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Verscharen D, Wicks RT, Alexandrova O, Bruno R, Burgess D, Chen CHK, D’Amicis R, De Keyser J, de Wit TD, Franci L, He J, Henri P, Kasahara S, Khotyaintsev Y, Klein KG, Lavraud B, Maruca BA, Maksimovic M, Plaschke F, Poedts S, Reynolds CS, Roberts O, Sahraoui F, Saito S, Salem CS, Saur J, Servidio S, Stawarz JE, Štverák Š, Told D. A Case for Electron-Astrophysics. EXPERIMENTAL ASTRONOMY 2021; 54:473-519. [PMID: 36915623 PMCID: PMC9998602 DOI: 10.1007/s10686-021-09761-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 05/07/2021] [Indexed: 06/18/2023]
Abstract
The smallest characteristic scales, at which electron dynamics determines the plasma behaviour, are the next frontier in space and astrophysical plasma research. The analysis of astrophysical processes at these scales lies at the heart of the research theme of electron-astrophysics. Electron scales are the ultimate bottleneck for dissipation of plasma turbulence, which is a fundamental process not understood in the electron-kinetic regime. In addition, plasma electrons often play an important role for the spatial transfer of thermal energy due to the high heat flux associated with their velocity distribution. The regulation of this electron heat flux is likewise not understood. By focussing on these and other fundamental electron processes, the research theme of electron-astrophysics links outstanding science questions of great importance to the fields of space physics, astrophysics, and laboratory plasma physics. In this White Paper, submitted to ESA in response to the Voyage 2050 call, we review a selection of these outstanding questions, discuss their importance, and present a roadmap for answering them through novel space-mission concepts.
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Affiliation(s)
- Daniel Verscharen
- Mullard Space Science Laboratory, University College London, Dorking, UK
- Space Science Center, University of New Hampshire, Durham, NH USA
| | - Robert T. Wicks
- Mullard Space Science Laboratory, University College London, Dorking, UK
- Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Newcastle-upon-Tyne, UK
| | - Olga Alexandrova
- Laboratoire d’Études Spatiales et d’Instrumentation en Astrophysique, Observatoire de Paris-Meudon, Paris, France
| | - Roberto Bruno
- Instituto di Astrofisica e Planetologia Spaziali, INAF, Rome, Italy
| | - David Burgess
- School of Physics and Astronomy, Queen Mary University of London, London, UK
| | | | | | - Johan De Keyser
- Royal Belgian Institute for Space Aeronomy, Brussels, Belgium
| | - Thierry Dudok de Wit
- Laboratoire de Physique et Chimie de l’Environment et de l’Espace, CNRS, University of Orléans and CNES, Orléans, France
| | - Luca Franci
- School of Physics and Astronomy, Queen Mary University of London, London, UK
- Osservatorio Astrofisico di Arcetri, INAF, Firenze, Italy
| | - Jiansen He
- School of Earth and Space Sciences, Peking University, Beijing, China
| | - Pierre Henri
- Laboratoire de Physique et Chimie de l’Environment et de l’Espace, CNRS, University of Orléans and CNES, Orléans, France
- CNRS, UCA, OCA, Lagrange, Nice, France
| | - Satoshi Kasahara
- Department of Earth and Planetary Science, University of Tokyo, Tokyo, Japan
| | | | - Kristopher G. Klein
- Lunar and Planetary Laboratory and Department of Planetary Sciences, University of Arizona, Tucson, AZ USA
| | - Benoit Lavraud
- Laboratoire d’astrophysique de Bordeaux, Université de Bordeaux, CNRS, Pessac, France
- Institut de Recherche en Astrophysique et Planétologie, CNRS, UPS, CNES, Université de Toulouse, Toulouse, France
| | - Bennett A. Maruca
- Department of Physics and Astronomy, Bartol Research Institute, University of Delaware, Newark, DE USA
| | - Milan Maksimovic
- Laboratoire d’Études Spatiales et d’Instrumentation en Astrophysique, Observatoire de Paris-Meudon, Paris, France
| | | | - Stefaan Poedts
- Centre for Mathematical Plasma Astrophysics, KU Leuven, Leuven, Belgium
- Institute of Physics, University of Maria Curie-Skłodowska, Lublin, Poland
| | | | - Owen Roberts
- Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | - Fouad Sahraoui
- Laboratoire de Physique des Plasmas, CNRS, École Polytechnique, Sorbonne Université, Observatoire de Paris-Meudon, Paris Saclay, Palaiseau, France
| | - Shinji Saito
- Space Environment Laboratory, National Institute of Information and Communications Technology, Tokyo, Japan
| | - Chadi S. Salem
- Space Sciences Laboratory, University of California, Berkeley, CA USA
| | - Joachim Saur
- Institut für Geophysik und Meteorologie, University of Cologne, Cologne, Germany
| | - Sergio Servidio
- Department of Physics, Università della Calabria, Rende, Italy
| | | | - Štěpán Štverák
- Astronomical Institute and Institute of Atmospheric Physics, Czech Academy of Sciences, Prague, Czech Republic
| | - Daniel Told
- Max Planck Institute for Plasma Physics, Garching, Germany
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Viall NM, Borovsky JE. Nine Outstanding Questions of Solar Wind Physics. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2020; 125:e2018JA026005. [PMID: 32728511 PMCID: PMC7380306 DOI: 10.1029/2018ja026005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 01/15/2020] [Accepted: 01/22/2020] [Indexed: 06/11/2023]
