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We demonstrate that a nonthermal distribution of particles described by a kappa distribution can be accurately approximated by a weighted sum of Maxwell-Boltzmann distributions. We apply this method to modeling collision processes in…

Solar and Stellar Astrophysics · Physics 2015-09-09 Michael Hahn , Daniel Wolf Savin

Estimating the temperature of the solar wind particles and their anisotropies is particularly important for understanding the origin of these deviations from thermal equilibrium as well as their effects. In the absence of energetic events…

Space Physics · Physics 2016-08-17 V. Pierrard , M. Lazar , S. Poedts , S. Stverak , M. Maksimovic , P. M. Travnicek

In this paper, we prove that the kappa distribution is the stationary solution of the Vlasov-Poisson system in an inhomogeneous plasma under the polytropic equation of state and an assumption restricting the local velocity distribution to a…

Plasma Physics · Physics 2020-12-17 Ran Guo

We use observations from the Interstellar Boundary Explorer (IBEX) and Ulysses to explore the possibility that the interstellar neutral helium flowing through the inner solar system possesses an intrinsic non-Maxwellian velocity…

Solar and Stellar Astrophysics · Physics 2019-08-21 Brian E. Wood , Hans-Reinhard Mueller , Eberhard Moebius

Adopting a bottom-up perspective, we propose a novel two-parametric nonadditive entropy, $S_{\kappa\ell}$, associated with a Kappa-type power-law velocity distribution, $F_{\kappa\ell}(v)$, recently derived in the literature. By formulating…

Statistical Mechanics · Physics 2025-12-04 J. A. S. Lima , M. H. Benetti

The paper develops a theoretical relationship between the polytropic index and the temperature anisotropy that may characterize space plasmas. The derivation is based on the correlation among the kinetic energies of particles with…

Space Physics · Physics 2021-03-17 George Livadiotis , George Nicolaou

The recently developed concept of "entropic defect" is important for understanding the foundations of thermodynamics in space plasma physics, and more generally, for systems with physical correlations among their particles. Using this…

Plasma Physics · Physics 2022-11-30 George Livadiotis , David J. McComas

Velocity-space anisotropy can significantly modify fusion reactivity. The nature and magnitude of this modification depends on the plasma temperature, as well as the details of how the anisotropy is introduced. For plasmas that are…

Plasma Physics · Physics 2021-05-11 E. J. Kolmes , M. E. Mlodik , N. J. Fisch

Particle velocity distribution functions (VDF) in space plasmas often show non Maxwellian suprathermal tails decreasing as a power law of the velocity. Such distributions are well fitted by the so-called Kappa distribution. The presence of…

Space Physics · Physics 2015-05-18 V. Pierrard , M. Lazar

This paper studies sufficient conditions for deriving the kappa distribution in polytropic plasmas by an improved method compared with the previous work [R. Guo, Phys. Plasmas \textbf{27}, 122104 (2020)]. We find that the polytropic…

Plasma Physics · Physics 2024-09-05 Ran Guo

A two-dimension self-similar solution is proposed for a plasma expansion with anisotropic pressure. With the solution, it depends on the relationship between the ratio of the longitudinal and the transverse temperature of the plasma,…

Plasma Physics · Physics 2008-12-01 Yongsheng Huang , Yuanjie Bi , Xiaojiao Duan , Naiyan Wang , Xiuzhang Tang , Zhe Gao

In this paper we derive the dielectric tensor for a plasma containing particles described by an anisotropic superthermal (bi-kappa) velocity distribution function. The tensor components are written in terms of the two-variables kappa plasma…

Plasma Physics · Physics 2016-06-14 Rudi Gaelzer , Luiz Fernando Ziebell , Anelise Ramires Meneses

Recent studies have outlined the interest for the evaluation of transport coefficients in space plasmas, where the observed velocity distributions of plasma particles are conditioned not only by the binary collisions, e.g., at low energies,…

Plasma Physics · Physics 2022-03-15 Edin Husidic , Klaus Scherer , Marian Lazar , Horst Fichtner , Stefaan Poedts

We use information entropy to test the isotropy in the nearby galaxy distribution mapped by the Two Micron All-Sky redshift survey (2MRS). We find that the galaxy distribution is highly anisotropic on small scales. The radial anisotropy…

Cosmology and Nongalactic Astrophysics · Physics 2017-04-19 Biswajit Pandey

Anisotropic, non-thermal, and multi-temperature distributed particle momenta are commonly observed in collisionless space plasmas, such as the solar wind. Using Liouville's theorem, we argue that anisotropic compression or expansion of the…

Plasma Physics · Physics 2026-02-12 Torsten Enßlin , Christoph Pfrommer

The polytropic index of electrons in a magnetized plasma is experimentally investigated in the presence of heating and anisotropic work done, incorporating the effective dimensionality arising from temperature anisotropy. The study is…

Plasma Physics · Physics 2024-10-18 Ayesha Nanda , Sudeep Bhattacharjee

The fast solar wind is a collisionless plasma permeated by plasma waves on many different scales. A plasma wave represents the natural interplay between the periodic changes of the electromagnetic field and the associated coherent motions…

Space Physics · Physics 2011-07-29 Daniel Verscharen , Eckart Marsch

We study the effect of the velocity distributions of the plasma particles on the equilibrium charge of dust particles which suffer collisional charging, considering different forms of both isotropic and anisotropic Kappa distributions for…

Plasma Physics · Physics 2025-09-25 Luiz Fernando Ziebell , Rudi Gaelzer

The generally accepted representation of $\kappa$-distributions in space plasma physics allows for two different alternatives, namely assuming either the temperature or the thermal velocity to be $\kappa$-independent. The present paper aims…

Solar and Stellar Astrophysics · Physics 2016-04-13 M. Lazar , H. Fichtner , P. H. Yoon

In classical thermodynamics the entropy is an extensive quantity, i.e.\ the sum of the entropies of two subsystems in equilibrium with each other is equal to the entropy of the full system consisting of the two subsystems. The extensitivity…

Plasma Physics · Physics 2018-12-05 H. Fichtner , K. Scherer , M. Lazar , H. J. Fahr , Z. Vörös