SuperConductivity: Research & Findings & Thoughts

[MGmirkin]

This page has some nice resources and ideas:

Dendritic flux avalanches in superconductors

When a superconducting film is placed in a perpendicular magnetic field, the flux penetration sometimes occurs via abrupt avalanches that result in remarkable dendritic flux patterns that can be observed using magneto-optical imaging

Magneto-optical images of flux dendrites
Magneto-opitcal studies of a c-oriented MgB2 film show that below 10 K the global penetration of vortices is dominated by complex dendritic structures abruptly entering the film. This behavior contrasts the gradual uniform penetration usually found in superconducting films.

Figure shows magneto-optical images of flux penetration (image brightness represents flux density) into the virgin state at 5 K. The respective images were taken at applied fields (perpendicular to the film) of 3.4, 8.5, 17, 60, 21, and 0 mT.

Simultaneous Penetration of Flux and Antiflux Dendrites in MgB2 rings

Flux dendrites with opposite polarities simultaneously penetrate superconducting, ring-shaped MgB2 films. By applying a perpendicular magnetic field, branching dendritic structures nucleate at the outer edge and abruptly propagate deep into the rings. When these structures reach close to the inner edge, where flux with opposite polarity has penetrated the superconductor, they occasionally trigger anti-flux dendrites. These anti-dendrites do not branch, but instead trace the triggering dendrite in the backward direction. Two trigger mechanisms, a non-local magnetic and a local thermal, are considered as possible explanations for this unexpected behaviour. Increasing the applied field further, the rings are perforated by dendrites which carry flux to the center hole. Repeated perforations lead to a reversed field profile and new features of dendrite activity when the applied field is subsequently reduced.

Dendrites avoid crossing
Before
After
Difference
MO images taken before and after invasion of a dendrite. The new dendrite had to turn the growth direction several times (indicated by arrows) to avoid crossing the existing dendrites. The last image is obtained by subtraction of the first two. The grown dendrite is seen white, while the black regions indicate branches of existing dendrites affected by appearing the new one.

Simulations

Flux and temperature distribution produced by vortex dynamics simulations
White dots: individual vortices;
Red: regions of enhanced temperature due to vortex motion
Green: traces of recently moving vortices

http://www.fys.uio.no/super/dend/

Men do not beat drums before they hunt for tigers.
http://www.kungfu-guide.com/pilot.html

The formation of a macroscopic current-carrying critical state in type II superconductors occurs via penetration of the magnetic flux front of pinned vortices from the surface of the sample. Recent advances in the magneto-optical imaging have revealed puzzling instabilities of the critical state, including magnetic macro-turbulence, kinetic front roughening, magnetic avalanches and dendritic-type instabilities. These phenomena display remarkable similarities with other dendritic structures in crystal growth, nonequilibrium chemical and biological systems, and crack propagation.


Here we study numerically and analytically the system of coupled nonlinear Maxwell and thermal diffusion equations which describes nonisothermal dendritic flux penetration in superconducting films. We show that spontaneous branching of propagating flux filaments occurs due to nonlocal magnetic flux diffusion and positive feedback between flux motion and Joule heat generation. The branching is triggered by thermomagnetic edge instability which causes stratification of the critical state. The resulting distribution of magnetic microavalanches depends on spatial distribution of defects. Our results are in good agreement with experiments performed on Nb films.

At the bottom of this page (for the link to the original link which has a bigger .gif and some movies): http://mti.msd.anl.gov/highlights.html

Good god man, why didn't somebody point me to this stuff sooner? Ya' been holding out on me?

I'm gobsmacked! I guess this is what happens why I don't browse one of the sub-forums for a while... Egah!

This is golden! Thanks StefanR! "Flux Dendrites" and "Dendritic Flux Avalanches."

*Wanders off muttering...*

Guess we've got our mechasnism, eh...

Gonna' have to go look that up...

Cheers,
~Michael Gmirkin

[webolife]

StefanR said:
"So could one say that 'a particle free vacuum' is a bad conducter. And that in a opposite way it might have the added effect of
"Flux Impulsion" to put in a rather forced way (but I think you get my drift)?"

Could you expound on this statement further? I don't think I get your drift... I very recently came to the "conclusion" that space has the essential attributes of a superconductor. I would particularly like clarification of what you understand superconductor and flux expulsion and flux impulsion to mean.
Thanks in advance.

