The solar wind is swirly

The solar wind is swirly
Tiny turbulent swirls in the solar wind.

(Phys.org)—Using ESA's Cluster quartet of satellites as a space plasma microscope, scientists have zoomed in on the solar wind to reveal the finest detail yet, finding tiny turbulent swirls that could play a big role in heating it.

Turbulence is highly complex and all around us, evident in water flowing from a tap, around an aircraft wing, in experimental fusion reactors on Earth, and also in space.

In the stream of charged particles emitted by the Sun – the solar wind – turbulence is thought to play a key part in maintaining its heat as it streams away and races across the Solar System.

As the solar wind expands, it cools down, but to a much smaller extent than would be expected if the flow were smooth.

Turbulence arises from irregularities in the flow of particles and , but understanding how this energy is transferred from the large scales where it originates, to the small scales where it is dissipated, is like trying to trace energy as it is transferred from the smooth, laminar flow of a river down to the small turbulent eddies formed at the bottom of a waterfall.

In a new study, two of the four Cluster satellites have made extremely detailed observations of plasma turbulence in the solar wind.

They were separated by just 20 km along the direction of the plasma flow and operated in 'burst mode' to take 450 measurements per second.

By comparing the results with , scientists confirmed the existence of sheets of electric current just 20 km across, on the borders of turbulent swirls.

"This shows for the first time that the solar wind plasma is extremely structured at this high resolution," says Silvia Perri of the Universita della Calabria, Italy, and lead author of the paper reporting the result.

Cluster previously detected current sheets on much larger scales of 100 km in the magnetosheath, the region sandwiched between Earth's – the – and the that is created as it meets the solar wind.

At the borders of these turbulent eddies the process of 'magnetic reconnection' was detected, whereby oppositely directed field lines spontaneously break and reconnect with other nearby field lines, thus releasing their energy.

"Although we haven't yet detected reconnection occurring at these new, smaller scales, it is clear that we are seeing a cascade of energy which may contribute to the overall heating of the ," said Dr Perri.  

Future missions such as ESA's Solar Orbiter and NASA's Solar Probe Plus will be able to determine whether similar processes are also in play closer to the Sun, while NASA's Magnetospheric Multiscale mission will specifically probe the small-scale regions where reconnection can occur.

"This Cluster result demonstrates the mission's unique capability to probe universal physical phenomena, in this case pushing the mission's instrument measurement capabilities to their limit to unlock features at small scales," comments Matt Taylor, ESA's Cluster Project Scientist.

"Future multi-spacecraft missions will make very detailed studies of these small-scale plasma phenomena and provide further context to our Cluster measurements."


Explore further

Cluster opens a new window on 'magnetic reconnection' in the near-Earth space

More information: Perri, S. et al., Detection of small scale structures in the dissipation regime of solar wind turbulence. Physical Review Letters, 8 November, 2012
Journal information: Physical Review Letters

Citation: The solar wind is swirly (2012, December 19) retrieved 18 July 2019 from https://phys.org/news/2012-12-solar-swirly.html
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Dec 19, 2012
Voyager also detected these "magnetic bubbles" and a highly turbulent region at the termination shock


Yes, but please note that the above article is talking about the bow shock in front of the Earth, not the bow shock in front of the solar system. These are things happening inside the solar system, in the solar wind. Conditions in the interstellar medium are an entirely different story.

Dec 19, 2012
"Magnetic reconnection is pseudo-science" Hannes Alfven

And there is no "bow shock" in a plasma environment, it is instead called a double layer. The release of energy is from an exploding double layer, not "reconnection". Hannes Alfven pointed this out quite clearly in his Nobel acceptance speech, but as with in the past he has been largely ignored.
Read Current free double layers;
http://www.thunde...apter-5/

And Current carrying double layers;
http://www.thunde...apter-7/

Dec 19, 2012
Also note the cellular and filamentary characteristics of the inset image, all should have been expected if the proper application of plasma physics were employed.

Dec 19, 2012
The misrepresentation due to "semantics" leads to misunderstanding of the phenomenon. And it was my understanding that science needs to be very specific in it's nomenclature. Just as we don't call ice a liquid, we also shouldn't label plasma a gas. If something is what it is, why call it something it isn't? It leads to confusion and misunderstanding among both the people who are studying it as well as the layman.

Dec 20, 2012
and say it is because the heliosphere isn't moving through the ISM, it is moving with it as would happen if you suspend a magnetic bubble inside a magnetic web, the entire region has the same inertial reference frame


That seems plausible. I think that once Voyager gets into the ISM, we'll have a better idea of what to look for next. That might mean building a specialized observatory, or sending a dedicated probe into the ISM with instruments specifically designed to answer whatever questions the Voyagers leave us with.

I tend to think that the ISM will teach us some things about quantum theory. The ISM is a region where quantum effects might be observed in bulk. We can't mimic that environment here on Earth, since we can't get anywhere near that level of vaccum. It might be interesting to try some fundamental experiments there.

Dec 20, 2012
It may take voyager a year to record directional changes in the ISMF, or I could be way off and the region could be complete chaos...or very quiet


I think that we have already seen evidence that it is chaotic. Remember that Voyager moved into and back out of the boundary zone several times before moving beyond it. That seems to indicate that the boundary shifts forward and backwards a lot. We know the solar wind is fairly constant at that distance, as well as the solar magnetic fields. Voyager measured that. So the only thing that could make the boundary region shift around so much would be variations from the other side. If we're moving 'with' the ISM, then it must be very turbulent. If we're moving 'through' it, then it must be either turbulent, varrying in density, or both. I'm leaning towards the 'both' option.

Dec 23, 2012
Does anyone else here see the fluid dynamics aspect of this sort of info? Sounds suspiciously like Aether Theory is making an endaround play...

Dec 23, 2012
Does anyone else here see the fluid dynamics aspect of this sort of info? Sounds suspiciously like Aether Theory is making an endaround play...

Fluid dynamics doesn't apply to plasma.
"The fluids states of gas and liquid are treated with the Navier-Stokes equation whereas plasmas are treated with the Boltzmann and Maxwell equations."

http://plasmauniv...derstand

Dec 23, 2012
Does anyone else here see the fluid dynamics aspect of this sort of info? Sounds suspiciously like Aether Theory is making an endaround play...

Fluid dynamics doesn't apply to plasma.
"The fluids states of gas and liquid are treated with the Navier-Stokes equation whereas plasmas are treated with the Boltzmann and Maxwell equations."

http://plasmauniv...derstand

I don't care how someone may calculate it's actions - it still acts in a fluid LIKE manner.

Dec 24, 2012
Does anyone else here see the fluid dynamics aspect of this sort of info? Sounds suspiciously like Aether Theory is making an endaround play...

Fluid dynamics doesn't apply to plasma.
"The fluids states of gas and liquid are treated with the Navier-Stokes equation whereas plasmas are treated with the Boltzmann and Maxwell equations."

http://plasmauniv...derstand

I don't care how someone may calculate it's actions - it still acts in a fluid LIKE manner.

No, not really. It is FAR more complex and not at all fluid "like" at all. The essential point to bear in mind when considering space plasma is that it often behaves entirely unlike a gas. The charged particles which are the defining feature of a plasma are affected by electromagnetic fields, which the particles themselves can generate and modify. Fluids are not self organizing/modifying in this manner. I know I'm splitting hairs here, but it's really apples and oranges.

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