Modelling plasma turbulence observed by Parker Solar Probe during its first two orbits with hybrid-kinetic simulations

We employ 2D and 3D high-resolution hybrid kinetic simulations of plasma turbulence to explore the physical conditions encountered by the Parker Solar Probe (PSP) spacecraft during its first two orbits, modelling the turbulent cascade self-consistently from large fluid scales down to kinetic scales. By varying key parameters (e.g., the ion and electron plasma beta, the level of fluctuations with respect to the ambient magnetic field, the injection scale), we explore different plasma conditions. We identify a new kinetic-scale regime with respect to what has previously been found in both hybrid simulations and spacecraft observations of the solar wind and of the near-Earth environment, characterized among other things by a steeper magnetic field spectrum. Our simulations reproduce PSP observations and thus offer the opportunity to investigate the physical mechanism(s) behind such change in the turbulent cascade properties. We discuss our results in the framework of theoretical models of the nonlinear interaction of dispersive wave modes, field-particle interactions, and magnetic reconnection in low-beta plasmas. We also analyse intermittency, magnetic compressibility, polarization of wave-like fluctuations, and statistics of magnetic reconnection events by means of iterative filters, a new method for the analysis of nonlinear nonstationary signals. Together with our previous numerical results in quantitative agreement with MMS observations in the Earth&#8217;s magnetosheath, our new findings confirm the ability of the hybrid approach to model in-situ observations, which is fundamental for interpreting observational results and for planning future spacecraft missions.

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Structure functions analysis of sub-ion scale turbulent fluctuations and dissipation range in a magnetized plasma

10.5194/egusphere-egu21-9050 ◽

2021 ◽

Author(s):

Giuseppe Arrò ◽

Francesco Califano ◽

Giovanni Lapenta

Keyword(s):

Magnetic Field ◽

Magnetic Reconnection ◽

Plasma Turbulence ◽

Structure Functions ◽

Magnetized Plasma ◽

Small Scale ◽

Turbulent Fluctuations ◽

The Magnetic Field ◽

Turbulent Cascade ◽

Dissipation Range

Turbulence in collisionless magnetized plasmas is a complex multi-scale process involving many decades of scales ranging from large magnetohydrodynamic (MHD) scales down to small ion and electron kinetic scales, associated with different physical regimes. It is well know that the MHD turbulent cascade is driven by the nonlinear interaction of low-frequency Alfv&#233;n waves but, on the other hand, the properties of plasma turbulence at sub-ion scales are not yet fully understood. In addition to a great variety of relatively high frequency modes such as kinetic Alfv&#233;n waves and whistler waves, magnetic reconnection has been suggested to be a key element in the development of kinetic scale turbulence because it allows for energy to be transferred from large scales directly into sub-ion scales through currents sheets disruption. In this context, an unusual reconnection mechanism driven exclusively by the electrons (with ions being demagnetized), called "electron-only reconnection", has been recently observed for the first time in the Earth&#8217;s magnetosheath and its role in plasma turbulence is still a matter of great debate. Using 2D-3V hybrid Vlasov-Maxwell (HVM) simulations of freely decaying plasma turbulence, we investigate and compare the properties of the turbulence associated with standard ion-coupled reconnection and of the turbulence associated with electron-only reconnection [Califano et al., 2018]. By analyzing the structure functions of the turbulent magnetic field and ion fluid velocity fluctuations, we find that the turbulence associated with electron-only reconnection shows the same statistical features as the turbulence associated with standard ion-coupled reconnection and no peculiar signature related to electron-only reconnection is found in the turbulence statistics. This result suggests that the properties of the turbulent cascade in a magnetized plasma are independent of the specific mechanism associated with magnetic reconnection but depend only on the coupling between the magnetic field and the different particle species present in the system. Finally, the properties of the magnetic field dissipation range are discussed as well and we claim that its formation, and thus the dissipation of magnetic energy, is driven only by the small scale electron dynamics since ions are demagnetized in this range [Arr&#243; et al., 2020]. This work has received funding from the European Union Horizon 2020 research and innovation programme under grant agreement No 776262 (AIDA, www.aida-space.eu). References: G. Arr&#243;, F. Califano, and G. Lapenta. Statistical properties of turbulent fluctuations associated with electron-only magnetic reconnection. , 642:A45, Oct. 2020. doi: 10.1051/0004-6361/202038696. F. Califano, S. S. Cerri, M. Faganello, D. Laveder, M. Sisti, and M. W. Kunz. Electron-only magnetic reconnection in plasma turbulence. arXiv e-prints, art. arXiv:1810.03957, Oct. 2018.

