Spheroidal Foci and POPS?

Discuss how polywell fusion works; share theoretical questions and answers.

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alexjrgreen
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Post by alexjrgreen »

KitemanSA wrote:
alexjrgreen wrote: In fact I'm going to claim that this fluorescence is what you can see here, which would mean we already know what a wiffleball looks like...
No need to "claim" it. That fact has been stated in prior papers (or maybe it was just a posting).
Happy to be scooped if you can provide the link.
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D Tibbets
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Post by D Tibbets »

alexjrgreen wrote:
KitemanSA wrote:
alexjrgreen wrote: In fact I'm going to claim that this fluorescence is what you can see here, which would mean we already know what a wiffleball looks like...
No need to "claim" it. That fact has been stated in prior papers (or maybe it was just a posting).
Happy to be scooped if you can provide the link.
Fluorescence or glow discharge is more percisely a recombination event (or higher orbital electron falling back to a lower energy state) that releases the excess energy in the visible spectrum that we can see. The electron- neutral, or electron -ion collisions tend to be more energetic and if energy is released it is at shorter wavelengths- UV or X-ray). The glow discharge seen in the referenced picture shows the areas where recombination is occuring. For that to occur there has to be excited atoms or ions present, so the abscence of glow implies an absence (or significantly lower densities)of these products in these areas, or possibly a distribution ions/electrons that does not favor recombination. Look for discriptions of glow discharges.

[edit - corrected link]

http://www.plasma-universe.com/index.ph ... _discharge

The picture shows the distribution of the glow discharge- with cusps, etc. but does not imply a Wiffleball formation directly as that is a result of compression of the magnetic fields with choeking of the cusp entrences. A series of pictures of the glow discharge distribution and intensity at various charged partical currents and voltages might show the morphological changes consistant with a wiffleball. I suspect some type of measurment of ion and/ or electron flows and magnetic field distortions would be needed to confirm a wiffleball.

Dan Tibbets
Last edited by D Tibbets on Tue Nov 03, 2009 10:41 pm, edited 3 times in total.
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MSimon
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Post by MSimon »

alexjrgreen wrote:
alexjrgreen wrote:I wonder if it might be practical to create a college demo. What I have in mind is a 4 inch diameter glass round bottomed flask with six 1 1/2 inch diameter circular "trenches" dropped into it to create a polywell with its long diagonal along the centre line of the flask.

The magnet coils could then be dropped into the "trenches" from outside.

Not sure whether the vacuum rating would be adequate. Perhaps an engineer can comment.
Perhaps it's not even necessary to inset the coils for a college demo.

The e/m of the Electron Apparatus gives the basic idea. Just use six Helmholtz coils instead of two and cross-wire them.

This caught my attention:
The vacuum tube has a downward pointing electron gun in an evacuated bulb that has a little helium added so that the path of the electron in tube is visible. The helium gas added to the tube fluoresces when struck be the moving electrons and produce a bright, clear view of their circular path, Thus, the circular tracing of the electron path is undisturbed by the previously emitted electrons, contributing to a more accurate measurement.
I got to play with one of those for a couple of weeks in High School.
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D Tibbets
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Post by D Tibbets »

MSimon wrote:
alexjrgreen wrote:
alexjrgreen wrote:I wonder if it might be practical to create a college demo. What I have in mind is a 4 inch diameter glass round bottomed flask with six 1 1/2 inch diameter circular "trenches" dropped into it to create a polywell with its long diagonal along the centre line of the flask.

The magnet coils could then be dropped into the "trenches" from outside.

Not sure whether the vacuum rating would be adequate. Perhaps an engineer can comment.
Perhaps it's not even necessary to inset the coils for a college demo.

The e/m of the Electron Apparatus gives the basic idea. Just use six Helmholtz coils instead of two and cross-wire them.

This caught my attention:
The vacuum tube has a downward pointing electron gun in an evacuated bulb that has a little helium added so that the path of the electron in tube is visible. The helium gas added to the tube fluoresces when struck be the moving electrons and produce a bright, clear view of their circular path, Thus, the circular tracing of the electron path is undisturbed by the previously emitted electrons, contributing to a more accurate measurement.
I got to play with one of those for a couple of weeks in High School.
I see two problems with a 'Demo' Polywell with the magnets outside the glass. Even with some grooves in the glass (unless the grooves are indented well past the thickness of the magrid coils, which would introduce structural integrity against vacuum issues) the cusp flows would hit the glass before much of the spiky nature of the wiffleball could be demonstrated. Conversely, the charged particles (presumably mostly electrons) hitting the glass would result in glows on the glass that could show the distribution of the cusp flows at that radius. Possibly even showing well the actual shape and size of the corner/ funny cusps at that level.
Other than not having the spikes extending beyond the magnets to show where recycling could occur, the electron beams hitting the glass would cause local heating and increase the chances that the glass could fail and implode. A lot of glass shrapnel would result. A clear plastic shield could protect the observers, but the vessel would be destroyed.
permanent magnets placed inside the vacuum vessel (such as I have done) would show the idea well, with the caveat that the differences between the nature of permanent vs electromagnets was explained. Using a clear Bell jar instead of a small viewing window would improve the visibility and impact, so long as safety measures were followed. Of course it would take some explaining to clarify the difference between a central real cathode and a central virtual cathode with electron guns, etc.

