Peering into cosmic magnetic fields

January 22, 2015, Lawrence Livermore National Laboratory
Inside the Omega Laser Facility’s target chamber during a shot. Experiments at this facility have provided insight into magnetic field generation. Credit: University of Rochester’s Laboratory for Laser Energetics

The generation of cosmic magnetic fields has long intrigued astrophysicists. Since it was first described in 1959, a phenomenon known as Weibel filamentation instability—a plasma instability present in homogeneous or nearly homogeneous electromagnetic plasmas—has generated tremendous theoretical interest from astrophysicists and plasma physicists as a potential mechanism for seed magnetic field generation in the universe.

However, direct observation of Weibel-generated magnetic fields remained challenging for decades. In a Nature Physics paper (link is external) published this week, Lawrence Livermore National Laboratory (LLNL) researchers report for the first time well-developed, oriented magnetic filaments generated by the Weibel mechanism in counter-streaming, collision-less flows generated by high-power lasers.

"Comparison with 3D particle-in-cell simulations and a first-principles theoretical treatment proves that the generation in such flows is real, and quite efficient," said lead author Channing Huntington, a physicist at LLNL.

The team's findings demonstrate the power of the Weibel instability to produce small-scale seed magnetic fields throughout the cosmos, which can be then further amplified to larger scales, creating the ubiquitous magnetic fields that are seen to exist in astrophysical systems. In addition, Weibel-generated magnetic fields may trap plasma ions, creating localized shocks where cosmic ray particles could be accelerated.

Counter-streaming plasma flows are generated using several laser beams to heat opposing plastic disks. A separate set of beams directly implodes a glass capsule containing deuterium and helium gas. The implosion generates a burst of protons that stream through the plasma flows and are deflected by electric and magnetic fields before reaching a detector plate, effectively recording the pattern of fields in the system.

Peering into cosmic magnetic fields

The researchers employed protons produced by the implosion of a D-3He (deuterium and helium) capsule that produced single energy at high flux. This high-quality data unambiguously revealed the elusive Weibel filamentation instability, which is a fundamental result that, due to the scalability of this process, will have a strong impact on the thinking of astrophysicists. Additionally, the 3D simulations performed to complement the data utilize cutting-edge techniques in the field of advanced computation, further extending the applicability of this work. These experiments were conducted at the Omega Laser Facility at the University of Rochester's Laboratory for Laser Energetics.

"It is well-known that a range of magnetic field scales exist in the cosmos, but the origin of these fields has been an elusive question," Huntington said. "Weibel instability has long been theorized as a mechanism to generate these fields, but this work offers the most compelling experimental evidence to date that this is indeed possible."

Having developed a robust experimental platform and confirmed the generation of Weibel filamentation, the team envisions a broad range of follow-up experiments on OMEGA to test the magnetic field generation under conditions that are relevant to astrophysical systems (for example, in the presence of a pre-existing magnetic field, which may modify the instability growth). They also have begun a set of experiments at LLNL's National Ignition Facility, where larger, faster plasma flows are believed to produce even higher fields and the Weibel mediated shock formation will be fully mature. These experiments will reach conditions not previously achieved in a laboratory setting.

Explore further: The largest magnetic fields in the universe

More information: "Observation of magnetic field generation via the Weibel instability in interpenetrating plasma flows." Nature Physics (2015) DOI: 10.1038/nphys3178

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17 comments

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cantdrive85
Jan 22, 2015
This comment has been removed by a moderator.
Maggnus
2.9 / 5 (14) Jan 22, 2015
Of course, the title has "magnetic field" in it, so cantthink has to comment with some debunked EU garbage.

EU is pseudo-science.
rufusgwarren
3 / 5 (2) Jan 22, 2015
Huh? First magnetic fields imply charged particles moving with respect to us. What is the static field of these particles?
rufusgwarren
3 / 5 (2) Jan 22, 2015
And what is the "real" relative velocity? Based upon the wavefront of the field or the field itself, H does not lie!
rufusgwarren
1 / 5 (1) Jan 22, 2015
Isn't there a simpler way to understand the state of these sources? Flux density! Is only relative!
rufusgwarren
1 / 5 (1) Jan 22, 2015
Like to analyze this spectrum based upon relative speeds to produce H fields, etc. With and without GR. Gotta be some interesting identifiable fingerprints, both ways.
RealityCheck
3.2 / 5 (9) Jan 22, 2015
Hi Maggnus.
Of course, the title has "magnetic field" in it, so cantthink has to comment with some debunked EU garbage.
Be Maggnanimous, Maggnus. :)

Did you actually read the above article/paper? It supports what candrive and HannesAlfven have been saying about this particular aspect. That is, the KNOWN LABORATORY behavior/sources of plasma/fields have their larger-scale counterparts in the wider universal processeses.

Come on, Maggnus, admit that they were right on this bit at least. This mainstream team finally did what cantdrive and HannesAlfven have been recommending they do: explore/apply already well known LAB plasma streamflow/surface/instabilities/disruption/reconnection etc phenomena to astrophysical scales/observations/interpretations/conclusions re 'magnetic fields'; which, as above work demonstrates, is so dependent on, and 'shaped' and directed by, underlying PLASMA entities/states/flows as well as gravity effects.

