiPIMS), ces investigations ont permis l’extraction de profils spatiotemporels des propriétés électroniques. Cette étude s’est concentrée sur l’influence du type de gaz, du taux de répétition et de l’intensité du champ magnétique.Une source d’ions ECR a également été étudiée en régime pulsé et continu. L’influence du type de gaz, de la pression et de la puissance a été étudiée. En plus de l’étude de la dynamique électronique en régime pulsé, l’analyse de l’émission du plasma a permis de suivre les processus d’excitation et ionisation.Enfin, les propriétés électroniques selon les directions radiales et azimutales de propulseurs à effet Hall dans les configurations “standard” et “écrantage magnétique” ont été étudiées. L’influence du champ magnétique et des conditions de décharge ont été étudiées. Ce travail a révélé non seulement la présence d’anisotropies dans les propriétés des électroniques, mais également la présence de forte température dans les régions magnétisées du plasma du propulseur couplées à des FDEE fortement non maxwelliennes.Les résultats des travaux de cette thèse contribuent à la meilleure compréhension de ces plasmas et ouvrent une nouvelle voie pour leur modélisation et développement.

Incoherent Thomson Scattering (ITS) is one of the most reliable techniques for determining electron properties inside a plasma. Key information (electron density, temperature (more generally, the EEDF), and drift velocity) can be determined from the analysis of the intensity and spectral distribution of light of a laser pulse scattered by free electrons. In contrast to many conventional techniques, it is non-perturbative, gives access to spatiotemporally-resolved information, and can be applied in magnetized plasma regions. Yet ITS implementation in low-temperature plasmas poses a particular challenge due to the low plasma densities involved.This thesis focuses on the development and application of a new ITS diagnostic.Traditional diagnostics have commonly used triple grating spectrometers to filter the stray light signal (from Rayleigh scattering and laser reflections) in order to allow detection of the Thomson-scattered signal from electrons. Instead, this work uses a recently-commercialized notch filter for stray light reduction. This approach enabled the development of a diagnostic with notable sensitivity and compactness.This diagnostic, named THETIS, was used to gain insights into three low-temperature, magnetized plasmas sources operating at low pressure.A planar magnetron was studied in continuous (DCMS) and pulsed (HiPIMS) regimes, with these investigations allowing the extraction of spatial and temporal profiles of electron properties. This study focused on the influence of the gas type, repetition rate, and magnetic field intensity.A ECR ion source was also studied in pulsed and continuous regimes. The influence of the gas type, pressure and power were investigated. In addition to the study of the dynamics of electron properties in pulsed operation, insights into species excitation and ionization were gained from the analysis of the plasma emission.Lastly, electron properties along radial and azimuthal directions in Hall thrusters in “standard” and “magnetic shielding” configurations were investigated. The influence of the magnetic field intensity, configuration, and direction were investigated, as well as the discharge power and voltage. This work revealed not only the presence of anisotropies in electron properties, but also high electron temperatures in magnetized regions of the thruster plasma and the presence of strongly non-Maxwellian EEDFs in such regions.The information on electron properties, and the accompanying physical insights obtained in this work, contribute to current understanding of these plasmas and provides a new path forward for their modeling and development.; La diffusion Thomson incohérente (DTI) est l’une des techniques les plus fiables pour sonder les propriétés électroniques d’un plasma. Des informations clés (densité, température, vitesse de dérive et FDEE) peuvent être obtenues par analyse de l’intensité et de la distribution spectrale de la lumière diffusée sur les électrons libres. Cette technique est non perturbative, permet de bonnes résolutions spatiotemporelles et peut être appliquée dans des régions magnétisées du plasma. Pourtant, l’implémentation de diagnostiques de DTI dans les plasmas bas températures pose un défi en raison des faibles densités plasma.Cette thèse se concentre sur le développement et l’application d’un nouveau diagnostic DTI. Un nouveau type de filtre notch est utilisé pour atténuer la lumière parasite (provenant de la diffusion de Rayleigh et des réflexions laser) et faciliter la détection du signal de diffusion Thomson. Ce composant a permis le développement d’un diagnostic, nommé THETIS, à la fois sensible et compact pour étudier trois sources plasmas magnétisés basse température fonctionnant à basse pression.Un magnétron plan a été étudié en régime continu (DCMS) et pulsé (HiPIMS), ces investigations ont permis l’extraction de profils spatiotemporels des propriétés électroniques. Cette étude s’est concentrée sur l’influence du type de gaz, du taux de répétition et de l’intensité du champ magnétique.Une source d’ions ECR a également été étudiée en régime pulsé et continu. L’influence du type de gaz, de la pression et de la puissance a été étudiée. En plus de l’étude de la dynamique électronique en régime pulsé, l’analyse de l’émission du plasma a permis de suivre les processus d’excitation et ionisation.Enfin, les propriétés électroniques selon les directions radiales et azimutales de propulseurs à effet Hall dans les configurations “standard” et “écrantage magnétique” ont été étudiées. L’influence du champ magnétique et des conditions de décharge ont été étudiées. Ce travail a révélé non seulement la présence d’anisotropies dans les propriétés des électroniques, mais également la présence de forte température dans les régions magnétisées du plasma du propulseur couplées à des FDEE fortement non maxwelliennes.Les résultats des travaux de cette thèse contribuent à la meilleure compréhension de ces plasmas et ouvrent une nouvelle voie pour leur modélisation et développement.