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Topic: Electric field screening


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 Electric field screening - Wikipedia, the free encyclopedia
Screening is the damping of electric fields caused by the presence of mobile charge carriers.
Viewed from a large distance, this screening hole has the effect of an overlaid positive charge which cancels the electric field produced by the electron.
The first theoretical treatment of screening, due to Debye and Hückel (1923), dealt with a stationary point charge embedded in a fluid.
en.wikipedia.org /wiki/Electric_field_screening   (858 words)

  
 Field
The Dirac field transforms as the unconstrained Lagrangian for the Dirac field is The Dirac fields...
Electric field screening Screening is the damping of electric fields caused by the presence of mobile magnetism which is...
Lilies of the Field Lilies of the Field is a Lilia Skala, Lisa Mann, Isa Crino, Francesca Jarvis, Pamela Branch, Stanley...
www.brainyencyclopedia.com /topics/field.html   (4112 words)

  
 Electric field screening   (Site not responding. Last check: 2007-10-20)
Screening is the damping of electric field s caused by the presence of mobile charge carriers.
Fosters research and innovation in the field of electric and hybrid vehicles, and encourages the development of innovative technologies with respect to electric transportation.
Electric and Magnetic Fields (EMF) Analysis and views from the Edison Electric Institute.
www.serebella.com /encyclopedia/article-Electric_field_screening.html   (1311 words)

  
 Electric field screening   (Site not responding. Last check: 2007-10-20)
Screening is the damping of electric fields causedby the presence of mobile charge carriers.
In astrophysics, electric field screening is important because it makes electricfields largely irrelevant, but because the fluids involved have charged particles, they can generate and are affected by magnetism which is very relevant and complex area of astrophysics.
Each electron possesses an electric field which repels other electrons.As a result, it is surrounded by a region in which the density of electrons is lower than usual.
www.therfcc.org /electric-field-screening-179693.html   (800 words)

  
 Electric field screening -- Facts, Info, and Encyclopedia article   (Site not responding. Last check: 2007-10-20)
Screening is the damping of (A field of force surrounding a charged particle) electric fields caused by the presence of mobile (The price charged for some article or service) charge carriers.
The first theoretical treatment of screening, due to (Click link for more info and facts about Debye) Debye and (Click link for more info and facts about Hückel) Hückel (1923), dealt with a stationary point charge embedded in a fluid.
Let ρ denote the number density of electrons, and φ the (The difference in electrical charge between two points in a circuit expressed in volts) electric potential.
www.absoluteastronomy.com /encyclopedia/e/el/electric_field_screening.htm   (930 words)

  
 Coulomb collision - Wikipedia, the free encyclopedia
The efficiency of velocity-matched interactions is also the reason that fusion products tend to heat the electrons rather than (as would be desirable) the ions.
If an electric field is present, the faster electrons feel less drag and become even faster in a "run-away" process.
In passing through a field of ions with density n, an electron will have many such encounters simultaneously, with various impact parameters and directions.
en.wikipedia.org /wiki/Coulomb_logarithm   (609 words)

  
 Plasma   (Site not responding. Last check: 2007-10-20)
Although ionization can be caused by UV radiation, energetic particles, or strong electric fields, processes that tend to result in a non-Maxwellian electron distribution function, it is most commonly caused by heating the electrons in such a way that they are close to thermal equilibrium so the electron temperature is relatively well-defined.
The electric field is either capacitively or inductively coupled into the gas by means of a plasma source, e.g.
Due to the good electrical conductivity, the electric fields in plasmas tend to be very small, although where double layers are formed, the potential drop can be large enough to accelerate ions to relativistic velocities and produce synchrotron radiation such as x-rays and gamma rays.
www.apawn.com /search.php?title=Plasma   (1983 words)

  
 Screening
The use of a barrier, usually composed of conductive material to prevent electric, magnetic or electromagnetic fields from penetrating the screened area or to prevent such fields from escaping from that area.
Mass examination of the population to detect the existence of a particular disease, as diabetes or tuberculosis.
The Ministry for Refugees and Accommodation (MRA) is responsible for the screening and registration of refugees and new arrivals.
www.websters-online-dictionary.org /definition/english/Sc/Screening.html   (2552 words)

  
 Free Stock Screening   (Site not responding. Last check: 2007-10-20)
In astrophysics, electric field screening is important because it makes electric fields lar 11: reening hole".
Test screening 1: A '''test screening ''' is a preview screening of a filmmovie conducted before its general 4: r it may be more substantial.
High-throughput screening 1: '''High-throughput screening ''', often abbreviated as ''HTS'', is a method for 11: A screening facility typically holds a library of ''stock pla 15: It still takes a highly specialized and expensive screening lab to run an HTS operation, however, so in many
www.elusiveeye.com /side40966-free-stock-screening.html   (545 words)

