Actual Polywell News!

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

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93143
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Re: Actual Polywell News!

Post by 93143 »

Joseph Chikva wrote:
93143 wrote:The electrons are fast where the ions are slow, and vice versa, which is one reason why the plasma doesn't neutralize.
Dubious too.
I'm not explaining how it works. I don't know how it works, or if it works. I'm explaining how it's supposed to work.

(Okay, it's not much of an explanation, but I don't have the time or mental energy to write a monster post detailing everything I currently think on the subject... those inevitably take me all day, and a lot of it isn't fresh in my mind...)

Joseph Chikva
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Re: Actual Polywell News!

Post by Joseph Chikva »

93143 wrote:I'm explaining how it's supposed to work.
Motion of ions can be considered as combination of two:
· harmonic oscillation around the center
· chaotic (thermal) motion
Because they are going to increase B-field strength from 0.8 to 10 T, so in12 times, and expect that number density will increase in 144 times (also dubious expectation), chaotic motion intensity will become comparable with harmonic (so called thermalization) faster.

Due to permanent neutralization of electron cloud the depth of potential well will decrease by entering of new portion of ions.
So, amplitude of harmonic oscillation of ions entered machine later will be slower than initially.

etc. etc. etc.

chrismb
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Re: Actual Polywell News!

Post by chrismb »

93143 wrote:Has it really been so long that you've all forgotten how this is supposed to work? Or is there more data that I've missed somehow?

Potential well formation in Polywells is shown experimentally to occur, and to reach at least 80% of the drive voltage even in relatively primitive machines. Wiffleball formation was apparent from numerous tests, including both PXL-1 and WB-6, and is implied by Nebel's comments on the subject combined with the continued Navy funding.
The capability of a polywell configuration to trap electrons and form a potential well is not in question.

The question raised was whether a potential well formed by a charge from a virtual, mobile region of charge space could attract enough ions, and the challenge posed was:
ladajo wrote:Show me your numbers that you can not attract enough fuel ions to have a fusion event with a 15KV electron well using what we publically know about (e-) density in the polywell. You say Brillion limit, I say show me.
Those numbers cannot be challenged as all the assumptions are stated. The assumptions behind those numbers are open to interpretations, however, because no experiment has yet shown the extent to which a non-rigid electrode can attract ions.

chrismb, who used to post here, has performed his own experiments and observed motion of fixed, rigid wire electrodes in response to the electric fields of the potential well it forms. This is consistent with observations from other experimenters who have run fusors. That a rigid wire composed of matter that is some 14 orders of magnitude more massive than a cloud of electrons, at 10E22/m^3 density, can be physically moved and displaced by the potential well it forms for itself suggests that the assumption the electrons will stay put when acted on by the electric fields from positive ions is something that needs to be proved experimentally if there are only hand-wavy arguments to the contrary.

A magnetic field only contains charged particles in motion. Questions have to be asked as to how fast, and in what direction, these electrons are moving/caused to move, to determine the likely strength they can cause on the ions. Ions would be either side of this electron cloud, which would tend to pull it apart.

The whole process of inertial confinement isn't one that has shown any tendency to produce more power than it consumes. A fusor is some 9 orders of magnitude lower than a 'break even' point. Scale up a fusor, and it simply consumes even more power, relative to the fusion rate.

So, the challenge, regarding numbers, was posed, and was answered. What one does/interprets with those numbers is up to the beholder.

D Tibbets
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Re: Actual Polywell News!

Post by D Tibbets »

chrismb wrote: ........

The whole process of inertial confinement isn't one that has shown any tendency to produce more power than it consumes. A fusor is some 9 orders of magnitude lower than a 'break even' point. Scale up a fusor, and it simply consumes even more power, relative to the fusion rate.

......
This absolute statement is miss leading. With fusors, fusion does scale faster than losses with a fixed grid transparency as the size increases. It is just that the difference is small. For a Fusor to reach breakeven, the size needs to be very large- foot ball stadium to Earth diameter, depending on various assumptions. Some very intelligent people like George Miley, and Nebel felt that this goal might be obtainable with doable engineering and tweeks at even smaller scales. Even Rider conceded that D-D fusion might be profitable with IEC techniques if some hurdles were overcome.

