The hidden mechanics of magnetic field reconnection, a key factor in solar storms and fusion energy reactors

October 12, 2017
The hidden mechanics of magnetic field reconnection, a key factor in solar storms and fusion energy reactors
Coronal loops on the sun are linked to magnetic fields. Princeton Plasma Physics Laboratory experiments are combining with Oak Ridge National Laboratory supercomputer simulations to illuminate how the fields break apart and reconnect. Credit: NASA/Solar Dynamics Observatory.

In July 2012, a powerful solar storm almost struck Earth. Scientists estimate that had the storm, called a coronal mass ejection (CME), hit the planet, the impact would have crippled power grids worldwide, burning out transformers and instruments.

A NASA probe that happened to lie in the CME's path detected some of the charged particles it contained. Data the satellite collected showed the storm was twice as powerful as a 1989 event that knocked out Quebec's entire power grid, disrupted power delivery across the United States and made the northern lights visible as far south as Cuba. In fact, the recent storm might have been stronger than the first and most powerful CME known to hit the planet, the Carrington event. That 1859 storm sprayed sparks from telegraph lines, setting fire to telegraph stations. Researchers put the odds of a Carrington-size CME occurring by 2024 – and possibly hitting Earth – at 12 percent.

Such events occur when lines in the sun's massive magnetic system snap and reconnect. "Magnetic fields are a reservoir of an enormous amount of energy, and major eruptive events occur in which this energy is liberated," says Amitava Bhattacharjee, a physicist at the Princeton Plasma Physics Laboratory (PPPL), a Department of Energy facility in Princeton, New Jersey. "Charged particles tend to get tied to like beads on a wire – when the wire breaks, the beads get thrown off at enormous speeds."

The phenomenon, known as fast magnetic reconnection, remains a mystery. No one knows how field lines break and rejoin fast enough to expel the billions of tons of material unleashed in a CME, or even in the smaller eruptions of common solar flares. In laboratory experiments and simulations, Bhattacharjee and his colleagues have revealed new mechanisms that help explain fast magnetic reconnection.

Bhattacharjee has been in pursuit of such mechanisms since graduate school, when he realized that plasma physics is "a beautiful, classical field with wonderful equations that were good things to analyze and do computer simulations with," he says. At the same time, he saw that plasmas – which constitute 99.5 percent of the visible universe – are also the key to "a very practical and important problem for humanity, namely magnetic fusion energy."

For decades, nuclear fusion machines, such as doughnut-shaped tokamaks, have promised a virtually limitless supply of relatively clean energy. But a working fusion device is still out of reach, partly because of fast magnetic reconnection. "Magnetic fusion reactors have magnetic fields in them, and these magnetic fields can also reconnect and cause disruptive instabilities within a tokamak fusion plasma," says Bhattacharjee, professor of astrophysical sciences at Princeton University and head of PPPL's Theory and Computation Division.

In the present model of reconnection, opposing magnetic fields are pushed together by some external force, such as plasma currents. A thin, flat contact area forms between the two fields, building tension in the field lines. In this thin region, called a current sheet, plasma particles – ions and electrons – collide with one another, breaking field lines and allowing them to form new, lower-energy connections with partners from the opposing magnetic field. But under this model, the lines reconnect only as fast as they are pushed into the current sheet – not nearly fast enough to explain the tremendous outpouring of energy and particles in a fast-reconnection event.

Since this slow reconnection model depends on plasma particle collisions, many research groups have searched for collisionless effects that might account for fast reconnection. Promising explanations focus on the behavior of charged particles in the current sheet, where field strength is close to zero. There, the charged properties of the massive, sluggish ions are suppressed, and the nimble electrons are free to carry the current and whip field lines into new configurations.

For laboratory experiments on hidden mechanisms, Bhattacharjee's team uses powerful lasers at the University of Rochester's Omega facility. To develop computer models, the group uses Titan, a Cray XK7 supercomputer at the Oak Ridge Leadership Computing Facility, a DOE Office of Science user facility, through the Office of Science's Innovative and Novel Computational Impact on Theory and Experiment (INCITE) program. The Office of Science's Fusion Energy Sciences program and the DOE National Nuclear Security Administration sponsor the experiments.