[StevenO]

StefanR said:
"So could one say that 'a particle free vacuum' is a bad conducter. And that in a opposite way it might have the added effect of
"Flux Impulsion" to put in a rather forced way (but I think you get my drift)?"

Could you expound on this statement further? I don't think I get your drift... I very recently came to the "conclusion" that space has the essential attributes of a superconductor. I would particularly like clarification of what you understand superconductor and flux expulsion and flux impulsion to mean.
Thanks in advance.

I would rephrase the statement to: "a particle(matter) free vacuum has no laws of induction, so instead of following EM laws electrostatics and magnetism should be viewed in separation".

[webolife]

Help me more... I'm still not sure what you ascribing to space here.

[StefanR]

The Meissner Effect
Superconductors are actually perfect diamagnets and not perfect conductors. Perfect diamagnetism implies zero resistance that we have measured plus and added effect called "Flux Expulsion". The difference is quite subtle but can be readily seen by cooling the superconducting sample down while the magnet is sitting on its surface.

http://www.thunderbolts.info/wp/forum/phpB ... 4876#p4876

So could one say that 'a particle free vacuum' is a bad conducter. And that in a opposite way it might have the added effect of
"Flux Impulsion" to put in a rather forced way (but I think you get my drift)?

And how about a dielectric like water or air?

Well, I'm sorry I was not a little more clear, but understand, I'm groping for some understanding too. What I meant to say or indicate is what can one deduce from the effects or medium by assuming the opposite properties.
Let me just give a little bit of what I found interesting in relation to this by Meyl. He can be wrong most definitely but it's still interesting maybe:

4.2 Duality of the vortex properties
The rules of duality dictate for the vortex of the electric and of the magnetic field the
following characteristics:
1. Whereas currents and eddy currents demand a good conductivity, potentials and
potential vortices can only form with bad conductivity, thus in a dielectric and best in
the vacuum.
2. Eddy currents run apart, strive towards infinity and thus show the well-known "skin
effect" with a spatially limited arrangement of the conductor. According to the rules of
duality the potential vortex will strive towards the vortex centre and in this way will
show a "concentration effect".
3. Another property of vortices is shown in fig. 4.2.
On the left side a plane eddy current is indicated. Since the discovery of Ampere's law
it is well-known to us that such a circular current (I) forms a magnetic dipole standing
perpendicular to the vortex plane.
On the right hand side the dual phenomenon is sketched. Here charges are piled up
circularly to a planar potential vortex (U). Thereby an electric dipole forms, standing
perpendicular to the vortex plane. This relation directly follows from the equations of
the field-theoretical approach.
Whereas circular currents and current eddies produce magnetic dipoles, the postulated
potential vortices will form electric dipoles.
With these three interesting properties some key questions of quantum physics, that until
now have stayed a mystery to science (fig. 4.4), can be answered conclusively and without
compulsion e.g.:
I.Why are there no magnetically charged particles?
The better the conductivity of a medium is, the higher as a consequence the number of free
charge carriers is. the more strongly eddy currents are formed. The answer to question I is
inferred from the opposite case:
In the ideal vacuum no charge carriers at all are present, why no currents, no current
eddies and consequently no magnetic poles can exist.
With this well-known fact the first question already is answered. The question why in the
microcosm there can not exist magnetically charged elementary particles, why the search
for magnetic monopoles doesn't make any sense. Let's ask further:
II. Why are there only electrically charged particles?
Let us for that consider the dual conditions. The worse the conductivity of a medium is, the
more the potential vortex -will be favoured that because of this property also can be
understood as the vortex of the dielectric.
In the mentioned extreme case of the ideal vacuum, no electric conductivity is present for
reason of the missing charge carriers. But this circumstance favours the potential vortex
and that, according to fig. 4.2, forms electric poles and with this also the second question
would be answered clearly.
It can be traced back to the boundary conditions of the microcosm that without exception
electricallv charged particles are entitled to exist; a realization derived from the fieldtheoretical
approach, that covers all experiences.

