Magnetic reconnection and physical processes

[Michael Mozina]

"Let's try to get real focused here for a second. Is the photosphere fully ionized in your opinion or is it "dusty" with non ionized gases in it?"

Irrelevant and off topic.

Oh that's a riot:

Once again, you demonstrate your cluelessness. That picture is indeed a discharge. And guess what, Michael? It's happening in air. Which is a gas.

Send many mixed messages?

 

[Michael Mozina]

You don't get it. It doesn't matter if gasses can conduct a little bit. The dielectric breakdown is still an abrupt and giant transition in conductivity, and there is no such transition in a plasma.

That depends entirely on the plasma and the current flow involved. A z-pinch can still form inside a "plasma". There can also be a giant transition in conductivity between different ionization states within the same plasma.

 

[Ziggurat]

That depends entirely on the plasma and the current flow involved. A z-pinch can still form inside a "plasma".

I never said a z-pinch couldn't form inside a plasma. I said dielectric breakdown couldn't happen in a plasma, since it's already conducting.

There can also be a giant transition in conductivity between different ionization states within the same plasma.

Yes, when it's subjected to giant differences in conditions. Which is in marked contrast to dielectric breakdown, where small changes in conditions (namely, the field) lead to giant changes in conductivity. The transitions between different ionization levels in a plasma, as well as the conductivity of that plasma, are gradual, not abrupt. You still haven't wrapped your head around this simple concept. It's such a fundamental part of the difference between plasmas and gasses that one would have thought you'd be aware of it. But you not only weren't aware of it, you're trying to deny it even when being told of it.

 

[Tim Thompson]

Dusty Plasma

Gah. Have you even read Cosmic Plasma yet?

So, how about a show of hands from Michael Mozina:
Have you read Magnetic Reconnection: MHD Theory and Practice by Priest & Forbes?
Have you read Nonlinear Magnetohydrodynamics by Deiter Biskamp?
Have you read Fundamentals of Plasma Physics by Paul Bellan?
Have you read The Physics of Plasmas by T.J.M. Boyd & J.J. Sanderson?
Have you read Plasma Physics for Astrophysics by Russell Kulsrud?
Have you read Plasma Astrophysics by Toshiki Tajima & Kazunari Shibata?
Have you read Conversations on Electric and Magnetic Fields in the Cosmos by Eugene Parker?

Well? have you?

All plasmas are "dusty"

Is the photosphere fully ionized in your opinion or is it "dusty" with non ionized gases in it?

Watching you try to "talk science" can be really amusing. I hate to break the bad news, but "dusty" plasmas have to have dust in them; that's why they are called dusty, get it?. The presence of neutral gas does not qualify as "dusty", but rather only "partially ionized". Now, had you read, say, Fundamentals of Plasma Physics by Paul Bellan, from the list above, you would have encountered chapter 17 (title: Dusty Plasma) and thus avoid the public embarrassment of having someone demonstrate that you can't tell the difference between "gas" and "dust". But self-imposed ignorance rides again! The point is that dust grains are quite massive compared to the surrounding gas molecules, and therefore have a much different charge to mass ratio, which in turn affects the dynamics of the plasma (the dust is also almost always charged, not necessarily neutral).

Therefore, when you say ... All plasmas are "dusty" ... you are talking complete nonsense. Only plasmas with "dust" in them are "dusty".

So riddle me this, Batman ... Why should we seriously consider that a guy who can't tell the difference between "gas" and "dust" can still overturn all of modern physics?

 

[Zeuzzz]

I never said a z-pinch couldn't form inside a plasma. I said dielectric breakdown couldn't happen in a plasma, since it's already conducting.

