A case study of storm commencement and recovery plasmaspheric electric fields near L=2.5 at equinox

Abstract. Data from the VLF Doppler experiment at Faraday, Antarctica (65° S, 64° W) are used to study the penetration of the high-latitude convection electric field to lower latitudes during severely disturbed conditions. Alterations of the electric field at L-values within the range 2.0 - 2.7 are studied for two cases at equinox (10 - 12 September 1986 and 1 - 3 May 1986). The recovery of the electric field is found to be approximately an exponential function of time. Values for the equatorial meridional E×B drift velocity, inferred from the data, are used as inputs to a model of the plasmasphere and ionosphere. The model and experimental results are used to investigate the post-storm alteration of ionospheric coupling processes. The magnitude of the effect of ionosphere-plasmasphere coupling fluxes on NmF2 values and the O+-H+ transition height is dependent on the local time of storm commencement, and on the orientation of the electric field. The coupling fluxes appear to have a maximum influence on ionospheric content during the main phase of geomagnetic activity that produces outward motion of plasmaspheric whistler ducts.

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Storm-time meridional flows: a comparison of CINDI observations and model results

Annales Geophysicae ◽

10.5194/angeo-32-659-2014 ◽

2014 ◽

Vol 32 (6) ◽

pp. 659-668 ◽

Cited By ~ 4

Author(s):

M. Hairston ◽

N. Maruyama ◽

W. R. Coley ◽

R. Stoneback

Keyword(s):

Electric Field ◽

Geomagnetic Storm ◽

Electric Fields ◽

Previous Analysis ◽

Coupled Model ◽

Polar Ionosphere ◽

Inner Magnetosphere ◽

Ion Flow ◽

The Earth ◽

Coupling Processes

Abstract. During a large geomagnetic storm, the electric field from the polar ionosphere can expand far enough to affect the mid-latitude and equatorial electric fields. These changes in the equatorial zonal electric field, called the penetration field, will cause changes in the meridional ion flows that can be observed by radars and spacecraft. In general this E × B ion flow near the equator caused by the penetration field during undershielding conditions will be upward on the dayside and downward on the nightside of the Earth. Previous analysis of the equatorial meridional flows observed by CINDI instrument on the C/NOFS spacecraft during the 26 September 2011 storm showed that all of the response flows on the dayside were excess downward flows instead of the expected upward flows. These observed storm-time responses are compared to a prediction from a physics-based coupled model of thermosphere–ionosphere–inner-magnetosphere in an effort to explain these observations. The model results suggest that the equatorial downward flow could be attributed to a combined effect of the overshielding and disturbance dynamo processes. However, some discrepancy between the model and observation indicates a need for improving our understanding of how sensitive the equatorial electric field is to various model input parameters that describe the magnetosphere–ionosphere coupling processes.

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A Bond Bundle Case Study of Diels-Alder Catalysis Using Oriented Electric Fields

10.26434/chemrxiv-2021-17wpx-v2 ◽

2022 ◽

Author(s):

Timothy Wilson ◽

Mark Eberhart

Keyword(s):

Electric Field ◽

Charge Density ◽

Electric Fields ◽

Chemical Reactions ◽

Catalytic Effect ◽

Reaction Pathway ◽

Three Dimensional ◽

Atomic Charge ◽

Diels Alder

Bond bundles are chemical bonding regions, analogous to Bader atoms, uniquely defined according to the topology of the gradient bundle condensed charge density, itself obtained by a process of infinitesimal partitioning of the three-dimensional charge density into differential zero-flux surface bounded regions. Here we use bond bundle analysis to investigate the response of the charge density to an oriented electric field in general, and the catalytic effect of such a field on Diels-Alder reactions in particular, which in this case is found to catalyze by allowing the transition state valance bond bundle configuration to be achieved earlier along the reaction pathway. Using precise numerical values, we arrive at the conclusion that chemical reactions and electric field catalysis can be understood in terms of intra-atomic charge density redistribution, i.e., that charge shifts within more so than between atoms account for the making and breaking of bonds.

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A Bond Bundle Case Study of Diels-Alder Catalysis Using Oriented Electric Fields

10.26434/chemrxiv-2021-17wpx ◽

2021 ◽

Author(s):

Timothy Wilson ◽

Mark Eberhart

Keyword(s):

Electric Field ◽

Charge Density ◽

Electric Fields ◽

Chemical Reactions ◽

Catalytic Effect ◽

Reaction Pathway ◽

Three Dimensional ◽

Atomic Charge ◽

Diels Alder

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Monte Carlo Analysis of Effect of Alloy Scattering on Electron Transport in Wurtzite Zn1-xMgxO

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.873.861 ◽

2013 ◽

Vol 873 ◽

pp. 861-864

Author(s):

Lin Lin Hu ◽

Ping Wang ◽

Tao Shang ◽

Jiu Xu Song

Keyword(s):

Monte Carlo ◽

Steady State ◽

Electric Field ◽

Electric Fields ◽

Drift Velocity ◽

Monte Carlo Model ◽

Monte Carlo Analysis ◽

Alloy Scattering ◽

Ensemble Monte Carlo ◽

Velocity Decrease

Steady-state and transient electron characteristics of wurtzite Zn1xMgxO are studied in detail. An ensemble Monte Carlo model is established considering alloy scattering. From the steady-state characteristics, it is found that alloy scattering makes the drift velocity decrease at different electric fields. For 10% Mg, the transient peak drift velocity decreases from 2.48×107cm/s to 2.13×107cm/s at 2000 kV/cm. While for 20% Mg, a higher electric field is needed for the onset of the overshoot, which corresponds to the larger peak electric field in the steady-state velocity-field characteristics.