P.55 Scalar Waves-Meyl

5.3 Physical interpretation of the fundamental field equation
In nature the different types of equations always occur in a combined manner.
1. Let's take the concrete case of the particle-free vacuum. Here the specific conductivity
is zero. The relaxation time constant ((small reference to equation)) responsible for the decay of vortices tends
towards infinity according to equation 5.3 and the terms (c) and (e) are cancelled from the
field equation 5.7. What remains is the by potential vortices (d) damped wave equation (b)
(equation 5.12).
2. The reversed case (with (small reference to equation)) will consequently occur in materials without
resistance, super conducting materials. We now are dealing with the well-known case of
the wave damped by eddy currents (equation 5.12*).
Vi r t u a l l y all in nature existing materials however don't fulfil these boundary conditions,
from which it follows that both damping terms always occur together and in addition the
stationary term (e) becomes active.
It is true that every antenna demonstrates that the electromagnetic wave is convertible in
high-frequency alternating currents and voltages, which then are amplified in the receiver.
But until this fundamental equation was written down it however was not understood that
this transition takes place by means of a vortex. Used are either antennas from well conducting
material, or wave guides and horn radiators, which only have a minimal conductivity,
because they are filled with air. Actually the wave can be converted in two dual
ways; by means of the rolling up to current eddies or to potential vortices (fig. 1.4).
Now we finally are capable to explain, why wave guides make possible a better degree of
effectiveness: Owing to the concentration effect of the potential vortex the HF-power is
bound in the inside and not emitted until the antenna is reached as happens for a wire for
reason of the skin effect.
Therefore, physically, one has to imagine this relation, which describes the transition of an
electromagnetic wave into a vortex, in the way that the wave spontaneously can roll up to
a vortex in case it is disturbed from the outside. The more vortices are generated, the
larger consequently is the damping of the wave (equations 5.12 and 5.12*).
3. The life span of the vortices is limited and is determined by the electric conductivity.
The at first stored vortices decay with their respective time constant ((t)).This process is
described by the diffusion equation 5.12**. The final stage of the decaying vortices
finally is described by the Poisson equation (a, e: equation 5.8).
If the vortex falls apart, it converts the in the vortex stored energy in heat. These processes
are known from the eddy current. We speak of heating losses, that the stationary currents
cause in the conductor material.
But new is the concept that such vortex phenomena can occur as dielectric losses in
capacitors or in the air. The microwave oven or induction welding are good examples of
this.

P.81 Scalar Waves-Meyl

Soorry, this is just half the information, but I was wandering how to approach the opposite extreme of superconducting.

[StefanR]

*Wanders off muttering...*

That was my initial reaction too when encountering this info

[StevenO]

Help me more... I'm still not sure what you ascribing to space here.

Charge is the fabric of space. But space itself has no observable. Current is one dimensional movement of charge. Magnetism is two dimensional rotation of charge. Maxwell's laws describe the interaction of charge with matter, which itself is 3 dimensional energy (3D rotation). As a result currents through matter induce magnetism and vice-versa. However, this mutual induction does not happen in free space!

(Where the edge of 'free space' itself starts is maybe out of the scope of the discussion).

For an explanation of superconductivity, check here: http://www.reciprocalsystem.com/rs/cwkvk/phenomenon.htm
It can be best "imagined" by two electrons jointly rotating in time.

[MGmirkin]

*Wanders off muttering...*

That was my initial reaction too when encountering this info

In a good way of course...

Like "HELLO!"

Nothing like finding an answer one has been looking for.

Cheers,
~Michael Gmirkin

[MGmirkin]

(Flux dendrites of opposite polarity in superconducting MgB2 rings observed
with magneto-optical imaging)
http://www.fys.uio.no/super/files/olsen06.pdf

Is it weird that page 3 of this PDF makes perfect sense to me? And the pink image of page 4?

Why? Think Lightning. It's the SAME process they're seeing, in my opinion! They're seeing the stepped leader(s), and the opposing streamer... Which will tend to follow the "best" / "strongest" path available. It's makese perfect sense to me that even at the small scale we'd see exactly the same process going on. I'm pretty sure that if they took this kind of magneto-optical image of lightning with the right sensitivities, they'd see precisely the same processes going on! The main branching streamers descent from the cloud in many directions, eventually the strongest one of them encounters a rising streamer and completes the circuit. Then the charges from the ground flows up through the strongly established channel.

At least, that's my assumption of what's going on here. Having read up a while back on lightning processes. Here's some resources detailing the current understanding of lightning. I see direct parallels. Love that plasma scaling!

