scholarly journals On the role of neutral flow in field-aligned currents

2018 ◽  
Vol 36 (1) ◽  
pp. 53-57 ◽  
Author(s):  
Anthony J. Mannucci ◽  
Olga P. Verkhoglyadova ◽  
Xing Meng ◽  
Ryan McGranaghan
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Rest Frame ◽  
Geomagnetic Storms ◽  
Electron Flow ◽  
Lower Ionosphere ◽  
Momentum Balance ◽  
Neutral Atmosphere ◽  
Magnetospheric Dynamics

Abstract. In this brief note we explore the role of the neutral atmosphere in magnetosphere–ionosphere coupling. We analyze momentum balance in the ion rest frame to form hypotheses regarding the role of neutral momentum in the lower ionosphere during geomagnetic storms. Neutral momentum that appears in the ion rest frame is likely the result of momentum imparted to ionospheric ions by solar wind flow and the resultant magnetospheric dynamics. The resulting ion-neutral collisions lead to the existence of an electric field. Horizontal electron flow balances the momentum supplied by this electric field. We suggest a possible role played by the neutral atmosphere in generating field-aligned currents due to local auroral heating. Our physical interpretation suggests that thermospheric neutral dynamics plays a complementary role to the high-latitude field-aligned currents and electric fields resulting from magnetospheric dynamics. Keywords. Ionosphere (ionosphere–magnetosphere interactions; polar ionosphere) – magnetospheric physics (magnetosphere–ionosphere interactions)

scholarly journals Elucidating the Influence of Electric Fields toward CO2 Activation on YSZ (111)

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 271
Author(s):  
Nisa Ulumuddin ◽  
Fanglin Che ◽  
Jung-Il Yang ◽  
Su Ha ◽  
Jean-Sabin McEwen
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Heterogeneous Catalysts ◽  
Co2 Reduction ◽  
Total Density ◽  
Reverse Water Gas Shift ◽  
High Thermodynamic Stability ◽  
Shift Reaction ◽  
Water Gas

Despite its high thermodynamic stability, the presence of a negative electric field is known to facilitate the activation of CO2 through electrostatic effects. To utilize electric fields for a reverse water gas shift reaction, it is critical to elucidate the role of an electric field on a catalyst surface toward activating a CO2 molecule. We conduct a first-principles study to gain an atomic and electronic description of adsorbed CO2 on YSZ (111) surfaces when external electric fields of +1 V/Å, 0 V/Å, and −1 V/Å are applied. We find that the application of an external electric field generally destabilizes oxide bonds, where the direction of the field affects the location of the most favorable oxygen vacancy. The direction of the field also drastically impacts how CO2 adsorbs on the surface. CO2 is bound by physisorption when a +1 V/Å field is applied, a similar interaction as to how it is adsorbed in the absence of a field. This interaction changes to chemisorption when the surface is exposed to a −1 V/Å field value, resulting in the formation of a CO3− complex. The strong interaction is reflected through a direct charge transfer and an orbital splitting within the Olatticep-states. While CO2 remains physisorbed when a +1 V/Å field value is applied, our total density of states analysis indicates that a positive field pulls the charge away from the adsorbate, resulting in a shift of its bonding and antibonding peaks to higher energies, allowing a stronger interaction with YSZ (111). Ultimately, the effect of an electric field toward CO2 adsorption is not negligible, and there is potential in utilizing electric fields to favor the thermodynamics of CO2 reduction on heterogeneous catalysts.

scholarly journals Electric potential differences across auroral generator interfaces

2013 ◽  
Vol 31 (2) ◽  
pp. 251-261 ◽  
Author(s):  
J. De Keyser ◽  
M. Echim
Keyword(s):  
Electric Field ◽  
High Altitude ◽  
Electric Fields ◽  
Electric Potential ◽  
Equilibrium Configuration ◽  
Potential Difference ◽  
Field Profile ◽  
Electric Potential Difference ◽  
Electric Field Profile

Abstract. Strong localized high-altitude auroral electric fields, such as those observed by Cluster, are often associated with magnetospheric interfaces. The type of high-altitude electric field profile (monopolar, bipolar, or more complicated) depends on the properties of the plasmas on either side of the interface, as well as on the total electric potential difference across the structure. The present paper explores the role of this cross-field electric potential difference in the situation where the interface is a tangential discontinuity. A self-consistent Vlasov description is used to determine the equilibrium configuration for different values of the transverse potential difference. A major observation is that there exist limits to the potential difference, beyond which no equilibrium configuration of the interface can be sustained. It is further demonstrated how the plasma densities and temperatures affect the type of electric field profile in the transition, with monopolar electric fields appearing primarily when the temperature contrast is large. These findings strongly support the observed association of monopolar fields with the plasma sheet boundary. The role of shear flow tangent to the interface is also examined.

scholarly journals Role of filament plasma remnants in ICMEs leading to geomagnetic storms

