Magnetic reconnection and physical processes

[Reality Check]

What is the textbook where the "E orientation of MHD theory" is defined?

No, that is not my position Tim. My position is that you are "short circuiting" two "circuits" in plasma and calling it "magnetic reconnection" only because you converted all the E's to B's! The process occurs in nature Tim, it's just a "circuit topology change" from the E orientation of MHD theory.

First asked 2 February 2010
Michael Mozina,
What is the textbook where the "E orientation of MHD theory" is defined?

Is this the E orientation of ideal MHD theory (where magnetic reconnection cannot happen since the topology of the magnetic field is fixed)?

Or is this the E orientation of resistive MHD theory?

 

[tusenfem]

Exactly. The 'ignorance is bliss' approach to science......

Yeah, you would be the expert on that.

So, it was a cheap shot, but if you keep on ignoring direct questions, keep on ignoring explanations that are given, what do you expect?

What do you think the difference will be if you transform the MHD in such a way that you eliminate B and only look at E? Do you think that "circuits" will pop up suddenly? I dare you to show us here (not that you will).

I dare you to show us how these electrons of yours create the magnetic field along which they are supposed to flow. If you look at Cosmic Electrodynamics by Alfven and Falthammar you will see what a flux tube is in 3.13.1 figure 3.18 (a). That is just a collection of field lines, they write Consider a cylindrical flux tube (Fig . 3 .18 (a)) with length l and radius R << l. Now this field B = Bz, the z-component of this field is curl free and thus there is no current in along the field. Also it can easily be that the tube is empty and there is only magnetic field. Then they start to twist one of the footpoints, and then something happens and currents will be set up to facilitate the twist of the field. However, NOTE that ALFVEN and Falthammar do not discuss any current or plasma *AT ALL* when calculating the magnetic energy created by the twisting in Eq. 4 on page 117. The only place where gas starts to play a role is on page 118 where they write: The magnetic force is radial and in equilibrium it is balanced by
a radial pressure gradient.

Very very interesting.

 

[Michael Mozina]

Yeah, you would be the expert on that.

So, it was a cheap shot, but if you keep on ignoring direct questions, keep on ignoring explanations that are given, what do you expect?

Wow. You never take the low road. I'm entertained actually.

What do you think the difference will be if you transform the MHD in such a way that you eliminate B and only look at E? Do you think that "circuits" will pop up suddenly? I dare you to show us here (not that you will).

http://www.thesurfaceofthesun.com/A...r Atmosphere And A Theory Of Solar Flares.pdf

http://arxiv.org/abs/0908.0813

Did those "macroscopic circuits" just pop up and blow your show or what?

 

[brantc]

Everything that I have listed can be traced to the flow of electrons creating magnetic fields but not all at the point where the magnetic reconnection happens.

• In the magnetic reconnection experiments in labs, from the electric currents running through the magnets.
• In the Earth's magnetosphere, from the origin of the Sun's magnetic field (thought to be from the motion of plasma in the Sun).
• In solar flares, usually from the creation of coronal loops within the solar body before they well up through the photosphere.

I dont know why you would change the magnetic field generation mechanism when you get to a reconnection.

That makes no sense at all to me.

The suns magnetic field has nothing to do with the instabilities(not turbulence) in a reconnection. Those flows of electrons make their own magnetic field locally stronger than the suns.


Your story.
So the suns moving plasma makes the magnetic flux tubes that stick up out of the suns surface, the magnetic fields in turn drive the plasma that flows through the flux tubes(but carries no energy) and then by some mechanism by which we are not sure causes the magnetic fields interact in something called a reconnection.



My story.
Electric field drives plasma up from the suns surface causing it to form magnetic field that constricts the plasma into a pair of flux tubes(or loop).
The flowing plasma experiences changes in the gyro radius that cause the pair of flux tubes to touch causing a change in the plasma path(releasing radiation and particles) that causes the magnetic fields to change configuration to match the plasma flow.


Better known as reconnection.

 

[brantc]

Also, would Tusenfem or other real physicists actually respect or publish anything in an engineering journal?

Cheers,

Dave

Absolutely. I would call that journal an experimental journal. They build things and perform tests. They have hands on experience with the physics that theorists are writing the math for. Some of their results dont conform to "know laws of reality as described by theorists" so thats why there is controversy. Science for pure experimental science.

Math describes reality.

PhD EE is a pretty serious combination.
Dont get me wrong. I work with some great PhD's etc... I respect them. You just cant use it like a club.

