The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Fabrice Doveil - One of the best experts on this subject based on the ideXlab platform.
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Electromagnetic momenta for Wave-Particle systems in vacuum waveguides - Universality of the Abraham-Minkowski dilemma beyond dielectric materials
The European Physical Journal D : Atomic molecular optical and plasma physics, 2020Co-Authors: Damien Minenna, Yves Elskens, Fabrice Doveil, Frédéric AndréAbstract:Whenever light is slowed down, for any cause, two different formulas give its momentum. The coexistence of those momenta was the heart of the century-old Abraham-Minkowski dilemma, recently resolved for dielectrics. We demonstrate that this framework extends to momentum exchange in Wave-Particle Interaction; in particular to vacuum waveguides of electron tubes (dispersive metallic slow-wave structures). In waveguides, the dilemma can be easily investigated since energy and force are well established through the use of Maxwell equations in vacuum, and since waveguides can have a strong refractive index. Our theory is assessed with simulations validated against measurements from a traveling-wave tube. In addition, we show that the dilemma resolution is not limited to discriminating between kinematic and canonical momenta but also involves a non-negligible flowing momentum from Maxwell’s electromagnetic stress. The existence of two momenta for diverse systems like materials, plasmas and waveguides, for which light velocity modification has entirely different origin, points to the universality of the Abraham-Minkowski dilemma.
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DIMOHA: A Time-Domain Algorithm for Traveling-Wave Tube Simulations
IEEE Transactions on Electron Devices, 2019Co-Authors: Damien Minenna, Frédéric André, Yves Elskens, Jérôme Puech, Alexandre Poyé, Fabrice DoveilAbstract:To simulate traveling-wave tubes (TWTs) in time domain and more generally the Wave-Particle Interaction in vacuum devices, we developed the DIscrete MOdel with HAmiltonian approach (dimoha) as an alternative to current particle-in-cell (PIC) and frequency approaches. Indeed, it is based on a longitudinal N-body Hamiltonian approach satisfying Maxwell's equations. Advantages of dimoha comprise: (i) it allows arbitrary waveform (not just field envelope), including continuous waveform (CW), multiple carriers or digital modulations (shift keying); (ii) the algorithm is much faster than PIC codes thanks to a field discretization allowing a drastic degree-of-freedom reduction, along with a robust symplectic integrator; (iii) it supports any periodic slow-wave structure design such as helix or folded waveguides; (iv) it reproduces harmonic generation, reflection, oscillation and distortion phenomena; (v) it handles nonlinear dynamics, including intermodulations, trapping and chaos. dimoha accuracy is assessed by comparing it against measurements from a commercial Ku-band tapered helix TWT and against simulations from a sub-THz folded waveguide TWT with a staggered double-grating slow-wave structure. The algorithm is also tested for multiple-carriers simulations with success.
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The traveling-wave tube in the history of telecommunication
The European Physical Journal H, 2019Co-Authors: Damien Minenna, Frédéric André, Yves Elskens, Fabrice Doveil, Jean-françois Auboin, Jérôme Puech, Élise DuverdierAbstract:The traveling-wave tube is a critical subsystem for satellite data transmission. Its role in the history of wireless communications and in the space conquest is significant, but largely ignored, even though the device remains widely used nowadays. This paper presents, albeit non-exhaustively, circumstances and contexts that led to its invention, and its part in the worldwide (in particular in Europe) expansion of TV broadcasting via microwave radio relays and satellites. We also discuss its actual contribution to space applications and its conception. The originality of this paper comes from the wide period covered (from first slow-wave structures in 1889 to present space projects) and from connection points made between this device and commercial exploitations. The appendix deals with an intuitive pedagogical description of the wave–particle Interaction.