In an early experiment led by PPPL research physicist Will Fox, the team pointed two intense Omega lasers at materials that yield plasma bubbles under the beams. Each bubble spontaneously generated its own magnetic field through an effect known as the Biermann battery. As happens in the sun and nuclear fusion devices, charged plasma particles lined up on the magnetic field lines. The bubbles plowed into each other, and a current sheet formed between them. The reconnection rate between the fields was fast – too fast for classical theory.

"That's where we were first establishing the underlying mechanism for reconnection happening in this machine," Bhattacharjee says. The team now had a model for fast magnetic reconnection, one applicable to earlier pioneering experiments conducted by groups in the United Kingdom and the United States. A simulation on Titan showed that more field lines were crammed together in the current sheet than anyone had realized, a phenomenon called flux pileup. The study showed that, in addition to previously suggested collisionless effects, flux pileup plays a role in fast reconnection.

In later experiments led by Gennady Fiksel, now at the University of Michigan, the team didn't want to rely solely on spontaneously generated magnetic fields. "We felt we needed greater control on the magnetic fields we were using for the reconnection process," Bhattacharjee says. "And so we used an external generator called MIFEDS (magneto-inertial fusion electrical discharge system), which produced external magnetic fields we could control."

To capture changes in this field, the team filled the space with a thin background plasma, generated by a third laser, and imaged it using a beam of protons, which magnetic fields deflect. When two plasma bubbles impinged on the external magnetic field, the team created the clearest image so far of events taking place in the region where field lines reconnect. The new configuration also showed flux pileup, followed by a reconnection event that included small plasma bubbles forming in the region between the bubbles and, finally, abrupt annihilation of the .

"The mechanism that we found is that you form this thin current sheet that can then be unstable, in what we call a plasmoid instability that breaks up this thin current sheet into little magnetic bubbles," Bhattacharjee says. "The plasmoid instability is a novel mechanism for the onset of fast reconnection, which happens on a time scale that is independent of the resistance of the plasma."

Bhattacharjee and his colleagues are working to understand how their discovery fits into the big picture of solar activity, solar storms and nuclear fusion devices. Once they and the broader community of plasma physicists fully understand , the ability to predict CMEs and tame some of the plasma instabilities inside tokamak reactors, for example, may be within reach.

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tallenglish
1 / 5 (2) Oct 12, 2017
I am pretty confident that we have dark matter compressing the sun (direct reason it is in a stable fusion state and not blow itself apart), that dark matter will create a gravity hill (opposite to the normal gravity well for mass). That causes the magnetic fields we see to be reflected back into the star, keeping fusion going. It is that same gravity hill that causes field lines to snap and accelerate the flare or light away from the sun once its over the hill. It is that process that causes the corona to be hotter than the surface as well.

Bonus: the gravity waves we are seeing with LIGO are also are stretching/squeezing this planet and the sun, and are likely candidates for all the increased volcanic and fault activity (maybe even heating the sun up a bit more giving us a higher risk of flares.

https://docs.goog...=sharing
cantdrive85
1 / 5 (3) Oct 12, 2017
"Charged particles tend to get tied to magnetic field lines like beads on a wire – when the wire breaks, the beads get thrown off at enormous speeds."

When a scientist has to resort to pseudoscience to explain phenomena it is a sure sign that "scientist" is more appropriately a pseudoscientist.
"Magnetic reconnection is pseudoscience" Hannes Alfven

And this article is literally peppered with pseudoscientific mumbo jumbo.
rrwillsj
1 / 5 (1) Oct 12, 2017
te, please correct me if I am misunderstanding your comments.

Upon what evidence are you basing the opinion that CM is a measurable fraction of our Sun's mass?

Would not your opinion, if proven correct, have an even greater effect upon stars with greater masses?