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Transient and localized processes in the magnetotail: a review

Annales Geophysicae ◽

10.5194/angeo-26-955-2008 ◽

2008 ◽

Vol 26 (4) ◽

pp. 955-1006 ◽

Cited By ~ 91

Author(s):

A. S. Sharma ◽

R. Nakamura ◽

A. Runov ◽

E. E. Grigorenko ◽

H. Hasegawa ◽

...

Keyword(s):

Magnetic Reconnection ◽

Current Sheet ◽

Spatial Scales ◽

Theoretical Models ◽

Particle Interactions ◽

Transient Field ◽

Theoretical Frameworks ◽

Flux Ropes ◽

Night Side ◽

Bursty Bulk Flows

Abstract. Many phenomena in the Earth's magnetotail have characteristic temporal scales of several minutes and spatial scales of a few Earth radii (RE). Examples of such transient and localized mesoscale phenomena are bursty bulk flows, beamlets, energy dispersed ion beams, flux ropes, traveling compression regions, night-side flux transfer events, and rapid flappings of the current sheet. Although most of these observations are linked to specific interpretations or theoretical models they are inter-related and can be the different aspects of a physical process or origin. Recognizing the inter-connected nature of the different transient and localized phenomena in the magnetotail, this paper reviews their observations by highlighting their important characteristics, with emphasis on the new results from Cluster multipoint observations. The multi-point Cluster measurements have provided, for the first time, the ability to distinguish between temporal and spatial variations, and to resolve spatial structures. Some examples of the new results are: flux ropes with widths of 0.3 RE, transient field aligned currents associated with bursty bulk flows and connected to the Hall current at the magnetic reconnection, flappings of the magnetotail current sheet with time scales of 100 s–10 min and thickness of few thousand km, and particle energization including velocity and time dispersed ion structures with the latter having durations of 1–3 min. The current theories of these transient and localized processes are based largely on magnetic reconnection, although the important role of the interchange and other plasma modes are now well recognized. On the kinetic scale, the energization of particles takes place near the magnetic X-point by non-adiabatic processes and wave-particle interactions. The theory, modeling and simulations of the plasma and field signatures are reviewed and the links among the different observational concepts and the theoretical frameworks are discussed. The mesoscale processes in the magnetotail and the strong coupling among them are crucial in developing a comprehensive understanding of the multiscale phenomena of the magnetosphere.

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Flux tubes and energetic particles in Parker Solar Probe orbit 5: magnetic helicity - PVI method and ISOIS observations

10.5194/egusphere-egu21-9911 ◽

2021 ◽

Author(s):

Francesco Pecora ◽

Sergio Servidio ◽

Antonella Greco ◽

Stuart D. Bale ◽

David J. McComas ◽

...