 

[brantc]

But I am glad you reject MDH, that will really make MM happy.

Nope. I dont reject MHD. I just dont think it tells the whole or correct story. Its useful in macroscopic situations for describing the movement of the magnetized fluid. As a fluid STREAM.

But it doesnt tell you the true source of the energy. That assumption is already made with the top down turbulence model of MHD. Then they ran with it not realizing it was just a gross description

It says nothing about a bottom up description of the actual particles..

That why they are doing PIC simulations with reconnection at the Large Plasma Device. MHD does not give you fine details.

 

[brantc]

A completely correct and totally irrelevant observation. Hold two magnets far apart under paper with iron filings (or the functional equivalent) on it. Move the magnets so they slide close past each other and you can see the magnetic field topology change before your very eyes, visualized by the iron filings. There may even be a video of such things out there (or some enterprising reader can make one). The fields reconnect & disconnect. They are not visibly different before & after the event, but it's what happens during the event that counts. That's when the fields reconnect. And if those fields can reconnect, then fields immersed in a conductive plasma will certainly reconnect as well (which everyone except perhaps yourself & Zeuzzz understands quite well).

If the magnetic fields are NS they merge or attract. Same poles they have a 'dividing' line between the magnets. The iron filings just indicate where the magnetic field is in general.

With electromagnetism the situation is different. The magnetic field lags behind the current flow. When you turn the current on it take a instant to build up as well as dissipate as back EMF.

In a plasma generated magnetic field(flux tube) the field follows the current.

The situation is the same in a plasma. The topological change in the flux tube configuration(plasma flow) is mirrored by the change in magnetic field configuration. The is no snapping of any thing. That only happens when you look at macroscopic time scales. If you were to look at microscopic time scales you would see as the tubes touched a change in the flow to crosswise. As this change took place the parallel magnetic field would decay, there would be a jet from the pinch effect.
http://sci.esa.int/science-e-media/img/39/Reconnection-scales400.jpg

A magnetic field either grows or decays following a change in current. If the current changes direction so does the magnetic field.

 

[brantc]

That is not what I asked, Michael. You are a real gem at answering questions that are not asked and not answering questions that are asked.

That current can flow along field lines should be obvious from the papers I have written about that, which you know, so I am hardly asking about that.

First of all on the wiki page, "multi-terawatt pulsed power generators" can generate "birkeland currents", well I call them field aligned currents (as you can read on the top of the page). However, I created field aligned currents in a plasma in the laboratory (creating double layers) with a voltage of 200 V and I did not need any "multi-terawatt blahbalh". (here is the paper in case you are interested).

What I wanted to know from you was what these "hollow beam electrons" are, and why you are specifically referring to them. Also, I want you (or actually brantc, but he seems incapable of answering) how these electrons create the field they are flowing along. Seems not too difficult a question, now does it? And this time please give a real answer, thank you very much.

I think there is some confusion between 2 different effects.

There are the cathode ray pencil straight beams that are the effects of electric field acceleration. Mostly electrons. Nothing to do with magnetic fields.
These have been noticed in the upper solar latitudes.

Then there are flux tubes which are flows of plasma which are the result of potential differences between areas in a plasma that is denser like at the solar equator. These generally are a twisted pair like the flux tube that lives on the day line in the magnetopause.

"We have found in our study of 130 reconnection events that, in general, magnetic reconnection occurs along an extended line across the dayside magnetopause," said Dr. Karlheinz Trattner, Lockheed Martin space plasma physicist at the ATC. "Previously, there was considerable debate concerning the nature of this reconnection line. Some scientists believed that this reconnection line was not continuous across the dayside magnetopause, while others thought it was. The results from this study have resolved this long-standing debate."


"These bursts of electrons are well confined in a small scale flux rope structure as implied by the magnetic field and plasma measurements. Energetic electrons were flowing dawnward from the cusp region along (but anti-parallel to) the magnetic field. No stable energetic electron flux that indicates the cusp has a general open field line geometry has been observed."
http://www.sciencedirect.com/scienc...serid=10&md5=856c3e3181ab107b2d4249c0ad135bd4

Abstract The signatures of flux ropes with obvious core magnetic field are detected by Cluster II at the dayside magnetopause during 11:00–11:15 UT on Mar. 2, 2001. The similar characteristics can be found from the magnetic field variations recorded by the four spacecrafts (Cluster II C1–C4).
http://www.springerlink.com/content/73781086212n0132/

etc....

At interfaces between flux tubes and current sheets, instabilities form known as Dicotron Instabilities.

