The Electric Comet theory

Status
Not open for further replies.
Sol88 said:
DD my trollish friend, you need to do a little more studying before you can grasp what this thread is about, your complete lack of understanding here is blindingly obvious.

please re read this post


Then come back and write an intelligent comment on what you understand the EC theory as.
Click to expand...

Yeah sure, it's my fault you can't post a coherent argument. Why don't you explain the density of comets again, how a body that is in the asteroid belt acquires a charge different from the other bodies in the asteroid belt and why a comet has more of a charge after it passes the sun?

Please call me a troll it makes you look even sillier.
 
Sol88 said:
DD make sure you read and understand what Reality check wrote in this POST this will stop a lot of going round in circles!
Click to expand...


Nope, you are incoherent, the fact that your theory has no evidence is your problem, keep making it up.


the problem is you have a mish mosh of nonsense and refuse to put it to the acid test.

Why are comets larger after they pass the sun?
 
Dancing David said:
Nope, you are incoherent, the fact that your theory has no evidence is your problem, keep making it up.


the problem is you have a mish mosh of nonsense and refuse to put it to the acid test.

Why are comets larger after they pass the sun?
Click to expand...

what? please explain.
 
The EC assumption of EDM machining does not produce jets

EC universe:
Sol88 quoted Wal Thornhill:
The dust and gases that form the comet''s tail are not evaporated by the heat of the sun, but instead are electrically 'machined' from the nucleus by cathode arcs. Laboratory examination of cathode arcs shows that they jump around on the cathode surface, removing surface material in jets to form small circular craters. The industrial process of Electric Discharge Machining (EDM) uses this feature to erode a surface to accurate depth. To the naked eye, the EDM surface looks remarkably smooth. However, when viewed at high magnification, the peculiarities of the machined surface become clear. The tendency for the cathode arc to erode one high point then move to the next high point tends to generate chains of flat-floored craters. The finished surface appears as if someone used a circular cookie cutter to produce extended depressions and channels with scalloped edges. Variations in arc current will produce a layered or terraced effect both within craters and between adjacent craters.
Click to expand...
No mention of jets or how EDM machining produces them.

Real universe:
Jets cannot be produced from EDM machining of "high points" on comets. The heating of the surface to machine it will cause material to escape in all directions. So there will be fans not jets. This will happen even if the "high point" is a flat surface.

To get jets in the real universe the EDM would have to happen at the bottom of pits or craters. By definition the walls of pits and craters are higher than their bottoms. The EDM will always happen at the "higher point". Therefore no jets.
 
Reality Check said:
EC universe:
Sol88 quoted Wal Thornhill:

No mention of jets or how EDM machining produces them.

Real universe:
Jets cannot be produced from EDM machining of "high points" on comets. The heating of the surface to machine it will cause material to escape in all directions. So there will be fans not jets. This will happen even if the "high point" is a flat surface.

To get jets in the real universe the EDM would have to happen at the bottom of pits or craters. By definition the walls of pits and craters are higher than their bottoms. The EDM will always happen at the "higher point". Therefore no jets.
Click to expand...

Go down to your local $2 shop and grab a plasma globe, observe the coronal discharge happening on the inner electrode, see the strands of light reaching the outer glass, these are commonly referred to as a beam or "jet"!

Plasma filaments extend from the inner electrode to the outer glass insulator, giving the appearance of multiple constant beams of colored light (see corona discharge and electric glow discharge). The beams initially follow the electric field lines of the dipole, but move upwards due to convection.[citation needed]
Click to expand...
wiki

Slightly different in space but more or less the same process!

now compare that to YOUR (reality checks) understanding of "jet" production under the only option mainstream have

The black crust of the nucleus helps the comet absorb heat, which in turn causes some of the ices under the crust to turn to a gas. With pressure now building beneath the crust, the serene, but frozen landscape begins to bulge in places. Eventually the weakest areas of the crust shatter from the pressure beneath, and the gas shoots outward like a geyser and is referred to by astronomers as a jet. Any dust that had been mixed in with the gas is thrown out as well. As more and more jets appear, a tenuous gas and dust shell forms around the nucleus and this is called the coma.
Click to expand...

Might convince the mindless sheep, but something is not right with that theory of jet production, as found by Deep space 1

"It's mind-boggling and stupendous," agreed Dr. Laurence Soderblom, the leader of Deep Space 1's imaging team, and a geologist with the U.S. Geological Survey, Flagstaff, Ariz. "These pictures have told us that comet nuclei are far more complex than we ever imagined. They have rugged terrain, smooth rolling plains, deep fractures and very, very dark material."