Dan Tibbets
To error is human... and I'm very human.

ladajo
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Post by ladajo »

alexjrgreen wrote:
KitemanSA wrote:
MSimon wrote: At 10KV and up there is no such thing as a safe supply.
Which is why I put the word safe in quotes. What is needed is a power source that is as safe as experts can make it, without any of the potentially fatal mistakes that the non-expert may introduce.
Something like this?

A High Voltage Power Supply for your Lab
Alex - the issue is safely driving the coils, this supply has not the amperage to go with the voltage to get a meaningful field. Remember that Dr Nebel and Co are blasting their coils with a truckload of car batteries for a high amp hit. Apples and Oranges (Volts and Amps :D )

I think that a hack job on a pressure cooker like Dan's with a standoff to the vessel to hang each coil winding from, and penetrations to power each at two of the coil standoff bases, hooked up to a reasonable amperage variable DC power supply should do the trick for dial a field and "Spikeyball" exploration. All Dan's points about recombination verses actual electron recirc well noted. But I think the pressure cooker is dirty enough a system for ions that it will at least let us see how the field effects the electrons and ions and if the chamber is big enough outside the coil volume, even possible recirc paths (demonstrated by recomb glow). Plus we get to see what it looks like without nubs between the coils.
using supports like EMC2 did to support WB6 on the bottom should do the trick for each coil independantly. (I believe MSIMON talked to this a while or so ago, pure memory...).

KitemanSA
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Post by KitemanSA »

Related (dumb?) question. Does a glass container make a better vacuum chamber than a steel one? I.e., can you get to very low Torr esier with glass than with steel?

I have heard that steel has problems due to evolution of interstitial gasses. Does glass have the same problem?

If not, would a metalic glass sphere be like the metal or the glass?

Giorgio
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Post by Giorgio »

KitemanSA wrote:Related (dumb?) question. Does a glass container make a better vacuum chamber than a steel one? I.e., can you get to very low Torr esier with glass than with steel?
Not from a pratical point of view.

Giorgio.

alexjrgreen
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Post by alexjrgreen »

ladajo wrote:
alexjrgreen wrote:
KitemanSA wrote: Which is why I put the word safe in quotes. What is needed is a power source that is as safe as experts can make it, without any of the potentially fatal mistakes that the non-expert may introduce.
Something like this?

A High Voltage Power Supply for your Lab
Alex - the issue is safely driving the coils, this supply has not the amperage to go with the voltage to get a meaningful field. Remember that Dr Nebel and Co are blasting their coils with a truckload of car batteries for a high amp hit. Apples and Oranges (Volts and Amps :D )
In which case the word "safe" doesn't have any relevance at all.

Talk to your nearest reputable manufacturer and take appropriate care.
Ars artis est celare artem.

alexjrgreen
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Post by alexjrgreen »

D Tibbets wrote:C:\Dan's Documents\Fusion\Reference\Electric glow discharge - (The Plasma Universe Wikipedia).mht
Not many of us can see that. Perhaps you meant Electric glow discharge.

Most of these pictures show where the ions go. I'm claiming that the WB7 picture shows the electrons in the wiffleball.
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alexjrgreen
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Post by alexjrgreen »

alexjrgreen wrote:
KitemanSA wrote:
alexjrgreen wrote: In fact I'm going to claim that this fluorescence is what you can see here, which would mean we already know what a wiffleball looks like...
No need to "claim" it. That fact has been stated in prior papers (or maybe it was just a posting).
Happy to be scooped if you can provide the link.
Several people have skirted round this, but I can't find anyone stating it explicitly:

viewtopic.php?p=5171&highlight=#5868
Tom Ligon wrote:Keegan,

I'm no longer sure I'm correct about that assertion you can't see the wiffleball.