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Electron Transport Characteristics of Wurtzite GaN

ISRN Condensed Matter Physics ◽

10.1155/2013/654752 ◽

2013 ◽

Vol 2013 ◽

pp. 1-6 ◽

Cited By ~ 1

Author(s):

F. M. Abou El-Ela ◽

A. Z. Mohamed

Keyword(s):

Relaxation Time ◽

Electron Transport ◽

Electric Field ◽

Electric Fields ◽

Drift Velocity ◽

Differential Resistance ◽

Polar Optical Phonon ◽

Average Electron Energy ◽

Wide Range ◽

High Electric Fields

A three-valley Monte Carlo simulation approach was used to investigate electron transport in wurtzite GaN such as the drift velocity, the drift mobility, the average electron energy, energy relaxation time, and momentum relaxation time at high electric fields. The simulation accounted for polar optical phonon, acoustic phonon, piezoelectric, intervalley scattering, and Ridley charged impurity scattering model. For the steady-state transport, the drift velocity against electric field showed a negative differential resistance of a peak value of 2.9×105 m/s at a critical electric field strength 180×105 V/m. The electron drift velocity relaxes to the saturation value of 1.5×105 m/s at very high electric fields. The electron velocities against time over wide range of electric fields are reported.

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The relationship between electric fields, conductances and currents in the high-latitude ionosphere: a statistical study using EISCAT data

Annales Geophysicae ◽

10.1007/s00585-999-0043-3 ◽

1999 ◽

Vol 17 (1) ◽

pp. 43-52 ◽

Cited By ~ 4

Author(s):

J. A. Davies ◽

M. Lester

Keyword(s):

Electric Field ◽

Electric Fields ◽

High Latitude ◽

Statistical Study ◽

Field Vector ◽

Relative Contribution ◽

High Latitude Ionosphere ◽

The Times ◽

The Relationship ◽

Uhf Radar

Abstract. The relationship between electric fields, height-integrated conductivities and electric currents in the high-latitude nightside electrojet region is known to be complex. The tristatic nature of the EISCAT UHF radar facility provides an excellent means of exploring this interrelationship as it enables simultaneous estimates to be made of the full electric field vector and the ionospheric Hall and Pedersen conductances, further allowing the determination of both field-perpendicular electric current components. Over 1300 h of common programme observations by the UHF radar system provide the basis of a statistical study of electric fields, conductances and currents in the high-latitude ionosphere, from which preliminary results are presented. Times at which there is significant solar contribution to the ionospheric conductances have been excluded by limiting the observations according to solar zenith angle. Initial results indicate that, in general, the times of peak conductance, identified from the entire set of EISCAT observations, do not correspond to the times of the largest electric field values; the relative contribution of ionospheric conductance and electric field to the electrojet currents therefore depends critically on local time, a conclusion which corroborates work by previous authors. Simultaneous measurements confirm a tendency for a decrease in both Hall and Pedersen conductances to be accompanied by an increase in the electric field, at least for moderate and large electric field value, a tendency which is also identified to some extent in the ratio of the conductances, which acts as an indicator of the energy of precipitating particles.Key words. Ionosphere (auroral ionosphere; electric fields and currents)

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Evolution of Microwave Electric Field on Power Coupling to Plasma during Ignition Phase

Selected Topics in Plasma Physics ◽

10.5772/intechopen.92011 ◽

2020 ◽

Author(s):

Chinmoy Mallick ◽

Mainak Bandyopadhyay ◽

Rajesh Kumar

Keyword(s):

Electric Field ◽

Electric Fields ◽

Critical Density ◽

Coupling Mechanism ◽

Ignition Process ◽

Ion Acoustic Wave ◽

Power Coupling ◽

Gas Ignition ◽

Spatio Temporal ◽

Coupling Processes

During the gas ignition process, the plasma and the microwave electric fields are evolved with time together in the plasma volume. The spatio-temporal evolution pattern of microwave-radiated plasma parameters is reported here, highlighting the role of these electric fields on power coupling processes. Evolutions of electric field and so power coupling processes are calculated using the finite element method (FEM). It is observed that the main power coupling mechanism is electron cyclotron resonance (ECR) method; however, with the evolution of plasma, the mode shifts from ECR to off-ECR-type heating with time. Off-ECR heating in the form of upper hybrid resonance (UHR) method, electrostatic (ES) ion acoustic wave heating method is important heating mechanisms during highly dense plasma condition, when density is above critical density for launched frequency, 2.45 GHz. The conclusions on the shifting of heating mechanisms are also drawn based on the 3D maps of spatio-temporal plasma density and hot electron temperature evolution.

