Talk:Birkeland current

message: I removed the solar EUV image of the Bastille Day post-flare arcade.  It had been captioned as an example of a "solar Birkeland current", which it is not.  Post-flare arcades are formed by line-tied boundary conditions at the photosphere, together with magnetic reconnection (collapse of a current sheet) during a flare.  zowie 00:05, 3 October 2005 (UTC)
thread_title: deleted solar image

message: Image:Cygnus-loop.gif
Image:Birkeland-anode-globe-fig259.jpg
Image:Magnetic-rope.gif
Image:Jupiter-aurora.jpg
Will you upload this image in Commons? It was expected that I wrote an article about Birkeland current in Wikipedia Japan. 
Please cooperate.
: Can you upload the images yourself? All the images are in the public domain? --Iantresman 14:49, 31 October 2005 (UTC)
thread_title:  upload 

message: I read through the first part of the page, and there are a lot of inaccuracies that need to be changed.
# They are sometimes referred to as field-aligned currents. IMHO, in science they are always called field-aligned currents and only in magnetospheric they are called Birkeland currents.
# The current flows earthwards down the morning side of the Earth's ionosphere, around the polar regions, and spacewards up the evening side of the ionosphere. These Birkeland currents are now sometimes called auroral electrojets. Although the first part is okay, that the field aligned currents flow to the Earth at the dawn side, and away at the dusk side, I have trouble with stating that the electrojet is a Birkeland current. Birkeland currents are defined as field aligned currents, the electroject is perpendicular to the magnetic field and thus not a Birkeland current.
# They can heat up the upper atmosphere which results in increased drag on low-altitude satellites. Is the drag on satellites truely caused by a heated up atmosphere? I would think that the increased magnetic field strength, caused  by an active system in a magnetic storm would be the cause, because of stronger eddy currents in the spacecraft.
# Birkeland currents are also one of a class of plasma phenonena called a z-pinch Here cause and result are switched around. A Birkeland current is not a z-pinch. A z-pinch may occur when a field aligned current exists. But there are certain restrictions to that, a pinch can only occur when the field strength increases above a certain level. I am not sure that z-pinches have been observed in the Earth's Birkeland currents.
#  This can also twist, producing a helical pinch that spirals like a twisted or braided rope, and this most closely corresponds to a Birkeland current. Why does this most closely correspond to a Birkeland current?
# parallel Birkeland currents moving in opposite directions will repel with an electromagnetic force inversely proportional to their distance apart. But anti-parallel Birkeland currents will not occur, as the inflow is on the dawn side and the outflow is on the dusk side.
# Electrons moving along a Birkeland current may be accelerated by a plasma double layer. Electrons are not moving along a Birkeland current, they 'are' the Birkeland current.
# If the resulting electrons approach relativistic velocities (ie. the speed of light) they may subsequently produce a Bennett pinch No, this is not true, relativistic particles do not increase the current, so if the requirement for a Bennett pinch has not been fulfilled before, then making the electrons relativistic will not make any difference.
Well, I guess this is enough for a start. This page needs a big make-over.--Tusenfem 19:42, 20 May 2006 (UTC)
replies: text: Please go ahead and make any changes you see fit. --Iantresman 23:36, 20 May 2006 (UTC)
replies: text:  I have started to make the changes to this page, based on the comments above. --Tusenfem (talk) 09:57, 13 August 2008 (UTC)

text: Most of the Characteristics section needs to be re-written.  As it now stands, the article confuses field-aligned currents which are organized into lines or columns of current (i.e., the area of the current perpendicular to the field line is roughly a circle) with sheets of current (i.e., the area of the current perpendicular to the field line is much greater in one direction than a direction perpendicular to both the field line and the first direction).  Birkeland currents are a pair of sheet currents.  The following are my responses to the numbered comments above:
# Agreed.
# Agreed.  I intend to re-write the Characteristics section to show how the Birkeland currents and the auroral electrojets are related but not the same thing.
# I have already edited the article to explain that the increase drag is due to increased atmospheric density as the electric current in the ionospheric E-layer heat the atmosphere.  I will look at this again to be sure that my explanation is clear.
# I think the whole z-pinch discussion should be deleted.  A z-pinch is related to a line of current and not a pair sheet currents.
# The discussion of twist should be deleted.  It is relevant to a line of current and not a sheet of current.
# The electromagnetic attraction or repulsion due to the Birkeland currents is too small to be significant.  The total currents are quite large but the current density is quite small.
# Double layers in the ionosphere relate to the acceleration of electrons to create an auroral arc.  This is a small scale phenomenon compared to the scale of the Birkeland currents.  The existence Birkeland current system is a necessary condition for the double layers and arcs to exist but the Birkeland currents can exist without the double layers.
# Electrons which carry the Birkeland currents have energies between ~1 eV and ~10 keV.  Relativistic effects are not relevant.
Richfj (talk) 19:25, 21 July 2011 (UTC)
thread_title:  Inaccuracies and errors in the page 

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message: This assertion has as its "support" The Origin of Magnetic Storms. Rather than "scorn," the final sentence is "The view that the impact of the projected particles causes luminosity remains allowable, so that Prof. Birkeland’s theory of the aurora borealis is still tenable."
Schuster's grave seems like an odd place to plant a flag.
2600:1702:2670:D6A0:2805:953B:859F:D02A (talk) 07:30, 18 December 2021 (UTC)
thread_title:  "This view was scorned by other researchers"