Scientists also realized that Borrelly was different than they expected as Deep Space 1 flew through the dusty gaseous coma. They had expected that the solar wind (a stream of charged particles flowing from the Sun) would flow symmetrically around the coma with the nucleus in the center.

The solar wind did indeed flow symmetrically around the cloud, but the nucleus was off to one side shooting out a great jet of material forming the cloud that makes the comet visible from Earth. "The formation of the coma is not the simple process we once thought it was," said Dr. David Young of the University of Michigan, Ann Arbor, leader of the team that made the measurements. "Most of the charged particles are formed to one side, which is not what we expected."

More surprises may await scientists in the data beamed back from DS1. It's only been a few days since the speedy encounter, note researchers -- not enough time to completely explore the data set. The most extraordinary discoveries may be yet to come.
Click to expand...
LINK

Is that grumbles from the hallowed house of science I hear?
 
Sol88 said:
what? please explain.
Click to expand...


Why are the tails of comets longer after they pass thesun, in the electric model.

After all it is not sublimation of frozen material.
You have said it is from the charge difference (which creates the coma and tail), which means that the charge difference is growing larger as the comet approaches the sun and passes the sun. And on it's way back out.
 
Dancing David said:
Why are the tails of comets longer after they pass thesun, in the electric model.

After all it is not sublimation of frozen material.
You have said it is from the charge difference (which creates the coma and tail), which means that the charge difference is growing larger as the comet approaches the sun and passes the sun. And on it's way back out.
Click to expand...


I do not understand?

Did you read this somewhere? link?
 
Sol88 said:
I do not understand?

Did you read this somewhere? link?
Click to expand...
A bit of Googling reveals some statements that comet tails show their maximum development shortly after perihelion, e.g. this page about Hale-Bopp.
IMHO, the decrease happens after perihelion in the mainstream model because of the heat latency of the comet nucleus (it takes time to heat up to its maximum and then start to cool down).

EC proponents may have a mechanism to delay the decrease in EDM until after perihelion. Sol88?
 
Reality Check said:
EC universe:
Sol88 quoted Wal Thornhill:

No mention of jets or how EDM machining produces them.

Real universe:
Jets cannot be produced from EDM machining of "high points" on comets. The heating of the surface to machine it will cause material to escape in all directions. So there will be fans not jets. This will happen even if the "high point" is a flat surface.

To get jets in the real universe the EDM would have to happen at the bottom of pits or craters. By definition the walls of pits and craters are higher than their bottoms. The EDM will always happen at the "higher point". Therefore no jets.
Click to expand...

Also you forget to mention that EDM will NOT machine watergroup ions, at most maybe oxygen from the crust (but who knows a clear description has never been given of what exactly happens in EDM) and thus the watergroup ions are supposed to be generated through local oxygen and solar wind hydrogen. Again no dynamic description of this process is given (as far as I can judge EDM will emit positively charged ions (O+????) because of the energetics, so how do O+ and H+ get together?)
 
tusenfem said:
Also you forget to mention that EDM will NOT machine watergroup ions, at most maybe oxygen from the crust (but who knows a clear description has never been given of what exactly happens in EDM) and thus the watergroup ions are supposed to be generated through local oxygen and solar wind hydrogen. Again no dynamic description of this process is given (as far as I can judge EDM will emit positively charged ions (O+????) because of the energetics, so how do O+ and H+ get together?)
Click to expand...
There are so many things wrong with the EDM concept within the electric comet idea that it will probbaly take weeks to cover it all!

Another example, where is the dielectric fluid that the EDM manufacturing process requires?
Electric discharge machining (EDM), sometimes colloquially also referred to as spark machining, spark eroding, burning, die sinking or wire erosion,[1] is a manufacturing process whereby a wanted shape of an object, called workpiece, is obtained using electrical discharges (sparks). The material removal from the workpiece occurs by a series of rapidly recurring current discharges between two electrodes, separated by a dielectric liquid and subject to an electric voltage.
Click to expand...
 
Sol88 said:
I do not understand?

Did you read this somewhere? link?
Click to expand...

Which part don't you understand?
Comets are longer in terms of tails on their way back out? he size of the coma and tail being increasing is common knowledge.
Or what you posted about charge difference?
 
Dancing David said:
Which part don't you understand?
Comets are longer in terms of tails on their way back out? he size of the coma and tail being increasing is common knowledge.
Or what you posted about charge difference?
Click to expand...