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Electromagnetic power and momentum in N-body hamiltonian approach to Wave-Particle dynamics in a periodic structure
EPL - Europhysics Letters, 2018Co-Authors: Damien Minenna, Frédéric André, Yves Elskens, Fabrice DoveilAbstract:To model momentum exchange in nonlinear Wave-Particle Interaction, as in amplification devices like traveling-wave tubes, we use an $N$-body self-consistent hamiltonian description based on Kuznetsov's discrete model, and we provide new formulations for the electromagnetic power and the conserved momentum. This approach leads to fast and accurate numerical simulations in time domain and in one-dimensional space.
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Channeling chaotic transport in a Wave-Particle experiment
The European Physical Journal D : Atomic molecular optical and plasma physics, 2006Co-Authors: Alessandro Macor, Fabrice Doveil, Cristel Chandre, Guido Ciraolo, Ricardo Lima, Michael VittotAbstract:A numerical and experimental study of a control method aimed at channeling chaos by building barriers in phase space is performed on a paradigm for Wave-Particle Interaction, i.e., a traveling wave tube. Control of chaotic diffusion is achieved by adding small apt modifications to the system with a low additional cost of energy. This modification is realized experimentally through additional waves with small amplitudes. Robustness of the method is investigated both numerically and experimentally.
Didier Mourenas - One of the best experts on this subject based on the ideXlab platform.
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Oblique Whistler-Mode Waves in the Earth’s Inner Magnetosphere: Energy Distribution, Origins, and Role in Radiation Belt Dynamics
Space Science Reviews, 2016Co-Authors: Anton Artemyev, O V Agapitov, Didier Mourenas, Vladimir Krasnoselskikh, Vitalii Shastun, F S MozerAbstract:In this paper we review recent spacecraft observations of oblique whistler-mode waves in the Earth’s inner magnetosphere as well as the various consequences of the presence of such waves for electron scattering and acceleration. In particular, we survey the statistics of occurrences and intensity of oblique chorus waves in the region of the outer radiation belt, comprised between the plasmapause and geostationary orbit, and discuss how their actual distribution may be explained by a combination of linear and non-linear generation, propagation, and damping processes. We further examine how such oblique wave populations can be included into both quasi-linear diffusion models and fully nonlinear models of Wave-Particle Interaction. On this basis, we demonstrate that varying amounts of oblique waves can significantly change the rates of particle scattering, acceleration, and precipitation into the atmosphere during quiet times as well as in the course of a storm. Finally, we discuss possible generation mechanisms for such oblique waves in the radiation belts. We demonstrate that oblique whistler-mode chorus waves can be considered as an important ingredient of the radiation belt system and can play a key role in many aspects of Wave-Particle resonant Interactions.
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Kinetic equation for nonlinear resonant Wave-Particle Interaction
Physics of Plasmas, 2016Co-Authors: A V Artemyev, Anatoly Neishtadt, Alexei Vasiliev, Didier MourenasAbstract:We investigate the nonlinear resonant Wave-Particle Interactions including the effects of particle (phase) trapping, detrapping, and scattering by high-amplitude coherent waves. After deriving the relationship between probability of trapping and velocity of particle drift induced by nonlinear scattering (phase bunching), we substitute this relation and other characteristic equations of Wave-Particle Interaction into a kinetic equation for the particle distribution function. The final equation has the form of a Fokker-Planck equation with peculiar advection and collision terms. This equation fully describes the evolution of particle momentum distribution due to particle diffusion, nonlinear drift, and fast transport in phase-space via trapping. Solutions of the obtained kinetic equation are compared with results of test particle simulations.
