Flux Ropes in the Solar Wind

[CosmicLettuce]

First sentence of the introduction is fabulous!

"Twisted magnetic flux tubes, or flux ropes (FRs), are at least present in all astrophysical magnetic media that can be analysed with enough spatial resolution."

Just a quick glance tells me that this is a pretty significant article from an EU perspective.

Oh wow -- read the last paragraph, too. Very exciting.

http://arxiv.org/abs/1408.5520

Peace, CL

[Sparky]

Oh wow -- read the last paragraph, too. Very exciting.

But not worth posting here?!?

[Haig]

Oh wow -- read the last paragraph, too. Very exciting.

But not worth posting here?!?

Here is the last paragraph ...

Finally, a significant advance on the subject of the nature of flux ropes in the interplanetary medium is expected to be provided by the future Solar Orbiter and Solar Probe Plus missions. Indeed, with these missions, in situ data will be collected much closer to the Sun, where the propagation effects are weaker than at 1 AU.

Full paper in this PDF http://arxiv.org/pdf/1408.5520v1.pdf

[upriver]

He is some stuff I found awhile ago...

Flux tube texture of the solar wind: Strands of the magnetic carpet at 1 AU?
http://adsabs.harvard.edu/abs/2008JGRA..113.8110B


Voyager sees the flux tubes extending all the way to the heliosphere......

Observation of the multifractal spectrum at the termination shock by Voyager 1
http://www.cbk.waw.pl/~macek/publ/recent/macet11.pdf


proposal
ftp://ftp.lanl.gov/public/rfriedel/coll ... iscont.pdf

Tracking Back the Solar Wind to its Photospheric Footpoints from Wind Observations — A Statistical Study
http://xxx.tau.ac.il/pdf/1403.0901.pdf



"Abstract: PM9.00005 : Flux-Tube Texture of the Solar Wind: Weakly Compressible MHD Theory and Direct Numerical Simulations

Over the years, there has been a steady accumulation of observational evidence that the solar wind may be thought of as a network of individual magnetic flux tubes each with its own magnetic and plasma characteristics [Bartley et al. 1966, Marliani et al. 1973, Tu and Marsch 1990, Bruno et al. 2001, Borovsky 2008]. The weakly compressible MHD (WC-MHD) model [Bhattacharjee et al., 1998], which incorporates the effect of background spatial inhomogeneities, has been used recently to characterize the anisotropic magnetic fluctuation spectra (the so-called variance anisotropy) observed by ACE spacecraft. For a model of local pressure-driven interchange turbulence in a generic solar wind flux tube, the WC-MHD theory uses the Invariance Principle approach [Connor and Taylor 1997, Bhattacharjee and Hameiri 1988] to calculate explicitly the scaling of magnetic field fluctuations with plasma beta and other background plasma parameters. We test these theoretical predictions by direct numerical simulations of interchange turbulence in a flux tube using the DEBS MHD code. Synthetic variance anisotropy within a generic flux tube is computed in the high-Lundquist-number regime, and shows remarkable similarity with ACE observations."
http://meeting.aps.org/Meeting/DPP12/Session/PM9.5

[neilwilkes]

Magnetic Flux Tube aka Birkeland Currents.

[jjohnson]

See "Daughters of Pleione" under the TPOD heading below for a discussion of terminology. Scientists who stick with discussions based on "magnetic flux tubes" and ignore electrical side are shorting themselves and bamboozling the public. Intentional, or not?

jjohnson

[Metryq]

^ Can establishment astrophysicists be charged under Ohm's Law? How many amps will it take to break through this resistance to EU? They really need to be well grounded in an EE course.

[CharlesChandler]

Magnetic Flux Tube aka Birkeland Currents.

Literally -- the solar "flux tubes" are tied directly to the auroral currents, which is what Birkeland was studying when he developed the concept of magnetic field-aligned currents.