  
 IBM Research | Projects | Atomic Wires and Molecular Devices
A first step on this road is to study the properties of atomic wires, short chains of atoms that conduct electricity between two contacts.
The figure shows complex changes in the metal-to-wire charge transfer, polarization by the electric field, and screening by the electrodes.
The electrostatic potential associated with this charge distribution shows the way in which the voltage drop between the electrodes is distributed spatially along the wire.
www.research.ibm.com /atomicwires   (457 words)

  
 Re: Charge screening
If you apply an electric field to a dielectric material, the electric field inside the material is only 1/epsilon as big as you'd expect if this polarization wasn't happening.
The point is that when you put electrons in a magnetic field, their spins like to line up in such a way that their magnetic field points the same way as the externally applied magnetic field, just like a compass needle does in the Earth's magnetic field.
Here I simply assume that, just as an electric field exerts a force on a electrically charged particle equal to q E, a magnetic field exerts a force on a magnetically charged particle equal to m B, where m is the magnetic charge.
www.lns.cornell.edu /spr/2002-08/msg0043225.html   (3387 words)

  
 Plasma_physics
The dynamics of plasmas interacting with external and self-generated magnetic fields are studied in the academic discipline of magnetohydrodynamics.
For many purposes the electric field in a plasma may be treated as zero, although when current flows the voltage drop, though small, is finite, and density gradients are usually associated with an electric field according to the Boltzmann relation.
The electric and magnetic fields are found from the charge and current densities with appropriate boundary conditions.
www.apawn.com /search.php?title=Plasma_physics   (1983 words)

  
 nanoelectronics centre - Research Themes - Microwave Electronics and Devices
The result shows that the field emission profile of VACNTs is dominated by protruding nanotubes and the proximity effect of electric field screening plays an important role.
A dramatic phase reversal of the reflected electrical signal at resonance, a bias and frequency dependent microstructure comprising of oriented carbon molecules forming a filamentary structure is revealed, establishing a the high phase coherence of the present disordered system.
This project shall examine the electrical transport properties of metallic and semiconducting nanotubes in both diode and triode structures.
www.ee.surrey.ac.uk /NEC/cbeprojects.htm   (1103 words)

  
 Paper   (Site not responding. Last check: 2007-10-20)
Abstract: Strong field-aligned electric field is believed to appear in the pulsar magnetosphere and accelerate high energy particles, which causes copious electron-positron pair plasmas.
It is shown that a previous belief that pairs with a higher density than the Goldreich-Julian desnity immediately screens out the accelerating electric field is unjustified.
Pairs are splitted in the unscreened electric field: particles with one sign return back to the star and left particels with the other sign behind, which makes screening futher difficult.
hea-www.harvard.edu /PSR_SNR2/present/getpaper_b.cfm?abstract_id=22   (132 words)

  
 National Grid EMF - Screening EMFs?   (Site not responding. Last check: 2007-10-20)
That is why houses screen the field inside them and trees, fences etc can provide screening as well, as they are all sufficiently conducting for this purpose.
The electric field inside a closed metal box is basically zero.
In practice, electric field screens are an approximation to this closed box.
www.emfs.info /what_Screening_EMF.asp   (157 words)

  
 Electric Field Screening   (Site not responding. Last check: 2007-10-20)
a material sample) being driven by an electric field is subjected...
is, the inspections by the FDA field investigators are...
Better clinical trial screening also could help researchers...
www.wikiverse.org /electric-field-screening   (953 words)

  
 Talk:Electric field screening - Information   (Site not responding. Last check: 2007-10-20)
This non-vanishing potential is therefore the consequence of the implicit assumption of collisions in Thermodynamic Equilibrium preventing the purely electrostatic screening which would hold in a collisionless plasma.
This in turn will produce self-consistent electric fields which serve to adjust the electron flux balance as to maintain local charge neutrality.
These plasma polarization fields are obviously not being screened by the plasma, as they are themselves the result of the dynamical imbalance between electrons and ions.
www.book-spot.co.uk /index.php/Talk:Electric_field_screening   (391 words)