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Wave-Particle Interactions in the outer radiation belts
arXiv: Space Physics, 2015Co-Authors: O V Agapitov, Didier Mourenas, F S Mozer, A V Artemyev, Vladimir KrasnoselskikhAbstract:Data from the Van Allen Probes have provided the first extensive evidence of non-linear (as opposed to quasi-linear) Wave-Particle Interactions in space with the associated rapid (fraction of a bounce period) electron acceleration to hundreds of keV by Landau resonance in the parallel electric fields of time domain structures (TDS) and very oblique chorus waves. The experimental evidence, simulations, and theories of these processes are discussed. {\bf Key words:} the radiation belts, Wave-Particle Interaction, plasma waves and instabilities
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Fast transport of resonant electrons in phase space due to nonlinear trapping by whistler waves
Geophysical Research Letters, 2014Co-Authors: A V Artemyev, Anatoly A. Vasiliev, O V Agapitov, Didier Mourenas, Vladimir Krasnoselskikh, David Boscher, Guy RollandAbstract:We present an analytical, simplified formulation accounting for the fast transport of relativistic electrons in phase space due to Wave-Particle resonant Interactions in the inhomogeneous magnetic field of Earth's radiation belts. We show that the usual description of the evolution of the particle velocity distribution based on the Fokker-Planck equation can be modified to incorporate nonlinear processes of Wave-Particle Interaction, including particle trapping. Such a modification consists in one additional operator describing fast particle jumps in phase space. The proposed, general approach is used to describe the acceleration of relativistic electrons by oblique whistler waves in the radiation belts. We demonstrate that for a wave power distribution with a hard enough power law tail inline image such that η < 5/2, the efficiency of nonlinear acceleration could be more effective than the conventional quasi-linear acceleration for 100 keV electrons.
O V Agapitov - One of the best experts on this subject based on the ideXlab platform.
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Oblique Whistler-Mode Waves in the Earth’s Inner Magnetosphere: Energy Distribution, Origins, and Role in Radiation Belt Dynamics
Space Science Reviews, 2016Co-Authors: Anton Artemyev, O V Agapitov, Didier Mourenas, Vladimir Krasnoselskikh, Vitalii Shastun, F S MozerAbstract:In this paper we review recent spacecraft observations of oblique whistler-mode waves in the Earth’s inner magnetosphere as well as the various consequences of the presence of such waves for electron scattering and acceleration. In particular, we survey the statistics of occurrences and intensity of oblique chorus waves in the region of the outer radiation belt, comprised between the plasmapause and geostationary orbit, and discuss how their actual distribution may be explained by a combination of linear and non-linear generation, propagation, and damping processes. We further examine how such oblique wave populations can be included into both quasi-linear diffusion models and fully nonlinear models of Wave-Particle Interaction. On this basis, we demonstrate that varying amounts of oblique waves can significantly change the rates of particle scattering, acceleration, and precipitation into the atmosphere during quiet times as well as in the course of a storm. Finally, we discuss possible generation mechanisms for such oblique waves in the radiation belts. We demonstrate that oblique whistler-mode chorus waves can be considered as an important ingredient of the radiation belt system and can play a key role in many aspects of Wave-Particle resonant Interactions.
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Wave-Particle Interactions in the outer radiation belts
arXiv: Space Physics, 2015Co-Authors: O V Agapitov, Didier Mourenas, F S Mozer, A V Artemyev, Vladimir KrasnoselskikhAbstract:Data from the Van Allen Probes have provided the first extensive evidence of non-linear (as opposed to quasi-linear) Wave-Particle Interactions in space with the associated rapid (fraction of a bounce period) electron acceleration to hundreds of keV by Landau resonance in the parallel electric fields of time domain structures (TDS) and very oblique chorus waves. The experimental evidence, simulations, and theories of these processes are discussed. {\bf Key words:} the radiation belts, Wave-Particle Interaction, plasma waves and instabilities
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Fast transport of resonant electrons in phase space due to nonlinear trapping by whistler waves
Geophysical Research Letters, 2014Co-Authors: A V Artemyev, Anatoly A. Vasiliev, O V Agapitov, Didier Mourenas, Vladimir Krasnoselskikh, David Boscher, Guy RollandAbstract:We present an analytical, simplified formulation accounting for the fast transport of relativistic electrons in phase space due to Wave-Particle resonant Interactions in the inhomogeneous magnetic field of Earth's radiation belts. We show that the usual description of the evolution of the particle velocity distribution based on the Fokker-Planck equation can be modified to incorporate nonlinear processes of Wave-Particle Interaction, including particle trapping. Such a modification consists in one additional operator describing fast particle jumps in phase space. The proposed, general approach is used to describe the acceleration of relativistic electrons by oblique whistler waves in the radiation belts. We demonstrate that for a wave power distribution with a hard enough power law tail inline image such that η < 5/2, the efficiency of nonlinear acceleration could be more effective than the conventional quasi-linear acceleration for 100 keV electrons.
