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Author Topic: What are Birkeland Currents?  (Read 4005 times)

Offline Joe L. Ogan

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What are Birkeland Currents?
« on: 07/02/2010 20:59:26 »
What are Birkeland Currents?  They appear to carry electrical currents through the plasma.  How often do they occur?  Do they present any dangers?  Thanks for comments.  Joe L. Ogan


 

Offline yor_on

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What are Birkeland Currents?
« Reply #1 on: 08/02/2010 21:41:15 »
 

Offline Soul Surfer

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What are Birkeland Currents?
« Reply #2 on: 09/02/2010 00:25:54 »
I very much agree yor_on  Joe please note also my reply to your question on wiggle z and put a bit more effort into explaining your questions properly.
 

Offline Joe L. Ogan

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What are Birkeland Currents?
« Reply #3 on: 09/02/2010 00:47:20 »
I very much agree yor_on  Joe please note also my reply to your question on wiggle z and put a bit more effort into explaining your questions properly.

Sorry, I did not intend to offend anyone with my questions.  My knowledge in some areas is quite limited.  If I knew all about it I would not ask.  I thank you for your guidance.  I shall try to do better in future.  In the meantime, I, now, feel somewhat inhibited in asking questions.  Thanks for your comments.  Joe L. Ogan
 

Offline yor_on

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What are Birkeland Currents?
« Reply #4 on: 09/02/2010 16:07:59 »
Nobody's offended Joe.
But I still don't know why, and instead of informing you act as if we have disturbed your sensitivities?
It's easier for me to understand if you just tell me why you suspect they might be dangerous.
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Just as a clarification. If you at some other website seen a statement that you now test against this site then that's nothing wrong, as long as you're not advertising, that is.
 

Offline Joe L. Ogan

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What are Birkeland Currents?
« Reply #5 on: 09/02/2010 16:45:34 »
Nobody's offended Joe.
But I still don't know why, and instead of informing you act as if we have disturbed your sensitivities?
It's easier for me to understand if you just tell me why you suspect they might be dangerous.
==

Just as a clarification. If you at some other website seen a statement that you now test against this site then that's nothing wrong, as long as you're not advertising, that is. 

Hi, yor-on.  No, I am not offended.  I just thought some of you were jumping at me because I thought some of the things that are believed in science today will be proven wrong.  As far as the Birkeland current is concerned, I thought it may be dangerous to pass through them with a spacecraft.  Thanks for comments.  Joe L. Ogan
« Last Edit: 09/02/2010 16:53:41 by Joe L. Ogan »
 

Offline yor_on

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What are Birkeland Currents?
« Reply #6 on: 09/02/2010 18:52:04 »
Okay, that's one I can't really answer, as a guess it has to have a electromagnetic field right? And then it should be able to foul up the electronics on the space shuttle f.ex depending on field strength.

"A Birkeland current generally refers to any electric current in a space plasma, but more specifically when charged particles in the current follow magnetic field lines (hence, Birkeland currents are also known as field-aligned currents). They are caused by the movement of a plasma perpendicular to a magnetic field. Birkeland currents often show filamentary, or twisted "rope-like" magnetic structure.

Originally Birkeland currents referred to electric currents that contribute to the aurora, caused by the interaction of the plasma in the Solar Wind with the Earth's magnetosphere. 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.

Auroral Birkeland currents can carry about 1 million amperes.[2] They can heat up the upper atmosphere which results in increased drag on low-altitude satellites."

And it's a plasma as i understands it. Plasma_cosmology

 

Offline Geezer

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What are Birkeland Currents?
« Reply #7 on: 09/02/2010 19:23:28 »
The total currents involved are fairly spectacular, and a million or so amps flowing through a spacecraft might do some rather bad things to it, although that is not necessarily the case. For example, the currents that flow through an aircraft when it is struck by lightning can be rather spectaular too.

However, I don't think there is any danger of seeing those sorts of currents flowing through a spacecraft in this case because the current is flowing through a large cross sectional area in space, so the current density at any point is not that great.
 

Offline yor_on

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What are Birkeland Currents?
« Reply #8 on: 09/02/2010 20:40:45 »
Good idea Gezzer, I looked it up and it seems that the antennas and electronics of a modern airplane can be susceptible to lightening, creating havoc, even though it seems that the electronics might recover after some time?

Normally it seems that the lightening is 'steered' by the aluminum shell of normal aircrafts "from one end of the aircraft to the other is unbroken, thus assuring that the aircraft will not be harmed."

But really modern air crafts as the Airbuss..

--Quote--

The Airbus makes extensive use of composite (non-metallic) materials. This makes lightning protection more of an engineering challenge. Engineers have to take extra steps to make sure the conductive path is unbroken by, for example, embedding the composite parts with metallic mesh.  The mesh maintains a conductive path along the aircraft's exterior.

If there is a discontinuity in the conductive path, the lightning can cause a “burn-through” of the aircraft structure, which can be catastrophic. In addition, sparks can ignite fuel tanks. However, the last time an aircraft was brought down by a lightning strike was 40 years ago. So while lightning can theoretically cause catastrophic structural damage, it is unlikely.

---end of quote---

So maybe it to some degree also will depend on what materials those space objects are built of? Don't they use a lot of ceramics? And there are more accidents, comparatively seen, involving cars than aircrafts as I understands it. Not that it have any relevance to this :)
« Last Edit: 09/02/2010 20:47:46 by yor_on »
 

Offline Geezer

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What are Birkeland Currents?
« Reply #9 on: 09/02/2010 20:47:23 »
Ah ha! Beat you to it. I started a new topic  ;D
 

Offline yor_on

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What are Birkeland Currents?
« Reply #10 on: 09/02/2010 20:48:16 »
Awhhhh...
 

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What are Birkeland Currents?
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