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Topic: Poynting flux

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Poynting theorem

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	Flux - Wikipedia, the free encyclopedia
		Except in the case of active transport, net flux is directly proportional to the concentration difference across the membrane, the surface area of the membrane, and the membrane permeability constant.
		In [ecology]], flux is often considered at the ecosystem level - for instance, accurate determination of carbon fluxes (at a regional and global level) is essential for modelling the causes and consequences of global warming.
		For electromagnetic radiation, the flux of the Poynting vector through a surface is the power, or energy per unit time, passing through that surface.
	en.wikipedia.org /wiki/Flux (898 words)

	FLUX FACTS AND INFORMATION (Site not responding. Last check: 2007-10-05)
		In biology, flux refers to the movement of molecules across a membrane: the rate of diffusion of a substance across a permeable membrane.
		Net flux is directly proportional to the concentration difference across the membrane, the surface_area of the membrane, and the membrane permeability constant.
		For electromagnetic_radiation, the flux of the Poynting_vector through a surface is the power, or energy per unit time, passing through that surface.
	www.flowergods.com /flux (662 words)

	Marek Sikora (Site not responding. Last check: 2007-10-05)
		In particular, using high energy spectra of blazars, we derive the number flux of electrons and positrons.
		This flux is consistent with the rate of creation of pairs in the accretion disk corona and, therefore, there is no need for pair production in the jet.
		However, the momentum of the leptonic flux is too small to power radio lobes and, therefore, the energy flux of quasar jets must be dominated by magnetic fields and/or protons.
	www.mpa-garching.mpg.de /~bh-grow/Program/Speakers/MarekSikora.html (224 words)

	Observations at high-altitude of Intense Electric Fields in the (Site not responding. Last check: 2007-10-05)
		In addition, the figure, for simplicity, depicts the Poynting flux as associated with a time variable Alfven wave, but the Poynting flux could be associated with a steady state electric field structure with pairs of upward and downward field aligned currents producing the magnetic field perturbation (as illustrated in Mozer et al., 1980).
		The actual Poynting flux measured at lower altitudes should be less since it is dissipated (primarily through the energization of auroral electrons) as it propagates towards the earth.
		We emphasize (as the principle experimental result of this paper) that during this pass (as was the case during the 5/9/97 pass), the intervals of strong earthward Poynting flux at Polar altitudes occur when the spacecraft is magnetically conjugate to regions of strong auroral energy flux as estimated by the UVI images.
	ham.spa.umn.edu /mike/wygantpaper/psbl_poynt_flux_submit2.html (7703 words)

	Poynting vector - Wikipedia, the free encyclopedia
		The Poynting vector is the cross product of the electric field and the magnetic field.
		For an electromagnetic wave it points in the direction of energy flow and its magnitude is the power per unit area crossing a surface which is normal to it.
		where E is the electric field, H and B are the magnetic field and magnetic flux density respectively, and μ is the permeability of the surrounding medium.
	www.wikipedia.org /wiki/Poynting_flux (223 words)

	Ion outflows in the polar cap boundary acceleration (Alfvén auroral) region (Site not responding. Last check: 2007-10-05)
		The field-aligned Poynting flux (cross product of Figures 2d and 2e) shown in Figure 2f indicates wave energy traveling both up (negative) and down (positive) the field line, however, the downgoing flux is generally larger than that of the upgoing.
		Poynting fluxes of Alfvénic fluctuations are primarily in the downward direction carrying electromagnetic power toward the ionosphere.
		Additionally, the downward Poynting flux is dominate in the polar cap boundary acceleration indicating that the reflected Alfvén wave power is not significant.
	lasp.colorado.edu /~ysu/paper/2003JA010022.htm (4275 words)

	[No title] (Site not responding. Last check: 2007-10-05)
		Second, the Poynting flux calculations and the related discussion are removed since the results are somewhat unreliable (see the answers to the referees).
		The calculation of the Poynting flux was questioned by the referees.
		Poynting flux is excluded from the paper since part of the electric field data is less reliable.
	www.plasma.kth.se /~ivchenko/at2/grl_answer.txt (646 words)