Flux tubes form parallel and perpendicular magnetic fields by the combined motions of the electrons and the magnetic fields.
Some of the electrons go straight and are responsible for the right hand rule like a wire(curl).
Some of the electrons are in a wide orbit and are responsible for the parallel component of the magnetic field in a flux tube like a solenoid.

Some do the helical motion and are responsible for the shape of the flux tubes.

Part of the parallel component depends on the location of the current flow.
If its a true Birkeland current its dominated by the field aligned current because the parallel component is doubled by the i.e. earths magnetic field..

Flux tubes are long lived structures that reconnect on a continual basis.

 

[Reality Check]

I dont know why you would change the magnetic field generation mechanism when you get to a reconnection.

I do not - the Sun does.

The suns magnetic field has nothing to do with the instabilities(not turbulence) in a reconnection. Those flows of electrons make their own magnetic field locally stronger than the suns.

The suns magnetic field has nothing to do with the instabilities(not turbulence) in a reconnection. But I did not say that.

Get close enough to an electric current and its induced magnetic field strength will greater than any other magnetic field, e.g. the magnetic filed of a neutron star.
Your point is?

Your story.
So the suns moving plasma makes the magnetic flux tubes that stick up out of the suns surface, the magnetic fields in turn drive the plasma that flows through the flux tubes(but carries no energy) and then by some mechanism by which we are not sure causes the magnetic fields interact in something called a reconnection.

The bit in bold is definitely wrong. All magnetic fields carry energy. All flows carry some kinetic energy.

The scientific story:My (limited) understanding of a scientific theory of the origin of solar flares is

1. The Sun's differential rotation, convection and turbulence make magnetic flux tubes inside the body of the Sun.
2. The magnetic flux tubes cause the plasma around then to be less dense than the surrounding plasma. Thus the magnetic flux tubes float up into the photosphere and above.
3. A complex process that is quite well understood (but not totally) called magnetic reconnection happens.
4. The energy contained in the agnetic filed is released and creates a solar flare.

I suspect that I have the details wrong and that the actual models presented in textbooks are much more precise and details. If you want the actual scientific theory I suggest that you read a textbook.

My story.
Electric field drives plasma up from the suns surface causing it to form magnetic field that constricts the plasma into a pair of flux tubes(or loop).
The flowing plasma experiences changes in the gyro radius that cause the pair of flux tubes to touch causing a change in the plasma path(releasing radiation and particles) that causes the magnetic fields to change configuration to match the plasma flow.

Nice story.
Better known as nothing to do with magnetic reconnection in solar flares until you produce a mathematical model from your story and thus predictions that match observations.
But a few questions about this theory of yours:

• If it is not your theory then what textbook did you get it from?
• Where does the electric field come from?
• How does the electric field constrict the plasma into a pair of flux tubes?
• How strong does the electric field need to be to constrict the plasma into a pair of flux tubes?
• Why a pair of flux tubes (why not 1, 3, 4, etc.)?
• What directions are the electric currents going in each flux tube.
• What observational evidence do you have for this theory?
• What experimental evidence do you have for this theory?

 

[tusenfem]

Wow. You never take the low road. I'm entertained actually.

http://www.thesurfaceofthesun.com/A...r Atmosphere And A Theory Of Solar Flares.pdf

http://arxiv.org/abs/0908.0813

Did those "macroscopic circuits" just pop up and blow your show or what?

did you miss the posts where I discussed BOTH of these papers? Here is my discussion on A&C and here is my discussion of O&M. Notice that I have no problem with circuit descriptions, notice that I have done it myself. Etc. etc. you don't read what you don't like.

again I notice you answer NONE of my questions that I put to you, and you expect me to be a circus animal performing tricks for you, in this case, read whatever paper you throw at me/us and try to explain it to you.

 

[tusenfem]

Nope. I dont reject MHD. I just dont think it tells the whole or correct story. Its useful in macroscopic situations for describing the movement of the magnetized fluid. As a fluid STREAM.

Well, I hope that michael is not reading this, MDH was invented by Alfvén, you know!

But it doesnt tell you the true source of the energy. That assumption is already made with the top down turbulence model of MHD. Then they ran with it not realizing it was just a gross description

Sure it does, by simple EMF equations, which are valid in MDH, E = - v x B.
I have no idea why you come up with a "top down turbulence" thingy here. First of all you claim turbulence does not exist in plasmas and now you say it is implicit in MHD. You can't have your cake and eat it. This is all getting very confusing.

It says nothing about a bottom up description of the actual particles..

