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Related papers: A Parallel-Propagating Alfv\'enic Ion-Beam Instabi…

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Using Parker Solar Probe measurements of the solar wind, we demonstrate that $\beta_{\parallel}$ is the main driver that determines which instabilities limit proton temperature anisotropy. At radial distances from 10 to 30 solar radii,…

Solar and Stellar Astrophysics · Physics 2026-03-27 Matilde Coello-Guzmán , Víctor A. Pinto , Roberto E. Navarro , Pablo S. Moya

Parametric decay instability (PDI) of Alfv\'en wave is thought to play an important role in the dissipation of the large-amplitude Alfv\'en waves and in the heating of magnetized plasmas. Temperature anisotropy is frequently observed by…

Solar and Stellar Astrophysics · Physics 2026-04-28 Hayato Saguchi , Yohei Kawazura , Munehito Shoda , Yuto Katoh

Parametric instability of Alfv\'en wave packets with monochromatic carrier wave in low-$\beta$ plasma is studied using one-dimensional magnetohydrodynamic simulations. The results show spatial growth of incoming perturbations as they…

Solar and Stellar Astrophysics · Physics 2025-08-11 S. S Komissarov

Using linear Vlasov theory of plasma waves and quasi-linear theory of resonant wave-particle interaction, the dispersion relations and the electromagnetic field fluctuations of fast and Alfven waves are studied for a low-beta multi-ion…

Solar and Stellar Astrophysics · Physics 2013-08-16 Ming Xiong , Xing Li

In the parts of the solar corona and solar wind that experience the fewest Coulomb collisions, the component proton, electron, and heavy ion populations are not in thermal equilibrium with one another. Observed differences in temperatures,…

Solar and Stellar Astrophysics · Physics 2015-06-05 Steven R. Cranmer , Adriaan A. van Ballegooijen

The expanding solar wind plasma ubiquitously exhibits anisotropic non-thermal particle velocity distributions. Typically, proton Velocity Distribution Functions (VDFs) show the presence of a core and a field-aligned beam. Novel observations…

The classic Weber-Davis model of the solar wind is reconsidered by incorporating alpha particles and by allowing the solar wind to flow out of the equatorial plane in an axisymmetrical configuration. In the ion momentum equations of the…

Astrophysics · Physics 2007-05-23 Bo Li , Xing Li

The solar wind upstream of Mars's bow shock can be described in terms of Alfv\'enic turbulence, with an incompressible energy cascade rate of $10^{-17}$ J m$^{-3}$ s$^{-1}$ at magnetohydrodynamics (MHD) scales. The solar wind has more…

Solar and Stellar Astrophysics · Physics 2024-06-26 Norberto Romanelli , Christopher M. Fowler , Gina A. DiBraccio , Jared R. Espley , Jasper S. Halekas

We study correlations of the temperature ratio (which is an indicator for perpendicular ion heating) and the differential flow of the alpha particles with the power of transverse fluctuations that have wave numbers between 0.01 and 0.1…

Solar and Stellar Astrophysics · Physics 2011-11-14 S. Bourouaine , E. Marsch , F. M. Neubauer

The nature of the plasma wave modes around the ion kinetic scales in highly Alfv\'enic slow solar wind turbulence is investigated using data from the NASA's Parker Solar Probe taken in the inner heliosphere, at 0.18 Astronomical Unit (AU)…

It is shown that low-collisionality plasmas cannot support linearly polarized shear-Alfv\'en fluctuations above a critical amplitude $\delta B_{\perp}/B_{0} \sim \beta^{\,-1/2}$, where $\beta$ is the ratio of thermal to magnetic pressure.…

Plasma Physics · Physics 2016-10-19 J. Squire , E. Quataert , A. A. Schekochihin

In-situ observations of the fast solar wind in the inner-heliosphere show that minor ions and ion sub-populations often exhibit distinct drift velocities. Both alpha particles and proton beams stream at speeds that rarely exceed the local…

Solar and Stellar Astrophysics · Physics 2025-10-29 Luca Pezzini , Fabio Bacchini , Andrei N. Zhukov , Giuseppe Arrò , Rodrigo A. Lopez

According to \emph{Wind} observations between June 2004 and May 2019, this Letter investigates the proton and alpha particle temperatures in the space of ($\theta_d$, $V_d/V_A$) for the first time, where $\theta_d$ and $V_d$ are the radial…

Space Physics · Physics 2020-02-05 G. Q. Zhao , H. Q. Feng , D. J. Wu , J. Huang , Y. Zhao , Q. Liu , Z. J. Tian

Using numerical simulations, we investigate the onset and suppression of parametric decay instability (PDI) in the solar wind, focusing on the suppression effect by the wind acceleration and expansion. We also discuss the role of PDI in…

Solar and Stellar Astrophysics · Physics 2018-06-13 Munehito Shoda , Takaaki Yokoyama , Takeru K. Suzuki

Compensated-current systems created by energetic ion beams are widespread in space and astrophysical plasmas. The well-known examples are foreshock regions in the solar wind and around supernova remnants. We found a new oblique Alfv\'enic…

Solar and Stellar Astrophysics · Physics 2015-06-18 P. Malovichko , Y. Voitenko , J. De Keyser

Plasma processes occurring in the corona and solar wind can be probed by studying the thermodynamic properties of different ion species. However, most in-situ observations of positive ions in the solar wind are taken at 1 AU, where…

Space Physics · Physics 2019-03-06 D. Stansby , D. Perrone , L. Matteini , T. S. Horbury , C. S. Salem

The analysis of energy balance of coronal holes gives that to accelerate the fast solar wind streams the energy flux of the order of 800 erg/cm$^2$ s is needed. Axford and McKenzie suggested that the energy source, necessary to accelerate…

Plasma Physics · Physics 2007-05-23 Andrei Sadovski

We study the linear stability of a planar interface separating two fluids in relative motion, focusing on the symmetric configuration where the two fluids have the same properties (density, temperature, magnetic field strength, and…

High Energy Astrophysical Phenomena · Physics 2023-07-07 Anthony Chow , Michael E. Rowan , Lorenzo Sironi , Jordy Davelaar , Gianluigi Bodo , Ramesh Narayan

An accurate assessment of the Sun's angular momentum (AM) loss rate is an independent constraint for models that describe the rotation evolution of Sun-like stars. In-situ measurements of the solar wind taken by Parker Solar Probe (PSP), at…

We investigate the local proton energization at magnetic discontinuities/intermittent structures and the corresponding kinetic signatures in velocity phase space in Alfv\'enic and non-Alfv\'enic wind streams observed by Parker Solar Probe.…

Plasma Physics · Physics 2023-09-15 C. A. Gonzalez , J. L. Verniero , R. Bandyopadhyay , A. Tenerani