Scientists bring mysterious magnetic process down to earth

Oct 25, 2011 By John Greenwald
Scientists believe that magnetic reconnection is behind the extraordinary bursts of radiation that have emerged from the center of the Crab nebula, the remains of an exploded star. Astrophysicists from Princeton and other institutions are paying close attention to the efforts of the MRX research team, hoping to better understand some of the mysteries surrounding the phenomenon. Credit: NASA; the European Space Agency; and Jeff Hester and Allison Loll, Arizona State University

With the click of a computer mouse, a scientist at the U.S. Department of Energy's Princeton Plasma Physics Laboratory (PPPL) sends 10,000 volts of electricity into a chamber filled with hydrogen gas. The charge heats the gas to 100,000 degrees Celsius.

In an instant -- one-thousandth of a second, to be precise -- a process called "magnetic reconnection," a powerful force that can light up the skies, takes place in a device roughly the size of a sport utility vehicle.

PPPL researchers have run this and similar carefully controlled experiments -- called "shots" -- more than 100,000 times since 1995, and amassed volumes of data and numerous scientific papers. The shots recreate one of the most common but least understood phenomena in the universe -- one that gives rise to the , solar flares and geomagnetic storms, and that can disrupt cell phone service, black out and damage .

Researchers at PPPL have brought this basic process down to earth in miniature to be studied under laboratory conditions in the Magnetic Reconnection Experiment (MRX), the leading project of its kind in the world in terms of the quantity and quality of the data it has collected.

"Here we can actually recreate reconnection," said Masaaki Yamada, a PPPL physicist and principal investigator for MRX, "This is not theory or a computer simulation." Hantao Ji, principal research physicist at PPPL for MRX, concurred: "This provides a chance to see what's really going on in reconnection." 

The experiments seek to unravel the secrets of magnetic reconnection and ultimately provide benefits including improved prediction of solar outbursts and dangerous ; increased understanding of the formation of the sun and stars; and greater control of the nuclear fusion reactions that PPPL researchers are studying as a clean fuel for generating electric power.

Magnetic reconnection takes place when magnetic lines of force -- or field lines -- break apart and reconnect with a violent burst of energy that, in huge bodies such as the sun and stars, has the explosive power of millions of tons of TNT. This occurs when superheated and electrically charged gases called plasmas converge. Plasmas consist of electrons and ions -- atoms that have been stripped of one or more electrons -- and are the basic elements of the sun and stars.

William Slavin (center), head of PPPL's safety division, gives graduate students a tour of the MRX device, which resembles a large steel barrel attached to arrays of tubes and wires. The device allows PPPL researchers to recreate the magnetic reconnection process in a controlled setting. Credit: Elle Starkman

PPPL's study of the reconnection phenomenon is made possible by the MRX device, which resembles a large steel barrel attached to arrays of tubes and wires. Inside are two doughnut-shaped coil systems called "flux cores" that produce plasmas whose magnetic field lines reconnect while tiny probes measure the results. The MRX device can discharge 30,000 kilowatts of power for one-thousandth of a second, or enough energy to briefly power 25,000 homes.

PPPL, which is managed by Princeton University, launched the MRX project 16 years ago under the direction of Yamada to increase understanding of the role that magnetic reconnection plays in the disruption of plasma, which can force nuclear fusion reactors to shut down. Improved knowledge of magnetic reconnection would advance the development of fusion as a clean source of energy for generating electricity, which is the core mission of the laboratory.

The experiment soon caught the eye of the astrophysical community, which also saw benefits for its own field of study. Astrophysicists from Princeton and other institutions are closely watching the efforts by PPPL scientists to unravel some of the mysteries surrounding magnetic reconnection.

"Plasma processes, such as reconnection, influence the behavior of astronomical objects of all sizes, from to ionized gas jets that travel through galaxies," said Stewart Prager, director of PPPL. "One of the goals of PPPL is to understand the plasma universe, and MRX is making enormous contributions to that mission."

Studying the triggers of solar outbursts

A key puzzle that MRX researchers are trying to solve is why magnetic reconnection takes place in the sun many thousands of times faster than theorists have been able to understand. This mystery hinders forecasting of volatile "space weather," which is an important factor in the development of future space exploration missions. "You can't predict solar storms when you don't understand reconnection," noted Princeton astrophysicist James Stone.

Solar storms occur when reconnection causes huge plasmas to erupt from the sun and slam into the Earth's magnetosphere -- the magnetic field that surrounds the planet -- with a potentially damaging impact. One such eruption stirred up a geomagnetic disturbance that blacked out the city of Montreal and most of the Canadian province of Quebec for nearly 12 hours in 1989.

