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M Lazar - One of the best experts on this subject based on the ideXlab platform.
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electromagnetic ion cyclotron instability stimulated by the suprathermal ions in Space Plasmas a quasi linear approach
Physics of Plasmas, 2021Co-Authors: M Lazar, S M Shaaban, R SchlickeiserAbstract:In collision-poor Space Plasmas, protons with an excess of kinetic energy or temperature in the direction perpendicular to the background magnetic field can excite the electromagnetic ion cyclotron (EMIC) instability. This instability is expected to be highly sensitive to suprathermal protons, which enhance the high-energy tails of the observed velocity distributions and are well reproduced by the (bi-)Kappa distribution functions. In this paper, we present the results of a refined quasi-linear approach, able to describe the effects of suprathermal protons on the extended temporal evolution of EMIC instability. It is, thus, shown that suprathermals have a systematic stimulating effect on the EMIC instability, enhancing not only the growth rates and the range of unstable wavenumbers but also the magnetic fluctuating energy density reached at the saturation. In effect, the relaxation of anisotropic temperature also becomes more efficient, i.e., faster in time and closer to isotropy.
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electromagnetic ion cyclotron instability stimulated by the suprathermal ions in Space Plasmas a quasi linear approach
arXiv: Plasma Physics, 2020Co-Authors: M Lazar, S M Shaaban, R SchlickeiserAbstract:In collision-poor Space Plasmas protons with an excess of kinetic energy or temperature in direction perpendicular to background magnetic field can excite the electromagnetic ion cyclotron (EMIC) instability. This instability is expected to be highly sensitive to suprathermal protons, which enhance the high-energy tails of the observed velocity distributions and are well reproduced by the (bi-)Kappa distribution functions. In this paper we present the results of a refined quasilinear (QL) approach, able to describe the effects of suprathermal protons on the extended temporal evolution of EMIC instability. It is thus shown that suprathermals have a systematic stimulating effect on the EMIC instability, enhancing not only the growth rates and the range of unstable wave-numbers, but also the magnetic fluctuating energy density reached at the saturation. In effect, the relaxation of anisotropic temperature becomes also more efficient, i.e., faster in time and closer to isotropy.
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electromagnetic ion ion instabilities in Space Plasmas effects of suprathermal populations
arXiv: Solar and Stellar Astrophysics, 2020Co-Authors: S M Shaaban, M Lazar, R A Lopez, Stefaan PoedtsAbstract:In collision-poor Plasmas from Space, three distinct ion-ion instabilities can be driven by the proton beams streaming along the background magnetic field: left-hand resonant, non-resonant, and right-hand resonant instabilities. These instabilities are in general investigated considering only idealized proton beams with Maxwellian velocity distributions, and ignoring the implications of suprathermal populations, usually reproduced by the Kappa power-laws. Moreover, the existing theories minimize the kinetic effects of electrons, assuming them isotropic and Maxwellian distributed. In an attempt to overcome these limitations, in the present paper we present the results of an extended investigation of ion-ion instabilities, which show that their dispersion and stability properties (e.g. growth rates, wave frequencies, and the unstable wave numbers) are highly sensitive to the influence of suprathermal populations and anisotropic electrons. These results offer valuable explanations for the origin of the enhanced low-frequency fluctuations, frequently observed in Space Plasmas and associated with proton beams.
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Whistler instabilities from the interplay of electron anisotropies in Space Plasmas: a quasi-linear approach
Monthly Notices of the Royal Astronomical Society, 2019Co-Authors: S M Shaaban, M LazarAbstract:Recent statistical studies of observational data unveil relevant correlations between whistler fluctuations and the anisotropic electron populations present in Space Plasmas, e.g. solar wind and planetary magnetospheres. Locally, whistlers can be excited by two sources of free energy associated with anisotropic electrons, i.e. temperature anisotropies and beaming populations carrying the heat flux. However, these two sources of free energy and the resulting instabilities are usually studied independently preventing a realistic interpretation of their interplay. This paper presents the results of a parametric quasi-linear study of the whistler instability cumulatively driven by two counter-drifting electron populations and their anisotropic temperatures. By comparison to individual regimes dominated either by beaming population or by temperature anisotropy, in a transitory regime the instability becomes highly conditioned by the effects of both these two sources of free energy. Cumulative effects stimulate the instability and enhance the resulting fluctuations, which interact with electrons and stimulate their diffusion in velocity Space, leading to a faster and deeper relaxation of the beaming velocity associated with a core heating in perpendicular direction and a thermalization of the beaming electrons. In particular, the relaxation of temperature anisotropy to quasi-stable states below the thresholds conditions predicted by linear theory may explain the observations showing the accumulation of these states near the isotropy and equipartition of energy.