Instead of the observable Universe being 13+ gigayears in age... (it's just a baby!) Rather, the oldest visible stars would only last a few million years, as their accumulation of DM would be substantial?

If DM could, in any measurable quantity, increase the mass of a stellar object as small as our Sun? Even if undiscovered to date, then would not the total mass of the hydrogen and helium evident to make up our Sun, have to be of a completely unrealized elemental structure? To have less mass than generally accepted by astrophysics?
tallenglish
1 / 5 (2) Oct 12, 2017
rrwillsj, Mass forward and expanding (Chaos/Quantum -> Order/Macro), DM backwards and decaying (Order/Macro -> Chaos/Quantum). While mass pushes spacetime downward, DM pushes upward. So DM corals the matter as it tries to decay to smaller and smaller particles by surrounding it in all directions with negative gravity - which it can only excape if it has enough kinetic energy.

Snag is trying to figure a way to measure something we normally can't see. Ways we might be able to measure its affect is calculating the corona temp and surface temp of the sun and seeing the difference (what kinetic energy has it gained), but we would have to also try and figure out what push it got from the magnetic field lines as well and subtract that.

DM (if I am right) would mask some of the mass of the sun - so if we send this probe to "touch" the sun, we will easilly find out if I am right and it gets deflected away from the surface. So yes hubble constant may be way off, etc.
tallenglish
1 / 5 (2) Oct 12, 2017
If I am right DM was at its greatest at the big bang (why dark stars and supermassive black holes were possible then, but not any more). Stars will naturally get smaller and more of them as the dark matter is used up. And every star needs DM to start fusion and keep it going. As DM is used up the star expands and loses mass faster, eventually enough mass is lost the DM crushes the remaining star until it reaches equilibrium again. Even our planet has DM around it, it is the reason our core stays molten and magnetic.

Also we have LIGO detecting gravity waves, these are just DM ripples (ejectect from a neutron star or black hole), as those dark matter wave progress they reduce gravity for a short while stretching/compressing space as they pass - this is what LIGO detects, and its more than likely the culprit for volcanos and fault lines waking up and maybe even why humans are rather testy and quick tempered.
tallenglish
1 / 5 (2) Oct 12, 2017
We should also check flares, if the field lines snap at the same distance from the sun surface, that is where the maximum of the dark matter gravity hill will be. Anything inside that is reflected back in, anything outside ejected away from the surface.

Sorry, I need to learn the art of brevity...
rrwillsj
1 / 5 (1) Oct 13, 2017
te, in a few words. You are admitting that you have no empirical evidence for your suppositions about Dark Matter actually effecting individual stars?
691Boat
5 / 5 (4) Oct 13, 2017
When a scientist has to resort to pseudoscience to explain phenomena it is a sure sign that "scientist" is more appropriately a pseudoscientist.
"Magnetic reconnection is pseudoscience" Hannes Alfven

And this article is literally peppered with pseudoscientific mumbo jumbo.


I find it very interesting that you and your cohorts repeatedly say we should depend more on plasma research done in the lab to explain the universe, except apparently when it doesn't match your opinion.
This work is the epitome of good plasma lab work, performed across multiple sites with multiple methods, all showing similar results and expanding on one another's work.
What about it is pseudoscience? The fact that they haven't entirely proven the time scales or exact methods? That's what labs and scientists are for..to keep digging and learning.
tallenglish
1 / 5 (3) Oct 13, 2017
rrwillsj, I gave my theory/idea and ways we may likely detect it. If you don't think DM is responsible for propagating gravity waves then what is it (which were theorised by Einstein and now detected by LIGO - ergo we have it in our own system, so why can't it be everywhere else), as its not normal mass or light (or we would see it). Thats the challenge with DM, to find this imperical evidence you have to look for the effect (changes in gravity) as you can't see the cause (dark matter is always behind us, and the photons we measure everything with only go forwards), thats why so many scientists have a very hard time even believing it exists. We don't have much in the way of imperical evidence of DM in our own solar system except for LIGO as we aren't looking for it. My point is this explains our molten core, star birth, corona, midlife and death etc without having to say its "metalic hydrogen" which we can't explain either, for my idea - the sun is just compressed hydrogen.
cantdrive85
1 / 5 (3) Oct 14, 2017
This work is the epitome of good plasma lab work, performed across multiple sites with multiple methods, all showing similar results and expanding on one another's work.