Here you assume a homogenous based structure for the plasma which will, given its highly conductive state, make dielectric breakdown less likely. How ever in reality all plasmas are inhomogeneous, some to such an extent that repeating cellular structures and force free filaments form. The currents making the plasma always interact and large charge build up, in areas of the circuit with higher voltages, can lead to situations where dielectric breakdown does happen in plasma. The dielectric constant of a plasma can be found by setting w₀ to 0 and n to the number density of electrons where the characteristic frequency is the plasma frequency (from E = 1 - [w²_p / w²])

See this for a start;
Model for Dielectric Breakdown in Plasma-Polymerized Styrene Thin Films
http://jjap.ipap.jp/link?JJAP/21/483/

Or
Penetration of a dielectric barrier discharge plasma into textile structures at medium pressure
N De Geyter et al 2006 Plasma Sources Sci. Technol. 15 78-84
http://www.iop.org/EJ/abstract/0963-0252/15/1/012

Plasma treatment of textiles is becoming more and more popular as a surface modification technique. Plasma treatment changes the outermost layer of a material without interfering with the bulk properties. [...]
a dielectric barrier discharge to study the influence of pressure and treatment time. Current and voltage waveforms and Lichtenberg figures are used to characterize the discharge. Process pressure proved to have an important effect on the penetration of the plasma through the textile layers. This is caused not only by the pressure dependence of diffusive transport of textile modifying particles but also by a different behaviour of the barrier discharge.

And also you cant ignore the chemistry involved either, as pointed out here:

Dielectric breakdown in F-doped SiO2 films formed by plasma-enhanced chemical vapor deposition
http://ieeexplore.ieee.org/Xplore/l...0709302.pdf?arnumber=709302&authDecision=-203

Abstract

Fluorine-doped thin silicon dioxide films were synthesized by plasma-enhanced chemical vapor deposition of tetraethoxysilane and CF 4, and the dielectric strength was measured with a self-healing breakdown technique by applying short duration voltage pulses. As a result, the film containing a higher amount of fluorine has a higher dielectric strength. The reason for this increase is discussed from various aspects, and two persuasive mechanisms are presented

 

[Reality Check]

Here you assume a homogenous based structure for the plasma which will, given its highly conductive state, make dielectric breakdown less likely.

There is no assumption. This is what plasmas are. They are ionized gases. They can never experience dielectric breakdown because they conduct. In a sense they are always broken down.

Model for Dielectric Breakdown in Plasma-Polymerized Styrene Thin Films
http://jjap.ipap.jp/link?JJAP/21/483/

Nothing to do with plasmas.

Penetration of a dielectric barrier discharge plasma into textile structures at medium pressure
N De Geyter et al 2006 Plasma Sources Sci. Technol. 15 78-84
http://www.iop.org/EJ/abstract/0963-0252/15/1/012

Plasma treatment of textiles is applying a plasma to the textile. My guess is that "dielectric barrier discharge plasma" is plasma created from dielectric barrier discharge.

Dielectric breakdown in F-doped SiO2 films formed by plasma-enhanced chemical vapor deposition
http://ieeexplore.ieee.org/Xplore/lo...hDecision=-203

And nothing to do with dielectric breakdown in plasmas.

Does the lack of scientific papers on dielectric breakdown in plasmas tell you something, Zeuzzz?

Of course we could just start listing all 37,000 results from Google Scholar for 'dielectric breakdown in a plasma'!

 

[brantc]

Yes, discharges maybe, but not reconnection. But as reconnection is not a discharge, that is no problem at all.

That is an important point. With a single filament(lightning or any spark or arc) you have the pinch effect responsible for the constriction of a single stroke. This produces the high energy photons and particles.

With a reconnection, it takes place between 2 filaments and you have a change in direction of current flow momentarily across filaments changing the magnetic field topology. As this is happening there is a moment where a strong double layer is formed and this accelerates the particles producing the jets observed.

The interesting case is the FTE's that happen. You begin to get an idea of how this system works from reading CLUSTER papers and looking at TRACE movies.

You have a current flow that builds up some magnetic field(Curl?) along the filament pair.
The reconnection happens which cuts the filament pair off from the rest of the filament. This filament piece is now a plasmoid because it is formed from the 2 pieces of the cut off filament joined.
This filament piece has a a curl? field and as it loses energy, it injects that as a current into the flux tube along the parallel field. This causes the field aligned current that helps reform the flux tube for the next cycle. The energy for this comes from the electric field at the end of the flux tube(rope).