There is a steady stream of electrons out of the Sun. There is also a toroidal magnetic field. This is shown in the 1st pane of the following image. So what do we know about electric currents flowing in the presence of magnetic fields? They get deflected in the direction of those fields. So the 2nd pane shows the currents deflected toward the equatorial plane. But before the electrons meet in the middle, electrostatic repulsion keeps them apart, and ultimately, the electrons are pulled on out into the heliosphere. Ah but the currents are still spinning, so they have axial fields. Thus these spinning currents being pulled out into the heliosphere, axial magnetic fields and all, splits the Sun's toroidal magnetic field into open field lines projecting outward, which wouldn't be possible otherwise, as shown in the 3rd pane. So this electric current out of the Sun in all directions gets consolidated into the equatorial plane, at the tip of the helmet streamers, and projects out into space as the heliospheric current sheet.

http://qdl.scs-inc.us/2ndParty/Images/C ... rs_wbg.png

So what happens to the HCS? All other factors being the same, eventually, the current will relax. When it does, it will no longer be generating the magnetic fields necessary to keep it organized. So electrostatic repulsion between the electrons will disperse them, and the "open" magnetic field lines will be free to close.

http://qdl.scs-inc.us/2ndParty/Images/C ... se_wbg.png

Now we have just one more piece. Sitting in the middle of the HCS is the Earth, and its magnetic field is just half the strength of the Sun's, and it's way more powerful than the fields within the HCS. So the Earth's field will dominate, and it will direct the currents down the magnetic field lines and into the Earth, forming the aurora.

http://qdl.scs-inc.us/2ndParty/Images/C ... th_wbg.png

Note that the polarity of the Earth's field only matches the polarity of the Sun's field during every other solar cycle (since the Sun's field flips every 11 years). If the fields are opposite, the "flux tubes" in the HCS will have to be twisted around, to get north-to-north and south-to-south. But like I said, the Earth's field is far more powerful, so it will sort out the polarities in the HCS, and send the currents toward the poles.

[Metryq]

These "open" (in quotes) magnetic field lines are not like the magnetic reconnection so often derided in EU writings, correct? I'm just trying to visualize this. I know the magnetic field "lines" are merely a graphical convention for something that is really a three-dimensional volume.

[Rossim]

These "open" (in quotes) magnetic field lines are not like the magnetic reconnection so often derided in EU writings, correct? I'm just trying to visualize this. I know the magnetic field "lines" are merely a graphical convention for something that is really a three-dimensional volume.

Open field lines are another manifestation of the graphical representation. Where there is not enough room on the paper to connect the line from pole to pole, it appears open. These don't exist in nature

[upriver]

The actual paper.
The flux tube texture of the solar wind.
http://www.readcube.com/articles/10.1029/2007JA012684

[CharlesChandler]

These "open" (in quotes) magnetic field lines are not like the magnetic reconnection so often derided in EU writings, correct? I'm just trying to visualize this. I know the magnetic field "lines" are merely a graphical convention for something that is really a three-dimensional volume.

Yes, the lines are just a graphical convention, but there is more to "open lines" that just ones leading off-paper. The Sun (especially during its quiet phase) has a toroidal field, just like the Earth. So lines exiting the north pole loop around and re-enter at the south pole. But surprisingly, the north/south lines in the Sun's toroidal field don't close on themselves. Rather, they look like they're going to, but at the tips of the helmet streamers, they veer out into space in the heliospheric current sheet. So in the 1st pane of the following image, that blue toroidal line is expected, but what is actually measured is shown in the 3rd pane.

http://qdl.scs-inc.us/2ndParty/Images/C ... rs_wbg.png

In the mainstream literature, this is all very mysterious, but IMO, all of the riddles answer each other. There is an electric current in the heliospheric current sheet, which strangely has no associated magnetic fields. Then there are the magnetic flux tubes, which strangely don't have an identified electric current. Well, the electric current in the heliospheric current sheet causes the magnetic fields in the so-called flux tubes. And strangely, the Sun's toroidal magnetic field doesn't close on itself. But this isn't strange in the context of the Birkeland currents in the HCS, because Birkeland currents have axial magnetic fields that don't close locally -- they go wherever the current goes. So while the Sun's magnetic field deflects the currents toward the tips of the helmet streamers, the currents ultimately proceed out into space, and they take the magnetic field lines with them.