Solar outbursts occur in 11-year cycles with a new cycle now starting and expected to reach a peak -- or "solar maximum" -- in 2013. However, scientists currently are unable to forecast the precise day or month of these eruptions.

MRX researchers are gradually zeroing in on the process behind the mysterious mechanism of reconnection that triggers the storms. Laboratory findings show that the electric current embedded into plasmas suddenly dissipates when these superhot gases converge, enabling reconnection to take place. Further experiments have confirmed that part of the reason for the abrupt dissipation is that the ions and electrons inside the plasmas have different velocities. The electrons thus behave differently from the ions -- as measured by a phenomenon called the "Hall effect" that is typically associated with magnetized electrons and unmagnetized ions in a plasma.

Such discoveries are redefining traditional notions of how reconnection works.

"The MRX is uncovering new physics that is modifying the theories that we thought had explained reconnection," said astrophysicist Russell Kulsrud, a Princeton professor emeritus. Through the experiment, PPPL scientists have "made many detailed measurements and (are) discovering many new things that we don't understand," Kulsrud added.

MRX findings will help guide a four-satellite exploration of reconnection that NASA scientists plan to launch in 2014. The spacecraft will sweep through the magnetosphere on a multiyear mission to study the regions where reconnection takes place.

"We hope to provide a database that will suggest what kind of data-taking is most efficient," Yamada said.

Knowledge of space weather will be vital to the safety of crews of possible future missions to Mars. The astronauts could be exposed to high levels of radiation if solar storms were to break out during flight, so the ability to pinpoint the timing of reconnection events that could lead to such storms is crucial, Yamada noted.

Gaining insights into bright skies, young stars and fusion energy

Through their work on the MRX experiment, PPPL researchers also aim to gain a better understanding of the forces behind issues ranging from the makeup of the skies and stars to clean energy development.

Magnetic reconnection underlies the northern lights, the brilliant auroras that light the night sky near the north and south poles. Auroras occur when relatively low-energy plasmas that stream from the sun connect with the magnetosphere and produce heated particles that give rise to the light shows. These plasma flows from the sun are known as "solar wind."

Magnetic reconnection is also suspected to be behind the extraordinary bursts of radiation that have emerged from the center of the Crab nebula -- the remains of an exploded star -- some 6,500 light years from Earth. Scientists trace the bursts to electrons that have accelerated to the highest level of energy ever observed in a fixed celestial body.

"You need something like reconnection to explain these very high-energy particles," said astrophysicist Jonathan Arons of the University of California-Berkeley.

Perhaps the most basic issue related to magnetic reconnection is its role in the creation of stars, which begin as clouds of charged particles that collapse under gravity. Accompanying this process is the reconnection of magnetic field lines that are present in the original cloud and must separate out for the star to be born. This activity happens much faster than current theory indicates, so MRX experiments "are constructed to find out the physics of what's actually going on," Princeton's Kulsrud noted.

Closer to home, reconnection creates a disruption in plasmas during nuclear fusion experiments such as those under way at PPPL. This disruption can force fusion reactors to shut down.

While the impact of magnetic reconnection on fusion research was the inspiration for the launch of MRX, the nature of the project -- scaling down massive phenomena into a laboratory setting -- is yielding insights beyond PPPL.

"If you're in space you observe what happens," said University of Maryland physicist James Drake. "In the lab you can vary the plasma conditions, which provides a new avenue for exploring the process."

The ability to conduct controlled experiments is the key to the MRX project, which is funded by several federal agencies, including the U.S. Department of Energy, the National Science Foundation, the Office of Naval Research and NASA.

"The important part is that we can create with control, and then study the reconnection process," said PPPL's Yamada. "In nature you cannot."

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Isaacsname
not rated yet Oct 25, 2011
So what does this mean ? The Hall coefficient is different under the influence of strong fields ?
dschlink
5 / 5 (1) Oct 25, 2011
The report is focused on new data that voids previous ideas about reconnection. I believe they are saying that the Hall effect is part of the reconnection mechanism and might explain why reconnection happens so much faster than current theory predicts.