The structure of an earthward propagating magnetic flux rope early
in its evolution: comparison of methods
http://www.ann-geophys.net/27/2215/2009/angeo-27-2215-2009.pdf


We have to remember that all of this stuff is not static. Its all dynamic. We are only looking at snap shots.

 

[Zeuzzz]

Of course we could just start listing all 37,000 results from Google Scholar for 'dielectric breakdown in a plasma'!

Aye could start scouring scholar, or actually re-learning all that dielectric strength etc mallarchy, or could go to bed. Latters more appealing tbh.

 

[Zeuzzz]

There is no assumption. This is what plasmas are. They are ionized gases. They can never experience dielectric breakdown because they conduct. In a sense they are always broken down.

Maybe in simplified or ideal equations but not in real life.

There will be neutral areas, boundaries and self sustaining features depending on a plethora of situations.

On the wp page for plasma physics:

Cellular structure

Narrow sheets with sharp gradients may separate regions with different properties such as magnetization, density, and temperature, resulting in cell-like regions. Examples include the magnetosphere, heliosphere, and heliospheric current sheet. Hannes Alfvén wrote: "From the cosmological point of view, the most important new space research discovery is probably the cellular structure of space. As has been seen in every region of space which is accessible to in situ measurements, there are a number of 'cell walls', sheets of electric currents, which divide space into compartments with different magnetization, temperature, density, etc ."[21]

[21]Hannes Alfvén (1981). "section VI.13.1. Cellular Structure of Space". Cosmic Plasma. Dordrecht. ISBN 9027711518.

Also

http://plasmascience.net/tpu/ubiquitous.html

While all matter is subject to gravitational forces, the positively charged nuclei, or ions, and the negatively charged electrons react strongly to electromagnetic forces, as formulated by James Clerk Maxwell (1831-1879) and Hendrik Antoon Lorentz (1853-1928). because of this strong interaction with electromagnetism, plasmas display a compexity in structure that far exceeds that found in matter in the gaseous, liquid, or solid states. In addition to the cellular structure, most visible to us on the Sun, plasmas most often display a filamentary structure. This structure drives from the fact that plasma, becaue ot its free electrons, is an excellent conductor of electricity, far exceeding the conducting properties of metals such as copper or gold. For example, the ballast resistor in a fluorescent lighting system is included for good reason. The florescent gas, as weakly ionized as it is, would completely short circuit the electrical main supply without the resistor. Wherever charged particles flow in a neutralizing medium, such as free electrons in a background of ions, the charged particle flow or current produces a ring of magnetic field around the current, pinching the plasma into multi-filamentary strands of conduction currents.

Beyond the filamentation, by far the most distinguishing characteristic of energetic plasma in comparison with the states of matter on the crustal regions of planets is that plasma are prodigious producers of electromagnetic radiation.

 

[Zeuzzz]

And one more and im off for a day

http://ieeexplore.ieee.org/Xplore/l...00045496.pdf?arnumber=45496&authDecision=-203

A review is presented of basic electrodynamic properties as revealed by laboratory and space plasma experiments, and their consequences. They include the coupling between magnetic fields and the motion of matter, filamentary and cellular structure, anomalous momentum coupling, and new mechanisms of chemical separation. It is concluded that some of these properties, obviously important for the understanding of the present-day universe, must also have been important in the cosmological evolution of which today's Universe is the result. As some of the crucial properties are still poorly understood, but are being investigated by laboratory and space-plasma experiments, the results of such experiments should also be relevant to the development of cosmology

 

[CaveDave]

The Man gave good links, which I guess I could have provided.

His links were excellent and very pertinent to my request.
You may have been mistaking me for a troll, which I cannot blame you for, due to the combative nature of certain posters here.

No problem.