And, of course I can think of two inertial confinement schemes that have definitely shown positive Q fusion. One is Stars, the other is hydrogen bombs.

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

chrismb
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Re: Actual Polywell News!

Post by chrismb »

D Tibbets wrote:This absolute statement is miss leading. With fusors, fusion does scale faster than losses with a fixed grid transparency as the size increases. It is just that the difference is small. For a Fusor to reach breakeven, the size needs to be very large- foot ball stadium to Earth diameter, depending on various assumptions.
Explain your assumptions, then. Numbers would be good. Show what the electric field gradient would be like, with an electrode at the centre of an earth-sized fusor.

The fusion in a fusor is from beam-target type processes, which are intrinsically lossy. This is why it cannot scale up.

The 'most efficient' (or rather least inefficient) beam target processes that have occurred experimentally is by the neutral beam injection of deuterium into a tokamak DT plasma. A 20MW beam of deuterium atoms at 100~200keV results in a direct beam-target type fusion power of 1 to 2 MW from the collisions of those neutral atoms directly with the plasma nucleii. It can't get much better than this; 5 barns of cross-section, neutral beams to reduce small-angle Coulombic scattering, and it still can't break even on the beam input power (disregarding any energy input to sustaining the tokamak plasma as a 'plasma target').

In any 'locally-hot but generally-cold' fusion reactor, the losses are in the fuel particle collisions themselves. Those can't be reduced without equally and proportionally reducing the fusion reactions. Fusion is such a low-probability outcome of a collision. In a 'generally-hot' thermal plasma, there are no such thermalisation losses. Instead there are bremsstrahlung radiation losses, so the two routes have different fundamental issues to overcome.
D Tibbets wrote:And, of course I can think of two inertial confinement schemes that have definitely shown positive Q fusion. One is Stars, the other is hydrogen bombs.
No. These are thermonuclear processes. It is a highly confused statement to make suggesting these processes are the same as a fusor, simply because they both use the word 'inertial'. This is very misleading.

D Tibbets
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Re: Actual Polywell News!

Post by D Tibbets »

chrismb wrote:
D Tibbets wrote:This absolute statement is miss leading. With fusors, fusion does scale faster than losses with a fixed grid transparency as the size increases. It is just that the difference is small. For a Fusor to reach breakeven, the size needs to be very large- foot ball stadium to Earth diameter, depending on various assumptions.
Explain your assumptions, then. Numbers would be good. Show what the electric field gradient would be like, with an electrode at the centre of an earth-sized fusor.

The fusion in a fusor is from beam-target type processes, which are intrinsically lossy. This is why it cannot scale up.

The 'most efficient' (or rather least inefficient) beam target processes that have occurred experimentally is by the neutral beam injection of deuterium into a tokamak DT plasma. A 20MW beam of deuterium atoms at 100~200keV results in a direct beam-target type fusion power of 1 to 2 MW from the collisions of those neutral atoms directly with the plasma nucleii. It can't get much better than this; 5 barns of cross-section, neutral beams to reduce small-angle Coulombic scattering, and it still can't break even on the beam input power (disregarding any energy input to sustaining the tokamak plasma as a 'plasma target').

In any 'locally-hot but generally-cold' fusion reactor, the losses are in the fuel particle collisions themselves. Those can't be reduced without equally and proportionally reducing the fusion reactions. Fusion is such a low-probability outcome of a collision. In a 'generally-hot' thermal plasma, there are no such thermalisation losses. Instead there are bremsstrahlung radiation losses, so the two routes have different fundamental issues to overcome.
D Tibbets wrote:And, of course I can think of two inertial confinement schemes that have definitely shown positive Q fusion. One is Stars, the other is hydrogen bombs.
No. These are thermonuclear processes. It is a highly confused statement to make suggesting these processes are the same as a fusor, simply because they both use the word 'inertial'. This is very misleading.
The Earth size is somewhat tongue in cheek. One actual estimate is ~ 10 meters- admittedly various assumptions were made. The type of fusion in a fusor is somewhat dependant on the density, low enough and beam beam may dominate, beam, background or beam target may dominate at higher densities unless the background neutrals are significantly less comon in the reaction space and surfaces are magnetically shielded. This would be the condition in a Polywell.

