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Point out news stories, on the net or in mainstream media, related to polywell fusion.

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ladajo
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Postby ladajo » Wed Mar 07, 2012 4:52 pm

Joseph Chikva wrote:
ladajo wrote:In the cae of Polywell, once the electrons are inside the shell, why do we care if the beam is destoyed?


ladajo wrote:We only want them to join the general populace of the potential well
The second quote is the answer on the first your question. Bunching of electron beams means that six electron beams do not intersect each other in the center. And may be you will not have the core (or waffleball) in the center. And even all will not develop according this catastrophic scenario, instability will not allow you to reach high beta.

Destroyed beam (if destroyed) will be splitted on separate bunches and all of them will be the low depth potential wells for ions instead of one and deep well as desired.


I don't think this is the case. Once an electron is inside the device, it becomes more and more governed by the group behavior with every collision, and the fact it entered on a beam becomes less and less relevant. In my mind, I think that you want to dial back the beam until you get sufficient energy to enter, but not so much that you drive the beam to any significant distance across the volume. The less the better. Otherwise, you risk increasing losses, as you in effect, drive the electrons out the other side.
I am still toying in my head with a means to 'bleed' electrons into the inside volume without providing a ground path, and possibly using the leakage exit routes as a possible entry route. Say for example, bleeding electrons directly from a point on the magrid casing to get picked up by a field line, and the letting the electron spiral up and out into the device, instead of sprialing down and in... or seeking to use the same effect at a cusp.
The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)
What I want to do is to look up C. . . . I call him the Forgotten Man. (Sumner)

KitemanSA
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Postby KitemanSA » Wed Mar 07, 2012 5:47 pm

Joseph Chikva wrote:
Two-stream instabilities are a major concern when beams propagate through plasmas.
WHAT beams? This is NOT a Migma machine that tries to interwaeve beams of ions thru the center of a complex magnetic device. No beams, no beam instability. Kay?

Joseph Chikva
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Postby Joseph Chikva » Wed Mar 07, 2012 6:01 pm

KitemanSA wrote:
Joseph Chikva wrote:
Two-stream instabilities are a major concern when beams propagate through plasmas.
WHAT beams? This is NOT a Migma machine that tries to interwaeve beams of ions thru the center of a complex magnetic device. No beams, no beam instability. Kay?
Not kay. As electron guns generate beams. Beams then enter into the space ocupated by plasma. Do you want plasma definition?
Good luck.

KitemanSA
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Postby KitemanSA » Wed Mar 07, 2012 7:41 pm

The "beams" stop being "beams" when they pass the MaGrid. There is no need nor desire to have "beams" inside the MaGrid. No beams, no beam instability. Now kay?

ladajo
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Postby ladajo » Wed Mar 07, 2012 8:31 pm

Joseph,
Do you understand that it is entirely possible the Polywell can operate without Electron guns?
One of Bussard's and Nebel's thoughts was to use the inherant gas in the chamber to charge and strip of electrons to create the electron source. They even theorized it oculd be possible to run the machine on just this as a source if electron confinement was good enough.
I do not know why you insist on driving high energy electron beams into the plasma, nor do I see why it really matters if you did or did not.
The Polywell IS NOT an opposing beam system. It only acts like one in some analysis aspect. Polywell is a distributed cloud system with independant driven random cyclic tendancies for all particles in the volume. In effect, it is a chaotic cloud with definite tendancies. Beams are not one of the tendancies.
The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)

What I want to do is to look up C. . . . I call him the Forgotten Man. (Sumner)

Roger
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Postby Roger » Wed Mar 07, 2012 9:09 pm

ladajo wrote: I do not know why you insist on driving high energy electron beams into the plasma, nor do I see why it really matters if you did or did not.
The Polywell IS NOT an opposing beam system. It only acts like one in some analysis aspect. Polywell is a distributed cloud system with independant driven random cyclic tendancies for all particles in the volume. In effect, it is a chaotic cloud with definite tendancies. Beams are not one of the tendancies.


All a Polywell needs is to 'introduce' electrons inside of the MCGrid, right?

Joe whats the big deal?
I like the p-B11 resonance peak at 50 KV acceleration. In2 years we'll know.

TallDave
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Postby TallDave » Wed Mar 07, 2012 10:33 pm

ladajo is correct -- as Rick explained long ago, electron behavior in the interior is stochastic. Two-stream is not an issue, as it isn't a beam machine.

This is very basic to how Polywells work. The definitive aspect of the PW is the wiffleball confinement, and when people don't understand the WB they tend to make these kinds of inapplicable arguments, similar to when Art kept making LTE arguments about a machine that is not in LTE.
n*kBolt*Te = B**2/(2*mu0) and B^.25 loss scaling? Or not so much? Hopefully we'll know soon...

Robthebob
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Postby Robthebob » Thu Mar 08, 2012 12:15 am

Skipjack wrote:I am not saying that his thing 100% sure to work, but the likelyhood that it will result in an economic reactor is infinitely higher than it is for Toks, which have a likelyhood of 0.


come on now Skipjack, no name calling. Toks can work, it'll just be very hard. It's proven to work as a reactor, but not as a good reactor...
Throwing my life away for this whole Fusion mess.

Skipjack
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Postby Skipjack » Thu Mar 08, 2012 12:28 am

come on now Skipjack, no name calling. Toks can work, it'll just be very hard. It's proven to work as a reactor, but not as a good reactor...

Reread what I said "economic reactor". Toks will work for sure, but they will never result in anything competitive on the energy market.