That's splitt'n hairs in it?

Which tail would you like to talk about?
 
tusenfem said:
Also you forget to mention that EDM will NOT machine watergroup ions, at most maybe oxygen from the crust (but who knows a clear description has never been given of what exactly happens in EDM) and thus the watergroup ions are supposed to be generated through local oxygen and solar wind hydrogen. Again no dynamic description of this process is given (as far as I can judge EDM will emit positively charged ions (O+????) because of the energetics, so how do O+ and H+ get together?)
Click to expand...


What watergroup ions? Where's the water?

Did you miss the post about how the're thinking about go'n 'bout it on the Moon?
 
EDM in the EC idea needs a dielectric material which does not exist!

I had foolishly thought that the proposers of the electric comet idea knew a bit about electrical discharge machining. It seems that they do not.

EC universe: EDM removes material from the surface of comets and creates water from the material somehow.

Real universe:
Electric discharge machining (EDM), sometimes colloquially also referred to as spark machining, spark eroding, burning, die sinking or wire erosion,[1] is a manufacturing process whereby a wanted shape of an object, called workpiece, is obtained using electrical discharges (sparks). The material removal from the workpiece occurs by a series of rapidly recurring current discharges between two electrodes, separated by a dielectric liquid and subject to an electric voltage. One of the electrodes is called tool-electrode and is sometimes simply referred to as ‘tool’ or ‘electrode’, whereas the other is called workpiece-electrode, commonly abbreviated in ‘workpiece’. When the distance between the two electrodes is reduced, the intensity of the electric field in the volume between the electrodes is expected to become larger than the strength of the dielectric (at least in some point(s)) and therefore the dielectric breaks allowing some current to flow between the two electrodes.
Click to expand...
If there is no dielectric material between the electrodes then there are no sparks and there is no machining.
In the EDM idea the workpiece-electrode is the surface of the comet. I do not know what the tool-electrode is (the coma?, the tails? the solar wind? maybe the Sun!).

There is no dielectric material above the surface of a comet - just lots of highly conductive plasma in the coma, solar wind and tail.
 
No EDM sparks are seen in images of comet nuclei

The last post just about kills the EC idea. But lets throw in a couple more points just for fun :).

EC universe: EDM removes material from the surface of comets and creates water from the material somehow.

Real universe:
EDM involves sparking between electrodes. Sparks are quite visible. No such sparks have been seen in the images that have been taken of comet nuclei. The best example are the details images of Tempel 1. Thus the EC idea requires EDM sparks that are invisible in X-rays and visible light.
 
No EDM hot spots are seen in thermal maps of Tempel 1

EC universe: EDM removes material from the surface of comets and creates water from the material somehow.

Real universe:
Every jet that EDM in the EC idea produces must have an associated area of increased temperture (a hot spot) where EDM is converting/removing material. About twenty jets means about 20 hot spots.

We have a temperature map of Tempel 1.
How hot is it on Tempel 1? Researchers made a temperature map of the sunlit side. and found the hottest point nearly directly under the sun. It's 329 degrees Kelvin under the sun and 260 in the shade.
The coldest temperature is important because the temperature at which ices such as water, carbon dioxide and carbon monoxide turn directly into gas is below 200 degrees Kelvin.
As you might expect, Tempel 1 is in equilibrium with sunlight meaning that there are no internal heat sources as there are within some planets. And that the surface does not retain the heat from the sun for long, it heats up quickly and cools quickly.
Click to expand...

No mention of hot spots here except the one under the Sun.
Where are the other 19?
 
Reality Check said:
I had foolishly thought that the proposers of the electric comet idea knew a bit about electrical discharge machining. It seems that they do not.

EC universe: EDM removes material from the surface of comets and creates water from the material somehow.

Real universe:

If there is no dielectric material between the electrodes then there are no sparks and there is no machining.
In the EDM idea the workpiece-electrode is the surface of the comet. I do not know what the tool-electrode is (the coma?, the tails? the solar wind? maybe the Sun!).

There is no dielectric material above the surface of a comet - just lots of highly conductive plasma in the coma, solar wind and tail.
Click to expand...

The new device, a reactor developed by Derek Fray and his colleagues, was created from a modified electrochemical process the team invented in 2000 to get metals and alloys from metal oxides. The process uses the oxides — also found in Moon rocks — as a cathode, together with an anode made of carbon. To get the current flowing through the system, the electrodes sit in an electrolyte solution of molten calcium chloride (CaCl2), a common salt with a melting point of almost 800 °C.
Click to expand...