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Magnetic Flux ◽

Magnetic Reconnection ◽

Energetic Particle ◽

Plasma Turbulence ◽

Small Scale ◽

Flux Tubes ◽

Particle Measurements ◽

The Magnetic Field

Plasma turbulence can be viewed as a magnetic landscape populated by large- and small-scale coherent structures, consisting notionally of magnetic flux tubes and their boundaries. Such structures exist over a wide range of scales and exhibit diverse morphology and plasma properties. &#160;Moreover, interactions of particles with turbulence may involve temporary trapping in, as well as exclusion from, certain regions of space, generally controlled by the topology and connectivity of the magnetic field. &#160;In some cases, such as SEP "dropouts'' the influence of the magnetic structure is dramatic; in other cases, it is more subtle, as in edge effects in SEP confinement. With Parker Solar Probe now closer to the sun than any previous mission, novel opportunities are available for examination of the relationship between magnetic flux structures and energetic particle populations.&#160;We present a method that is able to characterize both the large- and small-scale structures of the turbulent solar wind, based on the combined use of a filtered magnetic helicity (Hm) and the partial variance of increments (PVI). The synergistic combination with energetic particle measurements suggests whether these populations are either trapped within or excluded from the helical structure.This simple, single-spacecraft technique exploits the natural tendency of flux tubes to assume a cylindrical symmetry of the magnetic field about a central axis. Moreover, large helical magnetic tubes might be separated by small-scale magnetic reconnection events (current sheets) and present magnetic discontinuity with the ambient solar wind. The method was first validated via direct numerical simulations of plasma turbulence and then applied to data from the Parker Solar Probe (PSP) mission. In particular, ISOIS energetic particle (EP) measurements along with FIELDS magnetic field measurements and SWEAP plasma moments, are enabling characterization of observations of EPs closer to their sources than ever before. &#160; This novel analysis, combining Hm and PVI methods, reveals that a large number of flux tubes populate the solar wind and continuously merge in contact regions where magnetic reconnection and particle acceleration may occur. Moreover, the detection of boundaries, correlated with high-energy particle measurements, gives more insights into the nature of such helical structures as "excluding barriers'' suggesting a strong link between particle properties and fields topology. This research is partially supported by the Parker Solar Probe project.&#160;

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Self-generated turbulence by plasmas and magnetic field collective interaction in 3D large temporal-spatial turbulent magnetic reconnection: I. The Basic Feature

10.5194/egusphere-egu2020-7950 ◽

2020 ◽

Author(s):

Bojing Zhu ◽

Hui Yan ◽

Huihong Cheng ◽

Ying Zhong ◽

Yunfei Du ◽

...

Keyword(s):

Magnetic Field ◽

Magnetic Reconnection ◽

Plasma Turbulence ◽

Math Model ◽

Collective Interaction ◽

Magnetic Fluctuation ◽

Fully Coupled ◽

Appl Math

The role of turbulence is one of key issues for understanding the magnetic and plasma energy conversion, plasma heating and high energy particles acceleration in large temporal-spatial scale turbulent magnetic reconnection (LTSTMR; observed current sheet thickness to characteristic electron length, Larmor radius for low-beta and electron inertial length for high-beta, ratios on the order of ten to the power of ten or higher; observed evolution time to electron cyclotron time ratios on the order of ten to the power of ten or higher) . Solar atmosphere activities (e.g., limbs, flares, coronal mass ejections, solar winds and so on), which are the most important phenomenon in the solar and Sun-Earth space systems, are typical LTSTMRs.Here we&#160;used our newly developed RHPIC-LBM algorithm[*] &#160;to perform the role of&#160;&#160;turbulence in the magnetic fluctuation-induced self-generating-organization&#160; (MF-ISGO), the turbulence in the plasma turbulence-induced self-feeding-sustaining (PT-ISFS), and the interaction of turbulence between MF-ISGO and PT-ISFS in the continuous kinetic-dynamic-hydro fully coupled LTSTMR.&#160;First, we find that the self-generated turbulence by magnetic field and plasma motion collective interaction include two fully coupled processes of 1) fluid vortex induced magnetic reconnection (MR) and 2) MR induced fluid vortex.&#160;The Biermann battery effect and&#160;&#160;alpha-effect can not only generate magnetic fields, but can server them to trigger MR, the Spitzer resistance and turbulence resistance (beta-effect)&#160;&#160;can not only generate magnetic eddies, but can server&#160;&#160;them to trigger fluid turbulence.&#160;&#160;Then, we find that these interaction leads to vortex splitting and phase separating instabilities, and there are four species instabilities coexist in the evolution process. 1) Vortex separation interface instabilities. 2)Magnetic fluctuation-induced self-generating-organization instabilities. 3) Plasma turbulence-induced self-feeding-sustaining instabilities. 4) Vortex shedding instabilities.Finally, the nuanced details of the magnetic topological structure and the topological characterization of flow structures in plasma of the simulated 3D LTSTMR are also presented.The characterization of turbulence anisotropy and the turbulence acceleration of the LTSTMR are presented in Part II and Part III of this three-paper series study.*Techniques and algorithms for RHPIC-LBM have been developed in previous studies (e.g.,Zhu2020a, Zhu2020b)ReferencesZhu, B. J., Yan, H., Zhong, Y., et al. 2020a, Appl Math Model, 78, 932, doi: 10.1016/j.apm.2019.09.043Zhu, B. J., Yan, H., Zhong, Y., et al. 2020b, Appl Math Model, 78, 968,doi: 10.1016/j.apm.2019.05.027

