scholarly journals Interpolation of magnetic and electric fields using spherical elementary current systems

2012 ◽  
Author(s):  
C.D. Beggan ◽  
S.A. McLay
Keyword(s):  
Electric Fields ◽  
Current Systems

scholarly journals A statistical study of intense electric fields at 4−7 R<sub><i>E</i></sub> geocentric distance using Cluster

2005 ◽  
Vol 23 (7) ◽  
pp. 2579-2588 ◽  
Author(s):  
T. Johansson ◽  
T. Karlsson ◽  
G. Marklund ◽  
S. Figueiredo ◽  
P.-A. Lindqvist ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Time Distribution ◽  
Statistical Study ◽  
Auroral Oval ◽  
Field Structure ◽  
Geocentric Distance ◽  
Using Data ◽  
Auroral Phenomena ◽  
Current Systems

Abstract. Intense high-latitude electric fields (>150 mV/m mapped to ionospheric altitude) at 4–7 RE geocentric distance have been investigated in a statistical study, using data from the Cluster satellites. The orbit of the Cluster satellites limits the data collection at these altitudes to high latitudes, including the poleward part of the auroral oval. The occurrence and distribution of the selected events have been used to characterize the intense electric fields and to investigate their dependance on parameters such as MLT, CGLat, altitude, and also Kp. Peaks in the local time distribution are found in the evening to morning sectors but also in the noon sector, corresponding to cusp events. The electric field intensities decrease with increasing latitude in the region investigated (above 60 CGLat). A dependence on geomagnetic activity is indicated since the probability of finding an event increases up to Kp=5–6. The scales sizes are in the range up to 10 km (mapped to ionospheric altitude) with a maximum around 4–5km, consistent with earlier findings at lower altitudes and Cluster event studies. The magnitudes of the electric fields are inversely proportional to the scale sizes. The type of electric field structure (convergent or divergent) is consistent with the FAC direction for a subset of events with electric field intensities in the range 500–1000 mV/m and with clear bipolar signatures. The FAC directions are also consistent with the Region 1 and NBZ current systems, the latter of which prevail only during northward IMF conditions. For scale sizes less than 2 km the majority of the events were divergent electric field structures. Both converging and diverging electric fields were found throughout the investigated altitude range (4–7 RE geocentric distance). Keywords. Magnetospheric physics (Electric fields; Auroral phenomena; Magnetosphere-ionosphere interactions)

scholarly journals Beam-Return Current Systems in Solar Flares

1985 ◽  
Vol 107 ◽  
pp. 519-520
Author(s):  
D. S. Spicer ◽  
R. N. Sudan
Keyword(s):  
Solar Flare ◽  
Electric Fields ◽  
Solar Flares ◽  
Electron Beams ◽  
Clear Understanding ◽  
Return Current ◽  
Current Systems

The importance of electron beams in solar flare dynamics is well known. In order to understand the dynamics produced by beams it is essential to have a clear understanding of the role beam driven return currents play and whether electrostatic or inductive electric fields maintain the return current. We show that inductive electric fields are responsible for driving return currents under solar conditions.

scholarly journals Role of inductive electric fields and currents in dynamical ionospheric situations

2007 ◽  
Vol 25 (2) ◽  
pp. 437-455 ◽  
Author(s):  
H. Vanhamäki ◽  
O. Amm ◽  
A. Viljanen
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Temporal Variations ◽  
Ionospheric Currents ◽  
Calculation Technique ◽  
Induced Field ◽  
Ionospheric Electric Field ◽  
Electric Fields And Currents ◽  
Current Systems

Abstract. We study the role of ionospheric induction in different commonly observed ionospheric situations. These include an intensifying electrojet, westward travelling surge (WTS) and Ω-band. We use data based, realistic models for these phenomena and calculate the inductive electric fields that are created due to the temporal variations of ionospheric currents. The ionospheric induction problem is solved using a new calculation technique that can handle non-uniform, time-dependent conductances and electric fields of any geometry. We find that in some situations inductive effects are not negligible and the ionospheric electric field is not a pure potential field, but has a significant induced rotational part. In the WTS and Ω-band models the induced electric field is concentrated in a small area, where the time derivatives are largest. In the electrojet model the induced field is significant over a large part of the jet area. In these examples the induced electric field has typical values of few mV/m, which amounts to several tens of percents of the potential electric field present at the same locations. The induced electric field is associated with ionospheric and field aligned currents (FAC), that modify the overall structure of the current systems. Especially the induced FAC are often comparable to the non-inductive FAC, and may thus modify the coupling between the ionosphere and magnetosphere in the most dynamical situations. We also present some examples with very simple ionospheric current systems, where the effect of different ionospheric parameters on the induction process is studied.