	Space Physics Group Activites 2002-2003
		Correlation analysis shows that while Poynting flux is correlated with ion outflows, the single parameter that best describes the outflows is the number density of precipitating soft electrons.
		While the force exerted by the magnetic pressure slows flux tubes down near the stagnation point (unlike the pressure gradient force as gas dynamic models would predict), the pressure gradient force parallel to the flux tubes accelerates plasma away from the subsolar point, thus depleting the flux tubes.
		Flux transfer events (FTEs) have been known for more than 20 years now, yet their nature is still elusive.
	www-ssc.igpp.ucla.edu /ssc/spgroup/activities.html (4211 words)

	Correlation of Alfvén wave Poynting flux in the plasma sheet at 4–7 R
		The Poynting flux measured at high altitudes by Polar was correlated with the intensity of the conjugate auroral emission in the ultraviolet frequency range, which can be used to estimate energy deposition due to precipitating electron beams.
		The mapped Poynting flux was in almost all events larger by a factor of 1–10 than the ionospheric electron energy flux.
		Furthermore, the large Poynting flux events observed at the outer edge of the plasma sheet were conjugate to the poleward border of the active auroral regions, giving further evidence that at least some of the discrete aurora connects to the plasma sheet boundary layer.
	www.agu.org /pubs/crossref/2002/2001JA900140.shtml (485 words)

	The Poynting vector, power transmission, and the CFA.
		Yet there is a local elemental Poynting vector, which, if we interpret it as a local power flow, has no basis in the Physics of the situation.
		But once they are static, the Poynting theorem tells us that it is the divergence of the Poynting vector which is zero over any volume of space where the static fields exist, providing that there are no sources or sinks of energy inside the volume.
		Normally, for a capacitative load on the end of a transmission line, the power reflection coefficient is unity and the voltage at the terminals is in phase quadrature with the current.
	www.ee.surrey.ac.uk /Personal/D.Jefferies/poynting.html (3085 words)

	The structure equations of MHD accretion discs
		The next two magnetic terms are the Poynting flux lost in the wind and the work done against the disc by magnetic tension.
		If the flux tube is not disrupted, its rise through the accretion disk leads to a Poynting flux of electromagnetic energy.
		Another factor which diminishes the Poynting flux is the filling factor of such flux tubes within the disc.
	www.atnf.csiro.au /pasa/16_3/dekool/paper/node1.html (1677 words)

	Abstract (Site not responding. Last check: 2007-10-05)
		It is shown that, in a dissipative medium, also the interaction energy contributions must be considered in the summary energy flux in addition to the energy fluxes of the individual waves.
		Using the results derived for energy fluxes of summary waves, the energy balance at a structural interface between two anisotropic dissipative media is studied.
		The instantaneous energy flux R/T coefficients are closely connected with the energy normalized R/T coefficients, used broadly in the seismic ray method.
	seis.karlov.mff.cuni.cz /papers/r11vc3.htm (424 words)

	Astron. Astrophys. 319, 1025-1035 (1997) (Site not responding. Last check: 2007-10-05)
		The flux surfaces near the jet axis are not directly connected with the accretion disk.
		Depending on the disk magnetic flux distribution, the curvature of the field lines close to the disk is rather different.
		It seems to be obvious that along a flux surface perpendicular to the disk, a wind driven by centrifugal instability is not possible.
	aa.springer.de /papers/7319003/2301025/sc4.htm (1718 words)

	definitions (Site not responding. Last check: 2007-10-05)
		As the primary flux loop oscillates between modes it periodically enters the H-loop mode where the structure displays the characteristics of an electric dipole structure.
		Typically the neutron generation occurs at the greatest rate along the poloidal axis at the inner equator; the resultant neutron flux is utilized to enhance (by the contribution of neutrons) reactions catalyzed in the core.
		These are generated by a process the effect of which is the same as if there had been a pi/2 radian rotation of the magnetic flux density vector of an ordinary macro scale closed magnetic flux loop system around the axis of the Poynting vector which is everywhere a normal to a flux loop quasi-surface.
	www.singtech.com /definitions.html (4778 words)