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Statistical properties of turbulent fluctuations associated with electron-only magnetic reconnection

Astronomy and Astrophysics ◽

10.1051/0004-6361/202038696 ◽

2020 ◽

Vol 642 ◽

pp. A45

Author(s):

G. Arró ◽

F. Califano ◽

G. Lapenta

Keyword(s):

Magnetic Field ◽

Magnetic Reconnection ◽

Fluid Velocity ◽

Turbulent Energy ◽

Plasma Turbulence ◽

Statistical Properties ◽

Energy Cascade ◽

Magnetized Plasma ◽

Field Energy ◽

Turbulent Fluctuations

Context. Recent satellite measurements in the turbulent magnetosheath of Earth have given evidence of an unusual reconnection mechanism that is driven exclusively by electrons. This newly observed process was called electron-only reconnection, and its interplay with plasma turbulence is a matter of great debate. Aims. By using 2D-3V hybrid Vlasov–Maxwell simulations of freely decaying plasma turbulence, we study the role of electron-only reconnection in the development of plasma turbulence. In particular, we search for possible differences with respect to the turbulence associated with standard ion-coupled reconnection. Methods. We analyzed the structure functions of the turbulent magnetic field and ion fluid velocity fluctuations to characterize the structure and the intermittency properties of the turbulent energy cascade. Results. We find that the statistical properties of turbulent fluctuations associated with electron-only reconnection are consistent with those of turbulent fluctuations associated with standard ion-coupled reconnection, and no peculiar signature related to electron-only reconnection is found in the turbulence statistics. This result suggests that the turbulent energy cascade in a collisionless magnetized plasma does not depend on the specific mechanism associated with magnetic reconnection. The properties of the dissipation range are discussed as well, and we claim that only electrons contribute to the dissipation of magnetic field energy at sub-ion scales.

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Effects of plasma turbulence on the nonlinear evolution of magnetic island in tokamak

Nature Communications ◽

10.1038/s41467-020-20652-9 ◽

2021 ◽

Vol 12 (1) ◽

Cited By ~ 1

Author(s):

Minjun J. Choi ◽

Lāszlo Bardōczi ◽

Jae-Min Kwon ◽

T. S. Hahm ◽

Hyeon K. Park ◽

...

Keyword(s):

Magnetic Field ◽

Nonlinear Evolution ◽

Plasma Turbulence ◽

Magnetized Plasmas ◽

Tokamak Plasmas ◽

Magnetic Islands ◽

Magnetic Island ◽

Reconnection Site ◽

Ambient Turbulence

AbstractMagnetic islands (MIs), resulting from a magnetic field reconnection, are ubiquitous structures in magnetized plasmas. In tokamak plasmas, recent researches suggested that the interaction between an MI and ambient turbulence can be important for the nonlinear MI evolution, but a lack of detailed experimental observations and analyses has prevented further understanding. Here, we provide comprehensive observations such as turbulence spreading into an MI and turbulence enhancement at the reconnection site, elucidating intricate effects of plasma turbulence on the nonlinear MI evolution.