About sunrise and sunset, there is a difference between the "dawn" side and the "dusk" side of the magnetosphere with the latter being more active than the former.

Those were the terms I had seen and I incorrectly called them by the wrong names.

Thank you for clarifying my confusion.


[EXPLANATORY DERAIL]
A brief explanation of my type of understanding.

I may be an oddity (most of my friends think so!), but I tend to be VERY visual and verbal in the mode of my learning; sometimes a picture (or schematic diagram or graphed function) plus a descriptive paragraph, will convey, to MY mind, far more than a dozen equations would to more normal-thinking math-based person.
I understand what I am looking at when I see an equation, in that I know the basic operators (even up to integrals and derivatives, and vector operations) and what (most) variables stand for, and could , with some difficulty, substitute actual numbers in, to graph the function, but a simple graph (or set of graphs) with well-defined axes tells me far more.

I hated arithmetic, but loved geometry, trigonometry, differentiation and integration, Venn diagrams, matrices, determinants, Symbolic Logic, and vectors. They were more visual.

I hated English class until we studied sentence graphing; now I "see" sentences as graphs.

I love music, and can hear the separate parts, and even visualize the score, but I fail miserably anytime I try to play an instrument. I have very good Relative (probably not Perfect) Pitch, and can hear off-key notes easily, but I can't name key signatures or chords even after years of lessons.

I don't know why it is so, but it has always been this way.

Please bear with me.
[/EXPLANATORY DERAIL]

Cheers,

Dave

 

[tusenfem]

I said a textbook or scientific paper.
Not the same old debunked web page that you keep on regurgitating. Bruce was ignorant enough to think that solid particles can exist at temperatures of 6000K in the Sun. Actually he ignores the science that shows that the photosphere is 6000K and arbitarily states that it is 4000K (also no solid particles!)
Do not be as dumb as him.


z-pinch

Here are TT's comments on Bruce

 

[tusenfem]

Let's try to get real focused here for a second. Is the photosphere fully ionized in your opinion or is it "dusty" with non ionized gases in it?

No, the photosphere is not 100% ionized, but then again neutrals are NOT dust. Just one more redefinition of Michael Mozina in order to confuse people. A dusty plasma: A dusty plasma is a plasma containing nanometer or micrometer-sized particles suspended in it.

Let's take neutral iron, which MM must like because of his "iron crust" which must get sputtered by the impacting electron beams created by his zeta-pinches.

The size of a neutral Fe atom, depending on how you measure it varies between 125 - 150 pico meter, which is at least a factor of 10 smaller than the smallest particles that can be considered "dust" in a plasma.

Also, dust is usually negatively charged, whereas the neutral atoms will get ionized and thus become positive.

However, whether the photosphere is fully ionized or not (and you can use the Saha relation to calculate the exact ratio of you like) is irrelevant, as the present ions and electrons will have good enough conductivity already to create conducting path ways such that discharges as we see in the Earth's atmosphere in lightning will not be present, as there is no dielectric to break down after a large electrostatic charge has been build up.

 

[Reality Check]

Maybe in simplified or ideal equations but not in real life.

There will be neutral areas, boundaries and self sustaining features depending on a plethora of situations.

In real life: Plasmas are ionized gases (but not all ionized gases are plasma!).
There will not be any dielectric breakdown because plasmas are not insulators and you need an insulating medium for electrical discharges through dielectric breakdown to happen.

There will be neutral areas, boundaries and self sustaining features depending on a plethora of situations, e.g. double layers.
None of these will turn the plama into an insulating medium for the simple reason that a plasma that insulates is a gas: Comparison of plasma and gas phases.

I find this simple to understand. I do not know why you cannot.

 

[tusenfem]

[commenting on X and gamma rays comment by MM]
Yes, discharges maybe, but not reconnection. But as reconnection is not a discharge, that is no problem at all.

That is an important point. With a single filament(lightning or any spark or arc) you have the pinch effect responsible for the constriction of a single stroke. This produces the high energy photons and particles.