Locally hot and cold can describe so many different situations that it can be interpreted as you wish. With a potential well the KE energy and potential energy of the particles can shift, but this does not imply that the cold (low KE and high potential energy) particles in local areas have to be high loss portals. There are many complexities.

As for inertial fusion, I mearly used your term- inertial confinement, you did not stipulate electrostatic. Certainly a bomb produces useful amounts of fusion because temperature and density is maintained long enough for significant fusion ( along with fission) to occur. The tamper is an important piece of the bomb. This dense material like depleted uranium contains the explosion/ x-rays long enough because of the inertial properties. Granted stars are more fuzzy. The gravitational confinement is what holds things together, But a stellar example where inertial effects plays a major role is in stellar explosions, especially core collapse supernova.

A review paper by Dolan is a good source of inertial electrostatic confinement fusion, especially with magnetic shielding. There is a bibliography of nearly 200 references . It seams some seem to assume that EMC2 operated alone, and that there is no body of theory and experimentation to support their reasoning. Dolan covers the then understanding and expectations. I have not finished re reading it but one scheme mentioned looks a lot like what EMC2 tried to do with WB5- cusp plugging with electron repellars close to the cusps. This is one aspect that apparently didn't work out, but the recirculation approach apparently has the benefits without the penalties of cold electrons in the cusps.

It also mentions spindle cusp arrangements that suffer from small internal B field free volumes. This ties in with the Polywell, but the small volume is significantly increased (along with better cusp confinement) due to the Wiffleball effect. And this ties in with Nebel's assertion that the Wiffleball effect is of paramount importance in this confinement method.

http://www.askmar.com/Fusion_files/Magn ... nement.pdf

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

chrismb
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Re: Actual Polywell News!

Post by chrismb »

D Tibbets wrote:Locally hot and cold can describe so many different situations that it can be interpreted as you wish.
A fusion reaction process is either intending towards working with thermalisation, or intending away from it. This is the explicit difference. Absolutely no interpretation whatsoever.

D Tibbets wrote:As for inertial fusion, I mearly used your term- inertial confinement, you did not stipulate electrostatic.
In linguistic analysis, context is everything.

The two distinct 'inertial' fusion type-processes are either;
- where the 'inertial' of individual fast particles keeps them moving through a surrounding medium (with which they can fuse, or do 'whatever'), or
- where the 'inertial' of a surrounding material prevents the escape of fast particles through it.

'Inertia' in the former case (fusors, polywell-design-intent, 'IEC') references the consequential behaviour of the fast particles by the inertial they have gained, whereas 'inertial' in thermonuclear reactions references the lack of inertia and consequent reluctance of the background to move out of the way quick enough of fast particles that they are effectively contained, and thermalise. Again, quite distinct, and different. It is clear that the surrounding material in the former must be several oom lower in density than that of the latter, for this to hold true.

paperburn1
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Re: Actual Polywell News!

Post by paperburn1 »

I would like to start a rumor,
As the guys at skunk works have helped out polywell before I am wondering if they might actively be involved right now with EMC and working together on the two most likely approaches that could achieve polywell fusion. Just one of those random thoughts that keep pecking at the back of my brain. with all the vague references lately to "electric ships", high energy defence and offence by those up in the puzzle palace I have to wonder
/
I am not a nuclear physicist, but play one on the internet.

Torulf2
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Re: Actual Polywell News!

Post by Torulf2 »

If Lockheed Skunkworks use the wafelaball effect, it is a polywell with only two point cusp and only one coil.
Here is my a picture showing how I guess its looks like. (2 visions)
Image
Image

Skipjack
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Re: Actual Polywell News!

Post by Skipjack »

Hmm, what if there were two coils?

