Clarification on Polarity of Bipolar Electric Field Solitary Structures in Space Plasmas with Satellite Observation

2011 ◽  
Vol 28 (2) ◽  
pp. 025204 ◽  
Author(s):  
Jian-Kui Shi ◽  
Zhen-Xing Liu
Keyword(s):  
Electric Field ◽  
Satellite Observation ◽  
Space Plasmas ◽  
Solitary Structures

Theoretical properties of offset bipolar electric field solitary structures in space plasmas

2010 ◽  
Vol 45 (10) ◽  
pp. 1219-1223
Author(s):  
M.N.S. Qureshi ◽  
Jiankui Shi ◽  
Klaus Torkar ◽  
Zhenxing Liu
Keyword(s):  
Electric Field ◽  
Space Plasmas ◽  
Solitary Structures

scholarly journals Dispersive MHD waves and alfvenons in charge non-neutral plasmas

2008 ◽  
Vol 15 (4) ◽  
pp. 681-693 ◽  
Author(s):  
K. Stasiewicz ◽  
J. Ekeberg
Keyword(s):  
Soliton Solutions ◽  
Theoretical Models ◽  
Mhd Waves ◽  
Space Plasmas ◽  
Charge Effects ◽  
Novel Technique ◽  
Solitary Structures ◽  
Spatial Dimensions ◽  
Electric Potentials ◽  
Linear And Nonlinear

Abstract. Dispersive properties of linear and nonlinear MHD waves, including shear, kinetic, electron inertial Alfvén, and slow and fast magnetosonic waves are analyzed using both analytical expansions and a novel technique of dispersion diagrams. The analysis is extended to explicitly include space charge effects in non-neutral plasmas. Nonlinear soliton solutions, here called alfvenons, are found to represent either convergent or divergent electric field structures with electric potentials and spatial dimensions similar to those observed by satellites in auroral regions. Similar solitary structures are postulated to be created in the solar corona, where fast alfvenons can provide acceleration of electrons to hundreds of keV during flares. Slow alfvenons driven by chromospheric convection produce positive potentials that can account for the acceleration of solar wind ions to 300–800 km/s. New results are discussed in the context of observations and other theoretical models for nonlinear Alfvén waves in space plasmas.

Transport ratios of the kinetic Alfvén mode in space plasmas

2020 ◽  
Author(s):  
Yasuhito Narita ◽  
Zoltan Vörös ◽  
Owen Wyn Roberts ◽  
Masahiro Hoshino
Keyword(s):  
Electric Field ◽  
Hall Current ◽  
Space Plasma ◽  
Space Plasmas ◽  
Dielectric Tensor ◽  
Parallel Component ◽  
Electric Field Polarization ◽  
The Mean ◽  
Analytic Expression ◽  
Field Rotation

<p>Electric field properties of the kinetic Alfvén mode are analytically studied by constructing the dielectric tensor of the plasma using the linear Vlasov theory and reducing (and identifying) the tensor elements into that of the fluid picture such as the polarization drift, the Hall current, and the diamagnetic current. Off-diagonal dielectric responses do not primarly contribute to the dispersion relation of the kinetic Alfvén mode, but play an important role in the electric field polarization (field rotation sense around the mean magnetic field) and parallel component of the field. The polarization becomes more circular and the parallel component enhances at larger perpendicular wavenumbers. Analytic expression of fluctuation sense serves as a tool to identify the kinetic Alfvén mode in space plasma observations.</p>

scholarly journals The relationship between the magnetosphere and magnetospheric/auroral substorms

2013 ◽  
Vol 31 (3) ◽  
pp. 387-394 ◽  
Author(s):  
S.-I. Akasofu
Keyword(s):  
Electric Field ◽  
Growth Phase ◽  
Magnetic Energy ◽  
Dissipative System ◽  
Satellite Observation ◽  
Recovery Phase ◽  
Release Process ◽  
Expansion Phase ◽  
Auroral Substorms ◽  
The Relationship

Abstract. On the basis of auroral and polar magnetic substorm studies, the relationship between the solar wind-magnetosphere dynamo (the DD dynamo) current and the substorm dynamo (the UL dynamo) current is studied. The characteristics of both the DD and UL currents reveal why auroral substorms consist of the three distinct phases after the input power ε is increased above 1018 erg s−1. (a) The growth phase; the magnetosphere can accumulate magnetic energy for auroral substorms, when the ionosphere cannot dissipate the power before the expansion phase. (b) The expansion phase; the magnetosphere releases the accumulated magnetic energy during the growth phase in a pulse-like manner in a few hours, because it tries to stabilize itself when the accumulated energy reaches to about 1023 erg s−1. (c) The recovery phase; the magnetosphere becomes an ordinary dissipative system after the expansion phase, because the ionosphere becomes capable of dissipating the power with the rate of 1018 ~ 1019 erg s−1. On the basis of the above conclusion, it is suggested that the magnetosphere accomplishes the pulse-like release process (resulting in spectacular auroral activities) by producing plasma instabilities in the current sheet, thus reducing the current. The resulting contraction of the magnetic field lines (expending the accumulated magnetic energy), together with break down of the "frozen-in" field condition at distances of less than 10 RE, establishes the substorm dynamo that generates an earthward electric field (Lui and Kamide, 2003; Akasofu, 2011). It is this electric field which manifests as the expansion phase. A recent satellite observation at a distance of as close as 8.1 RE by Lui (2011) seems to support strongly the occurrence of the chain of processes suggested in the above. It is hoped that although the concept presented here is very crude, it will serve in providing one way of studying the three phases of auroral substorms. In turn, a better understanding of auroral substorms will also be useful in studying the magnetosphere, because various auroral activities can be the visible guide for this endeavor.