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The Location of Magnetic Reconnection at Earth’s Magnetopause

Space Science Reviews ◽

10.1007/s11214-021-00817-8 ◽

2021 ◽

Vol 217 (3) ◽

Author(s):

K. J. Trattner ◽

S. M. Petrinec ◽

S. A. Fuselier

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Magnetic Reconnection ◽

Ion Beams ◽

Review Article ◽

Observational Evidence ◽

Magnetic Shear ◽

General Direction ◽

Shear Model ◽

Wide Range

AbstractOne of the major questions about magnetic reconnection is how specific solar wind and interplanetary magnetic field conditions influence where reconnection occurs at the Earth’s magnetopause. There are two reconnection scenarios discussed in the literature: a) anti-parallel reconnection and b) component reconnection. Early spacecraft observations were limited to the detection of accelerated ion beams in the magnetopause boundary layer to determine the general direction of the reconnection X-line location with respect to the spacecraft. An improved view of the reconnection location at the magnetopause evolved from ionospheric emissions observed by polar-orbiting imagers. These observations and the observations of accelerated ion beams revealed that both scenarios occur at the magnetopause. Improved methodology using the time-of-flight effect of precipitating ions in the cusp regions and the cutoff velocity of the precipitating and mirroring ion populations was used to pinpoint magnetopause reconnection locations for a wide range of solar wind conditions. The results from these methodologies have been used to construct an empirical reconnection X-line model known as the Maximum Magnetic Shear model. Since this model’s inception, several tests have confirmed its validity and have resulted in modifications to the model for certain solar wind conditions. This review article summarizes the observational evidence for the location of magnetic reconnection at the Earth’s magnetopause, emphasizing the properties and efficacy of the Maximum Magnetic Shear Model.

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Entropy generation analysis for MHD flow of water past an accelerated plate

Scientific Reports ◽

10.1038/s41598-021-89744-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Tarek N. Abdelhameed

Keyword(s):

Magnetic Field ◽

Entropy Generation ◽

Transfer Problem ◽

Finite Difference Methods ◽

Mhd Flow ◽

Bejan Number ◽

Physical Conditions ◽

Flow Parameters ◽

The Laplace Transform ◽

Constant Heating

AbstractThis article examines the entropy generation in the magnetohydrodynamics (MHD) flow of Newtonian fluid (water) under the effect of applied magnetic in the absence of an induced magnetic field. More precisely, the flow of water is considered past an accelerated plate such that the fluid is receiving constant heating from the initial plate. The fluid disturbance away from the plate is negligible, therefore, the domain of flow is considered as semi-infinite. The flow and heat transfer problem is considered in terms of differential equations with physical conditions and then the corresponding equations for entropy generation and Bejan number are developed. The problem is solved for exact solutions using the Laplace transform and finite difference methods. Results are displayed in graphs and tables and discussed for embedded flow parameters. Results showed that the magnetic field has a strong influence on water flow, entropy generation, and Bejan number.

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Synchronized periodic maser flares of multiple OH and CH3OH lines in G323.459–0.079

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab462 ◽

2021 ◽

Vol 502 (4) ◽

pp. 5658-5667

Author(s):

G C MacLeod ◽

Derck P Smits ◽

J A Green ◽

S P van den Heever

Keyword(s):

Magnetic Field ◽

Excited State ◽

Central Region ◽

Time Lags ◽

Field Reversal ◽

Methanol Maser ◽

Physical Conditions ◽

Upper Limit ◽

Methanol Masers ◽

Magnetic Field Reversal

ABSTRACT The first confirmed periodically varying 6.031 and 6.035 GHz hydroxyl masers are reported here. They vary contemporaneously with the 6.7 GHz methanol masers in G323.459–0.079. The 1.665 GHz hydroxyl and 12.2 GHz methanol masers associated with G323.459–0.079 are also periodic. Evidence for periodicity is seen in all features in all transitions save a single 1.665 GHz hydroxyl maser feature. Historical excited-state hydroxyl maser observations set a stricter upper limit on the epoch in which a significant accretion event occurred. The associated burst in 6.7 GHz methanol maser activity has subsided significantly while the hydroxyl transitions are brightening possibly the result of changing physical conditions in the masing cloudlets. Time lags in methanol are confirmed and may be the result of the periodic flaring propagating outward from the central region of maser activity. A possible magnetic field reversal occurred during the accretion event.

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