	Fogal Transistor: Notes and Reference
		We stress that the north pole (positive magnetic charge) represents a broken symmetry in the virtual photon flux of vacuum, and this asymmetry is the source which extracts and gates the energy in the magnetic field.
		That is, from particle physics, as is well-known the dipole is a broken symmetry in the virtual photon flux exchange between the vacuum and the charges comprising the ends of the dipole (in fact it is two broken symmetries, one for each end).
		Consequently, the wire antenna actually "slaps" the vacuum flux medium (i.e., the virtual photon flux of the vacuum) with an injection of two simultaneous disturbances: one from the electron gas "slap" and one from the nuclei "slap." By "slap" we refer to the quantum field theoretic injection of virtual photons.
	www.eskimo.com /~ghawk/fogal_device/notes.htm (12310 words)

	Sir James Jeans - remarks on the Poynting vector. (Site not responding. Last check: 2007-10-05)
		"The integral of the Poynting Flux over a closed surface gives the total flow of energy into or out of a surface, but it has not been proved, and we are not entitled to assume, that there is an actual flow of energy at every point equal to the Poynting Flux.
		The Poynting theorem actually is a relationship between the divergence (div S) of the Poynting vector flux S and the sources of energy at a point.
		For a region containing no sources or sinks of energy, the Poynting theorem merely states that div S = 0, and therefore by the divergence theorem, that the integral of the normal component of S over a closed surface surrounding a region containing no sources or sinks of energy must also be zero.
	www.ee.surrey.ac.uk /Personal/D.Jefferies/jjeans.html (312 words)

	Phase skipping and Poynting flux of continuous pulsations (Site not responding. Last check: 2007-10-05)
		By using both the electric field and magnetic field data of the ISEE 1 spacecraft, we find that the Poynting flux of Pc3-4 pulsations in the outer magnetosphere has an impulsive nature.
		The direction of time-average Poynting flux changes every several wave cycles, and the phase skips in wave signals, both in the magnetic field and electric field, are often found between two adjacent Poynting flux bursts.
		Furthermore, the phase difference between the electric wave and the magnetic wave indicates that Pc3-4 waves are generally not in exact resonance, counter to the traditional field line resonance paradigm.
	www-ssc.igpp.ucla.edu /personnel/russell/papers/skip_ed (254 words)

	sm21a in fm03
		This Poynting flux is often capable of providing the power necessary for the acceleration of auroral electrons and creating intense auroral displays.
		Strong electric and magnetic fields associated with MHD waves carrying Poynting flux directed towards the Earth are observed in the high beta plasma sheet near 9 Re during repetitive intervals of magnetic field dipolarization during major geomagnetic storms.
		Finally, observations from the Cluster spacecraft studies demonstrate that strong Poynting flux is radiated from the reconnection region near ~20 Re in association with magnetic field energy conversion in the tail.
	www.agu.org /cgi-bin/SFgate/SFgate?&listenv=table&multiple=1&range=1&directget=1&application=fm03&database=/data/epubs/wais/indexes/fm03/fm03&maxhits=200&="SM21A" (2009 words)

	Jahrbuch-CD der MPG 2003 - Dissipation in Poynting-flux-do
		Flows in which energy is transported predominantly as Poynting flux are thought to occur in pulsars, gamma-ray bursts, and relativistic jets from compact objects.
		In each case, solutions are presented that give the Lorentz factor of a spherical wind containing a transverse, oscillating magnetic field component as a function of radius.
		In the case of the Crab Pulsar, we find that the Poynting flux can be dissipated before the wind reaches the inner edge of the Nebula if the pulsar emits electron-positron pairs at a rate (N)over dot(+/-) >10(40) s(-1), thus providing a possible solution to the "sigma-problem."
	www.mpg.de /forschungsergebnisse/wissVeroeffentlichungen/archivListenJahrbuch/2003/37/publZIM73.html (153 words)

	Science Fair Projects - Poynting theorem
		The Poynting theorem is a statement due to John Henry Poynting about the conservation of energy for the electromagnetic field.
		where S is the Poynting vector representing the flow of energy, J is the current density and E is the electric field.
		Since the magnetic field does no work, the right hand side gives the total work done by the electromagnetic field.
	www.all-science-fair-projects.com /science_fair_projects_encyclopedia/Poynting_theorem (271 words)

	jgr_abs
		During substorms the (1-100) keV ions are accelerated in the tail plasma sheet and injected by short pulses into the auroral flux tubes carrying the information on the source distance, scale-size and temporal history of plasma acceleration.
		We present observations by CLUSTER crossing the auroral zone flux tubes at ~4 Re distance during the substorm on February 14, 2001, when signatures of near-Earth reconnection was observed by Geotail at 23 Re in the plasma sheet.
		Coexistence of Beam1 and Beam2 particles in the same flux tube could be explained by impulsive acceleration in the closed inward-convecting plasma sheet flux tubes (inward propagation of fast wave from impulsive reconnection source?) or by convection-related spatial velocity filtering (version 1).
	geo.phys.spbu.ru /~victor/CLUST1402b.htm (1357 words)