And interpreted using pseudoscientific concepts.
What about it is pseudoscience?

I already pointed that out in the previous comment;
"Charged particles tend to get tied to magnetic field lines like beads on a wire – when the wire breaks, the beads get thrown off at enormous speeds."

Magnetic fields are not frozen-in, this is a pseudoscientific concept. Magnetic field lines are not like wires nor can they break, another pseudoscientific concept.
It is acceptable to use an approximation to explain a certain phenomena, however their explanation reifies the approximation into having physical attributes which creates an action. This is crossing the line into pseudoscience.
691Boat
5 / 5 (4) Oct 16, 2017
Magnetic fields are not frozen-in, this is a pseudoscientific concept. Magnetic field lines are not like wires nor can they break, another pseudoscientific concept.

Considering they have multiple avenues of proof and evidence of reconnection, I would say it is pretty well proven to not be pseudoscience.
But hey, electro-disharge machining carved out the Grand Canyon, right? No pseudoscience there, since we have lots of evidence and proof that it happens.

cantdrive85
1 / 5 (3) Oct 16, 2017
Once again, you are confusing concepts, interpretation, and reality. There is no argument against an explosive event, this obviously occurs. There is in fact no "proof" that magnetic field line reconnection occurs, it cannot due to the fact it is an erroneously held pseudoscientific belief.
If you want to suggest electrical discharge is a pseudoscientific belief then it is up to you to do so, good luck with that one.
jonesdave
5 / 5 (3) Oct 16, 2017

There is in fact no "proof" that magnetic field line reconnection occurs, it cannot due to the fact it is an erroneously held pseudoscientific belief.


Calling Falthammar a pseudoscientist again? Tut tut.
cantdrive85
1 / 5 (3) Oct 16, 2017
Hey jonesdumb;
Read that paper Fathammar wrote about moving magnetic field lines you keep posting, ironically believing it supports your pseudoscientific POV. He is quite clear about the fact that moving and breaking field lines is pseudoscientific belief. Has MRx been used as the label of said energetic event? Undoubtedly, but just as planetary nebula aren't at all planetary nebula, neither is there any magnetic reconnection occurring.
Da Schneib
5 / 5 (2) Oct 16, 2017
When you whine that "physicist[sic] are making up teh theories up without lab work" and then the lab work gets done and the theories are substantiated by the lab data, it's pretty disingenuous to call the lab work "pseudoscientific."

Especially when the lab work was done by people who would get famous and win a Nobel Prize in Physics for proving the theory wrong.

Just sayin'.
Da Schneib
not rated yet Oct 16, 2017
I have also asked for list of Nobel Winners in the past that turned out to be wrong.

I have not received a response and I don't think that's an accident or that the Nobel Prize Committee got it wrong.
Da Schneib
not rated yet Oct 16, 2017
I should be more specific: Nobel Prizes in Literature and Peace are often disputed for political reasons. However Nobel Prizes in Physics have not been overturned, or except in one or two cases even disputed, ever.

If you believe differently here is your opportunity to post an incorrect Nobel Prize in Physics.
cantdrive85
1 / 5 (4) Oct 16, 2017
Do you keep mentioning the Nobel because of your discovery of the magnetic monopole at the end of your "open field line"?