2013 ◽  
Vol 8 (S300) ◽  
pp. 493-494 ◽  
Author(s):  
Rahul Sharma ◽  
Nandita Srivastava ◽  
D. Chakrabarty
Keyword(s):  
Electric Field ◽  
Geomagnetic Storms ◽  
Interplanetary Coronal Mass Ejections ◽  
Plasma Dynamics ◽  
Terrestrial Magnetosphere ◽  
Auroral Substorms ◽  
Polarity Reversals ◽  
Ionospheric Electric Field ◽  
Filament Plasma

AbstractWe studied three interplanetary coronal mass ejections associated with solar eruptive filaments. Filament plasma remnants embedded in these structures were identified using plasma, magnetic and compositional signatures. These features when impacted the Earth's terrestrial magnetosphere - ionosphere system, resulted in geomagnetic storms. During the main phase of associated storms, along with high density plasma structures, polarity reversals in the Y-component (dawn-to-dusk) of the interplanetary electric field seem to trigger major auroral substorms with concomitant changes in the polar ionospheric electric field. Here, we examine the cases where plasma dynamics and magnetic structuring in the presence of the prompt penetration of the electric field into the equatorial ionosphere affected the space weather while highlighting the complex geomagnetic storm-substorm relationship.

scholarly journals Can Electric Fields Drive Chemistry for an Aqueous Microdroplet?

2021 ◽  
Author(s):  
Hongxia Hao ◽  
Itai Leven ◽  
Teresa Head-Gordon
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Water Droplet ◽  
Reaction Rates ◽  
Surface Reactivity ◽  
Bulk Solution ◽  
Excess Charge ◽  
Electronic Effects ◽  
Rate Acceleration

Abstract Reaction rates of common organic reactions have been reported to increase by one to six orders of magnitude in aqueous microdroplets compared to bulk solution, but the reasons for the rate acceleration are poorly understood. We investigate the role of electric fields at water droplet surfaces that might explain the promotion of unusual reactive chemistry, along with changes in electric field profiles as a function of excess charge to model the electrospray fragmentation process. We find that electric field alignments along free O-H bonds at the surface yield field strength distributions that are ~30 MV/cm larger on average than that found for O-H bonds in the interior of the water droplet, consistent with greater surface reactivity. We emphasize the importance of both nuclear and electronic effects at the surface, and the non-linear coupling of intramolecular solute polarization with intermolecular solvent modes, as a necessary feature for predicting the higher field strengths at water droplet surfaces.

Ionospheric Irregularities During Disturbed Geomagnetic Conditions Over Argentinian EIA Region

2021 ◽  
Author(s):  
Gilda de Lourdes González
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Geomagnetic Storms ◽  
Ionospheric Irregularities ◽  
The Other ◽  
Scintillation Index ◽  
Navigation Systems ◽  
Radio Communication ◽  
Spread F ◽  
Bottom Side

Abstract Ionospheric irregularities can severely degrade radio communication and navigation systems. Geomagnetic storms may affect the generation of these irregularities in a way that is not yet fully understood. To improve the forecasting of this phenomenon, we need to study the ionosphere in different regions of the world, and in particular in the equatorial ionization anomaly (EIA) where irregularities are usually more intense. This study analyses the effect of geomagnetic storms on ionospheric irregularities. We examined the occurrence of irregularities at the southern crest of the EIA in Argentina (Tucumán, 26.9°S, 294.6°E, dip latitude 15.5° S) during three intense and one moderate geomagnetic storm of different solar sources, between 2015 and 2018. We used data from an ionosonde, a Global Positioning System (GPS) receiver and magnetometers. Ionogram spread-F, the F-layer bottom side (h'F), the critical frequency of the F2-layer (foF2), the rate of TEC index (ROTI) and the S4 scintillation index were analysed. The data show irregularities were present as range spread-F and moderate TEC fluctuations in one storm: 27 May 2017 (a coronal mass ejection CME-driven storm occurred on local winter), and were absent in the other events. We suggest that eastward disturbance dynamo electric field and over-shielding prompt penetration electric fields may create favourable conditions for developing these irregularities. Whereas, westward storm time electric fields might inhibit the growth of irregularities during the other storms considered. During co-rotating interaction region CIR-driven storms, the westward disturbance dynamo electric field may be associated with the non-occurrence of irregularities.