Robthebob
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Postby Robthebob » Thu Mar 08, 2012 12:33 am

ladajo wrote:Joseph,
Do you understand that it is entirely possible the Polywell can operate without Electron guns?
One of Bussard's and Nebel's thoughts was to use the inherant gas in the chamber to charge and strip of electrons to create the electron source. They even theorized it oculd be possible to run the machine on just this as a source if electron confinement was good enough.
I do not know why you insist on driving high energy electron beams into the plasma, nor do I see why it really matters if you did or did not.
The Polywell IS NOT an opposing beam system. It only acts like one in some analysis aspect. Polywell is a distributed cloud system with independant driven random cyclic tendancies for all particles in the volume. In effect, it is a chaotic cloud with definite tendancies. Beams are not one of the tendancies.


I thought you had to drive the electrons through guns, because the electron losses are too fast, you need a gun to keep the well going. That was the Sydney people's paper was partially about.
Throwing my life away for this whole Fusion mess.

ladajo
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Postby ladajo » Thu Mar 08, 2012 1:57 am

Loss rates remain to be seen.

We can assume for sure that confinement has improved from device to device, as that has been the primary theme.
To what reduction of loss rate we know not in public.

Some results apparently were encouraging enough to generate talk of the possibility that the machine could self sustain the electron population from electrons stripped off fuel particles.

As my old buddy used to say, "we will know when we know".

Bottom line, you do not necessarily need electron guns to feed the monster. There may be other ways. The guns do not drive well depth, they just drive the electrons in from outside.
The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)

What I want to do is to look up C. . . . I call him the Forgotten Man. (Sumner)

Joseph Chikva
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Postby Joseph Chikva » Thu Mar 08, 2012 3:05 am

ladajo wrote:Joseph,
Do you understand that it is entirely possible the Polywell can operate without Electron guns?
One of Bussard's and Nebel's thoughts was to use the inherant gas in the chamber to charge and strip of electrons to create the electron source. They even theorized it oculd be possible to run the machine on just this as a source if electron confinement was good enough.
I do not know why you insist on driving high energy electron beams into the plasma, nor do I see why it really matters if you did or did not.
The Polywell IS NOT an opposing beam system. It only acts like one in some analysis aspect. Polywell is a distributed cloud system with independant driven random cyclic tendancies for all particles in the volume. In effect, it is a chaotic cloud with definite tendancies. Beams are not one of the tendancies.
Points.
1. Electron source for creation of virtual cathode is needed
2. In designs that I have seen external electron guns are arranged outside the chamber. So, they create three pairs of oppositely directed electron beams in cubic geometry of Polywell.
3. The depth of potential well depends on electron density in the center.
4. Electron density in the center and average electron density in entire chamber should not be equal each other. In opposite case we can not organize the "right" motion in Polywell when virtual cathode attracts ions being at the edge.
5. We can not inject the quantity of electrons exceeded the certain limit defined with geometric dimensions of chamber and phase volume of electron beams. And phase volume of beams increases in case of instability. Even those instabilities will not destruct beams. And all speculations about possibility of beta to be equal to 1 I consider as a big nonsense. Regardless to what “said Richard and Rick”.

Sorry and thanks.

MSimon
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Postby MSimon » Thu Mar 08, 2012 3:41 am

Joel Rogers did some simulations that show that beams form spontaneously. It has also been theorized based on other considerations (experimental results). And the beams self synchronize and do meet in the center.

As to electron energies: as long as the drive is less than well depth all should be well in terms of entering beam losses.

The advantage of neutral injection is that electron stripping happens near zero energy for the electrons (near the surface of the MaGrid) and the electrons produced are inherently less energetic than the well depth until they join one of the packs tooing and froing through the system.

Which reminds me. I did a bit on self powering POPS (using a high Q resonator in the DC feed) that was dependent on oscillating beams. Think: high power vacuum tube. Which Polywell is.
Engineering is the art of making what you want from what you can get at a profit.

Joseph Chikva
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Postby Joseph Chikva » Thu Mar 08, 2012 4:02 am

MSimon wrote:Joel Rogers did some simulations that show that beams form spontaneously. It has also been theorized based on other considerations (experimental results). And the beams self synchronize and do meet in the center.
Doing simulation means some the usage of some models. Models differs from reality with some simplifing. So, very likely that you can loss some significant points during modeling.
For example did Mr./Dr. Roders take into the consideration this option of modeling?: http://www.netlib.org/utk/lsi/pcwLSI/text/node180.html
9.3.3 Electron Beam Plasma Instability
The problem used to benchmark the one-dimensional electrostatic GCPIC code on the Mark IIIfp was a simulation of an instability in a plasma due to the presence of an electron beam...At early times, the unstable waves grow exponentially...

MSimon
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Postby MSimon » Thu Mar 08, 2012 5:58 am

Joseph Chikva wrote:
MSimon wrote:Joel Rogers did some simulations that show that beams form spontaneously. It has also been theorized based on other considerations (experimental results). And the beams self synchronize and do meet in the center.
Doing simulation means some the usage of some models. Models differs from reality with some simplifing. So, very likely that you can loss some significant points during modeling.
For example did Mr./Dr. Roders take into the consideration this option of modeling?: http://www.netlib.org/utk/lsi/pcwLSI/text/node180.html
9.3.3 Electron Beam Plasma Instability
The problem used to benchmark the one-dimensional electrostatic GCPIC code on the Mark IIIfp was a simulation of an instability in a plasma due to the presence of an electron beam...At early times, the unstable waves grow exponentially...


Did you note that there were experimental results that supported the model? Not in detail though. More like "consistent with the model". In the early days this topic was beat to death. The conclusion was: no two beam instability in theory or practice. Of course that could have been wrong.

We await experimental verification either way.
Engineering is the art of making what you want from what you can get at a profit.


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