New data and soon new theories.
Isaacsname
not rated yet Oct 25, 2011
Ahh, thanks, I should have read further down the Wiki page before asking, lol. Gyrofrequency ? I'm still trying to wrap my brain around classical electrodynamics.
HannesAlfven
2.6 / 5 (9) Oct 25, 2011
Physics majors and scientists alike should bring themselves up to speed on the controversy associated with the work of Hannes Alfven. It is one of the most remarkable stories in the history of the Nobel Physics Prize, insofar as Alfven came to realize that MHD was problematic under numerous cosmic scenarios by the time he received his prize. He decided to use his acceptance speech as an opportunity to dissuade MHD practitioners from continuing the mistake. That was in 1970. Needless to say, he was WIDELY IGNORED ...

http://www.scient...e_09.pdf
Cynical1
1 / 5 (1) Oct 25, 2011
Wow! Just read an incredibly interesting article on Hannes A. It verifies (to me, at least) the absolute fractal/ergodic nature of the energized universe we are a part of (notice I didn't say - live in).
And the data this kind of research provides -
Hell, I haven't even gotten to the Wikiped article yet!
HannesAlfven
2 / 5 (4) Oct 26, 2011
Physicists of the future are going to make jokes about this one day. But, we're still living it, unfortunately ...

"Currently when scientists create a "reconnection" event in the lab between two electrically charged plasma sheets the 'reconnection' event takes place at twice the speed MHD theory predicts.

So far no one has been able to rectify this problem, nor have they been able to produce a 'reconnecting' magnetic field without first applying current to the plasma sheets they are observing. The reason being obvious of course, in order to create a magnetic field, one must first induce an electrical current. So far, this is the only known way of producing a magnetic field in a plasma that can be tested.

As soon as the current shuts off, so too does the magnetic field."
Cynical1
not rated yet Oct 26, 2011
As soon as the current shuts off, so too does the magnetic field."
Guess that's why they call it - "ELECTRO magnetism".
So. Have any possible explanations been posited as to the "faster than predicted" puzzle?
HannesAlfven
2 / 5 (4) Oct 26, 2011
Re: "Guess that's why they call it - "ELECTRO magnetism"."

Yes, indeed.

"Hannes Alfvén was an electrical engineer who struggled to understand and eliminate the destructive explosions that occurred on high voltage transmission lines in his native Sweden. He determined that the energy being released so calamitously was originally stored in the magnetic fields that surround the electrical currents being transmitted along the lines. Any abrupt interruption of those currents leads to an explosive energy release. He said:

> "In the case of the instability leading to the
> extinction of the current, it should be remembered
> that every electric circuit is explosive in the
> sense that if we try to disrupt the current, a
> release of the whole inductive energy at the point
> of disruption will occur." - H. Alfvén, Cosmic
> Plasma, Reidel, Holland, Boston, 1981, p.27.
HannesAlfven
1 / 5 (2) Oct 26, 2011
Re: "Guess that's why they call it - "ELECTRO magnetism"."

Hannes Alfvén was an electrical engineer who struggled to understand and eliminate the destructive explosions that occurred on high voltage transmission lines in his native Sweden. He determined that the energy being released so calamitously was originally stored in the magnetic fields that surround the electrical currents being transmitted along the lines. Any abrupt interruption of those currents leads to an explosive energy release. He said:

> "In the case of the instability leading to the
> extinction of the current, it should be remembered that
> every electric circuit is explosive in the sense that
> if we try to disrupt the current, a release of the
> whole inductive energy at the point of disruption will
> occur." - H. Alfvén, Cosmic Plasma, Reidel, Holland,
> Boston, 1981, p.27.
HannesAlfven
1 / 5 (3) Oct 26, 2011
[continued]

Alfvén extrapolated his findings about terrestrial power lines to the study of magnetized cosmic plasma. In the case of the disruption of an electric current within such a plasma, he said, "If the current disruption is caused by an instability in the plasma, the inductive energy in the circuit will be released in the plasma. The disruption of a current through a plasma is often caused by a double layer becoming unstable."

Astrophysicists ignore Alfvéns work. They attempt to arrive at a de novo explanation for the release of such energy by embracing the notion that the motion and interaction of magnetic field lines is its root cause. They expound on the (basically false) idea that magnetic fields are frozen into plasma, and by moving and breaking, these lines carry the plasma along and spew it out into space.
HannesAlfven
1 / 5 (2) Oct 26, 2011
[continued]

Alfvén ridiculed this explanation by saying, "A magnetic field line is by definition a line which is everywhere parallel to the magnetic field. If the current system changes, the shape of the magnetic field line changes but it is meaningless to speak about a translational movement of magnetic field lines." - Alfvén, op cit, p.12.(Emphasis in original) Despite his warnings about this, astrophysicists persist in the notion that moving and interacting magnetic field lines independent of any electrical current causality produce the release of energy and plasma during solar flares. They have named this process reconnection.
HannesAlfven
1 / 5 (2) Oct 26, 2011
Isn't it peculiar that physics students are not taught these things? Another direct quote from Alfven ...