Abstract
In situ measurements of the solar wind have been available for almost 60 years, and in that time plasma physics simulation capabilities have commenced and ground-based solar observations have expanded into space-based solar observations. These observations and simulations have yielded an increasingly improved knowledge of fundamental physics and have delivered a remarkable understanding of the solar wind and its complexity. Yet there are longstanding major unsolved questions. Synthesizing inputs from the solar wind research community, nine outstanding questions of solar wind physics are developed and discussed in this commentary. These involve questions about the formation of the solar wind, about the inherent properties of the solar wind (and what the properties say about its formation), and about the evolution of the solar wind. The questions focus on (1) origin locations on the Sun, (2) plasma release, (3) acceleration, (4) heavy-ion abundances and charge states, (5) magnetic structure, (6) Alfven waves, (7) turbulence, (8) distribution-function evolution, and (9) energetic-particle transport. On these nine questions we offer suggestions for future progress, forward looking on what is likely to be accomplished in near future with data from Parker Solar Probe, from Solar Orbiter, from the Daniel K. Inouye Solar Telescope (DKIST), and from Polarimeter to Unify the Corona and Heliosphere (PUNCH). Calls are made for improved measurements, for higher-resolution simulations, and for advances in plasma physics theory.
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Statistical Uncertainties of Space Plasma Properties Described by Kappa Distributions. ENTROPY 2020; 22:e22050541. [PMID: 33286313 PMCID: PMC7517033 DOI: 10.3390/e22050541] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 05/10/2020] [Accepted: 05/11/2020] [Indexed: 11/17/2022]
Abstract
The velocities of space plasma particles often follow kappa distribution functions, which have characteristic high energy tails. The tails of these distributions are associated with low particle flux and, therefore, it is challenging to precisely resolve them in plasma measurements. On the other hand, the accurate determination of kappa distribution functions within a broad range of energies is crucial for the understanding of physical mechanisms. Standard analyses of the plasma observations determine the plasma bulk parameters from the statistical moments of the underlined distribution. It is important, however, to also quantify the uncertainties of the derived plasma bulk parameters, which determine the confidence level of scientific conclusions. We investigate the determination of the plasma bulk parameters from observations by an ideal electrostatic analyzer. We derive simple formulas to estimate the statistical uncertainties of the calculated bulk parameters. We then use the forward modelling method to simulate plasma observations by a typical top-hat electrostatic analyzer. We analyze the simulated observations in order to derive the plasma bulk parameters and their uncertainties. Our simulations validate our simplified formulas. We further examine the statistical errors of the plasma bulk parameters for several shapes of the plasma velocity distribution function.
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Nicolaou G, Livadiotis G, Wicks RT. On the Determination of Kappa Distribution Functions from Space Plasma Observations. ENTROPY 2020; 22:e22020212. [PMID: 33285987 PMCID: PMC7516642 DOI: 10.3390/e22020212] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 02/09/2020] [Accepted: 02/10/2020] [Indexed: 12/02/2022]
Abstract
The velocities of space plasma particles, often follow kappa distribution functions. The kappa index, which labels and governs these distributions, is an important parameter in understanding the plasma dynamics. Space science missions often carry plasma instruments on board which observe the plasma particles and construct their velocity distribution functions. A proper analysis of the velocity distribution functions derives the plasma bulk parameters, such as the plasma density, speed, temperature, and kappa index. Commonly, the plasma bulk density, velocity, and temperature are determined from the velocity moments of the observed distribution function. Interestingly, recent studies demonstrated the calculation of the kappa index from the speed (kinetic energy) moments of the distribution function. Such a novel calculation could be very useful in future analyses and applications. This study examines the accuracy of the specific method using synthetic plasma proton observations by a typical electrostatic analyzer. We analyze the modeled observations in order to derive the plasma bulk parameters, which we compare with the parameters we used to model the observations in the first place. Through this comparison, we quantify the systematic and statistical errors in the derived moments, and we discuss their possible sources.