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temperature anisotropy instabilities stimulated by the interplay of the core and halo electrons in Space Plasmas
Physics of Plasmas, 2018Co-Authors: M Lazar, S M Shaaban, Horst Fichtner, Stefaan PoedtsAbstract:Two central components are revealed by electron velocity distributions measured in Space Plasmas, a thermal bi-Maxwellian core and a bi-Kappa suprathermal halo. A new kinetic approach is proposed to characterize the temperature anisotropy instabilities driven by the interplay of core and halo electrons. Suggested by the observations in the solar wind, direct correlations of these two populations are introduced as co-variations of the key parameters, e.g., densities, temperature anisotropies, and (parallel) plasma betas. The approach involving correlations enables the instability characterization in terms of either the core or halo parameters and a comparative analysis to depict mutual effects. In the present paper, the instability conditions are described for an extended range of plasma beta parameters, making the new dual approach relevant for a wide variety of Space Plasmas, including the solar wind and planetary magnetospheres.
S M Shaaban - One of the best experts on this subject based on the ideXlab platform.
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electromagnetic ion cyclotron instability stimulated by the suprathermal ions in Space Plasmas a quasi linear approach
Physics of Plasmas, 2021Co-Authors: M Lazar, S M Shaaban, R SchlickeiserAbstract:In collision-poor Space Plasmas, protons with an excess of kinetic energy or temperature in the direction perpendicular to the background magnetic field can excite the electromagnetic ion cyclotron (EMIC) instability. This instability is expected to be highly sensitive to suprathermal protons, which enhance the high-energy tails of the observed velocity distributions and are well reproduced by the (bi-)Kappa distribution functions. In this paper, we present the results of a refined quasi-linear approach, able to describe the effects of suprathermal protons on the extended temporal evolution of EMIC instability. It is, thus, shown that suprathermals have a systematic stimulating effect on the EMIC instability, enhancing not only the growth rates and the range of unstable wavenumbers but also the magnetic fluctuating energy density reached at the saturation. In effect, the relaxation of anisotropic temperature also becomes more efficient, i.e., faster in time and closer to isotropy.
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electromagnetic ion cyclotron instability stimulated by the suprathermal ions in Space Plasmas a quasi linear approach
arXiv: Plasma Physics, 2020Co-Authors: M Lazar, S M Shaaban, R SchlickeiserAbstract:In collision-poor Space Plasmas protons with an excess of kinetic energy or temperature in direction perpendicular to background magnetic field can excite the electromagnetic ion cyclotron (EMIC) instability. This instability is expected to be highly sensitive to suprathermal protons, which enhance the high-energy tails of the observed velocity distributions and are well reproduced by the (bi-)Kappa distribution functions. In this paper we present the results of a refined quasilinear (QL) approach, able to describe the effects of suprathermal protons on the extended temporal evolution of EMIC instability. It is thus shown that suprathermals have a systematic stimulating effect on the EMIC instability, enhancing not only the growth rates and the range of unstable wave-numbers, but also the magnetic fluctuating energy density reached at the saturation. In effect, the relaxation of anisotropic temperature becomes also more efficient, i.e., faster in time and closer to isotropy.
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electromagnetic ion ion instabilities in Space Plasmas effects of suprathermal populations
arXiv: Solar and Stellar Astrophysics, 2020Co-Authors: S M Shaaban, M Lazar, R A Lopez, Stefaan PoedtsAbstract:In collision-poor Plasmas from Space, three distinct ion-ion instabilities can be driven by the proton beams streaming along the background magnetic field: left-hand resonant, non-resonant, and right-hand resonant instabilities. These instabilities are in general investigated considering only idealized proton beams with Maxwellian velocity distributions, and ignoring the implications of suprathermal populations, usually reproduced by the Kappa power-laws. Moreover, the existing theories minimize the kinetic effects of electrons, assuming them isotropic and Maxwellian distributed. In an attempt to overcome these limitations, in the present paper we present the results of an extended investigation of ion-ion instabilities, which show that their dispersion and stability properties (e.g. growth rates, wave frequencies, and the unstable wave numbers) are highly sensitive to the influence of suprathermal populations and anisotropic electrons. These results offer valuable explanations for the origin of the enhanced low-frequency fluctuations, frequently observed in Space Plasmas and associated with proton beams.
