Questions about FPGeneration

Discuss the technical details of an "open source" community-driven design of a polywell reactor.

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kurt9
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Questions about FPGeneration

Post by kurt9 »

I stumbled upon a website (www.fpgeneration.com), which describes a mutli-pole ion source version of an IEC polywell. The guy, Alex Klein, has previously worked with Dr. Bussard.

Can anyone here comment on Alex Klein's MIX approach to polywell fusion and how it compares with Dr. Bussard's approach? Any comments are appreciated.

drmike
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Post by drmike »

On their web site it says
Klien wrote:The magnetic field also creates space charge lenses at the openings of the electromagnet so-called magnetic mirrors, which in turn serve to continually refocus beams of ions as they pass in and out of the core. The focusing action can be made to exactly counteract the effect of Coulomb collisions between particles, and ions can re-circulate on stable orbits thousands of times through the device without colliding with a material structure, preventing the loss of energy that limits the efficiency of conventional machines.
I don't see how random collisions can be "exactly counteracted". It is also curious how a 3 dimensional coil might be constructed with interwoven loops in they way picture it. It's possible, but I don't see how it would be efficient. It would be asymmetrical (assuming the fields add linearly). You would have 2 strong mirrors and 6 weak ones.

Worth paying them to do the experiment to see what happens. I don't think it will work the way they think it will. It's nice to be wrong though!

TallDave
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Post by TallDave »

Thanks for the link. Very interesting.
With higher densities, electrons and ions can arrange themselves in alternating layers of positive and negative charge, forming "virtual electrodes" that can result in yet higher densities of ions at the center of the machine, and a trapped ion population that never intersects any material structure. Evidence for this effect has previously been observed in operating IEC machine.
And they use POPS, too:
The addition of a small radio frequency modulation of the cathode voltage will drive trapped ions to converge simultaneously at megahertz rates in the very center of the machine at high energies, provided a harmonic electric potential can be maintained inside the cathode, an effect called POPS (Periodically Oscillating Plasma Sphere) that has been documented in previous IEC experiments.


It's exciting to see so many IEC approaches out there. It really raises my confidence that something will pan out into a commercially viable energy source.

Altough, I have to say, Dr. Klein appears to have been standing a little too close to the reactor...

http://www.fpgeneration.com/aboutus/index.html

TallDave
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Post by TallDave »

I don't see how random collisions can be "exactly counteracted".
This looks like an active mechanism for something like the edge annealing Bussard was talking about.

I've seen people argue against the annealing saying essentially "you can't reduce entropy without doing work, so there must be losses here" but entropic considerations are secondary to energy effects; particles will seek their lowest energy state regardless of whether that happens to reorder them, so you don't necessarily need to do work to reorder them.

MSimon
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Post by MSimon »

TallDave wrote:
I don't see how random collisions can be "exactly counteracted".
This looks like an active mechanism for something like the edge annealing Bussard was talking about.

I've seen people argue against the annealing saying essentially "you can't reduce entropy without doing work, so there must be losses here" but entropic considerations are secondary to energy effects; particles will seek their lowest energy state regardless of whether that happens to reorder them, so you don't necessarily need to do work to reorder them.
I'm beginning to wonder if "edge annealing" isn't more of a klystron type effect.

With the beams oscillating they should pick up electrons at various velocities and bring them into the proper order.
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jlumartinez
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Post by jlumartinez »

FPGeneration was also mentioned before in these others threads:

viewtopic.php?p=2406

viewtopic.php?t=62

TallDave
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Post by TallDave »

MSimon wrote:
TallDave wrote:
I don't see how random collisions can be "exactly counteracted".
This looks like an active mechanism for something like the edge annealing Bussard was talking about.

I've seen people argue against the annealing saying essentially "you can't reduce entropy without doing work, so there must be losses here" but entropic considerations are secondary to energy effects; particles will seek their lowest energy state regardless of whether that happens to reorder them, so you don't necessarily need to do work to reorder them.
I'm beginning to wonder if "edge annealing" isn't more of a klystron type effect.

With the beams oscillating they should pick up electrons at various velocities and bring them into the proper order.
Is that the "beam bunching" effect the MIT team found?

93143
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Post by 93143 »

The entropy argument isn't valid here because the high-entropy state is not in thermodynamic equilibrium.