Moon rock/asteroid/comet rock!!!

Electrolyte solution is the plasma that surrounds it and the dialectic is the comet surface itself
 
Reality Check said:
The last post just about kills the EC idea. But lets throw in a couple more points just for fun :).

EC universe: EDM removes material from the surface of comets and creates water from the material somehow.

Real universe:
EDM involves sparking between electrodes. Sparks are quite visible. No such sparks have been seen in the images that have been taken of comet nuclei. The best example are the details images of Tempel 1. Thus the EC idea requires EDM sparks that are invisible in X-rays and visible light.
Click to expand...

Heard of coronal discharge
In electricity, a corona discharge is an electrical discharge brought on by the ionization of a fluid surrounding a conductor, which occurs when the potential gradient (the strength of the electric field) exceeds a certain value, but conditions are insufficient to cause complete electrical breakdown or arcing.
Click to expand...

Look it up sport :)
 
Sol88 said:
Moon rock/asteroid/comet rock!!!

Electrolyte solution is the plasma that surrounds it and the dialectic is the comet surface itself
Click to expand...
If there is no dielectric material between the electrodes then there are no sparks and there is no machining.
In the EDM idea the workpiece-electrode is the surface of the comet. I do not know what the tool-electrode is (the coma?, the tails? the solar wind? maybe the Sun!).

There is no dielectric material above the surface of a comet - just lots of highly conductive plasma in the coma, solar wind and tail.
 
A collection of problems with the EC idea

This will be updated as we discuss the many problems with the EC idea.

EC universe: Ignore the physical evidence such as the measured density of comets.
Real universe: Use the physical evidence such as the measured density of comets to construct theories.

EC universe: Comets are rocks.
Real universe:
  1. Comets have meaured densities that are much less than that of rocks (asteroids).
  2. Comets may not have the composition of asteriods
  3. Deep Impact confirmed that comet nuclei are made of dust and ice not rock. There were a couple of surprises in that the dust was talcum powder rather than sand and the amount of ice was smaller than expected.
    "Analysis of data from the Swift X-ray telescope showed that the comet continued outgassing from the impact for 13 days, with a peak five days after impact. A total of 5 million kilograms (11 million pounds) of water[35] and between 10 and 25 million kilograms (22 and 55 million pounds) of dust were lost from the impact."WP
EC universe: Comet jets, coma and tails are created from material that that is created from rock by electrical discharge machining.
Real universe:
Start with Tim Thompson's posts about this
Then look at
EC universe: Rocky bodies that have an orbit with an eccentricity above a minimum value will be comets.N.B. Solar activity may cut tails in two but there have been no observations of comets turning off during low solar activity.(Sol88: I may be wrong - if so please provide the citations to these marvelous events.)
However this assertion has the fatal flaw of EC predictions - no mathematics or numbers.
But we can do their work for them can't we Sol88?

There are 4 observed main-belt comets with a minimum eccentricity of 0.1644 (133P/Elst-Pizarro). So the EC minimim must be this (or lower!).

Real universe: There are at least 173,583 asteroids (rocky bodies) that have an orbit with an eccentricity above a minimum value that are not comets. This includes asteroids that have been observed for decades.
Why EC comets are not asteriods


EC universe: Only give qualitative predictions.
Sol88 posted a list of EC "predictions" for Tempel 1 and Deep Impact. The closes it gets to an actual quantitative predictions is "The most obvious would be a flash (lightning-like discharge) shortly before impact." (emphasis added).

What actually happened was a flash on or after impact followed by a bigger one from deeper in the nucleus (according to NASA).

Real universe: Scientific theories model the data mathematically and produce both qualitative and quantitative predictions.
Someone could start with the papers of Whipple
  1. Whipple, Fred L. (1950). "A Comet Model. I. The acceleration of Comet Encke". Astrophys. J. 111: 375–394.
  2. Whipple, Fred L. (1951). "A Comet Model. II. Physical Relations for Comets and Meteors". Astrophys. J. 113: 464.
  3. Whipple, Fred L. (1955). "A Comet Model. III. The Zodiacal Light". Astrophys. J. 121: 750.
and then go ointo the 1000's of scientific papers and many textbooks about comets. Tim Thompson recommened Introduction to Comets by Brandt & Chapman (Cambridge University Press, 2004, 2nd edition).