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A statistical study of the propagation characteristics of whistler waves observed by Cluster
Geophysical Research Letters, 2011Co-Authors: O V Agapitov, Vladimir Krasnoselskikh, Yuri V. Khotyaintsev, Guy RollandAbstract:[1] VLF waves play a crucial role in the dynamics of radiation belts, and are responsible for the loss and the acceleration of energetic electrons. Modeling wave‐particle Interactions requires the best possible knowledge for how wave energy and wave‐normal directions are distributed in L‐shells and for the magnetic latitudes of different magnetic activity conditions. In this work, we performed a statistical study for VLF emissions using a whistler frequency range for nine years (2001–2009) of Cluster measurements. We utilized data from the STAFF‐SA experiment, which spans the frequency range from 8.8 Hz to 3.56 kHz. We show that the wave energy distribution has two maxima around L ∼ 4.5 − 6 and L ∼ 2, and that wave‐normals are directed approximately along the magnetic field in the vicinity of the geomagnetic equator. The distribution changes with magnetic latitude, and so that at latitudes of ∼30°, wave‐normals become nearly perpendicular to the magnetic field. The observed angular distribution is significantly different from Gaussian and the width of the distribution increases with latitude. Since the resonance condition for wave‐particle Interactions depends on the wave normal orientation, our results indicate that, due to the observed change in the wave‐normal direction with latitude, the most efficient particle diffusion due to wave‐particle Interaction should occur in a limited region surrounding the geomagnetic equator.
Vladimir Krasnoselskikh - One of the best experts on this subject based on the ideXlab platform.
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Oblique Whistler-Mode Waves in the Earth’s Inner Magnetosphere: Energy Distribution, Origins, and Role in Radiation Belt Dynamics
Space Science Reviews, 2016Co-Authors: Anton Artemyev, O V Agapitov, Didier Mourenas, Vladimir Krasnoselskikh, Vitalii Shastun, F S MozerAbstract:In this paper we review recent spacecraft observations of oblique whistler-mode waves in the Earth’s inner magnetosphere as well as the various consequences of the presence of such waves for electron scattering and acceleration. In particular, we survey the statistics of occurrences and intensity of oblique chorus waves in the region of the outer radiation belt, comprised between the plasmapause and geostationary orbit, and discuss how their actual distribution may be explained by a combination of linear and non-linear generation, propagation, and damping processes. We further examine how such oblique wave populations can be included into both quasi-linear diffusion models and fully nonlinear models of Wave-Particle Interaction. On this basis, we demonstrate that varying amounts of oblique waves can significantly change the rates of particle scattering, acceleration, and precipitation into the atmosphere during quiet times as well as in the course of a storm. Finally, we discuss possible generation mechanisms for such oblique waves in the radiation belts. We demonstrate that oblique whistler-mode chorus waves can be considered as an important ingredient of the radiation belt system and can play a key role in many aspects of Wave-Particle resonant Interactions.