BTW, I already mentioned one Nobel Prize that was wrong, Alfven's in 1970. And he explained the limitations and failures of MHD in the very acceptance speech for receiving the award for which he was awarded. Irony is a bitch!
jonesdave
5 / 5 (3) Oct 17, 2017
In fact, the most interesting plasma physics occurs pre­cisely where and because this equation is not satisfied, such as the auroral acceleration region, ***magnetic field reconnection***, turbu­lence, shocks, and many wave modes.


http://onlinelibr...0002/pdf
jonesdave
5 / 5 (4) Oct 17, 2017
A special kind of violation of the frozen field condition is the process of reconnection. In the classic review article by Vasyliunas (1975) reconnection was defined as "the process whereby plasma flows across a surface separating regions containing topologically different magnetic field lines" (cf. also Priest and Forbes, 2000). But change of connectivity between plasma elements is possible without a separator. Independently of topology, two elements of plasma that are at one instant of time on a common magnetic field line can be on different magnetic field line at another instant,


Falthammar
http://www.diva-p...XT01.pdf
jonesdave
5 / 5 (3) Oct 17, 2017
Reconnection is considered to be one of the most important phenomena in cosmic plasma, as a means of topology change and energy release. In the Earth's magnetosphere, reconnection takes place both at the magnetopause and in the tail current sheet. In addition, local reconnection of limited strands of magnetic flux, so-called flux transfer events, are also common (Le et al. 2008).


Falthammar
http://www.diva-p...XT01.pdf
jonesdave
5 / 5 (4) Oct 17, 2017
The reconnection events in the geomagnetic tail that are associated with magnetospheric substorms have many similarities to the fast energy release that takes place in solar flares
(Lin et al., 2008). In the magnetosphere, the phenomenon can be studied empirically in great detail by means of in situ measurements (Paschmann, 2008). The value of this for understanding solar flares and other kinds of energy release in cosmic plasmas can hardly be exaggerated.


Falthammar
http://www.diva-p...XT01.pdf
jonesdave
5 / 5 (4) Oct 17, 2017
Reconnection is an extremely complicated phenomenon, and this makes it even more important to have actual measurements to guide theoretical work. One reason for complexity is that reconnection involves coupling between widely different spatial scales, from system-scale structure through on scales and down to electron scales. Therefore, multipoint measurements are essential. Multipoint measurements are at present being made with the still operational Cluster satellites and the more recent fives satellites of the THEMIS project.


Falthammar
http://www.diva-p...XT01.pdf
jonesdave
5 / 5 (4) Oct 17, 2017
Due to the widely different spatial scales involved in reconnection, a major advance would be simultaneous multipoint measurements on each of the three spatial scales. Such a project, called Cross Scale, is part of ESA's long term plan Cosmic Vision. It involves 10 or 12 satellites forming tetrahedrons on each scale.


Falthammmar
http://www.diva-p...XT01.pdf

Anybody else out there who still thinks Alfven's former friend, colleague and co-author doesn't accept that reconnection happens? Lol.
barakn
3.4 / 5 (5) Oct 17, 2017
JonesDave is trying to hammar the point home.
jonesdave
5 / 5 (1) Oct 17, 2017
JonesDave is trying to hammar the point home.


Yes, I came over all Chris Reevish!
jonesdave
5 / 5 (2) Oct 17, 2017
JonesDave is trying to hammar the point home.


Yes, I came over all Chris Reevish!


A better reply might have said: "I Falt I had to." :)
cantdrive85
1 / 5 (3) Oct 18, 2017
And nowhere does he resort to using pseudoscientific concepts to explain the event, unlike most of his plasma ignoramus colleagues.
jonesdave
3 / 5 (2) Oct 18, 2017
And nowhere does he resort to using pseudoscientific concepts to explain the event, unlike most of his plasma ignoramus colleagues.


He's describing reconnection as it is used and understood by many scientists working in the field. He even references other people to support his paper. Why don't you read some of their stuff as well? You'll find that Falthammar's use of it is no different.
So what particular pseudoscientific concepts are you on about?
cantdrive85
1 / 5 (3) Oct 18, 2017
Nowhere does he refer to moving or breaking field lines, he even wrote a paper explaining its misuse, you have even reffered to it yourself.
jonesdave
5 / 5 (3) Oct 18, 2017
Nowhere does he refer to moving or breaking field lines, he even wrote a paper explaining its misuse, you have even reffered to it yourself.