EC universe: Turn yourself into a crackpot idea by not publishing papers in peer reviewed journals.
Real universe: Take the risk being wrong and become part of the scientific process by publishing papers in peer reviewed journals, e.g. Fred L. Whipple.
 
Last edited:
Sol88 said:
That's splitt'n hairs in it?

Which tail would you like to talk about?
Click to expand...

Your being very silly.

try just explaing why the tail gets longer as it passes the sun. By then the charge difference should have balanced out. And why do the four cometary asteroid get a charge difference from the other asteroiads.

Your theory, your explanation.

They come from the outer solar system witha charge, that charge causes an interaction you say cause the coma and tail to develop. So why is it larger after they pass the sun?
 
Hi all. First post here. What fun, mind if I jump in? :)
First...EDM. EDM is the erosion or etching of an electrode. It could be a rapid, dramatic process, or a slow, steady process. Spark machining is used on very hard materials in industrial manufacturing processes. The slow erosion of the electrodes in a neon sign is a slower, less obvious form of EDM. We could say coronal discharge etching, but the electro-static potential may, at times, reach the threshold for arcing. We say EDM because there are multiple discharge levels occurring on comets, from electrostatic cleaning of dust, coronal discharge erosion, "magnetic vortex" etching, and possibly, infrequent arc machining.
The voltage potential between the comet and the solar wind plasma (concentrated at the plasma double layer which makes the boundary of the coma, where the x-ray's are produced, in the DL) induces electro-chemical reaction chains on the nucleus, which together form a positive feedback, increasing the efficiency of each. The chemical reactions are similar to an acid H+ (solar wind plasma ions) and base/alkali (mineral rock, i.e. comet) reaction. The by products would include hydrogen, oxygen and carbon groups in abundance, and to a lesser extent, sodium, nitrogen and sulfur groups. H2O is a common by-product of an acid base reaction, this would be the source of the .026% surface area of 3 thin ice layers detected on Tempel-1, probably deposited as the comet moved further away and the reactions subsided, because the final reaction in that chain produces OH. :D
 
OK. As for composition. Composition and structure are what's important, not density. As the stardust mission indicates, the material consisted of crystaline silicates, a variety of other minerals and metals. A very good semi-conductor. Density is irrelevant in EC, it's a red herring that Reality Check continues to go in circles over.
I am in no way an official spokesperson for EU or EC. However, until we actually land on a comet and poke at it, we don't really know the density. My personal prediction (NOT official EU/EC) is that it should be around 2.8g/cm3, +/- .2, based on the material collected from stardust and comparing to the density of quartz.
An EC rock has the same definition as any rock.
What makes a rock into a comet is sufficient electro-static voltage potential to induce an electro-chemical reaction/coronal discharge. That could be produced by an eccentric orbit, or a stream or bubble of solar wind plasma with a significantly different charge density, or composition, than the surrounding plasma.

sol88 has used some incorrect terminology. Allow me to clear up any confusion.
The EC comet is not a dielectric, it's a semi-conductor, capable of accumulating an electric charge. The solar wind plasma is an electrolyte, a conductive, chemically reactive material.
Otherwise, good job sol88!

I find it quite humorous and ironic that the MESSENGER probe to Mercury discovered chemical sputtering all over the surface, and "magnetic tornado's" ripping ions and neutrals from the surface, and detected a filamentary tail. Pretty much a "dark comet". ;) The chemical reaction off-gassing was even similar to that found from comets, including OH :p. But they can't connect the dots. :(
We should study the weaker processes on Mercury for an idea of what an energetic EC comet is about.
 
Welcome to JREF Forum, solrey. :)

One thing I found interesting is that there are no numbers in your posts!

For example, what potential differences and/or currents are needed to cause what amount of EDM? And are there any thresholds (e.g. below certain values, no EDM takes place, period)?

Further, what's the evidence for the existence of potential differences, and currents, in the parts of the interplanetary medium through which comets move? Specifically, what are the estimated max (and min) values of potential differences (between various pairs of objects, or locations) and currents?

Chemistry: what are the specific reactions, or classes of reactions, that you think could give rise to the observed levels of OH? AFAIK, the existing body of knowledge - experiments, theory - is more than adequate to provide a basis for testing specific hypotheses concerning OH production ...

Oh, and I am unaware of the MESSENGER results you mention; normally, I'd ask for some reference material, but you won't be able to provide any until your post count exceeds 15 (IIRC) ...
 