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Whistler instability stimulated by the suprathermal electrons present in Space Plasmas
Astrophysics and Space Science, 2019Co-Authors: Marian Lazar, S M Shaaban, Stefaan Poedts, R A Lopez, Horst FichtnerAbstract:In the absence of efficient collisions, deviations from thermal equilibrium of plasma particle distributions are controlled by the self-generated instabilities. The whistler instability is a notorious example, usually responsible for the regulation of electron temperature anisotropy \(A = T_{\perp }/T_{\parallel }> 1\) (with \(\perp , \parallel \) respective to the magnetic field direction) observed in Space Plasmas, e.g., solar wind and planetary magnetospheres. Suprathermal electrons present in these environments change the plasma dispersion and stability properties, with expected consequences on the kinetic instabilities and the resulting fluctuations, which, in turn, scatter the electrons and reduce their anisotropy. In order to capture these mutual effects we use a quasilinear kinetic approach and PIC simulations, which provide a comprehensive characterization of the whistler instability under the influence of suprathermal electrons. Analysis is performed for a large variety of plasma conditions, ranging from low-beta Plasmas encountered in outer corona or planetary magnetospheres to a high-beta solar wind characteristic to large heliospheric distances. Enhanced by the suprathermal electrons, whistler fluctuations stimulate the relaxation of temperature anisotropy, and this influence of suprathermals increases with plasma beta parameter.
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Whistler instabilities from the interplay of electron anisotropies in Space Plasmas: a quasi-linear approach
Monthly Notices of the Royal Astronomical Society, 2019Co-Authors: S M Shaaban, M LazarAbstract:Recent statistical studies of observational data unveil relevant correlations between whistler fluctuations and the anisotropic electron populations present in Space Plasmas, e.g. solar wind and planetary magnetospheres. Locally, whistlers can be excited by two sources of free energy associated with anisotropic electrons, i.e. temperature anisotropies and beaming populations carrying the heat flux. However, these two sources of free energy and the resulting instabilities are usually studied independently preventing a realistic interpretation of their interplay. This paper presents the results of a parametric quasi-linear study of the whistler instability cumulatively driven by two counter-drifting electron populations and their anisotropic temperatures. By comparison to individual regimes dominated either by beaming population or by temperature anisotropy, in a transitory regime the instability becomes highly conditioned by the effects of both these two sources of free energy. Cumulative effects stimulate the instability and enhance the resulting fluctuations, which interact with electrons and stimulate their diffusion in velocity Space, leading to a faster and deeper relaxation of the beaming velocity associated with a core heating in perpendicular direction and a thermalization of the beaming electrons. In particular, the relaxation of temperature anisotropy to quasi-stable states below the thresholds conditions predicted by linear theory may explain the observations showing the accumulation of these states near the isotropy and equipartition of energy.
R Schlickeiser - One of the best experts on this subject based on the ideXlab platform.
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electromagnetic ion cyclotron instability stimulated by the suprathermal ions in Space Plasmas a quasi linear approach
Physics of Plasmas, 2021Co-Authors: M Lazar, S M Shaaban, R SchlickeiserAbstract:In collision-poor Space Plasmas, protons with an excess of kinetic energy or temperature in the direction perpendicular to the background magnetic field can excite the electromagnetic ion cyclotron (EMIC) instability. This instability is expected to be highly sensitive to suprathermal protons, which enhance the high-energy tails of the observed velocity distributions and are well reproduced by the (bi-)Kappa distribution functions. In this paper, we present the results of a refined quasi-linear approach, able to describe the effects of suprathermal protons on the extended temporal evolution of EMIC instability. It is, thus, shown that suprathermals have a systematic stimulating effect on the EMIC instability, enhancing not only the growth rates and the range of unstable wavenumbers but also the magnetic fluctuating energy density reached at the saturation. In effect, the relaxation of anisotropic temperature also becomes more efficient, i.e., faster in time and closer to isotropy.