Take a shock wave in air. The air upstream and downstream is in equilibrium, and the entropy downstream is higher than the entropy upstream. But the shock itself is not in equilibrium, and if you look closely at it, you see that the entropy increases from the low upstream value to a peak, and then drops again to the downstream value.

Or consider a particle distribution with a certain average energy. It is entirely possible to mathematically construct a distribution with a wider energy spread than that specified by the Maxwellian; such a distribution will have higher entropy. Boltzmann's H-theorem dictates that, left to itself, this distribution will eventually relax to the Maxwellian, resulting in an entropy reduction.

The Second Law of Thermodynamics only applies to complete processes that begin and end in thermal equilibrium. A Polywell will generate entropy, but the total rate of entropy generation need not be as high globally as it is in the core.

MSimon
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Post by MSimon »

TallDave wrote:Is that the "beam bunching" effect the MIT team found?
Yes.
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TallDave
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Post by TallDave »

Well put 93143.

I wonder if Nebel's team has the diagnostics to say something about edge annealing or beam bunching. That would be almost as interesting in and of itself as the validation of WB-6's results.

kurt9
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Thanks...

Post by kurt9 »

I just read the previous threads about FPGeneration and about POPS, in general. POPS is essentially a pulsed bias such that you have an oscillating plasma sheath. POPS is interesting to me because it reminds me of a specialized coating process technology called Plasma Source Ion Immersion (PSII).

The similarity between these two techniques also explains why all of the guys I met at Los Alamos in 1997 who were working on PSII deposition of diamond-like carbon coatings were all ex-fusion researchers. We visited these guys while I was working for a Japanese equipment maker (called Nanotec). We wanted to develop PSII coating technology because of its vast market potential for DLC coatings onto many different materials.

The vacuum chamber they were using to develop the PSII process (with a bunch of GM piston heads in it) was used previously for fusion research. They had worked on something they called a spheromak (if I remember correctly), but had their funding cut because it conflicted with the Almighty tokamak and ITER, which they told me has zero chance of working.

Anyways, nanotec developed the PSII process, although it took them 5 years to do it. I think Nanotec could develop and build these IEC fusion devices that Bussard's group and others are working on.

MSimon
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Post by MSimon »

TallDave wrote:Well put 93143.

I wonder if Nebel's team has the diagnostics to say something about edge annealing or beam bunching. That would be almost as interesting in and of itself as the validation of WB-6's results.
Yes!
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Nanos
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Post by Nanos »

I wonder how much funding they are looking for ?

And whether there is room to look at using permenant magnets at all in their approach.

MSimon
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Post by MSimon »

TallDave wrote:
I don't see how random collisions can be "exactly counteracted".
This looks like an active mechanism for something like the edge annealing Bussard was talking about.

I've seen people argue against the annealing saying essentially "you can't reduce entropy without doing work, so there must be losses here" but entropic considerations are secondary to energy effects; particles will seek their lowest energy state regardless of whether that happens to reorder them, so you don't necessarily need to do work to reorder them.
What they fail to take into account is that the process of an electron/ion returning energy to a charged grid is exactly totally reversible if there are no collisions.

Which is why (in the ideal case) you get 100% power conversion from a decelerator and at best only 30 to 50% conversion from a thermal system.

People get very confused when discussing this stuff. Even a lot of PhDs in physics. Fortunately we have a few smarter physicists on our team.
Engineering is the art of making what you want from what you can get at a profit.

hanelyp
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Post by hanelyp »

drmike wrote:I don't see how random collisions can be "exactly counteracted". It is also curious how a 3 dimensional coil might be constructed with interwoven loops in they way picture it. It's possible, but I don't see how it would be efficient. It would be asymmetrical (assuming the fields add linearly). You would have 2 strong mirrors and 6 weak ones.
Looks to me like they're trying a symmetric octopole magnet. 4 face poles around each vertex, neighboring poles having opposite polarity. Current would not be continuous around a flat ring, but 4 sectors of current in opposite directions. (I considered a similar magnet configuration several years ago for another fusion device.)

Ions coming from a source are focused by a magnetic lens at a face to the center of the device. Providing an ion isn't too badly scattered passing through the center, it's focused through the magnetic lens on the opposite face, and collected at the opposite emitter with recovery of most of its energy. So scattering doesn't have to be perfectly countered, just enough to return the ion to the emitter/collector zone.

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