That why they are doing PIC simulations with reconnection at the Large Plasma Device. MHD does not give you fine details.

Naturally MDH does not say anything about particles as they are "averaged away," and yes PIC simulations need to be done for real reconnection, but that can be done only for small scales, and fluid models have to be used for large scales, otherwise your CPU will explode.

 

[GeeMack]

again I notice you answer NONE of my questions that I put to you, and you expect me to be a circus animal performing tricks for you, in this case, read whatever paper you throw at me/us and try to explain it to you.

Standard operating procedure for a crackpot. Misunderstanding the burden of proof and relying on arguments from incredulity and ignorance seem to be the foundation of their position.

 

[tusenfem]

I think there is some confusion between 2 different effects.

There are the cathode ray pencil straight beams that are the effects of electric field acceleration. Mostly electrons. Nothing to do with magnetic fields.
These have been noticed in the upper solar latitudes.

Then there are flux tubes which are flows of plasma which are the result of potential differences between areas in a plasma that is denser like at the solar equator. These generally are a twisted pair like the flux tube that lives on the day line in the magnetopause.

And the electric field comes from ...

Flux tubes may contain plasma flows. A flux tube is just a bundle of magnetic field lines B, nothing more nothing less, defined in such a way that a surface perpendicular to the field, which moves along the field lines, shrinks or stretches with the field lines, in such a way that the product BS remains constant. That is a flux tube, which may or may not contain plasma.

If the footpoints get sheared or twisted, then an EMF is generated (see Alfven for example). I have no idea what you mean with "at the solar equator" flux tubes come out all over the sun and mainly in the band with sun spots.

I do not understand what you mean with "a twisted pair" which you say is "living on the day line of the magnetopause". Why a "pair"? I can just have one flux tube, which can get twisted into a rope by current flow through the tube.

So you still not telling us how the tube field is "produced by the current flowing along it."

"We have found in our study of 130 reconnection events that, in general, magnetic reconnection occurs along an extended line across the dayside magnetopause," said Dr. Karlheinz Trattner, Lockheed Martin space plasma physicist at the ATC. "Previously, there was considerable debate concerning the nature of this reconnection line. Some scientists believed that this reconnection line was not continuous across the dayside magnetopause, while others thought it was. The results from this study have resolved this long-standing debate."

So we move from Sun to Earth. What is it that this is supposed to show? The "paired" flux tubes?

(Some more abstracts taken out)

At interfaces between flux tubes and current sheets, instabilities form known as Dicotron Instabilities.

Is this an interface between flux tubes and an interface between current sheets, or an interface between a flux tube and a current sheet.

I rather doubt that the diocotron instability will happen, maybe the Kelvin-Helmholtz instability, as the former can only occur under very special conditions. Which is why one almost never sees this instability discussed in plasma physics books. For one, a charge separation will have had to have taken place.

Flux tubes form parallel and perpendicular magnetic fields by the combined motions of the electrons and the magnetic fields.

I guess this is your way of saying that the current flow in a flux tube creates a toroidal field (which is perpendicular to the guide field). However the current flow cannot create the parallel field. Please show me how you want to do that.

Some of the electrons go straight and are responsible for the right hand rule like a wire(curl).

"electrons are responsible for the right hand rule ..."
See above

Some of the electrons are in a wide orbit and are responsible for the parallel component of the magnetic field in a flux tube like a solenoid.

Why do they go in a "wide orbit" if the guide field still has to be created by these magical electrons? This is just wrong electrodynamics. You want the electrons to gyrate to create a "parallel" magnetic field (parallel to the "electrons that go straight), but in order for them to gyrate, there has to be this parallel field.

Some do the helical motion and are responsible for the shape of the flux tubes.

No, if you put a voltage drop over the flux tube all electrons will move in helical paths, some more wound then others, if we assume a Maxwellian distribution.

Part of the parallel component depends on the location of the current flow.
If its a true Birkeland current its dominated by the field aligned current because the parallel component is doubled by the i.e. earths magnetic field..

Flux tubes are long lived structures that reconnect on a continual basis.

What is that supposed to mean, "part of the parallel component." I guess you mean that the winding of the field depends on where in the flux rope you are.

A Birkeland current is ALWAYS a field aligned current.

Why is "the parallel component doubled by the (and I guess you mean e.g. [for example] instead of i.e. [that is]) Earth's magnetic field?"