Control of Metal Alloy Oxidation with Electric Fields

1973 ◽  
Vol 31 ◽  
pp. 164-165
Author(s):  
R. R. Dils ◽  
P. S. Follansbee
Keyword(s):  
Electric Fields ◽  
Oxidation Process ◽  
Base Alloy ◽  
Oxide Surface ◽  
Platinum Electrodes ◽  
Insulating Layer ◽  
Iron Base Alloy ◽  
Alloy Oxidation ◽  
Aluminum Oxide Layer ◽  
And Control

Electric fields have been applied across oxides growing on a high temperature alloy and control of the oxidation of the material has been demonstrated. At present, three-fold increases in the oxidation rate have been measured in accelerating fields and the oxidation process has been completely stopped in a retarding field.The experiments have been conducted with an iron-base alloy, Pe 25Cr 5A1 0.1Y, although, in principle, any alloy capable of forming an adherent aluminum oxide layer during oxidation can be used. A specimen is polished and oxidized to produce a thin, uniform insulating layer on one surface. Three platinum electrodes are sputtered on the oxide surface and the specimen is reoxidized.

Electron-Mirror Microscopic Aspects of Ferroelectric Domains of BaTiO3 And Ca2Sr (C2H5CO2)6

1970 ◽  
Vol 28 ◽  
pp. 478-479
Author(s):  
Teruo Someya ◽  
Jinzo Kobayashi
Keyword(s):  
Surface Layer ◽  
Electric Fields ◽  
Quantitative Study ◽  
Recent Progress ◽  
Ferroelectric Domain ◽  
Resolving Power ◽  
Surface Pattern ◽  
Crystal Surfaces ◽  
One Dimensional ◽  
Ferroelectric Domains

Recent progress in the electron-mirror microscopy (EMM), e.g., an improvement of its resolving power together with an increase of the magnification makes it useful for investigating the ferroelectric domain physics. English has recently observed the domain texture in the surface layer of BaTiO3. The present authors ) have developed a theory by which one can evaluate small one-dimensional electric fields and/or topographic step heights in the crystal surfaces from their EMM pictures. This theory was applied to a quantitative study of the surface pattern of BaTiO3).

Electron Microscope Observations of Magnetic and Electric Effects

1970 ◽  
Vol 28 ◽  
pp. 430-431
Author(s):  
John Silcox
Keyword(s):  
Electron Microscope ◽  
Electric Fields ◽  
Magnetic Image ◽  
Magnetic Effects ◽  
Ferromagnetic Films ◽  
Diffraction Contrast ◽  
Microscope Images ◽  
Electric Effects ◽  
Image Detail

Several aspects of magnetic and electric effects in electron microscope images are of interest and will be discussed here. Clearly electrons are deflected by magnetic and electric fields and can give rise to image detail. We will review situations in ferromagnetic films in which magnetic image effects are the predominant ones, others in which the magnetic effects give rise to rather subtle changes in diffraction contrast, cases of contrast at specimen edges due to leakage fields in both ferromagnets and superconductors and some effects due to electric fields in insulators.

Electron microscopy studies of PZT ferroelectric film capacitor structures

1992 ◽  
Vol 50 (2) ◽  
pp. 1364-1365
Author(s):  
V. Kaushik ◽  
P. Maniar ◽  
J. Olowolafe ◽  
R. Jones ◽  
A. Campbell ◽  
...  
Keyword(s):  
Electric Fields ◽  
Sol Gel ◽  
Ferroelectric Material ◽  
Dielectric Constants ◽  
Dielectric Films ◽  
Lead Zirconium Titanate ◽  
Si Substrate ◽  
Film Capacitor ◽  
Pzt Films ◽  
High Dielectric

Lead zirconium titanate films (Pb (Zr,Ti) O3 or PZT) are being considered for potential application as dielectric films in memory technology due to their high dielectric constants. PZT is a ferroelectric material which shows spontaneous polarizability, reversible under applied electric fields. We report herein some results of TEM studies on thin film capacitor structures containing PZT films with platinum-titanium electrodes.The wafers had a stacked structure consisting of PZT/Pt/Ti/SiO2/Si substrate as shown in Figure 1. Platinum acts as electrode material and titanium is used to overcome the problem of platinum adhesion to the oxide layer. The PZT (0/20/80) films were deposited using a sol-gel method and the structure was annealed at 650°C and 800°C for 30 min in an oxygen ambient. XTEM imaging was done at 200KV with the electron beam parallel to <110> zone axis of silicon.Figure 2 shows the PZT and Pt layers only, since the structure had a tendency to peel off at the Ti-Pt interface during TEM sample preparation.

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