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Wave-Particle Interactions in the outer radiation belts
arXiv: Space Physics, 2015Co-Authors: O V Agapitov, Didier Mourenas, F S Mozer, A V Artemyev, Vladimir KrasnoselskikhAbstract:Data from the Van Allen Probes have provided the first extensive evidence of non-linear (as opposed to quasi-linear) Wave-Particle Interactions in space with the associated rapid (fraction of a bounce period) electron acceleration to hundreds of keV by Landau resonance in the parallel electric fields of time domain structures (TDS) and very oblique chorus waves. The experimental evidence, simulations, and theories of these processes are discussed. {\bf Key words:} the radiation belts, Wave-Particle Interaction, plasma waves and instabilities
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Fast transport of resonant electrons in phase space due to nonlinear trapping by whistler waves
Geophysical Research Letters, 2014Co-Authors: A V Artemyev, Anatoly A. Vasiliev, O V Agapitov, Didier Mourenas, Vladimir Krasnoselskikh, David Boscher, Guy RollandAbstract:We present an analytical, simplified formulation accounting for the fast transport of relativistic electrons in phase space due to Wave-Particle resonant Interactions in the inhomogeneous magnetic field of Earth's radiation belts. We show that the usual description of the evolution of the particle velocity distribution based on the Fokker-Planck equation can be modified to incorporate nonlinear processes of Wave-Particle Interaction, including particle trapping. Such a modification consists in one additional operator describing fast particle jumps in phase space. The proposed, general approach is used to describe the acceleration of relativistic electrons by oblique whistler waves in the radiation belts. We demonstrate that for a wave power distribution with a hard enough power law tail inline image such that η < 5/2, the efficiency of nonlinear acceleration could be more effective than the conventional quasi-linear acceleration for 100 keV electrons.
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A statistical study of the propagation characteristics of whistler waves observed by Cluster
Geophysical Research Letters, 2011Co-Authors: O V Agapitov, Vladimir Krasnoselskikh, Yuri V. Khotyaintsev, Guy RollandAbstract:[1] VLF waves play a crucial role in the dynamics of radiation belts, and are responsible for the loss and the acceleration of energetic electrons. Modeling wave‐particle Interactions requires the best possible knowledge for how wave energy and wave‐normal directions are distributed in L‐shells and for the magnetic latitudes of different magnetic activity conditions. In this work, we performed a statistical study for VLF emissions using a whistler frequency range for nine years (2001–2009) of Cluster measurements. We utilized data from the STAFF‐SA experiment, which spans the frequency range from 8.8 Hz to 3.56 kHz. We show that the wave energy distribution has two maxima around L ∼ 4.5 − 6 and L ∼ 2, and that wave‐normals are directed approximately along the magnetic field in the vicinity of the geomagnetic equator. The distribution changes with magnetic latitude, and so that at latitudes of ∼30°, wave‐normals become nearly perpendicular to the magnetic field. The observed angular distribution is significantly different from Gaussian and the width of the distribution increases with latitude. Since the resonance condition for wave‐particle Interactions depends on the wave normal orientation, our results indicate that, due to the observed change in the wave‐normal direction with latitude, the most efficient particle diffusion due to wave‐particle Interaction should occur in a limited region surrounding the geomagnetic equator.
Yves Elskens - One of the best experts on this subject based on the ideXlab platform.
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Electromagnetic momenta for Wave-Particle systems in vacuum waveguides - Universality of the Abraham-Minkowski dilemma beyond dielectric materials
The European Physical Journal D : Atomic molecular optical and plasma physics, 2020Co-Authors: Damien Minenna, Yves Elskens, Fabrice Doveil, Frédéric AndréAbstract:Whenever light is slowed down, for any cause, two different formulas give its momentum. The coexistence of those momenta was the heart of the century-old Abraham-Minkowski dilemma, recently resolved for dielectrics. We demonstrate that this framework extends to momentum exchange in Wave-Particle Interaction; in particular to vacuum waveguides of electron tubes (dispersive metallic slow-wave structures). In waveguides, the dilemma can be easily investigated since energy and force are well established through the use of Maxwell equations in vacuum, and since waveguides can have a strong refractive index. Our theory is assessed with simulations validated against measurements from a traveling-wave tube. In addition, we show that the dilemma resolution is not limited to discriminating between kinematic and canonical momenta but also involves a non-negligible flowing momentum from Maxwell’s electromagnetic stress. The existence of two momenta for diverse systems like materials, plasmas and waveguides, for which light velocity modification has entirely different origin, points to the universality of the Abraham-Minkowski dilemma.