 

[The Man]

No, that is not my position Tim. My position is that you are "short circuiting" two "circuits" in plasma and calling it "magnetic reconnection" only because you converted all the E's to B's! The process occurs in nature Tim, it's just a "circuit topology change" from the E orientation of MHD theory.

Again

Please identify these ‘circuits’ for the reconnection examples I have given.

 

[CaveDave]

Absolutely. I would call that journal an experimental journal. They build things and perform tests. They have hands on experience with the physics that theorists are writing the math for. Some of their results dont conform to "know laws of reality as described by theorists" so thats why there is controversy. Science for pure experimental science.

Math describes reality.

PhD EE is a pretty serious combination.
Dont get me wrong. I work with some great PhD's etc... I respect them. You just cant use it like a club.

My point was not that Engineers are necessarily crackpots (I consider myself to be more engineering oriented, even though I am self-educated, not degreed), but that they tend to THINK about things differently, e.g., Positive Current as opposed to Electron Current.

I was also meaning more along the lines of the (I assume) less rigorous publication standards and the (I have heard) small likelihood that a Research oriented Plasma Physicist or Astrophysicist would even have exposure to such a publication or would be comfortable translating the terminology and lack of math into their more specialized lingo.

I have no hostility toward IEEE (I wish I could afford a subscription), but it is, IMHO, in a different world from pure physics.

Cheers,

Dave

 

[Reality Check]

Absolutely. I would call that journal an experimental journal. They build things and perform tests. They have hands on experience with the physics that theorists are writing the math for. Some of their results dont conform to "know laws of reality as described by theorists" so thats why there is controversy. Science for pure experimental science.

I think the point is not that scientists distrust the papers published in IEEE.
It is that the IEEE is a journal of electrical engineering in all sorts of areas of physics, e.g. plasma physics. It tends to be peer reviewed by electrical engineers not astronomers.

It is accepted practice that papers should be published in a journal that concentrates on the subject area. That means that

• It will be peer reviewed by experts in the area.
• Experts in that area will read it.

The paper cited (here is its abstract )would have been better received if it was published in a astronomy or astrophysics specific journal.

The abstract is too general. "Sunspots, solar flares, and magnetospheric substorms" are not unsolved problems as far as I know. Their properties are quite well modeled but there is still several issues to be resolved. The fact that it has taken scientists 50 years to get to this point is more about the complexity of the phenomena rather than the model used.

 

[Michael Mozina]

Again

Again, that's called "magnetic attraction/repulsion", not "magnetic reconnection".

 

[Michael Mozina]

And the electric field comes from ...

Flux tubes may contain plasma flows.

Correction: All "flux tubes" in the solar atmosphere (IOW light plasma) *MUST* contain plasma flows.

A flux tube is just a bundle of magnetic field lines B, nothing more nothing less,

Magnetic lines by themselves do not create "flux tubes". They'd form simple lines like any normal magnetic field. The "current flow" in the plasma and of the plasma is what creates the "twisting" process.

This is where you seem to want to "cut out" the E field entirely, and ignore the whole role of moving charged particles. Your lines wouldn't "bundle" were it not for the current flow that creates the line and moving filament. It's a moving filament of charged particles, with current flow (in the form of electrons) flowing through the plasma tube filament. It works like any ordinary plasma filament, it's simply "scaled" in terms of "current flow' and therefore its' "magnetic field strength" is also scaled accordingly.

 

[sol invictus]

Again, that's called "magnetic attraction/repulsion", not "magnetic reconnection".

All forms of magnetic reconnection that Michael can't describe as "circuit reonnection" (whatever that is) are not magnetic reconnection, they're something else.

All forms of magnetic reconnection that Michael can describe as "circuit reconnection" aren't magnetic reconnection, they're "circuit reconnection".

Never mind the fact that magnetic fields are reconnecting in all these examples, and he's even admitted that.

 

[Michael Mozina]

I think the point is not that scientists distrust the papers published in IEEE.

It's just that they publish stuff you don't like and won't read, and won't consider, is that it?

It is that the IEEE is a journal of electrical engineering in all sorts of areas of physics, e.g. plasma physics. It tends to be peer reviewed by electrical engineers not astronomers.

EU theories are typically "better" suited to be reviewed by someone that understand circuit theory. Astronomers seem to be oblivious to the concept.

It is accepted practice that papers should be published in a journal that concentrates on the subject area. That means that
It will be peer reviewed by experts in the area.

It's not clear that your magnetic reconnection experts are actually experts in electrical engineering and circuit theory and EU theory is all about electricity and circuits and stuff. Your industry isn't qualified IMO to judge the papers in the first place!