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Affiliation(s)
- Georgios Nicolaou
- Department of Space and Climate Physics, Mullard Space Science Laboratory, University College London, Dorking, Surrey RH5 6NT, UK;
- Correspondence:
| | | | - Robert T. Wicks
- Department of Space and Climate Physics, Mullard Space Science Laboratory, University College London, Dorking, Surrey RH5 6NT, UK;
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Nicolaou G, Wicks R, Livadiotis G, Verscharen D, Owen C, Kataria D. Determining the Bulk Parameters of Plasma Electrons from Pitch-Angle Distribution Measurements. ENTROPY 2020; 22:e22010103. [PMID: 33285879 PMCID: PMC7516406 DOI: 10.3390/e22010103] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 01/10/2020] [Accepted: 01/11/2020] [Indexed: 12/02/2022]
Abstract
Electrostatic analysers measure the flux of plasma particles in velocity space and determine their velocity distribution function. There are occasions when science objectives require high time-resolution measurements, and the instrument operates in short measurement cycles, sampling only a portion of the velocity distribution function. One such high-resolution measurement strategy consists of sampling the two-dimensional pitch-angle distributions of the plasma particles, which describes the velocities of the particles with respect to the local magnetic field direction. Here, we investigate the accuracy of plasma bulk parameters from such high-resolution measurements. We simulate electron observations from the Solar Wind Analyser’s (SWA) Electron Analyser System (EAS) on board Solar Orbiter. We show that fitting analysis of the synthetic datasets determines the plasma temperature and kappa index of the distribution within 10% of their actual values, even at large heliocentric distances where the expected solar wind flux is very low. Interestingly, we show that although measurement points with zero counts are not statistically significant, they provide information about the particle distribution function which becomes important when the particle flux is low. We also examine the convergence of the fitting algorithm for expected plasma conditions and discuss the sources of statistical and systematic uncertainties.
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Affiliation(s)
- Georgios Nicolaou
- Department of Space and Climate Physics, Mullard Space Science Laboratory, University College London, Dorking, Surrey RH5 6NT, UK; (R.W.); (D.V.); (C.O.); (D.K.)
- Correspondence:
| | - Robert Wicks
- Department of Space and Climate Physics, Mullard Space Science Laboratory, University College London, Dorking, Surrey RH5 6NT, UK; (R.W.); (D.V.); (C.O.); (D.K.)
| | | | - Daniel Verscharen
- Department of Space and Climate Physics, Mullard Space Science Laboratory, University College London, Dorking, Surrey RH5 6NT, UK; (R.W.); (D.V.); (C.O.); (D.K.)
- Space Science Center, University of New Hampshire, Durham, NH 03824, USA
| | - Christopher Owen
- Department of Space and Climate Physics, Mullard Space Science Laboratory, University College London, Dorking, Surrey RH5 6NT, UK; (R.W.); (D.V.); (C.O.); (D.K.)
| | - Dhiren Kataria
- Department of Space and Climate Physics, Mullard Space Science Laboratory, University College London, Dorking, Surrey RH5 6NT, UK; (R.W.); (D.V.); (C.O.); (D.K.)
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Verscharen D, Klein KG, Maruca BA. The multi-scale nature of the solar wind. LIVING REVIEWS IN SOLAR PHYSICS 2019; 16:5. [PMID: 31929769 PMCID: PMC6934245 DOI: 10.1007/s41116-019-0021-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Accepted: 11/09/2019] [Indexed: 05/29/2023]
Abstract
The solar wind is a magnetized plasma and as such exhibits collective plasma behavior associated with its characteristic spatial and temporal scales. The characteristic length scales include the size of the heliosphere, the collisional mean free paths of all species, their inertial lengths, their gyration radii, and their Debye lengths. The characteristic timescales include the expansion time, the collision times, and the periods associated with gyration, waves, and oscillations. We review the past and present research into the multi-scale nature of the solar wind based on in-situ spacecraft measurements and plasma theory. We emphasize that couplings of processes across scales are important for the global dynamics and thermodynamics of the solar wind. We describe methods to measure in-situ properties of particles and fields. We then discuss the role of expansion effects, non-equilibrium distribution functions, collisions, waves, turbulence, and kinetic microinstabilities for the multi-scale plasma evolution.