  
 [No title]
These techniques, however, require large electrical or optical power consumption and cannot be conveniently scaled into two dimensions.
The optically-controlled electroabsorption modulators we investigated consume low electrical and optical powers, require simple electrical packaging, are input polarization independent, can monitor network performance, are electronically-reconfigurable, and possess realistic two-dimensional scalability.
The optical switching relies on electric field screening of multiple quantum wells and diffusive electrical conduction.
www.stanford.edu /group/dabmgroup/research/vsabnis/research.html   (1229 words)

  
 math lessons - Screened Poisson equation
² is the Laplace operator, λ is a constant, and f is an arbitrary function of position (known as the "source function".) The screened Poisson equation occurs frequently in physics, including Yukawa's theory of mesons and electric field screening in plasmas.
As we claimed above, this is a superposition of screened 1/r functions, weighted by the source function f and with λ acting as the strength of the screening.
The screened 1/r function is often encountered in physics as a screened Coulomb potential, also called a "Yukawa potential".
www.mathdaily.com /lessons/Screened_Poisson_equation   (321 words)

  
 CERN Courier - Dutch team uses nanostructur - IOP Publishing - article
There are still challenges to overcome, such as the difficulty in positioning the nanotubes accurately on the wafer, but emerging techniques, including a way to grow nanotubes directly on the chip, may solve this problem.
The team used a self-aligning technique, similar to the technique used to pattern CMOS gates, to create the gate, the insulator and the base for growing the nanotubes with one lithography mask.
A single nanotube per gate would boost the efficiency of the applied field by avoiding the electric field screening when nanotubes are close together.
www.cerncourier.com /main/article/41/10/13   (552 words)

  
 Feb 2002   (Site not responding. Last check: 2007-10-20)
E. Guilmeau, B. Andrzejewski, and G. Desgardin, "The effect of Bi2201 phase on the intergranular critical field and current density in Bi2223 superconductors." To be published in Physica C (in press).
Hiroshi Shimahara, "Enhancement of the upper critical field and a field-induced superconductivity in antiferromagnetic conductors." To be published in J. Phys.
Hiroshi Shimahara and Kentaro Moriwake, "Temperature dependence of the upper critical field of an anisotropic singlet superconductivity in a square lattice tight-binding model in parallel magnetic fields." Submitted to J. Phys.
www.iitap.iastate.edu /htcu/archive/2002February.html   (5064 words)

  
 Binding and Selectivity in L-Type Calcium Channels: A Mean Spherical Approximation -- Nonner et al. 79 (4): 1976 -- ...
The screening length is reduced as divalent Ca replaces monovalent Na in the filter solution.
The entropic expense involved in electrostatic screening is small compared to entropic effects resulting from volume exclusion.
is weaker and the long-range field is stronger.
www.biophysj.org /cgi/content/full/79/4/1976   (7658 words)

  
 Astro-ph for busy people   (Site not responding. Last check: 2007-10-20)
We propose a new mechanism to screen the electric field in the pulsar polar cap.
Previous studies have shown that if an electron beam from the stellar surface is accelerated to energies high enough to create electron-positron pairs, the required electric field parallel to the magnetic field lines is too strong to be screened out by the produced pairs.
Previous analytical results for a Schwarzschild fl hole are confirmed: The late-time behavior of the field as recorded by a static observer is given by $\psi(t)\sim t^{-5/6}\sin [\omega (t)\times t]$, where $\omega(t)$ depends weakly on time.
www.camk.edu.pl /~gwar/astro-ph/2004.08.27.html   (5813 words)

  
 R.G. Tobin Abstract   (Site not responding. Last check: 2007-10-20)
The vibrational Stark effect — the change of CO's vibrational frequency with externally applied electrostatic field — is also a factor 2.0 ± 0.2 larger for atop CO at the step edge than it is for atop CO on the terrace.
A model in which CO responds to the screened local field at a single point cannot simultaneously explain the observed site dependence of both the vibrational Stark effect and the vibrational cross-section.
The most plausible explanation is that CO's response to electric fields is nonlocal.
www.tufts.edu /~rtobin/abs.jcp95.html   (225 words)

  
 Microwave ovens   (Site not responding. Last check: 2007-10-20)
Call for an electromagnetic field evaluation of your home.
AC and DC magnetic field screening, including assessment of magnetization of innerspring mattress and metal bed frame
AC and DC electric field screening, especially at the sleeping areas
www.create-your-healthy-home.com /nature/microwave_ovens_safety_01.htm   (256 words)

  
 Nanogen issued patent relating to biological screening device
The '778 patent relates to a biological screening device used to monitor the activity of kinase, protease or phosphatase enzymes on peptide substrates.
The device may be used to monitor a change in net charge of a target molecule as a result of enzyme activity.
Kinase dependant phosphorylation screening is often used in drug discovery research to determine if lead drug candidates have an effect on the target of interest.
www.news-medical.net /?id=13334   (351 words)

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