DeiRenDopa, thanks for the warm welcome. :)

Forgot to mention that even though the EC comet would be considered a semi-conductor, the material at the surface involved in the discharge does act as a dielectric, however. Essentially the semi-conductor discharges through dielectric layers. ;)

Good questions deirendopa. As I can't post links yet, may I suggest to copy/paste this into google search: Physics of arcing, and implications to sputter deposition Anders
You should find the second entry down to be the PDF you want.

I think there is a lot of what you're looking for in there. Here's a taste:

Arc and glow discharges are defined based on their cathode processes. Arcs are characterized by collective electron emission, which can be stationary with hot cathodes (thermionic arcs), or non- stationary with cold cathodes (cathodic arcs).
Click to expand...

In the case of the EC comet, we are dealing primarily with cathodic arcs.

Arcing on sputter targets and negatively biased substrates is known as one of the most challenging issues in physical vapor deposition of thin films and coatings. This is particularly true when high-rate deposition with reactive gases, large area deposition, and high power pulse sputtering are considered... However, relatively little is known about the processes leading to arcs and the physics of the arcing events themselves. In this contribution, the issue of arcing is approached from the point of view of arc physics.
Click to expand...

One may consider the operation of cathodic arc spots as a rapid sequence of microexplosions. In these explosive events, large amounts of electrons can overcome the potential barrier. The cathode material in the vicinity of the spot experiences phase transformations, ultimately resulting in fully ionized, rapidly expanding plasma. Thermal conduction in the solid increases the active spot area and reduces the power density, while the electrical conductivity below the spot is reduced at high temperature. Therefore, a microexplosion destroys its own favorable condition. As a side effect of plasma formation, material located between the dense plasma and the much colder cathode is in the liquid phase, subject to the pressure of the plasma. As a result, the material is ejected as droplets or “macroparticles,” often under shallow angle to the cathode surface, and a crater is left on the cathode surface. The formation of macroparticles is highly undesirable and a major reason why arcing is of great concern to sputter deposition.
Click to expand...

Magnetron discharges are magnetically enhanced glow discharges, where the ionization probability of gas atoms or molecules by electron impact is greatly enhanced due to the motion of electrons in the ExB field. Although the plasma density is higher, and the operational pressure may be lower than in glow discharges without magnetic field, the cathode processes are still indicative for the glow nature of the discharge. Secondary electron emission by primary ions is only efficient when the impact energy exceeds about a couple of 100 V, hence the glow discharge voltage is high, usually many 100 V. Besides providing energy for secondary electron emission, primary ions bring enough energy to overcome the surface binding energy of atoms, leading to target sputtering, the desirable side effect that made us work in this field in the first place.
Click to expand...

Think of the bright spots on the surface of the nucleus where the jets originate. Conventional thinking is reflected sunlight, EC thinking is more like magnetron glow discharge, the suns magnetic field providing the magnetic enhancement. ;)
 
Have you seen that image of the Martian dust devil with the electric glow discharge at and just above the surface? The jets of the EC comet as applied to the above referenced magnetron glow discharge are a lot like that. :)
Actually, that discharge at the base of the dust devil is a magnetron glow discharge. ;)
 
solrey said:
Have you seen that image of the Martian dust devil with the electric glow discharge at and just above the surface? The jets of the EC comet as applied to the above referenced magnetron glow discharge are a lot like that. :)
Actually, that discharge at the base of the dust devil is a magnetron glow discharge. ;)
Click to expand...

You can post links in a modified form like www_engrish_com
 
solrey said:
DeiRenDopa, thanks for the warm welcome. :)

Forgot to mention that even though the EC comet would be considered a semi-conductor, the material at the surface involved in the discharge does act as a dielectric, however. Essentially the semi-conductor discharges through dielectric layers. ;)

Good questions deirendopa. As I can't post links yet, may I suggest to copy/paste this into google search: Physics of arcing, and implications to sputter deposition Anders
You should find the second entry down to be the PDF you want.

I think there is a lot of what you're looking for in there. Here's a taste:



In the case of the EC comet, we are dealing primarily with cathodic arcs.







Think of the bright spots on the surface of the nucleus where the jets originate. Conventional thinking is reflected sunlight, EC thinking is more like magnetron glow discharge, the suns magnetic field providing the magnetic enhancement. ;)
Click to expand...


http://www.osti.gov/bridge/servlets/purl/861163-A0F82g/861163.PDF
 
Thanks solrey.

I'm curious about this: "Think of the bright spots on the surface of the nucleus where the jets originate. Conventional thinking is reflected sunlight, EC thinking is more like magnetron glow discharge, the suns magnetic field providing the magnetic enhancement."