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Affiliation(s)
- Daniel Verscharen
- Mullard Space Science Laboratory, University College London, Dorking, RH5 6NT UK
- Space Science Center, University of New Hampshire, Durham, NH 03824 USA
| | - Kristopher G. Klein
- Lunar and Planetary Laboratory and Department of Planetary Sciences, University of Arizona, Tucson, AZ 85719 USA
| | - Bennett A. Maruca
- Bartol Research Institute, Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 USA
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López RA, Shaaban SM, Lazar M, Poedts S, Yoon PH, Micera A, Lapenta G. Particle-in-cell Simulations of the Whistler Heat-flux Instability in Solar Wind Conditions. THE ASTROPHYSICAL JOURNAL. LETTERS 2019; 882:10.3847/2041-8213/ab398b. [PMID: 32042401 PMCID: PMC7008930 DOI: 10.3847/2041-8213/ab398b] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In collision-poor plasmas from space, e.g., solar wind or stellar outflows, the heat flux carried by the strahl or beaming electrons is expected to be regulated by the self-generated instabilities. Recently, simultaneous field and particle observations have indeed revealed enhanced whistler-like fluctuations in the presence of counter-beaming populations of electrons, connecting these fluctuations to the whistler heat-flux instability (WHFI). This instability is predicted only for limited conditions of electron beam-plasmas, and has not yet been captured in numerical simulations. In this Letter we report the first simulations of WHFI in particle-in-cell setups, realistic for the solar wind conditions, and without temperature gradients or anisotropies to trigger the instability in the initiation phase. The velocity distributions have a complex reaction to the enhanced whistler fluctuations conditioning the instability saturation by a decrease of the relative drifts combined with induced (effective) temperature anisotropies (heating the core electrons and pitch-angle and energy scattering the strahl). These results are in good agreement with a recent quasilinear approach, and support therefore a largely accepted belief that WHFI saturates at moderate amplitudes. In the anti-sunward direction the strahl becomes skewed with a pitch-angle distribution decreasing in width as electron energy increases, which seems to be characteristic of self-generated whistlers and not to small-scale turbulence.
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Affiliation(s)
- R A López
- Centre for mathematical Plasma Astrophysics, KU Leuven, Celestijnenlaan 200B, B-3001 Leuven, Belgium
| | - S M Shaaban
- Centre for mathematical Plasma Astrophysics, KU Leuven, Celestijnenlaan 200B, B-3001 Leuven, Belgium
- Theoretical Physics Research Group, Physics Department, Faculty of Science, Mansoura University, 35516, Mansoura, Egypt
| | - M Lazar
- Centre for mathematical Plasma Astrophysics, KU Leuven, Celestijnenlaan 200B, B-3001 Leuven, Belgium
- Institut für Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universität Bochum, D-44780 Bochum, Germany
| | - S Poedts
- Centre for mathematical Plasma Astrophysics, KU Leuven, Celestijnenlaan 200B, B-3001 Leuven, Belgium
| | - P H Yoon
- Institute for Physical Science and Technology, University of Maryland, College Park, MD, USA
- School of Space Research, Kyung Hee University, Republic of Korea
- Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea
| | - A Micera
- Centre for mathematical Plasma Astrophysics, KU Leuven, Celestijnenlaan 200B, B-3001 Leuven, Belgium
- Solar-Terrestrial Centre of Excellence-SIDC, Royal Observatory of Belgium, B-1180 Brussels, Belgium
| | - G Lapenta
- Centre for mathematical Plasma Astrophysics, KU Leuven, Celestijnenlaan 200B, B-3001 Leuven, Belgium
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Wilson LB, Chen LJ, Wang S, Schwartz SJ, Turner DL, Stevens ML, Kasper JC, Osmane A, Caprioli D, Bale SD, Pulupa MP, Salem CS, Goodrich KA. Electron Energy Partition across Interplanetary Shocks. I. Methodology and Data Product. THE ASTROPHYSICAL JOURNAL. SUPPLEMENT SERIES 2019; 243:10.3847/1538-4365/ab22bd. [PMID: 31806920 PMCID: PMC6894189 DOI: 10.3847/1538-4365/ab22bd] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Analyses of 15,314 electron velocity distribution functions (VDFs) within ±2 hr of 52 interplanetary (IP) shocks observed by the Wind spacecraft near 1 au are introduced. The electron VDFs are fit to the sum of three model functions for the cold dense core, hot tenuous halo, and field-aligned beam/strahl component. The best results were found by modeling the core as either a bi-kappa or a symmetric (or asymmetric) bi-self-similar VDF, while both the halo and beam/strahl components were best fit to bi-kappa VDF. This is the first statistical study to show that the core electron distribution is better fit to a self-similar VDF than a bi-Maxwellian under all conditions. The self-similar distribution deviation from a Maxwellian is a measure of inelasticity in particle scattering from waves and/or turbulence. The ranges of values defined by the lower and upper quartiles for the kappa exponents are κ ec ~ 5.40-10.2 for the core, κ eh ~ 3.58-5.34 for the halo, and κ eb ~ 3.40-5.16 for the beam/strahl. The lower-to-upper quartile range of symmetric bi-self-similar core exponents is s ec ~ 2.00-2.04, and those of asymmetric bi-self-similar core exponents are p ec ~ 2.20-4.00 for the parallel exponent and q ec ~ 2.00-2.46 for the perpendicular exponent. The nuanced details of the fit procedure and description of resulting data product are also presented. The statistics and detailed analysis of the results are presented in Paper II and Paper III of this three-part study.