Brant: did you see what I was saying about the Earth's magnetic field latching onto the HCS, and thus perturbing the Parker Spiral? I don't know if this would alter your flare-up predictions, because I really just got to this point, and I'm still mulling it over, and I don't know how far downstream the effect would be. But I'm now thinking that there IS a direct electrical connection between the Sun and the Earth, and the other planets that have powerful magnetospheres, and that this connection is the HCS. In the vicinity of a planet, the HCS doesn't flag freely -- it's bound to the planet. The Earth's magnetic field is 10−5 teslas, while the HCS's (out at 1 AU) is10−9 teslas. So the Earth stays where it is, and the HCS follows the Earth's magnetic field lines. Your thoughts?

[CharlesChandler]

The actual paper.
The flux tube texture of the solar wind.
http://www.readcube.com/articles/10.1029/2007JA012684

Awesome! I just started into this, but rather than doing a thorough study, and posting a monograph on my thoughts, perhaps I should just make comments as I go.

First, the paper says that the scale of the flux tubes (aka Birkeland currents) corresponds roughly to the scale of granules on the Sun's surface. This is interesting because in my model, there is a steady drift of electrons away from the Sun. Electron drag creates the updrafts in the granules, while the downdrafts have to fight against electron drag. The implication for flux ropes is that the electron stream will be traveling the fastest coming out of the center of the granule, where the electrons lost the least amount of speed to collisions with +ions. Once out of the photosphere, these streams will accelerate, and get pinched into discrete tubes, each with its own surrounding magnetic field. So it makes sense that the flux tubes start out corresponding 1:1 with granules.

Also, it says that the polarity of the axial field within the flux tubes can vary from one to the next. This doesn't start out making sense. At the Sun, especially in the quiet phase, the ambient field is relatively consistent per hemisphere, so the electrons will all be thrown into Birkeland currents around axial fields pointing in the same direction. In one hemisphere of the Sun, it's one way, and in the other hemisphere, it's the opposite. But neighbors should have the same polarity. Ah, but what happens when we get out to 1 AU? The flux tubes come under the influence of the Earth's magnetosphere. Now, if the Sun's toroidal field happens to oriented opposite to the Earth's, flux tubes from one hemisphere of the Sun can feed directly into the same hemisphere of the Earth, as in the top pane in the following image. But in the following solar cycle, the Sun's polarity will be flipped. Then, the flux tubes have to cross each other, to enter the Earth's magnetosphere going in the right direction, as in the bottom pane of the image.

http://qdl.scs-inc.us/2ndParty/Images/C ... ty_wbg.png

In this crossing situation, it makes sense that the polarity of flux tubes changes from one to the next, as they weave their way past each other.

And of course during the active phase on the Sun, its magnetic fields are far more complex, so when the HCS reaches the Earth, there is going to be a lot more sorting, to get all of the north's going one way, and all of the south's going another, regardless of what part of the surface of the Sun created them in the first place.

And the ACE data that they used for that paper was from 1998~2004, which spanned an active phase, so the flux ropes would have been all mixed up. Once inside the geomagnetic field and down into the aurora, they are all sorted out. But at the surface of the Sun, it would have been a complex mix.

[upriver]

"NRL Scientists "See" Flux Rope Formation for the First Time"

"U.S. Naval Research Laboratory (NRL) scientists have observed, for the very first time, the formation of solar flux ropes, which are a type of solar magnetic field. Models of flux ropes have been drawn by theorists in the past, but scientists had never before observed them at the time they formed. The NRL team made their discovery using high-resolution images from the Atmospheric Imaging Assembly (AIA) aboard NASA's Solar Dynamics Observatory (SDO) and from the NRL-developed Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) telescopes aboard NASA's Solar Terrestrial Relations Observatory (STEREO).