How does dissipation work in the electron diffusion region of asymmetric magnetic reconnection

2020 ◽  
Author(s):  
Michael Hesse ◽  
Cecilia Norgren ◽  
Paul Tenfjord ◽  
James Burch ◽  
Yi-Hsin Liu ◽  
...  
Keyword(s):  
Electric Field ◽  
Magnetic Reconnection ◽  
Stagnation Point ◽  
Electric Fields ◽  
Current Density ◽  
Electron Flow ◽  
Diffusion Region ◽  
Density Maximum ◽  
Density Peak ◽  
Electron Diffusion

<p>At some level, magnetic reconnection functions by means of a balance between current dissipation, and current maintenance due to the reconnection electric field. While this dissipation is well understood process in symmetric magnetic reconnection, the way nonideal electric fields interact with the current density in asymmetric reconnection is still unclear. In symmetric reconnection, the current density maximum, the X point location, and the nonideal electric field determined by the divergence of the electron pressure tensor usually coincide. In asymmetric reconnection, however, the electric field at the X point can be partly provided by bulk inertia terms, implying that the X point cannot be the dominant location of dissipation. On the other hand, we know that the nongyrotropic pressure-based electric field must dominate at the stagnation point of the in-plane electron flow, and that electron distributions here feature crescents. The further fact that the current density peak is shifted off the position of the X point indicates that there may be a relation between this current density enhancement, the location of the stagnation point, and the electron nongyrotropies. In this presentation we report on further progress investigating the physics of the electron diffusion region in asymmetric reconnection with a focus on how to explain the dissipation operating under these conditions. </p>

Derivation of radial electric fields using kinetic theory in tokamak

2013 ◽  
Vol 79 (5) ◽  
pp. 513-517
Author(s):  
K. NOORI ◽  
P. KHORSHID ◽  
M. AFSARI
Keyword(s):  
Kinetic Theory ◽  
Electric Field ◽  
Electric Fields ◽  
Driving Forces ◽  
Radial Electric Field ◽  
Radial Pressure ◽  
Momentum Balance ◽  
Balance Equations ◽  
Radial Pressure Gradient ◽  
Poloidal Rotation

AbstractIn the current study, radial electric field with fluid equations has been calculated. The calculation started with kinetic theory, Boltzmann and momentum balance equations were derived, the negligible terms compared with others were eliminated, and the radial electric field expression in steady state was derived. As mentioned in previous researches, this expression includes all types of particles such as electrons, ions, and neutrals. The consequence of this solution reveals that three major driving forces contribute in radial electric field: radial pressure gradient, poloidal rotation, and toroidal rotation; rotational terms mean Lorentz force. Therefore, radial electric field and plasma rotation are connected through the radial momentum balance.

scholarly journals Vacuum instability in a constant inhomogeneous electric field: a new example of exact nonperturbative calculations

2020 ◽  
Vol 80 (2) ◽  
Author(s):  
T. C. Adorno ◽  
S. P. Gavrilov ◽  
D. M. Gitman
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Transition Probabilities ◽  
Particle Creation ◽  
Field Configuration ◽  
Quantum Processes ◽  
Reflection And Transmission ◽  
Vacuum Instability ◽  
Klein Gordon

Abstract Basic quantum processes (such as particle creation, reflection, and transmission on the corresponding Klein steps) caused by inverse-square electric fields are calculated. These results represent a new example of exact nonperturbative calculations in the framework of QED. The inverse-square electric field is time-independent, inhomogeneous in the x -direction, and is inversely proportional to x squared. We find exact solutions of the Dirac and Klein–Gordon equations with such a field and construct corresponding in- and out-states. With the help of these states and using the techniques developed in the framework of QED with x-electric potential steps, we calculate characteristics of the vacuum instability, such as differential and total mean numbers of particles created from the vacuum and vacuum-to-vacuum transition probabilities. We study the vacuum instability for two particular backgrounds: for fields widely stretches over the x-axis (small-gradient configuration) and for the fields sharply concentrates near the origin $$x=0$$x=0 (sharp-gradient configuration). We compare exact results with ones calculated numerically. Finally, we consider the electric field configuration, composed by inverse-square fields and by an x-independent electric field between them to study the role of growing and decaying processes in the vacuum instability.

FIRST-PRINCIPLES STUDY ON ELECTRIC-FIELD-INDUCED STATES OF SILICON MICROCLUSTERS

1996 ◽  
Vol 03 (01) ◽  
pp. 389-393 ◽  
Author(s):  
KAZUYUKI WATANABE ◽  
TAKASHI ABE ◽  
TSUYOSHI OGINO ◽  
SAKURA TAKEDA
Keyword(s):  
Electric Field ◽  
Bond Length ◽  
Electric Fields ◽  
First Principles ◽  
Bending Mode ◽  
Bond Stretching ◽  
Bond Bending ◽  
Cohesive Energies ◽  
Present Simulation

The first-principles molecular dynamics (FPMD) method is applied to a Si dimer and a Si trimer in electrostatic fields to calculate the charge polarization, the stable structures, and the cohesive energies. It is found that the bond length of the dimer increases, and the bond length and the bond angle of the trimer decrease as the electric field increases. The obtained structural change due to electric fields is compatible with the change in the cohesive energy. The vibrational dynamics of the dimer and trimer are also studied. The bond-bending mode of the trimer is found to be more largely influenced by the electric field than the bond-stretching mode. The present simulation revealed a fundamental role of electric fields in manipulating microclusters.

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