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Cross-field chaotic transport of electrons by ExB electron drift instability in Hall thruster
Physics of Plasmas, 2020Co-Authors: D. Mandal, Yves Elskens, N. Lemoine, F DoveilAbstract:A model calculation is presented to characterize the anomalous cross-field transport of electrons in a Hall thruster geometry. The anomalous nature of the transport is attributed to the chaotic dynamics of the electrons arising from their Interaction with fluctuating unstable electrostatic fields of the electron cyclotron drift instability that is endemic in these devices. Electrons gain energy from these background waves leading to a significant increase in their temperature along the perpendicular direction $T_\perp / T_\parallel \sim 4$ and an enhanced cross-field electron transport along the thruster axial direction. It is shown that the Wave-Particle Interaction induces a mean velocity of the electrons along the axial direction, which is of the same order of magnitude as seen in experimental observations.
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DIMOHA: A Time-Domain Algorithm for Traveling-Wave Tube Simulations
IEEE Transactions on Electron Devices, 2019Co-Authors: Damien Minenna, Frédéric André, Yves Elskens, Jérôme Puech, Alexandre Poyé, Fabrice DoveilAbstract:To simulate traveling-wave tubes (TWTs) in time domain and more generally the Wave-Particle Interaction in vacuum devices, we developed the DIscrete MOdel with HAmiltonian approach (dimoha) as an alternative to current particle-in-cell (PIC) and frequency approaches. Indeed, it is based on a longitudinal N-body Hamiltonian approach satisfying Maxwell's equations. Advantages of dimoha comprise: (i) it allows arbitrary waveform (not just field envelope), including continuous waveform (CW), multiple carriers or digital modulations (shift keying); (ii) the algorithm is much faster than PIC codes thanks to a field discretization allowing a drastic degree-of-freedom reduction, along with a robust symplectic integrator; (iii) it supports any periodic slow-wave structure design such as helix or folded waveguides; (iv) it reproduces harmonic generation, reflection, oscillation and distortion phenomena; (v) it handles nonlinear dynamics, including intermodulations, trapping and chaos. dimoha accuracy is assessed by comparing it against measurements from a commercial Ku-band tapered helix TWT and against simulations from a sub-THz folded waveguide TWT with a staggered double-grating slow-wave structure. The algorithm is also tested for multiple-carriers simulations with success.
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The traveling-wave tube in the history of telecommunication
The European Physical Journal H, 2019Co-Authors: Damien Minenna, Frédéric André, Yves Elskens, Fabrice Doveil, Jean-françois Auboin, Jérôme Puech, Élise DuverdierAbstract:The traveling-wave tube is a critical subsystem for satellite data transmission. Its role in the history of wireless communications and in the space conquest is significant, but largely ignored, even though the device remains widely used nowadays. This paper presents, albeit non-exhaustively, circumstances and contexts that led to its invention, and its part in the worldwide (in particular in Europe) expansion of TV broadcasting via microwave radio relays and satellites. We also discuss its actual contribution to space applications and its conception. The originality of this paper comes from the wide period covered (from first slow-wave structures in 1889 to present space projects) and from connection points made between this device and commercial exploitations. The appendix deals with an intuitive pedagogical description of the wave–particle Interaction.
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Recent discrete model for small-signal analysis of traveling-wave tubes
Physica Scripta, 2019Co-Authors: Damien Minenna, Frédéric André, Yves Elskens, Artem Terentyuk, Nikita RyskinAbstract:The numerical simulations of the Wave-Particle Interaction, as it occurs in particular in traveling wave tubes, require new tools especially to investigate near the band edges of those devices. We propose a new approach (not limited to traveling wave tubes) using field decomposition allowing an important reduction of degrees of freedom : the discrete model. To assess its validity, we compare it in small-signal regime with Pierce’s four-wave theory. For both models, we take the same simplified fluid model and we express the associated circuit- beam impedances. We show analytically and with a numerical example that the newly developed reduced model is very close to the Pierce model, especially where the latter is well-established. Small deviations do occur at the edges of the amplification band, where Pierce’s model is known to lose its accuracy while the reduced model offers a valid physical interpretation.
