Expanding-box Quasilinear Model of the Solar Wind

Seough, Jungjoon; Yoon, Peter H.; Nariyuki, Yasuhiro; Salem, C. S.

doi:10.3847/1538-4357/acde7d

Cited by 4 publications

(3 citation statements)

References 81 publications

(148 reference statements)

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“…Crucially, multi-scale coupling between global solar wind expansion and local kinetic processes governs the dynamic and thermodynamic evolution of solar wind plasma (Verscharen et al 2019;Seough et al 2023). These complex interactions can be traced through both in situ measurements of local plasma properties (for small-scale processes) and remote sensing observations of the origin of global structures (for large-scale processes).…”

Section: Kinetic Waves/instabilitiesmentioning

confidence: 99%

Long-Term Science Goals with In Situ Observations at the Sun-Earth Lagrange Point L4

Lee,

Kim,

Choi

et al. 2024

J. Astron. Space Sci.

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The Korean heliospheric community, led by the Korea Astronomy and Space Science Institute (KASI), is currently assessing the viability of deploying a spacecraft at the Sun-Earth Lagrange Point L4 in collaboration with National Aeronautics and Space Administration (NASA). The aim of this mission is to utilize a combination of remote sensing and in situ instruments for comprehensive observations, complementing the capabilities of the L1 and L5 observatories. The paper outlines long-term scientific objectives, underscoring the significance of multi-point in-situ observations to better understand critical heliospheric phenomena. These include coronal mass ejections, magnetic flux ropes, heliospheric current sheets, kinetic waves and instabilities, suprathermal electrons and solar energetic particle events, as well as remote detection of solar radiation phenomena. Furthermore, the mission’s significance in advancing space weather prediction and space radiation exposure assessment models through the integration of L4 observations is discussed. This article is concluded with an emphasis on the potential of L4 observations to propel advancements in heliospheric science.

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Section: Kinetic Waves/instabilitiesmentioning

confidence: 99%

Long-Term Science Goals with In Situ Observations at the Sun-Earth Lagrange Point L4

Lee,

Kim,

Choi

et al. 2024

J. Astron. Space Sci.

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“…This set of equations can be derived from the self-consistent quasilinear kinetic equation with the assumption of a bi-Maxwellian proton distribution function Yoon 2017). Such a scheme, which can be termed the velocity moment quasilinear theory, has been used for a number of applications Seough et al 2013Seough et al , 2023Yoon & Sarfraz 2017;Yoon et al 2019Yoon et al , 2023, and has compared quite well with the particle-in-cell or hybrid simulations (Seough et al 2014(Seough et al , 2015Sarfraz et al 2022;López et al 2023).…”

Section: Evolution Of Proton Temperature Anisotropy By Collective Rel...mentioning

confidence: 99%

Boundary of the Distribution of Solar Wind Proton Beta versus Temperature Anisotropy

Yoon,

Lazar,

Salem

et al. 2024

ApJ

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The frequency distribution of solar wind protons, measured in the vicinity of Earth’s orbit, is customarily plotted in (β ∥, T ⊥/T ∥) phase space. Here, T ⊥/T ∥ is the ratio of perpendicular and parallel temperatures, and β ∥ = 8π nT ∥/B 2 is the ratio of parallel thermal energy to background magnetic field energy, the so-called “parallel beta,” with ⊥ and ∥ denoting directions with respect to the ambient magnetic field. Such a frequency distribution, plotted as a two-dimensional histogram, forms a peculiar rhombic shape defined with an outer boundary in the said phase space. Past studies reveal that the threshold conditions for temperature anisotropy–driven plasma instability partially account for the boundary on the high-β ∥ side. The low-β ∥ side remains largely unexplained despite some efforts. Work by Vafin et al. recently showed that certain contours of collisional relaxation frequency, ν pp, when parameterized by T ⊥/T ∥ and β ∥, could match the overall shape of the left-hand boundary, thus suggesting that the collisional relaxation process might be closely related to the formation of the left-hand boundary. The present paper extends the analysis by Vafin et al. and carries out the dynamical computation of the collisional relaxation process for an ensemble of initial proton states with varying degrees of anisotropic temperatures. The final states of the relaxed protons are shown to closely match the observed boundary to the left of the (β ∥, T ⊥/T ∥) phase space. When coupled with a similar set of calculations for the ensemble in the collective instability regime, it is found that the combined collisional/collective effects provide the baseline explanation for the observation.

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“…Moreover, expansion may also play an indirect role in the heath flux regulation through the excited instabilities [38]. Under this context, Seough et al [41] introduced the effect of expansion at the kinetic level to add wave-particle relaxation to the well-known double adiabatic equations in the EB formalism. They considered the well-known moment-based quasilinear kinetic theory and added the EBM temperature evolution to the equations.…”

Section: Introductionmentioning

confidence: 99%

First Principles Description of Plasma Expansion Using the Expanding Box Model

Echeverría-Veas,

Moya,

Lazar

et al. 2023

Universe

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Multi-scale modeling of expanding plasmas is crucial for understanding the dynamics and evolution of various astrophysical plasma systems such as the solar and stellar winds. In this context, the Expanding Box Model (EBM) provides a valuable framework to mimic plasma expansion in a non-inertial reference frame, co-moving with the expansion but in a box with a fixed volume, which is especially useful for numerical simulations. Here, fundamentally based on the Vlasov equation for magnetized plasmas and the EBM formalism for coordinates transformations, for the first time, we develop a first principles description of radially expanding plasmas in the EB frame. From this approach, we aim to fill the gap between simulations and theory at microscopic scales to model plasma expansion at the kinetic level. Our results show that expansion introduces non-trivial changes in the Vlasov equation (in the EB frame), especially affecting its conservative form through non-inertial forces purely related to the expansion. In order to test the consistency of the equations, we also provide integral moments of the modified Vlasov equation, obtaining the related expanding moments (i.e., continuity, momentum, and energy equations). Comparing our results with the literature, we obtain the same fluids equations (ideal-MHD), but starting from a first principles approach. We also obtained the tensorial form of the energy/pressure equation in the EB frame. These results show the consistency between the kinetic and MHD descriptions. Thus, the expanding Vlasov kinetic theory provides a novel framework to explore plasma physics at both micro and macroscopic scales in complex astrophysical scenarios.

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Expanding-box Quasilinear Model of the Solar Wind

Cited by 4 publications

References 81 publications

Long-Term Science Goals with In Situ Observations at the Sun-Earth Lagrange Point L4

Long-Term Science Goals with In Situ Observations at the Sun-Earth Lagrange Point L4

Boundary of the Distribution of Solar Wind Proton Beta versus Temperature Anisotropy

First Principles Description of Plasma Expansion Using the Expanding Box Model

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