This movie shows a blended 131 and 171 angstrom view of flux ropes forming and erupting.
(Photo: SECCHI Team /NRL/NASA)

These flux ropes have been seen with coronal mass ejections, or CMEs, before, but scientists had argued for years about whether the flux ropes formed before the CME or were formed on-the-fly as the eruption occurred. The answer will determine whether the dominant mechanism for CMEs is plasma instability or changes in the magnetic field connectivity via magnetic reconnection, respectively. The observations made by visiting scientist Dr. Spiro Patsourakos, and NRL researchers Drs. Angelos Vourlidas and Guillermo Stenborg clearly reveal that the flux rope forms before the CME occurs. Their results are published in the Astrophysical Journal issue of February 20, 2013."

http://www.nrl.navy.mil/media/news-rele ... first-time

This lends a little bit to my railgun model of CME's.

[upriver]

Experimental 3D reconnection and unexpected dynamics of flux ropes
http://www.cmso.info/cmsopdf/usjapan_oct09/Intrator.pdf


The Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas (CMSO) is a Physics Frontier Center established by the National Science Foundation. Its aim is to investigate basic problems in plasma physics, common to the laboratory and cosmos. Magnetic self-organization refers to the tendency of plasmas to rearrange spontaneously through processes that involve changing magnetic fields. Four phenomena form the focus for the Center, all of which can occur as part of the process of magnetic self-organization: dynamos and flow driven magnetic instabilities, magnetic reconnection, particle energizations, and multi-process and system integration.

The Center brings together laboratory and astrophysical scientists (as well as experimentalists, theorists, and computational scientists) to work together on the common problems. Nine experiments are enlisted for this purpose:

PRINCETON UNIVERSITY
The Magnetic Reconnection Device (FLARE/MRD)

UNIVERSITY OF WISCONSIN - MADISON
Terrestrial Reconnection Experiment (T-REX)
Madison Symmetric Torus (MST)
Madison Plasma Dynamo Experiment (MPDX)
Plasma Couette Experiment (PCX)

UNIVERSITY OF ROCHESTER
OMEGA EP Laser Systems (Omega-EP)

PRINCETON PLASMA PHYSICS LABORATORY
Magnetic Reconnection Experiment (MRX)
Magnetorotational Instability Experiment (MRI)

SWARTHMORE COLLEGE
Swarthmore Spheromak Experiment (SSX)

This set of experiments displays particularly robust magnetic self-organization, and will permit joint investigations of a phenomenon over a range of physical parameters.

COMPUTATIONAL TOOLS
Among the computational tools are three large-scale fluid codes and two large-scale kinetic codes. The fluid codes are: the FLASH code (the University of Chicago) written originally for astrophysical applications and the NIMROD code (developed by researchers at many institutions, and sponsored by the US Department of Energy) written for laboratory applications, and the LA-COMPASS code (the Los Alamos National Laboratory) written originally for laboratory, space and astrophysical plasma applications. The kinetic codes are: the GENE code, a gyrokinetic Vlasov solver developed at the Max Plank Institute for Plasma Physics, originally for toroidal laboratory plasma applications, and the VPIC code (the Los Alamos National Laboratory), a relativistic fully kinetic code that has been applied to laboratory, space and astrophysical plasma applications. Computation, plus analytic theory, is employed to connect experimental results to theory and astrophysics, as well as to examine new physical mechanisms. Collaborations have also been established with other institutions.

Set up with a funding authorization of five years, the Center was initiated in September, 2003 and renewed in 2008. Much of the established infrastructure - experimental and computational ­ is maintained by the Department of Energy. Hence, the Center can be viewed as a partnership between the NSF and DOE.

http://cmso.uchicago.edu/overview.php