From what I have read, doing a bit of googling, a magnetron requires a magnetic field strength of at least a few gauss, yet the magnetic field strength in the solar wind is ~a few nT ... so how could there be a magnetron glow discharge at such low magnetic fields?

Also, what image analyses have been done (if any), to show that the emission from "the bright spots" is greater than the incident sunlight?
 
In the context of the magnetron glow discharge, it simply designates the presence of an external magnetic field, it could be weak or strong or all points in between. They are not literally referring to the magnetron as a device nor inferring a B field of similar strength. Any strength B field will have some effect. It is simply a magnetically enhanced glow discharge. I believe the authors definition and equations will confirm this.

As far as emission of the bright jets goes, I should have been more specific and clear that at or near the surface is mostly due to the glow discharge, but at some point reflectivity of the dust and discharge blend with distance from the nucleus until eventually it's mostly a result of reflection. Both glow and reflection are happening, but at or near the surface, there is the enhancement of the glow discharge. It's not necessarily one or the other, I should have been clear on that. :o

That also is analogous to the ionization distribution of the reaction by-product gases. The closer to the nucleus the more ionization, the free electrons liberated by the discharge combine with ions as both travel away from the nucleus, so there should be an increasing proportion of neutral atoms and molecules with increasing distance from the nucleus. I believe the conventional explanation would involve ionization due to friction, or triboluminesence.

The coma boundary is a plasma double layer. One of the functions is diffusing the voltage potential across a greater surface area, which mitigates the discharge to the surface, while dissipating most of the energy in the form of x-rays at the boundary of the coma, or DL. It's a well known plasma phenomena, and a prime reason for Alfven's eventual Nobel prize. He even said that DL's should be treated as a specific cosmologic/astrophysical phenomena. The tail is just the DL being stretched by the solar plasma stream, basically stretching between a positive and negative potential, from bow shock (+) to end of tail (-). The tail contains the twisted filaments of the discharge current, Biot-Savart law and the Bennet relation are applicable here.

One more point. The material from stardust mission that was formed in high temps could have come from the material being in plasma state in those micro-explosions of the glow discharge, described in the paper, prior to rapid cooling and re-solidification. ;)

This seems like a friendly forum, good questions, agree to disagree, respectful, yeah respectful...how refreshing. :D

Whew, busy day. Sanding a porch deck for refinishing and posting during breaks. Luv it, a little physical and mental exercise.
The deep thoughts keep me from getting bored stiff while sanding. :p
 
solrey said:
In the context of the magnetron glow discharge, it simply designates the presence of an external magnetic field, it could be weak or strong or all points in between. They are not literally referring to the magnetron as a device nor inferring a B field of similar strength. Any strength B field will have some effect. It is simply a magnetically enhanced glow discharge. I believe the authors definition and equations will confirm this.
Click to expand...
(bold added)

Yes, that does make it a bit clearer.

However, surely the details matter a great deal, don't they?

I mean if at 10nT the magnetic field enhances a glow discharge by 0.1% (or less), the distinction between a magnetron glow discharge and an ordinary glow discharge is, observationally, irrelevant, isn't it?

I haven't gone through the material you cited in detail yet, but as I'm sure you have, can you please point out the expected extent by which a magnetic field of strength typically found in the solar wind would enhance a glow discharge?

As far as emission of the bright jets goes, I should have been more specific and clear that at or near the surface is mostly due to the glow discharge, but at some point reflectivity of the dust and discharge blend with distance from the nucleus until eventually it's mostly a result of reflection. Both glow and reflection are happening, but at or near the surface, there is the enhancement of the glow discharge. It's not necessarily one or the other, I should have been clear on that. :o
Click to expand...
Thanks for the clarification.

From image analysis, of images returned by the various spaceprobes which have resolved the points where the jets originate, what evidence is there that the detected emission exceeds that expected from reflected sunlight? I assume, given the detail you have been posting on EC, that such analyses have been done.

That also is analogous to the ionization distribution of the reaction by-product gases. The closer to the nucleus the more ionization, the free electrons liberated by the discharge combine with ions as both travel away from the nucleus, so there should be an increasing proportion of neutral atoms and molecules with increasing distance from the nucleus. I believe the conventional explanation would involve ionization due to friction, or triboluminesence.
Click to expand...
This is related to the reactions that might be taking place; perhaps we could look at this in more detail after your postcount has reached 16?