Be objective on this one, hey? :)
rufusgwarren
3 / 5 (2) Jan 23, 2015
A magnetic field is reference to any frame and is translatable. However, so is the particles and field. Nobody's arguing the basic physics. It's translating the perceived data. If it is a current, then is this linear, nonlinear, .. I heard Weibull, then this is an opportunity to translate to all these frequency domains looking for known signatures. Sounds like a reasonable thing to do. i.e. spatial, temporal, and spectral, wave-front?? Anyway, the way I would search the spectrum, I'd look for known signatures everywhere.
rufusgwarren
1 / 5 (1) Jan 23, 2015
"It is well-known that a range of magnetic field scales exist in the cosmos, but the origin of these fields has been an elusive question," Huntington said. "Weibel instability has long been theorized as a mechanism to generate these fields, but this work offers the most compelling experimental evidence to date that this is indeed possible."


It is interesting to note that nowadays we still do not understand the basic nature of the familiar magnetic field created by a moving electron; maybe knowing the mechanism could lead to insight the vast magnetic field scales exist in the cosmos ….
http://www.vacuum...=7〈=en

The H is field is a result of a spatial-temporal variant e field, which is an obvious result of the moving singularity of the e field, charge. The singularity's motion may be translated to a static field, i.e. relative motion. So all that really exist is the singularity.
cantdrive85
3 / 5 (6) Jan 24, 2015
Huh? First magnetic fields imply charged particles moving with respect to us. What is the static field of these particles?

We need not be the center of the Universe, the charged particles need only to be moving in relation to the other charged particles.
cantdrive85
3.3 / 5 (7) Jan 24, 2015
Come on, Maggnus, admit that they were right on this bit at least. This mainstream team finally did what cantdrive and HannesAlfven have been recommending they do: explore/apply already well known LAB plasma streamflow/surface/instabilities/disruption/reconnection etc phenomena to astrophysical scales/observations/interpretations/conclusions re 'magnetic fields'; which, as above work demonstrates, is so dependent on, and 'shaped' and directed by, underlying PLASMA entities/states/flows as well as gravity effects.

Be objective on this one, hey? :)


He is incapable of objectivity, he only is able to mindlessly defend his dogmatic beliefs.
HannesAlfven
3.4 / 5 (5) Jan 24, 2015
Re: "This mainstream team finally did what cantdrive and HannesAlfven have been recommending they do: explore/apply already well known LAB plasma streamflow/surface/instabilities/disruption/reconnection etc phenomena to astrophysical scales/observations/interpretations/conclusions re 'magnetic fields'; which, as above work demonstrates, is so dependent on, and 'shaped' and directed by, underlying PLASMA entities/states/flows as well as gravity effects."

That complex "skeletal" electrical filament and hub structures naturally form in plasmas can be observed through careful photography of tokamaks, and nobody should imagine that there was any cosmological seed necessary in such laboratories to form them.
Whydening Gyre
3 / 5 (2) Jan 24, 2015
Some of you are forgetting the fact that SOME thing has to create the electric field first. How have been able to do that? Physical interaction of magnetic fields. The passing of an electron from one atomic shell to another via magnetic imbalance.
Sometimes simplest just means - simplest...

Yes, it can be that simple...
RealityCheck
2.6 / 5 (5) Jan 24, 2015
Hi Whyde. :) I was just about to log out, when I saw this from you above. Please be careful not to fall into the "that simple" trap. Be aware that the Electron's ELECTRIC field exists irrespective of interactions with other fields. That is what constitutes an Electron...its quantum Electric feature/structure in a combined cosmic "electro-magnetic" field context. It's he existence of electric fields per se as FUNDAMENTAL STATES of energy-space dynamics which makes possible the 'expression' of the "Magnetic effects' component of the COMPOSITE "electro-magnetic field" phenomena overall.

Magnetism wouldn't be possible without a-prior electric charge/field effects; which remain such when 'static relative'; but present the 'magnetic field effects' aspects of the 'electro-magnetic phenomena' when 'moving relative' to other electric charges...creating/effecting all the electro-magnetic complexity of features and flows we observe.

And GRAVITY moves Electrons too. Bye! :)
yep
2 / 5 (4) Feb 11, 2015
Funny how some of these trolls came by for down votes, but left no comments. I guess with the mighty Magnus getting owned they did not want to chance it.
Can't argue the point? Just down vote it? That's winning?
Choke on some crow boys and girls more data every day.
Vietvet
2.3 / 5 (6) Feb 11, 2015
Funny how some of these trolls came by for down votes, but left no comments. I guess with the mighty Magnus getting owned they did not want to chance it.
Can't argue the point? Just down vote it? That's winning?
Choke on some crow boys and girls more data every day.


EU is bull sh*t. It's a waste of my time arguing with idiots.
cantdrive85
3 / 5 (8) Feb 11, 2015
Funny how some of these trolls came by for down votes, but left no comments. I guess with the mighty Magnus getting owned they did not want to chance it.
Can't argue the point? Just down vote it? That's winning?
Choke on some crow boys and girls more data every day.


EU is bull sh*t. It's a waste of my time arguing with idiots.

Your senile old ass is far too stupid to argue anything other than which brand of adult diapers you prefer.

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