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electromagnetic ion cyclotron instability stimulated by the suprathermal ions in Space Plasmas a quasi linear approach
arXiv: Plasma Physics, 2020Co-Authors: M Lazar, S M Shaaban, R SchlickeiserAbstract:In collision-poor Space Plasmas protons with an excess of kinetic energy or temperature in direction perpendicular to background magnetic field can excite the electromagnetic ion cyclotron (EMIC) instability. This instability is expected to be highly sensitive to suprathermal protons, which enhance the high-energy tails of the observed velocity distributions and are well reproduced by the (bi-)Kappa distribution functions. In this paper we present the results of a refined quasilinear (QL) approach, able to describe the effects of suprathermal protons on the extended temporal evolution of EMIC instability. It is thus shown that suprathermals have a systematic stimulating effect on the EMIC instability, enhancing not only the growth rates and the range of unstable wave-numbers, but also the magnetic fluctuating energy density reached at the saturation. In effect, the relaxation of anisotropic temperature becomes also more efficient, i.e., faster in time and closer to isotropy.
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a new cosmic ray transport theory in partially turbulent Space Plasmas extending the quasilinear approach
The Astrophysical Journal, 2011Co-Authors: R SchlickeiserAbstract:A new transport theory of cosmic rays in magnetized Space Plasmas with axisymmetric incompressible magnetic turbulence is developed extending the quasilinear approximation to the particle orbit. Arbitrary gyrophase deviations from the unperturbed spiral orbits in the uniform magnetic field are allowed. For quasi-stationary and spatially homogeneous magnetic turbulence, we derive the small Larmor radius approximation gyrophase-averaged cosmic ray Fokker-Planck coefficients. The generalized Fokker-Planck coefficients correctly reduce to their known quasilinear values in the corresponding limit. New forms of the quasilinear Fokker-Planck coefficients in axisymmetric turbulence are derived which no longer involve infinite sums of products of Bessel functions, which facilitate their numerical computation for specified turbulence field correlation tensors. The Fokker-Planck coefficients for arbitrary phase orbits of the cosmic ray particles provide strict upper limits for the perpendicular and pitch-angle Fokker-Planck coefficients, which in turn yield strict upper and lower limits for the perpendicular and parallel spatial diffusion coefficients, respectively, describing the spatial diffusion of the isotropic part of the cosmic ray phase Space density. For the associated mean free paths, we find for this general case that the product of the minimum parallel mean free path with the sum of the maximum perpendicular mean free paths equals R 2 L , where RL denotes the cosmic ray gyroradius.
Kristof Stasiewicz - One of the best experts on this subject based on the ideXlab platform.
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Stasiewicz Reply on Comment on Theory and Observations of Slow-Mode Solitons in Space Plasmas
Physical Review Letters, 2005Co-Authors: Kristof StasiewiczAbstract:Stasiewicz Reply on Comment on Theory and Observations of Slow-Mode Solitons in Space Plasmas
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theory and observations of slow mode solitons in Space Plasmas
Physical Review Letters, 2004Co-Authors: Kristof StasiewiczAbstract:A generalized model for one-dimensional magnetosonic structures of large amplitude in Space Plasmas is presented. The model is verified with multipoint measurements on Cluster satellites in the magnetosheath and the boundary layer under conditions of plasma beta (plasma/magnetic pressure) between 0.1‐10. We demonstrate good agreement between the model and observations of large amplitude structures and wave trains, which represent increases of magnetic field and plasma density 2 ‐5 times the ambient values, or local decreases (holes) by �� 50‐80� %. Theoretically derived polarization and propagation properties of slow-mode nonlinear structures are also in agreement with in situ measurements in Space. We generalize previous models [1,2] of onedimensional solitons in two-fluid plasma approximation and show that the generalized equations with anisotropic ion pressure provide a good description for slow-mode solitary structures observed in the magnetosheath and other magnetospheric boundary layers by Cluster Spacecraft. We find that the magnetosheath, which is a turbulent layer formed downstream of the bow shock in front of the magnetopause, contains a large number of magnetosonic solitary waves with the magnetic field increased (bright solitons) or decreased (dark solitons or holes). Because the multipoint capabilities of Cluster make it possible to determine the velocity of the structures, we were able to experimentally verify not only the spatial shape of the solitons, but also their propagation angles and velocities. Since the magnetosheath contains shocked and thermalized solar wind plasma at strong turbulence, the presented theory and detailed in situ measurements of large scale and large amplitude solitons and nonlinear waves are of general interest for other disciplines where strong turbulence and transition between chaos and structure formation is of significance. The model is based on Hall-MHD equations for lowfrequency phenomena in a collisionless plasma [3]
D J Mccomas - One of the best experts on this subject based on the ideXlab platform.