In a discharge the size of the "filament" is determined by the size of the break down channel and when the discharge takes place a pinch effect will keep the current confined. I don't know a bout high energy photons, usually it is only visible light where most of the energy goes (if I am not mistaken), the 'high energy particles" are created by the potential drop that is "released" through the discharge and has nothing to do with the pinch.

With a reconnection, it takes place between 2 filaments and you have a change in direction of current flow momentarily across filaments changing the magnetic field topology. As this is happening there is a moment where a strong double layer is formed and this accelerates the particles producing the jets observed.

Yes, reconnection can happen between two filaments, it can also just happen in the Earth's magnetotail, which I would hardly call a filament.
What strong double layer? Do you actually know what a double layer is? Not every electric field that may appear in a plasma is immediately a double layer. Yes, there may be electric fields, created by induction, no there are no double layers which depend on charge separation.
And then it is unclear what jets you mean here. Do you mean the bulk acceleration of the plasma perpendicular to the magnetic field in the reconnection exhaust? Then double layers can impossibly do that, do you mean the field aligned currents along the separatrices (like in the paper I just linked to) then again double layers cannot produce them, because they are not created near the reconnection site, although the may occur further away along the separatrix under special conditions.

The interesting case is the FTE's that happen. You begin to get an idea of how this system works from reading CLUSTER papers and looking at TRACE movies.

FTE's are interesting yes.

You have a current flow that builds up some magnetic field(Curl?) along the filament pair.
The reconnection happens which cuts the filament pair off from the rest of the filament. This filament piece is now a plasmoid because it is formed from the 2 pieces of the cut off filament joined.

You really have to get clearer here. What filament pair are you talking about. Most of the reconnection does not happen in just filament pairs, but that as an aside.
"Which cuts the filament pair off from the rest of the filament" what is that supposed to mean? And then it is suddenly a plasmoid? I think you are reading too many papers without understanding the basics, why not start reading up on reconnection in a simple text book instead of diving into rather complicate papers?

This filament piece has a a curl? field and as it loses energy, it injects that as a current into the flux tube along the parallel field. This causes the field aligned current that helps reform the flux tube for the next cycle. The energy for this comes from the electric field at the end of the flux tube(rope).

"The filament piece has a curl?" I am glad it has at least a "?"
You really do not understand what "curl" is do you?
"it injects that as a current" I assume "that" refers to the "curl" but curl(B) IS a current. And the "filament piece" is that the "plasmoid" that you were talking about earlier or is it the "left over" piece that did not get to be a plasmoid or what?
"The electric field at the end of the flux tube" does not make any sense at all.

The structure of an earthward propagating magnetic flux rope early
in its evolution: comparison of methods
http://www.ann-geophys.net/27/2215/2009/angeo-27-2215-2009.pdf


We have to remember that all of this stuff is not static. Its all dynamic. We are only looking at snap shots.

Before you start discussing Christian's paper (he works upstairs from me), you should first read up on basic electrodynamics and basic reconnection (although Mostl's paper does not discuss MRx).

And we are highly aware that this all is not static, thank you.

 

[tusenfem]

Maybe in simplified or ideal equations but not in real life.

There will be neutral areas, boundaries and self sustaining features depending on a plethora of situations.

On the wp page for plasma physics:

Also

http://plasmascience.net/tpu/ubiquitous.html

Neutral here means neutral plasma, which means that there are equal amount of negative and positive charge in volumes greater than the DeBye sphere.

But you EU/EC/ES/PU/PC proponents keep on thinking that a neutral plasma is a plasma made up of neutral atoms

 

[sol invictus]

I never said a z-pinch couldn't form inside a plasma. I said dielectric breakdown couldn't happen in a plasma, since it's already conducting.

Here you assume a homogenous based structure for the plasma which will, given its highly conductive state, make dielectric breakdown less likely. How ever...

There is no assumption. This is what plasmas are. They are ionized gases. They can never experience dielectric breakdown because they conduct. In a sense they are always broken down.

Maybe in simplified or ideal equations but not in real life.