	The Tom Bearden Website
		"[Poynting's result] implies that a charged capacitor in a constant magnetic field which is not parallel to the electric field is the seat of energy flows even though all macroscopic phenomena are static."
		This is an extra environmental energy input to the resonant charged particles, though unaccounted in the present electrical engineering theory and therefore unaccounted by the researchers in the field of negative resonance absorption of the medium.
		This is the procedure which arbitrarily selects only a small component of the energy flow associated with a circuit—specifically, the small Poynting component being diverged into the circuit to power it—and then treats that tiny component as the "entire" energy flow.
	www.cheniere.org /techpapers/vanflandern.htm (8397 words)

	Acceleration of GRB outflows by Poynting flux dissipation (Site not responding. Last check: 2007-10-05)
		Acceleration of GRB outflows by Poynting flux dissipation
		Estimates are given for the thermal and non-thermal radiation expected to be emitted from the photosphere and the optically thin part of the flow respectively.
		A critical parameter of the model is the ratio of Poynting flux to kinetic energy flux at some initial radius of the flow.
	www.edpsciences.org /articles/aa/abs/2002/20/aah3387/aah3387.html (203 words)

	Electric Field and Poynting Flux
		First of all, the frequency of oscillations in the Poynting Flux is twice that of the oscillation in either of the fields.
		Also, the Poynting flux is not additive, which means that we cannot simply add the Poynting fluxes due to each eigenmode separately.
		An inward-pointing flux is coded as red, and an outward-pointing flux is coded as blue.
	astrog.physics.wisc.edu /~craigm/toroid/toroid/node8.html (511 words)

	Time average Poynting field (energy flux) (Site not responding. Last check: 2007-10-05)
		This movie shows the time average power flux on the surface of the sphere.
		The polarization effect makes the flux rather unsymmetrical: there is much more power close to the x-z-plane than in the y-z-plane.
		In the plane of polarization, the energy flux behaves almost like the velocity field of a fluid where the highest speed occurs in the smallest cross section.
	www.ifh.ee.ethz.ch /~pascal/sphere/srotlow.html (121 words)

	On the direction of the Poynting flux related to the mesoscale electromagnetic turbulence at high latitudes
		On the direction of the Poynting flux related to the mesoscale electromagnetic turbulence at high latitudes
		In about half of them the source of auroral structuring is supposed to be in the ionosphere, whereas a magnetospheric origin is inferred in others.
		Citation: Golovchanskaya, I., and Y. Maltsev (2004), On the direction of the Poynting flux related to the mesoscale electromagnetic turbulence at high latitudes, J.
	www.agu.org /pubs/crossref/2004/2004JA010432.shtml (342 words)

	ANGEO - Abstracts
		Field-aligned currents convey stress between the magnetosphere and ionosphere, and the associated low altitude magnetic and electric fields reflect the flow of electromagnetic energy to the polar ionosphere.
		The total electromagnetic energy flux was 50GW for these events.
		The power poleward of the Region 1 currents is about one-third of the total power, indicating significant energy flux over the polar cap.
	www.copernicus.org /EGU/annales/22/8/2861.htm (300 words)

	Alfven Wave Interactions (Site not responding. Last check: 2007-10-05)
		This corresponds to wavelengths reaching an Earth radius - this long-scale coherence, coupled with the notion that the wave is carried by ions and is capable of transporting significant energy in the form of Poynting flux towards the earth, indicates that Alfven waves may play a significant role in magnetosphere-ionosphere coupling.
		In addition to a standard Alfven wave, the effect of electron inertia is included (see equation on Electron Inertia page in poster).
		Further derivations reveal that u reduced field line tension, and affects the equations for Poynting flux and diffusion.
	ham.spa.umn.edu /barbara/alfven.htm (467 words)

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