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non equilibrium thermodynamic processes Space Plasmas and the inner heliosheath
The Astrophysical Journal, 2012Co-Authors: G Livadiotis, D J MccomasAbstract:Recently, empirical kappa distribution, commonly used to describe non-equilibrium systems like Space Plasmas, has been connected with non-extensive statistical mechanics. Here we show how a consistent definition of the temperature and pressure is developed for stationary states out of thermal equilibrium, so that the familiar ideal gas state equation still holds. In addition to the classical triplet of temperature, pressure, and density, this generalization requires the kappa index as a fourth independent thermodynamic variable that characterizes the non-equilibrium stationary states. All four of these thermodynamic variables have key roles in describing the governing thermodynamical processes and transitions in Space Plasmas. We introduce a novel characterization of isothermal and isobaric processes that describe a system's transition into different stationary states by varying the kappa index. In addition, we show how the variation of temperature or/and pressure can occur through an 'iso-q' process, in which the system remains in a fixed stationary state (fixed kappa index). These processes have been detected in the proton plasma in the inner heliosheath via specialized data analysis of energetic neutral atom (ENA) observations from Interstellar Boundary Explorer. In particular, we find that the temperature is highly correlated with (1) kappa, asymptotically related to isothermal ({approx}1,000,000 K)more » and iso-q ({kappa} {approx} 1.7) processes; and (2) density, related to an isobaric process, which separates the 'Ribbon', P Almost-Equal-To 3.2 pdyn cm{sup -2}, from the globally distributed ENA flux, P Almost-Equal-To 2 pdyn cm{sup -2}.« less
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invariant kappa distribution in Space Plasmas out of equilibrium
The Astrophysical Journal, 2011Co-Authors: G Livadiotis, D J MccomasAbstract:Recent advances in Space Physics theory have shown the connection between non-extensive Statistical Mechanics and Space Plasmas by providing a theoretical basis for the empirically derived kappa distributions commonly used to describe the phase-Space distribution functions of these systems. The non-equilibrium temperature and the kappa index that govern these distributions are the two independent controlling parameters of non-equilibrium systems. The significance of the kappa index is primarily given by its role in identifying the non-equilibrium stationary states and measuring their "thermodynamic distance" from thermal equilibrium, while its physical meaning is connected to the correlation between the system's particles. The classical, single stationary state at equilibrium is generalized into a whole set of different non-equilibrium stationary states labeled by the kappa index. This paper addresses certain crucial issues about the physical meaning and role of the kappa index in identifying stationary states. The origin of the emerged inconsistencies is that the kappa index is not an invariant physical quantity, but instead depends on the degrees of freedom of the system's particles. This leads in several misleading conclusions, such as (1) only large kappa index, practically infinite, can characterize the many-particle kappa distribution, and (2) the correlation between particles depends on the total number of the system's particles. Here we show that a modified kappa index, invariant for any number of degrees of freedom, can be naturally defined. Then, we develop and examine the relevant corrected formulation of many-particle multidimensional kappa distribution, and discuss the physical meaning of the invariant kappa index.
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beyond kappa distributions exploiting tsallis statistical mechanics in Space Plasmas
Journal of Geophysical Research, 2009Co-Authors: G Livadiotis, D J MccomasAbstract:[1] Empirically derived kappa distributions are becoming increasingly widespread in Space physics as the power law nature of various suprathermal tails is melded with more classical quasi-Maxwellian cores. Two different mathematical definitions of kappa distributions are commonly used and various authors characterize the power law nature of suprathermal tails in different ways. In this study we examine how kappa distributions arise naturally from Tsallis statistical mechanics, which provides a solid theoretical basis for describing and analyzing complex systems out of equilibrium. This analysis exposes the possible values of kappa, which are strictly limited to certain ranges. We also develop the concept of temperature out of equilibrium, which differs significantly from the classical equilibrium temperature. This analysis clarifies which of the kappa distributions has primacy and, using this distribution, the kinetic and physical temperatures become one, both in and out of equilibrium. Finally, we extract the general relation between both types of kappa distributions and the spectral indices commonly used to parameterize Space Plasmas. With this relation, it is straightforward to compare both spectral indices from various Space physics observations, models, and theoretical studies that use kappa distributions on a consistent footing that minimizes the chances for misinterpretation and error. Now that the connection is complete between empirically derived kappa distributions and Tsallis statistical mechanics, the full strength and capability of Tsallis statistical tools are available to the Space physics community for analyzing and understanding the kappa-like properties of the various particle and energy distributions observed in Space.