D Tibbets
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Re: Actual Polywell News!

Post by D Tibbets »

I have no idea what Chrismb is trying to say about hot and cold. Thermalization is certainly paramount in Tokamak type schemes which include fusion products thermalizing with and thus heating the fuel- ignition. It also determines fusion rates in the thermalized spread of fuel ions and considerations of energy balance with theis "mixed environment".

Hot and cold in a potential well is a different perspective, the energy is fixed, but the share between potential and kinetic energy varies locally. Cold ions on the edge are not stealing or draining energy that cools the hot central ions. And of course in the Polywell thermalization of the fusion ions with the fuel ions is insignificant. There is no ignition desired or needed.

Certainly if the average ion temperature lowers that implies that energy is lost from the system, but that is not what is happening in a potential well.

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

D Tibbets
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Re: Actual Polywell News!

Post by D Tibbets »

Torulf2,
The Skunks Works device is very similar to the Polywell in my interpretation. The picture they provided is essentially half of the device. It consists of three opposing magnets. This like a biconic cusp mirror machine just like the start for the Polywell. In the Polywell a series of magnets are placed between the two end magnets and this greatly decreases the equatorial line cusp losses by modifying this cusp into a complex collection of point or point like cusps. I may still eventually explain this morefully, but basically the Polyhedral arrangement is not the only solution. By placing a single ring magnet between the two end magnets you convert the single wide equatorial line cusp into two much narrower line cusps- Tropic of Cancer and Tropic of Capricorn cusps if you will. I think this will reduce cusp losses. There are two point cusps and two narrow line cusps compared to the 8 corner and 6 point cusps in the truncated cube Polywell. There is symetry along the central axis and importantly there is a central focus/ field free region just like in the Polywell. This may allow for Wiffleball inflation (absolutely essential) in this machine just as in the Polywell. There have been similar designs with cylindrical solenoid central magnets with ring end magnets, but I've not seen any of them with this central focus/ quasi spherical geometry. Magnets polarity would be opposing between adjacent magnets. This means the field directions are different on either side of the central ring magnet. This is different from the polyhedral design where all field orientations are the same, but the important consideration is that the adjacent magnets oppose each other.

Below is an image of the B fields with this three ring arrangement. The arrangement may work best if the central ring magnet has a larger diameter than the end magnets. Also the center magnet may tolerate some increased length along the axis of symmetry and allow for convex fields and maintaining the internal volume while narrowing the line cusps further.The B fields can be adusted to create the central field free zone while playing with magnet separation.


Image


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

Torulf2
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Re: Actual Polywell News!

Post by Torulf2 »

This is not how its looks like on the photo.
The outer magnets are bigger for bending the B-field round the central coil.
Perhaps there are more coils?

Robthebob
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Re: Actual Polywell News!

Post by Robthebob »

wait what? how is skunks machine using diamagnetic effect to counteract B field in order to get it to a condition that increase electron confinement by reducing escaping through cusps?
Throwing my life away for this whole Fusion mess.

D Tibbets
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Re: Actual Polywell News!

Post by D Tibbets »

Torulf2 wrote:This is not how its looks like on the photo.
The outer magnets are bigger for bending the B-field round the central coil.
Perhaps there are more coils?
In the Skunk Works photo, only portions of two magnets are shown. They look like ring magnets but which is the end and which is the center is not apparent. I interpret the left magnet as one of two end magnets, and the right magnet as the center. You could make a whole string of magnets and this might be usefull, but for central focus only three magnets maximum is possible. If you string a lot of them together , for each central focus you would have two narrow line cusps and almost only one point cusp.

Also, the advantage of a greater diameter central magnet is obvous from the magnetic field lines. If most of the leaks is the line cusps then fusion ions exit mostly here and the cones of ions may lend them to better direct conversion grid designs com[ared to the 14 spikes (or more) in a Polywell. The vacuum vessel may be smaller in diameter and this may lend itself to more compact designs, etc.

Also, the smaller end magnets may allow for closer placement while maintaining a central focus volume with relatively narrower line cusps.

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

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