You mean the one where C-G F says this:

The nonexistence of parallel electric fields was later challenged by Alfven, who suggested that auroral primary electrons may gain their energy from falling through a parallel potential drop above the ionosphere and described how ***parallel electric fields can 'cut' magnetic field lines***
.

He also, when mentioning MRx in that paper, references his co-author's paper:
Criteria for and statistics of elec­tron diffusion regions associated with subsolar magnetic field
reconnection,

Presumably, he agrees with his co-author's take on things, otherwise why co-author with him and reference his paper? In that paper, Mozer says:

However, on this scale, magnetic field lines still move with the E x B/B2 velocity,........


Strange, eh?
cantdrive85
1 / 5 (2) Oct 18, 2017
The nonexistence of parallel electric fields was later challenged by Alfven, who suggested that auroral primary electrons may gain their energy from falling through a parallel potential drop above the ionosphere and described how ***parallel electric fields can 'cut' magnetic field lines***

You do understand the context of that statement is being used to show that the frozen-in condition not valid when describing the fields. That is what is meant by "cutting" the lines. Note the "quotations" being used at "cut". It has relevance.
Da Schneib
5 / 5 (1) Oct 18, 2017
@jonesdave, what's most amusing is that I described the, pardon the pun, connection between the magnetic field line description and E and B field description literally months ago on another one of these threads about reconnection, never got a satisfactory reply, and moved on.

Quick reprise: what happens in the field description is that domains switch from allegiance to one field to allegiance to another at the interface between the fields as their relative strength at the interface changes due to source variations and distance variations; the description of magnetic lines disconnecting and reconnecting gives the same results as this field description.

As usual after being shown to be completely wrong the #physicscranks simply repeat their claims on a different thread like it never happened. This is standard EUdiot behavior.
jonesdave
5 / 5 (3) Oct 18, 2017
You do understand the context of that statement is being used to show that the frozen-in condition not valid when describing the fields.


Duh! You don't say! MRx absolutely requires that the frozen-in condition is not valid! It couldn't happen if it was. What do you think A & F were getting their knickers in a twist about, back in the day? Because they saw some people trying to use ideal MHD when describing MRx. Nobody does that anymore. Why do you think Falthammar never seemed to (or needed to) backtrack when deciding MRx was a real phenomenon? Because he had never dismissed it in the first place. He knew that it could only happen in non-ideal MHD situations.
cantdrive85
1 / 5 (3) Oct 18, 2017
All MHD models, ideal or otherwise, which are in use to describe the event are invalid, this is why the mysteries persist. Even non-ideal MHD omits the circuitry and other phenomena (such as double layers) which are of primary importance.
cantdrive85
1 / 5 (3) Oct 18, 2017
Hey da schnied, how's that monpole/open field line Nobel prize going?
jonesdave
5 / 5 (1) Oct 19, 2017
All MHD models, ideal or otherwise, which are in use to describe the event are invalid, this is why the mysteries persist. Even non-ideal MHD omits the circuitry and other phenomena (such as double layers) which are of primary importance.


Well, that's strange, because Falthammar's co-author, F.S. Mozer, whom he often references re MRx, says:

We present a correlative case study of the solar wind interaction with the magnetosphere using
in situ observations of the polar cusp and surrounding regions, ground-based and low-altitude spacecraft polar cap observations, and global MHD simulations during an extended period of strongly northward interplanetary magnetic field (IMF) on April 11, 1997.


http://onlinelibr...0091/pdf
jonesdave
5 / 5 (1) Oct 19, 2017
^^^^^^You will also find that Mozer most certainly does not ignore DLs, and has written quite a bit on them. I would suggest reading the following paper:

Time domain structures: What and where they are, what they do, and how they are made.
http://onlinelibr...946/full
Mozer, F.S. et al.

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