(Cloud-to-Ground Lightning, parts 1 & 2)
http://wvlightning.com/cgdesc.shtml
http://wvlightning.com/rsdesc.shtml

(Cloud-to-Ground Lightning)
http://wvlightning.com/cgdesc.shtml

Step 1

LightningStep1.jpg (3.29 KiB) Viewed 7974 times

(Cloud-to-Ground Lightning)
http://wvlightning.com/cgdesc.shtml

Step 2

LightningStep2.jpg (3.87 KiB) Viewed 7971 times

(Cloud-to-Ground Lightning)
http://wvlightning.com/cgdesc.shtml

Step 3

LightningStep3.jpg (4.47 KiB) Viewed 7971 times

(Cloud-to-Ground Lightning)
http://wvlightning.com/cgdesc.shtml

Step 4

LightningStep4.jpg (5.09 KiB) Viewed 7995 times

(Cloud-to-Ground Lightning)
http://wvlightning.com/cgdesc.shtml

Step 6

LightningStep6.jpg (3.24 KiB) Viewed 7968 times

(Dendritic flux avalanches in superconductors)
http://www.fys.uio.no/super/dend/#ring

Flux dendrites with opposite polarities simultaneously penetrate superconducting, ring-shaped MgB2 films. By applying a perpendicular magnetic field, branching dendritic structures nucleate at the outer edge and abruptly propagate deep into the rings. When these structures reach close to the inner edge, where flux with opposite polarity has penetrated the superconductor, they occasionally trigger anti-flux dendrites. These anti-dendrites do not branch, but instead trace the triggering dendrite in the backward direction.

Cheers,
~Michael Gmirkin

Update (8-8-08): See the new thread entitled [urlhttp://thunderbolts.info/wp/forum/phpBB3/viewtopic.php?f=4&t=910]Slow Motion Lightning Video[/url] for an approximate confirmation of some of the stuff I said above. The high speed camera caught lightning going off in slow motion, and you can quite clearly see the leading streamers are extremely bright compares to the ionized trails behind them. IE, it looks like the majority of the field strength gets concentrated at the leading edge of the stepped leader, ionizing whatever's next on down the line. Eventually a streamer either connects with ground or with an upward streamer, and the circuit carries a massive load and sometimes a few return strokes. Good times! ~MG

[junglelord]

It is my impression that the stepped leader is the Electrostatic discharge, and the return stroke is the EM discharge, if I understand APM correctly and what lightning is telling us with those two very different discharge displays.

THUNDER: This currrent flow heats the channel of air to a temperature greater than the surface of the sun in a split second. Heated air expands, explosively expanding when heated to such a high temperature with such speed. This explosive expansion generates supersonic shock waves moving outward from the channel in all directions. After travelling several feet, the shock waves slow to sound waves, which arrive to our ears as thunder.

The temperature of lightning always bothered my intellect when I believed in the thermonuclear furnace model of stars. Hotter then the surface of the sun (6000 degrees)....


Now that I understand the electric star model and the temperature of the corona is where the first interface occurs, well now I have no trouble with the surface temperature of the sun or the temperature of lightning...because lightning is an example of the plasma of the electric star corona, plasma discharge at its finest. They never relate the temperature of lightning to the temperture of the corona. Thats what they are missing. There is no way if its a thermonuclear furnace that lightning would be hotter then the surface.

[MGmirkin]

They never relate the temperature of lightning to the temperture of the corona. Thats what they are missing. There is no way if its a thermonuclear furnace that lightning would be hotter then the surface.

Lightning nothing. If it's a nuclear furnace, the corona shouldn't be hotter than the "surface!" IE, stuff should be getting progressively cooler in a gradient the further away you get from the radiating heat source (supposedly, in the center of the sun). NOT hotter, and not a funky temperature minimum and/or inversion.

IE, they say the core is supposed to be millions and millions of Kelvins, but then at some point that dips and dips and dips to become about 6000K at the photospheric "surface" of the sun and then inverts and gets up to about 10,000K-100,000K in the chromosphere and up to several million K again in the corona... It makes no sense, frankly. Why would heat fall off exponentially only to rise exponentially again? (Okay, maybe not exponentially, but you get the point; from millions to only 6,000 give or take and back to a couple million...)

Cheers,
~Michael Gmirkin

[nick c]

If it's a nuclear furnace, the corona shouldn't be hotter than the "surface!"

If the sun were a nuclear furnace, would it even have a corona? Why, would it even need one?

Nick

[MGmirkin]

If it's a nuclear furnace, the corona shouldn't be hotter than the "surface!"

If the sun were a nuclear furnace, would it even have a corona? Why, would it even need one?