> "Of course there can be no magnetic merging energy
> transfer. Despite.. this, we have witnessed at the
> same time an enormously voluminous formalism building
> up based on this obviously erroneous concept.

> I was naïve enough to believe that [magnetic
> reconnection] would die by itself in the scientific
> community, and I concentrated my work on more
> pleasant problems. To my great surprise the opposite
> has occurred: merging seems to be increasingly
> powerful. Magnetospheric physics and solar wind
> physics today are no doubt in a chaotic state, and
> a major reason for this is that part of the published
> papers are science and part pseudoscience, perhaps
> even with a majority in the latter group."
Vendicar_Decarian
1 / 5 (2) Oct 29, 2011
"Magnetic reconnection takes place when magnetic lines of force -- or field lines -- break apart and reconnect with a violent burst of energy that, in huge bodies such as the sun and stars, has the explosive power of millions of tons of TNT." - Article

Sorry Charlie, but there are no such things as "magnetic lines of force".

Magnetism is a fictitious force, the results from apparent charge imbalances caused by relativistic motion of charge and observer. It is the result of the assumption that charge density distribution is spherical and does not experience relativistic contraction or dilation, thus necessitating the invention of a fictitious force "Magnetism" to produce the difference between relativistic truth and pre-relativistic electric field theory.

To perpetuate the idea of magnetic field lines, is to perpetuate continued failure and misunderstanding of electrodynamics.
Cynical1
not rated yet Oct 29, 2011
Okay, VD. Think you may be onto something there. Maybe what we call magnetic lines of force is actually the dynamic boundary of an energy (electric or whatever someone wants to call it)field exhibiting properties(ie-magnetism) that effect other energy fields (inasmuch as it is fairly well accepted that everything is energy - just varying frquencies and levels).
On a larger scale could this somehow explain a gravity field?
Vendicar_Decarian
2.3 / 5 (3) Oct 29, 2011
There are no boundaries. EM fields are uniform to the quantum level. Field lines are an absolute fiction, be they magnetic or electric.

Magnetic field lines are to electromagnetism what lines of longitude and latitude are to geology.

"Maybe what we call magnetic lines of force is actually the dynamic boundary of an energy.." - Cynical1

Cynical1
not rated yet Oct 29, 2011
There are no boundaries. EM fields are uniform to the quantum level. Field lines are an absolute fiction, be they magnetic or electric.
Magnetic field lines are to electromagnetism what lines of longitude and latitude are to geology.

Really trying to wrap my head around this -
You're saying mag lines are what we use to represent boundaries?

And by saying there are no boundaries, do you mean they are everywhere at any given instant?

And lastly, are they just uniform TO the quantum level, or AT the quantum level, as well?
Isaacsname
not rated yet Oct 29, 2011
That's a little confusing for me as well, I can see " lines " formed by filings responding to magnetic materials, as opposed to seeing a Gaussian distribution.
Vendicar_Decarian
2.3 / 5 (3) Oct 29, 2011
"That's a little confusing for me as well, I can see " lines " formed by filings responding to magnetic materials" - isaacsname

What you are seeing are little iron bars aligning head to tail as a "magnetic field" is induced within them.

Their orientation is parallel to the "magnetic field" but their position can be displaced both along that field and at right angles to it.

There are no lines of force, only an orientation along a gradient, and clumping caused by the current induction withing the iron filings themselves.

Magnetic lines of force are like lines of equal altitude on a cartographers map.
Cynical1
not rated yet Oct 30, 2011
THAT is an interesting way of viewing "magnetism". Cogent, logical and reasoned.
vidyunmaya
1 / 5 (1) Oct 30, 2011
Sub:Magnetic Reconnection-Cosmological Projections
Let us take Science of Cosmology studies forward from Nobel Laur Hannes alfven . Van-Allen belts hold the key. 100Au forms a link from Cosmic Philosophy. Many links and projections are assumed in my books- Plasma Vision of the Universe-1993 and Plasma Regulated Electromagnetic Universe-1995. Then comes the heart and Center of the Universe around 100,000 LY beyond Milkyway.Source,fields,flows,Reflectors help to form protective Index -See Cosmology Vedas Interlinks-BOOKS BY VIDYARDHI NANDURI [1993-2011]-
http://vidyardhic...pot.com/
I welcome East-West Interaction. The above Crab Nebula image is included in my books

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