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Affiliation(s)
- Lynn B Wilson
- NASA Goddard Space Flight Center, Heliophysics Science Division, Greenbelt, MD, USA
| | - Li-Jen Chen
- NASA Goddard Space Flight Center, Heliophysics Science Division, Greenbelt, MD, USA
| | - Shan Wang
- NASA Goddard Space Flight Center, Heliophysics Science Division, Greenbelt, MD, USA
- Astronomy Department, University of Maryland, College Park, Maryland, USA
| | - Steven J Schwartz
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Boulder, CO, USA
| | - Drew L Turner
- Space Sciences Department, The Aerospace Corporation, El Segundo, CA, USA
| | - Michael L Stevens
- Harvard-Smithsonian Center for Astrophysics, Harvard University, Cambridge, MA, USA
| | - Justin C Kasper
- University of Michigan, Ann Arbor, School of Climate and Space Sciences and Engineering, Ann Arbor, MI, USA
| | - Adnane Osmane
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - Damiano Caprioli
- Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL, USA
| | - Stuart D Bale
- University of California Berkeley, Space Sciences Laboratory, Berkeley, CA, USA
| | - Marc P Pulupa
- University of California Berkeley, Space Sciences Laboratory, Berkeley, CA, USA
| | - Chadi S Salem
- University of California Berkeley, Space Sciences Laboratory, Berkeley, CA, USA
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9
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Nonlinear Development of Electron Heat Flux Instability: Particle in Cell Simulation. ACTA ACUST UNITED AC 2019. [DOI: 10.3847/1538-4357/ab12db] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Seough J, Nariyuki Y, Yoon PH, Saito S. STRAHL FORMATION IN THE SOLAR WIND ELECTRONS VIA WHISTLER INSTABILITY. ACTA ACUST UNITED AC 2015. [DOI: 10.1088/2041-8205/811/1/l7] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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12
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13
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“Lagrangian Temperature”: Derivation and Physical Meaning for Systems Described by Kappa Distributions. ENTROPY 2014. [DOI: 10.3390/e16084290] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Štverák Š, Trávníček P, Maksimovic M, Marsch E, Fazakerley AN, Scime EE. Electron temperature anisotropy constraints in the solar wind. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2007ja012733] [Citation(s) in RCA: 190] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Štěpán Štverák
- Institute of Atmospheric Physics; Academy of Sciences of the Czech Republic; Prague Czech Republic
- Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique; Observatoire de Paris, Centre National de la Recherche Scientifique, Université Pierre et Marie Curie, Université Paris Diderot; Meudon France
| | - Pavel Trávníček
- Institute of Atmospheric Physics; Academy of Sciences of the Czech Republic; Prague Czech Republic
- Astronomical Institute; Academy of Sciences of the Czech Republic; Prague Czech Republic
| | - Milan Maksimovic
- Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique; Observatoire de Paris, Centre National de la Recherche Scientifique, Université Pierre et Marie Curie, Université Paris Diderot; Meudon France
| | - Eckart Marsch
- Department for Sun and Heliosphere; Max Planck Institute for Solar System Research; Katlenburg-Lindau Germany
| | | | - Earl E. Scime
- Department of Physics; West Virginia University; Morgantown West Virginia USA
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