The coma boundary is a plasma double layer. One of the functions is diffusing the voltage potential across a greater surface area, which mitigates the discharge to the surface, while dissipating most of the energy in the form of x-rays at the boundary of the coma, or DL. It's a well known plasma phenomena, and a prime reason for Alfven's eventual Nobel prize. He even said that DL's should be treated as a specific cosmologic/astrophysical phenomena. The tail is just the DL being stretched by the solar plasma stream, basically stretching between a positive and negative potential, from bow shock (+) to end of tail (-). The tail contains the twisted filaments of the discharge current, Biot-Savart law and the Bennet relation are applicable here.
Click to expand...
There's a lot here, and I think it might be a good idea to look at it in a methodical fashion.

The aspect that I am most curious about, now, is why comets? I mean, why do comets have comas (and tails), but other solar system bodies do not?

Related to this: several spacecraft have travelled through comet comas, and they were equipped with functioning plasma physics instruments (IIRC). From the data returned from these instruments, what signature(s) of DLs are there (in these comet comas)?

One more point. The material from stardust mission that was formed in high temps could have come from the material being in plasma state in those micro-explosions of the glow discharge, described in the paper, prior to rapid cooling and re-solidification. ;)

This seems like a friendly forum, good questions, agree to disagree, respectful, yeah respectful...how refreshing. :D

Whew, busy day. Sanding a porch deck for refinishing and posting during breaks. Luv it, a little physical and mental exercise.
The deep thoughts keep me from getting bored stiff while sanding. :p
Click to expand...
Sounds like fun! :p
 
solrey said:
The voltage potential between the comet and the solar wind plasma (concentrated at the plasma double layer which makes the boundary of the coma, where the x-ray's are produced, in the DL) induces electro-chemical reaction chains on the nucleus, which together form a positive feedback, increasing the efficiency of each.
Click to expand...

Well, there is a lot of problems with this picture.
Take for example data that have been obtained at Comet Halley with the Vega flyby through the interesting regions of the coma, as reported by Harri Laakso.

Harri discerns three different regions:

Laakso said:
Based upon the behavior of the electric fields and the cold electrons, three regions can be identified in the cometosheath (in particular during the Vega 1 approach): transition layers are passed through at ∼780,000 km (R 1) and ∼360,000 km (R 2). The outer cometosheath (near and beyond R 1) is characterized by large-scale variations in the cold electron density and the electric field, peaking at ∼1 mHz. The R 2 crossing is detected in the plasma wave data as enhanced fluctuations at ∼15 mHz. About 25,000 km downstream of R 2, the spacecraft traverses a current layer (thickness ∼10,000 km) indicated by a sharp gradient in the dc electric field and the cold electron density.
Click to expand...

So, there is a DC electric field/current layer downstream of R2 with a thickness of ~10000 km. Now say that this would be the double layer (just for argument's sake, I am not saying it is really so) then the "bottom" of the DL would be at 360000 - 25000 - 10000 = 325000 km from the nucleus of the comet. That would be one humongous lightning flash or arc or whatever if the discharge would, for some reason which escapes me fully, go from the "electric field concentrated at the DL" and the nucleus of the comet.

For one, the problem is that if the electric field is indeed concentrated there, that means that any "discharges" would be inside the DL, there is no reason why there would be a discharge from the DL to the nucleus, as the inner side of the DL would have the same potential as the nucleus. Just like in a double plasma machine in which you generate a DL in the plasma column and one side has the potential of the anode and one side that of the cathode. (unfortunately I cannot find a figure of the potential in a double plasma machine at the moment).

Now, such discharges would emit radiation, specifically whistler mode waves. These are indeed observed, however Harri writes in the paper:

Laakso said:
The whistler emissions are excited by suprathermal electrons accelerated by lower hybrid waves, and therefore the intensity of whistler emission permits an assessment of the flux of suprathermal electrons [Galeev, 1987].
Click to expand...

There seems to be no indication that discharges happen, indeed they are not mentioned at all in the whole paper.

Then with respect to the X-rays, which supposedly are produced in the DL. It has been shown by Tim Thompson a few pages back that the X-rays are completely described by electron bremsstrahlung (for the continuum) and by nuclear excitation (for the line emissions). Just scroll a few pages back and you will find it.

Now, the question is, actually, what kind of double layer should be present in the coma of the comet? As you might or might not know, there are two different kinds of double layers, one carrying a current and one not carrying a current. You might think this is "nitpicking" but it has some very specific consequences for the physics.

So, it would be nice if an EC proponent would come with a real model.
 
Status
Not open for further replies.

Back
Top Bottom