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Responses of the field-aligned currents in the plasma sheet boundary layer to a geomagnetic storm

Earth and Planetary Physics 2023年第5期7卷 558-564页

作者： YuanQiang Chen MingYu Wu YangJun Chen SuDong Xiao GuoQiang Wang TieLong Zhang Shenzhen Key Laboratory of Numerical Prediction for Space Storm Harbin Institute of TechnologyShenzhen 518055China Key Laboratory of Solar Activity and Space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China Chinese Academy of Sciences Center for Excellence in Comparative PlanetologyHefei 230026China Space Research Institute Austrian Academy of SciencesGraz 8042Austria

Geomagnetic storms can result in large magnetic field disturbances and intense currents in the magnetosphere and even on the *** an important medium of momentum and energy transport among the solar wind,magnetosphere,and ionosphere,field-aligned currents(FACs)can also be strengthened in storm *** study shows the responses of FACs in the plasma sheet boundary layer(PSBL)observed by the Magnetospheric Multiscale(MMS)spacecraft in different phases of a large storm that lasted from May 27,2017,to May 29,*** of the FACs were carried by electrons,and several FACs in the storm time also contained sufficient ion *** FAC magnitudes were larger in the storm than in the quiet period,and those in the main phase were the *** this case,the direction of the FACs in the main phase showed no preference for tailward or earthward,whereas the direction of the FACs in the recovery phase was mostly *** results suggest that the FACs in the PSBL are closely related to the storm and could be driven by activities in the tail region,where the energy transported from the solar wind to the magnetosphere is stored and released as the storm is ***,the FACs are an important medium of energy transport between the tail and the ionosphere,and the PSBL is a significant magnetosphere–ionosphere coupling region in the nightside.

关键词： field-aligned currents plasma sheet boundary layer geomagnetic storm

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The Pattern of By Deflections Produced from field-aligned currents Earthward of the Activation Source in the Earth’s Magnetosphere

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International Journal of Geosciences 2016年第4期7卷 479-500页

作者： Dimitrios V. Sarafopoulos Department of Electrical and Computer Engineering Democritus University of Thrace Xanthi Greece

In this investigation effort, we eventually infer that the overall quadrapole pattern of By deflections, in the vicinity of a source in the Earth’s magnetotail, is most likely due to field aligned currents (FACs) and not to Hall currents associated with an X-type collisionless reconnection. This categorically expressed statement is based upon sufficient observational evidence tightly associated with our own suggested model and the preceded works of the same author. Using representative events measured by satellite, our main aim is to describe the nature of the fundamental mechanism determining the polarity of the By deflections associated with intense earthward ionplasma flows. A major finding is that we either observe magnetic flux rope (MFR) like structures (that is, entities having all the morphological features of ropes; i.e., a dipolar signature of Bz occurring simultaneously with peaked By and Btotal deflections) or mere By deflections, however, the sign for all these (Bydeflections) is always determined by the satellite placement in north (positive) or south (negative) plasma sheet. Therefore, the MFR-like structures located earthward of the source are most likely pseudo-MFRs;there is neither a tubular topology nor an axial magnetic field, the By deflections are produced by FACs. According to the presented model, a fundamental concept is that both ions and electrons are simultaneously accelerated at the source site;in turn, the earthward streaming electrons (ions) form a bifurcated electron (ion) FAC just outside the electron diffusion region-EDR (IDR). In this way, inside the IDR (and earthward of the source) positive (negative) By deflections in north (south) plasma sheet (PS) are produced due to FACs, and not to (inward) Hall currents as in the context of an X-line. Moreover, the ions form an “ion jet” within the IDR, while just outside this region they produ

关键词： Magnetic Reconnection Magnetic Flux Rope in Magnetotail field-aligned currents Plasma Sheet Double Layers

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Kinetic Instability of Anisotropic Drift Wave Accompanied by field aligned currents in Solar Coronal Loop

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Communications in Theoretical Physics 2018年第10期70卷 470-476页

作者： Hafsa Naim Ch.Uzma G.Murtaza Salam Chair Department of Physics GC University

Solar coronal loops are frequently accompanied by the field-aligned currents, which drive instabilities if the drift velocity u0 > v A the Alfv′en velocity. For our choice of parameters, the critical threshold value of u0/v A is ～ 3.0 for growth and the corresponding current filling factor ～ 10-3-10-4. Below this value we are no longer in the kinetic *** coronal loops also have short-scale density gradients within each loop. The electron resonance in the presence of density gradient causes the drift mode to grow. We study the effect of these two free energy sources, the electron drift and the density gradient, in the presence of temperature anisotropy T⊥_α > T∥_α. These effects simultaneously exist in the coronae. Using gyrokinetic theory, we investigate the influence of these effects, examine how they interplay with each other and study the consequent growth of the magnetosonic wave. We observe that kinetic instability driven by density gradient can be suppressed by field-aligned currents. The temperature anisotropy with chosen signatures causes further stabilizing effect. The results may prove useful to study the heating mechanism of solar coronal loops, acceleration of particles and confinement of particles in the thermonuclear reactors.

关键词： solar corona coronal loops temperature anisotropy density inhomogeneity field-aligned currents gyrokinetic

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Nonlinear Coupling of Kinetic Alfvén Waves and Ion Acoustic Waves in the Inner Heliosphere

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Research in Astronomy and Astrophysics 2024年第10期24卷 143-160页

作者： Mani K Chettri Vivek Shrivastav Rupak Mukherjee Nidhi Gaur R.P.Sharma Hemam D.Singh Department of Physics Sikkim University DAV Public School Plasma Simulation Laboratory Department of Energy Science and EngineeringIndian Institute of Technology Delhi

We study the nonlinear coupling of kinetic Alfvén waves with ion acoustic waves applicable to the Earth’s radiation belt and near-Sun streamer belt solar wind using dynamical equations in the form of modified Zakharov *** simulations show the formation of magnetic field filamentary structures associated with density humps and dips which become turbulent at later times,redistributing the energy to higher *** magnetic power spectra exhibit an inertial range Kolmogorov-like spectral index value of-5/3 for k⊥ρifield and the ion thermal gyroradius,*** quasilinear theory in terms of the Fokker–Planck equation in the region of wavenumber turbulent spectra,we find the particle distribution function flattening in the superthermal tail population which is the signature of particle energization and plasma heating.

关键词： Sun: chromosphere Sun: corona Sun: heliosphere SOLAR-WIND TURBULENCE field-aligned currents ALFVEN WAVES ASTROPHYSICAL GYROKINETICS COHERENT STRUCTURES DISSIPATION RANGE PROBE SCALE ACCELERATION PLASMA

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