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Equatorial electrojet as part of the global circuit: a case-study from the IEEY

Annales Geophysicae ◽

10.1007/s00585-998-0698-1 ◽

1998 ◽

Vol 16 (6) ◽

pp. 698-710 ◽

Cited By ~ 21

Author(s):

A. T. Kobea ◽

C. Amory-Mazaudier ◽

J. M. Do ◽

H. Lühr ◽

E. Houngninou ◽

...

Keyword(s):

Electric Field ◽

Geomagnetic Storm ◽

Electric Fields ◽

High Latitude ◽

Large Scale ◽

Equatorial Electrojet ◽

Doppler Frequency ◽

Time Interval ◽

Ground Field ◽

Equatorial Latitude

Abstract. Geomagnetic storm-time variations often occur coherently at high latitude and the day-side dip equator where they affect the normal eastward Sq field. This paper presents an analysis of ground magnetic field and ionospheric electrodynamic data related to the geomagnetic storm which occured on 27 May 1993 during the International Equatorial Electrojet Year (IEEY) experiment. This storm-signature analysis on the auroral, mid-latitude and equatorial ground field and ionospheric electrodynamic data leads to the identification of a sensitive response of the equatorial electrojet (EEJ) to large-scale auroral return current: this response consists in a change of the eastward electric field during the pre-sunrise hours (0400-0600 UT) coherently to the high-, mid-, and equatorial-latitude H decrease and the disappearance of the EEJ irregularities between the time-interval 0800-0950 UT. Subsequent to the change in h'F during pre-sunrise hours, the observed foF2 increase revealed an enhancement of the equatorial ionization anomaly (EIA) caused by the high-latitude penetrating electric field. The strengthening of these irregularities attested by the Doppler frequency increase tracks the H component at the equator which undergoes a rapid increase around 0800 UT. The ∆H variations observed at the equator are the sum of the following components: SR, DP, DR, DCF and DT.Keywords. Equatorial electrojet · Magnetosphere-ionosphere interactions · Electric fields and currents · Auroral ionosphere · Ionospheric disturbances

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The electron transport within bulk wurtzite zinc oxide in response to strong applied electric field pulses

MRS Proceedings ◽

10.1557/opl.2013.534 ◽

2013 ◽

Vol 1577 ◽

Cited By ~ 3

Author(s):

Walid A. Hadi ◽

Michael S. Shur ◽

Stephen K. O’Leary

Keyword(s):

Zinc Oxide ◽

Electron Transport ◽

Electric Field ◽

Electric Fields ◽

Drift Velocity ◽

High Field ◽

Electronic Devices ◽

Average Energy ◽

High Field Strength ◽

High Electric Fields

ABSTRACTStrong short electric field pulses are used to generate broadband terahertz radiation. Understanding the transport properties under such conditions is very important for the understanding of numerous terahertz photonic and electronic devices. In this paper, we report on transport simulations of the electrons within bulk wurtzite zinc oxide for pulsed high electric fields, with pulse durations of up to 400 fs. We focus on how key electron transport characteristics, namely the drift velocity and the corresponding average energy, vary with time since the onset of the pulse. For sufficiently high-field strength selections, we find that both of these parameters exhibit peaks. In addition, an electron drift velocity undershoot is observed following this peak. A contrast with the case of gallium nitride is considered; undershoot is not observed for the case of this material. Reasons for these differences in behavior are suggested.

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Affordable evaluation of low frequency electric fields from the standpoint of Directive 2013/35/EU

ACTA IMEKO ◽

10.21014/acta_imeko.v6i4.486 ◽

2017 ◽

Vol 6 (4) ◽

pp. 37 ◽

Cited By ~ 4

Author(s):

Alexandru Salceanu ◽

Eduard Lunca ◽

Marius Paulet

Keyword(s):

Electric Field ◽

Electric Fields ◽

Transmission Lines ◽

Low Frequency ◽

Numerical Approach ◽

Electric Field Sensors ◽

Original Contribution ◽

Exposure Levels

Since the 1st of July 2016, the Directive 2013/35/ EU on the employees’ health protection in terms of non-ionizing electromagnetic radiations acquired the force of law. An accessible methodology for the characterization of a workspace is proposed here, in terms of exposure to low-frequency electric fields.Firstly, the means whereby an external electric field can induce electrical processes in the human body are presented, followed by a comparative summary of differently expressed exposure levels (ICNIRP, European Directive, IEEE-ICES).Further on two electric field sensors are presented that can easily be hand-crafted in any laboratory, useful for extending the capabilities of a budget, low-frequency handheld spectrum analyzer. A realistic exposure metric is developed that cumulates the influence of all E-fields in the environment. A case study is presented on the cumulative assessment of exposure to low frequency electric fields produced in a laboratory-class where a network of 16 computers was working.A simple numerical approach based on FEMM 4.2 has also been developed for evaluating the E-field produced by overhead high voltage transmission lines.This paper is an extended version of the original contribution to the IMEKO TC 4 2016 symposium in Budapest, Hungary.

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