Nick

Well, right. That's kind of what I was getting at. You'd have a central nuclear furnace, and a nice smooth gradient out to the furthest reaches. Rather than what amounts to an anomalous "dip" in the temperature graph going from inside to outside. It's just weird.

Of course, I think it's covered in TES / TEU.

~Michael Gmirkin

[Solar]

(Flux dendrites of opposite polarity in superconducting MgB2 rings observed
with magneto-optical imaging)
http://www.fys.uio.no/super/files/olsen06.pdf

Is it weird that page 3 of this PDF makes perfect sense to me? And the pink image of page 4?

Why? Think Lightning. It's the SAME process they're seeing, in my opinion! They're seeing the stepped leader(s), and the opposing streamer... Which will tend to follow the "best" / "strongest" path available. It's makese perfect sense to me that even at the small scale we'd see exactly the same process going on. I'm pretty sure that if they took this kind of magneto-optical image of lightning with the right sensitivities, they'd see precisely the same processes going on! The main branching streamers descent from the cloud in many directions, eventually the strongest one of them encounters a rising streamer and completes the circuit. Then the charges from the ground flows up through the strongly established channel.

At least, that's my assumption of what's going on here.

I had the exact same thought regarding "dendritic avalanches" and cloud -to-ground and ground-to-cloud lightning but since you beat me to it I'll raise you one further interesting correspondence:

In a weak applied field a superconductor expels all magnetic flux. Although the magnetic field is completely expelled from the interior of the superconductor, there is not a sharp transition at the edges of a sample, but rather a rapid decay of field into the sample over a distance, the penetration depth. Each superconducting material has its own characteristic penetration depth. When the temperature of a superconductor in a weak magnetic field is cooled below the transition temperature, surface currents arise that generate a magnetic field which yields zero net magnetic field within the superconductor. - Meissner effect:

And:

In superconductors the diamagnetism arises from the persistent screening currents which flow to oppose the applied field; in normal materials diamagnetism arises as a direct result of an orbital rotation of electrons about the nuclei of an atom induced electromagnetically by the application of an applied field.

Might the "surface currents" or "screening currents" of diamagnetism in superconductivity be analogous to the Earths Telluric currents on the one hand and the Earth's Electrojet(s) on the other? To further the point I need to insert the appropriate causations into the the description.

With the Meissner effect as described:

If a conductor of electricity (Earth) is moved into a magnetic field (the magnetic field of the Sun), Faraday's Law of Induction would lead us to expect an induced electrical current in the conductor (Telluric currents) and its associated magnetic field (Earth's magnetophere) which would oppose the applied field (the Suns' magnetic field). The induced electrical current (Earth's Telluric currents) would not dissipate in a `perfect' conductor, and thus the associated magnetic field (Earth's magnetosphere) would also continue to oppose the applied field (the Sun's magnetic field). - The Meissner effect

So the question is: As with superconductivity and diamagnetism can the earth's magnetic field be primarily the result of induction from the Sun's ("applied") magnetic field as opposed to the iron core/dynamo theory etc? When coupled with ground-to-cloud and cloud-to-ground lightning demonstrating the "penetration depth" of dendritic avalanches (positive and negative) the induced magnetic field of the earth so "opposes" the "applied magnetic field" of the Sun.

All of which would demonstrates the "self organizing" characteristics of electro-plasma dynamics. Or something to that effect.

[StefanR]

I had the exact same thought regarding "dendritic avalanches" and cloud -to-ground and ground-to-cloud lightning

Yesindeed, the visual resemblance is quite.... well....fascinating

So the question is: As with superconductivity and diamagnetism can the earth's magnetic field be primarily the result of induction from the Sun's ("applied") magnetic field as opposed to the iron core/dynamo theory etc? When coupled with ground-to-cloud and cloud-to-ground lightning demonstrating the "penetration depth" of dendritic avalanches (positive and negative) the induced magnetic field of the earth so "opposes" the "applied magnetic field" of the Sun.

I also am thinking (trying that is) in that direction. But the athmosphere of Earth and space itself is not superconductive of course. But how can it be caracterized then? Is it dielectric or something else? And in what way do the fields have to be switched or inverted ? Difficult (for me at least ).

StefanR wrote:

MGmirkin wrote:*Wanders off muttering...*

That was my initial reaction too when encountering this info

In a good way of course...

Most surely, the mumbling was in the order of: How can it be? How could I have not seen this before? What to think of this?