Direct Measurement of Ion Cyclotron Resonance Between Wave Fields and Protons in Space Plasmas

2021 ◽  
Author(s):  
Qiaowen Luo ◽  
Xingyu Zhu ◽  
Jiansen He ◽  
Jun Cui ◽  
Hairong Lai ◽  
...  
Keyword(s):  
Kinetic Theory ◽  
Electric Field ◽  
Velocity Distribution ◽  
Wave Field ◽  
Cyclotron Resonance ◽  
Space Plasmas ◽  
Ion Cyclotron Resonance ◽  
Wave Fields ◽  
Ion Cyclotron Waves ◽  
Ion Cyclotron

<p>Ion cyclotron resonance is one of the fundamental energy conversion processes through wave field-particle interaction in collisionless plasma. However, the key evidence for cyclotron resonance (i.e., the coherence between wave field and ion phase space density pertaining to the ion cyclotron resonance and responsible for the dissipation of ion cyclotron waves (ICWs)) has yet to be directly observed. Based on the high-quality measurements of space plasma by the Magnetospheric Multiscale (MMS) satellites, we observe that both the wave electromagnetic field vectors and the disturbed ion velocity distribution rotate around the background magnetic field. Moreover, we find that the gyrophase angle difference between the fluctuations in the ion velocity distribution functions and the wave electric field vectors are always in the range of (0, 90) degrees, clearly suggesting the ongoing energy conversion from wave fields to particles. By invoking plasma kinetic theory, we find that the field-particle correlation for the dissipative ion cyclotron waves in the theoretical model matches well with our observations. Furthermore, all the wave electric field vectors (Ewave), the ion current (Ji) and the energy transfer rate (Ji ·Ewave) exhibit quasi-periodic oscillations, and the frequency of Ji ·Ewave is about twice the frequency of Ewave and Ji, consistent with plasma kinetic theory. Therefore, our combined analysis of MMS observations and kinetic theory provides direct, thorough, and comprehensive evidence for ICW dissipation in space plasmas.</p>

On Gravity Induced Electric Field in Space Plasmas

2005 ◽  
Vol 71 (3) ◽  
pp. 325-328 ◽  
Author(s):  
J Vranjes ◽  
M Y Tanaka
Keyword(s):  
Electric Field ◽  
Space Plasmas

scholarly journals The very low-frequency transmitter radio wave anomalies related to the 2010 Ms 7.1 Yushu earthquake observed by the DEMETER satellite and the possible mechanism

2020 ◽  
Vol 38 (5) ◽  
pp. 969-981
Author(s):  
Shufan Zhao ◽  
XuHui Shen ◽  
Zeren Zhima ◽  
Chen Zhou
Keyword(s):  
Electric Field ◽  
Electron Density ◽  
Low Frequency ◽  
Lower Ionosphere ◽  
Satellite Observation ◽  
Low Earth Orbit ◽  
Electron Content ◽  
Yushu Earthquake ◽  
Total Electron ◽  
Very Low Frequency

Abstract. Earthquakes may disturb the lower ionosphere through various coupling mechanisms during the seismogenic and coseismic periods. The VLF (very low-frequency) signal radiated from ground-based transmitters will be affected when it penetrates the disturbed ionosphere above the epicenter area, and this anomaly can be recorded by low-Earth orbit satellites under certain conditions. In this paper, the temporal and spatial variation of the signal-to-noise ratio (SNR) of the VLF transmitter signal in the ionosphere over the epicenter of 2010 Yushu Ms 7.1 earthquake in China is analyzed using DEMETER (Detection of Electro-Magnetic Emission Transmitted from Earthquake Regions) satellite observation. The results show that SNR over the epicenter of the Yushu earthquake especially in the southwestern region decreased (or dropped) before the main shock, and a GPS–TEC (Global Positioning System; total electron content) anomaly accompanied, which implies that the decrease in SNR might be caused by the enhancement of TEC. A full-wave method is used to study the mechanism of the change in SNR before the earthquake. The simulated results show SNR does not always decrease before an earthquake. When the electron density in the lower ionosphere increases by 3 times, the electric field will decrease about 2 dB, indicating that the disturbed-electric-field decrease of 20 % compared with the original electric field and vice versa. It can be concluded that the variation of electron density before earthquakes may be one of the important factors influencing the variation of SNR.

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