There will be neutral areas, boundaries and self sustaining features depending on a plethora of situations.

The only interesting thing about this discussion (apart from some quite informative comments posted by the experts here) is the astonishing level of ignorance of the basic physics of electrodynamics and plasmas exhibited by the EU cranks.

It's a level of ignorance that's matched only by the arrogance that always seems to accompany it.

Zeuzzz, how can you still not understand that plasmas are conductors? How many times have we told you? How basic can you get? Even your wiki article says that in the first two sentences of its introduction!

If anything is, conductivity is the single defining characteristic of a plasma - plasmas are ionized gases, and therefore nearly perfect conductors.

 

[Tubbythin]

Notice how you simply sidestepped the "cause/effect" question entirely? Was that really an intellectually honest way to address my point? Honestly T, you're not a GM or an RC, and I respect you. I simply can't believe you're going to try to ignore the concept of cause/effect and the importance of real empirical physical demonstrations of concept.

I wasn't aware that you had a point.

 

[Ziggurat]

Here you assume a homogenous based structure for the plasma

No I don't. I assume plasmas are conducting. Which they are. Homogeneity has nothing to do with it.

which will, given its highly conductive state, make dielectric breakdown less likely.

No, Zeuzzz. The fact that they are conductors makes dielectric breakdown impossible, regardless of homogeneity..

See this for a start;
Model for Dielectric Breakdown in Plasma-Polymerized Styrene Thin Films
http://jjap.ipap.jp/link?JJAP/21/483/

Zeuzzz, it isn't enough to just do a google search for terms, you need to understand what the results are. And you clearly don't. The breakdown is in a thin film, and that thin film is a solid (basically, plastic). Plasma is used in the preparation of the film, but the film itself is not a plasma, no breakdown is occurring in a plasma, and I doubt they even had a plasma during the dielectric breakdown measurements.

Or
Penetration of a dielectric barrier discharge plasma into textile structures at medium pressure
N De Geyter et al 2006 Plasma Sources Sci. Technol. 15 78-84
http://www.iop.org/EJ/abstract/0963-0252/15/1/012

Once again, Zeuzzz, it isn't enough to just see the terms you want, you need to understand the content. And you don't. What is dielectric barrier discharge? "electrical discharge between two electrodes separated by an insulating dielectric barrier." Now let's look at the text of the paper you cited to see their setup:

"Two circular copper electrodes (diameter = 7 cm) are placed within a cylindrical enclosure. Both electrodes are covered with a glass plate (thickness = 2 mm) and the interelectrode distance is 8 mm. The upper electrode is connected to an ac power source (frequency 50 kHz). The lower electrode is fixed and connected to the earth.
...
At the top of the cylindrical enclosure, air (Air Liquide—Alphagaz 1) is fed into the system at 0.5 l min−1."

Translation: air is the dielectric barrier, and it's being turned into plasma by the discharge. The air experiences dielectric breakdown when it changes from a gas to a plasma. The plasma never experiences a dielectric breakdown, because it's a conductor.

And also you cant ignore the chemistry involved either, as pointed out here:

Dielectric breakdown in F-doped SiO2 films formed by plasma-enhanced chemical vapor deposition
http://ieeexplore.ieee.org/Xplore/l...0709302.pdf?arnumber=709302&authDecision=-203

I don't even need to look at the link on that one, because it's obvious from the title how monumentally wrong you are. "Plasma-enhanced chemical vapor deposition" is a method for making thin films. SOLID thin films, in this case of glass. The films themselves are not plasma, they contain no plasma, they are not kept in plasma once they are manufactured. The dielectric breakdown occurs in the thin films when subjected to large electric fields, AFTER they are manufactured. No plasma is involved in the dielectric breakdown.

EPIC fail here, Zeuzzz. Simply epic.

 

[tusenfem]

EPIC fail here, Zeuzzz. Simply epic.

But ... but ... but ... they all have the word plasma in the title, so it must be relevant, coz ... coz ... coz, just because!