That was my working assumption when we did video and PMT studies of PXL-1 and WB3. In those, we did not have enough power supply to hold the voltage up during the bright events, and I was finding we had the deepest potential wells when there was little or no light output. The really bright glows tended to pull the voltage down too far for any hope of fusion. However, the bright events did frequently show the topology of a wiffleball.

From what Dr. Nebel has been saying, fusion conditions exist in the newer experiments at densities far higher than I expected. You still want to avoid runaway density, and I'd guess light output is still an indication of loss of ions, but they're driving with a lot more power than I ever had available, and can stand more recombination.
viewtopic.php?p=7142&highlight=#7142
seedload wrote:
kcdodd wrote:If line cusps have the same throughput as point cusps, yes; but I just posted a plot showing that the point cusps are the major loss factor.
I just wanted to say that it is really cool how much your picture looks like the picture of the WB7 in operation on the EMC2 website. Clearly, most of the junk is going out the point cusps.

I think Art is arguing that in wiffleball mode the line cusps will dominate.
viewtopic.php?p=8908&highlight=#8908
TallDave wrote:My guess is they got exactly what they expected: a good wiffle-ball tested with helium
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D Tibbets
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Post by D Tibbets »

alexjrgreen wrote:
D Tibbets wrote:C:\Dan's Documents\Fusion\Reference\Electric glow discharge - (The Plasma Universe Wikipedia).mht
Not many of us can see that. Perhaps you meant Electric glow discharge.

Most of these pictures show where the ions go. I'm claiming that the WB7 picture shows the electrons in the wiffleball.
I corrected the link in my prevous post. It is indead the site you linked.

I believe that with a good wiffleball and low pressures in the cusp regions and beyond (say pressures below ~ 5-10 microns) the electrons would dominate in the cusps as they are recirculating. But, if the ions are being contained well, the electrons will not have much to interact with so there would be very little glow discharge to see. What I suspect the EMC2 picture shows is the glow dischargw associated with the escaping ions and/or neutral atoms that have built up and reacting with the electrons in these cusp regions. In otherwords, the picture was taken during the terminal arc breakdown of the test run. The morphology of the magnetic containment is visualized, but I suspect these glows would be much tighter and fainter during B=1 Wiffleball conditions.
I suspect that in an ideal Polywell in Wiffleball mode, there would be no neutrals floating around, the ions would be contained well within the magrid, and the escaping/ recirculating electron beams would extend only a short distance beyond the midpoint radius of the magrids and would be invisible in the visual spectrum because there is nothing present for them to hit, so no (or tiny) fluoresance.

Dan Tibbets
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KitemanSA
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Post by KitemanSA »

Giorgio wrote:
KitemanSA wrote:Related (dumb?) question. Does a glass container make a better vacuum chamber than a steel one? I.e., can you get to very low Torr esier with glass than with steel?
Not from a pratical point of view.

Giorgio.
More please! Why not? What is your basis? 8| (attentive stare!)

KitemanSA
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Post by KitemanSA »

alexjrgreen wrote:
KitemanSA wrote:
alexjrgreen wrote: In fact I'm going to claim that this fluorescence is what you can see here, which would mean we already know what a wiffleball looks like...
No need to "claim" it. That fact has been stated in prior papers (or maybe it was just a posting).
Happy to be scooped if you can provide the link.
I did look back to try to find it, but couldn't in the time I was willing to spend. Basically I recall being told in one topic line that the bright glow in the WB7 picture in the EMC2 website was due to Helium being purposefully introduced at fairly high concentrations specifically to show the electron flow. Since the electrons flow withing the wiffleball and thru the cusps, QED. Best I can do for now.

ladajo
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Post by ladajo »

This is more than knowing what the wiffleball looks like (or so), it is about exploring the transition from mirror to wiffleball, and the proportional changes in the spikeyball (cusps) given changes in magnetic flux intensity(dial-a-field). As well as seeing if recirc is limited to one cusp(in/out pulsing), or does it really follow the field lines around (looping).
Lots of good fun and understanding to be had...

KitemanSA
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Post by KitemanSA »

ladajo wrote:This is more than knowing what the wiffleball looks like (or so), it is about exploring the transition from mirror to wiffleball, and the proportional changes in the spikeyball (cusps) given changes in magnetic flux intensity(dial-a-field). As well as seeing if recirc is limited to one cusp(in/out pulsing), or does it really follow the field lines around (looping).
Lots of good fun and understanding to be had...
I'm not sure anyone still thinks the electrons go all the way around the field lines, the loops of which should be VERY large, WAY larger than the rather short distance to the ground plane. Then again, maybe I am misunderstanding how far away the original electron sources are.

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