We need a new film on YouTube explaining the Polywell.

[happyjack27]

and faster ones leave. and new gas is puffed in, introducing ions w/a mix of energy levels.

Nope, they are introduced at the edge of the well and ionized there. Then they fall into, and gain the unique energy level of, the well. Mono-energetic.

Gas puff injection by definition distributes them as a "gas puff" does, by diffusion through pressure. And they are them ionized whereever the em forces are sufficient to ionize them. As they are ionized at different radii, they are ipso fact ionized and thus "initialized" at different energy levels.

[KitemanSA]

i'm not a physicists, but my first impulse would be to try to get a handle on the density of (cold) "neutrals" and a separate density of (hot) "ions".

Why should there be ANY recombination? Where in the system are the ions and electrons within a few eV of each other in energy?

[D Tibbets]

and faster ones leave. and new gas is puffed in, introducing ions w/a mix of energy levels.

Nope, they are introduced at the edge of the well and ionized there. Then they fall into, and gain the unique energy level of, the well. Mono-energetic.

Gas puff injection by definition distributes them as a "gas puff" does, by diffusion through pressure. And they are them ionized whereever the em forces are sufficient to ionize them. As they are ionized at different radii, they are ipso fact ionized and thus "initialized" at different energy levels.

A gas puff is indeed a gas puff. It will diffuse or disperse quickly. There is some capability to slow this some by using a collimated stream, but the important point is that the ionization occurs due to high energy electrons 'knocking off' electrons from the gas molecules. This direct collisional process greatly dominates over any e field effects, which is a dismal ionization mechanism except under some remarkable conditions. The collisional driven ionization is a fast process which will ionize half of the gas molecules in a few microseconds, half of the remaining in the next unit of time, etc. It is much like radioactive half lives. As the neutral gas is puffed in at modest velocities it begins ionizing. The survivors continue on , mostly deeper into the machine, till they pass the center and continue out the other side. This means the created ions are at different radii, most near the edge, fewer towards the center. This is time dependent and this neutral transit travel distance is relative to the machine diameter. The larger machine will have a higher percentage of neutral to ion conversions near the edge and also a greater total ion creation efficiency. Bussard pointed this out and admitted it was a problem in small machines. While he did not emphasize the effects on ion energy spread, he pointed out that the surviving neutrals that transited the machine (or were back scattered out of the machine) was significant enough that this neutral gas increased the overall density in the vacuum space to the point that Pashin arc- glow discharge became great enough that it terminated the tests. He pointed out that larger machines mostly resolves this problem as the longer transit times allows for significantly greater neutral gas ionization- which traps the ions inside the magrid where much superior contours and magnetic shielding resists the Pashin breakdown. He also pointed that the design of the gas puffers was not optimized.

Recombination of free electrons with ions can and does occur, but my appreciation from discussions here and literature is that at e fields of thousands of volts this is a minor problem. Apparently e-fields are not good at initiating ionization but they are good at maintaining ionization.

Charge exchange is another problem, An ion hits a neutral and transfers an electron. This results in hot ions interacting with cool neutrals and reducing the available hot ions for fusion (cools them). This occurs extensively in glow discharge fusors as neutrals generally outnumber the ions. In the Polywell though, the ions are contained/ concentrated inside the Wiffleball while any neutrals can diffuse throughout the vacuum chamber. The density of the neutrals outside the machine is limited by Pashin breakdown to ~ 0.1 to 1 Microns (about 1 millionth of an atmosphere). This places an upper limit on the permissible neutral density which is distributed evenly throughout the vacuum chamber. The ion density though may be ~ 1000 times higher within the Wiffleball. This means that the ions greatly outnumber the neutrals inside the machine and so charge exchange collisions are relatively rare.

Beam -background collisions are essentially hot ions hitting cool neutrals or cool ions, beam- target collisions are hot ions hitting walls / targets (that often have fusion fuel gas molecules embedded into the surface). These collisions that result in fusion do not scale as well as beam- beam fusion collisions. In the Polywell the dominate form of fusion is beam- beam because the hot ions hit other hot ions in the core where the energy is the greatest and the density per unit volume is greatest. There are few cool neutrals or cool ions available for collisions. This dominate beam- beam fusion gives the full D^2 scaling and because the sum of the colliding ion energy is twice the energy of the individual ions, the fusion cross sections are significantly better at the same input energy. Some argue that beam- beam fusion is not significant in the Polywell but the above considerations would seem to counter that view.

Dan Tibbets

[happyjack27]

i'm not a physicists, but my first impulse would be to try to get a handle on the density of (cold) "neutrals" and a separate density of (hot) "ions".

Why should there be ANY recombination? Where in the system are the ions and electrons within a few eV of each other in energy?

Possibly in the core sometimes, for a sufficiently down-scattered ion. Possibly not.

[Stubby]

Matt was banned from fusor.net forums.

[ladajo]

Why and When?

[Stubby]

Thread marked for deletion because of non-compliance of OP. Not using his Real Name/UserID. User is banned.

[edit spelling]

Post dated 16 may

http://www.fusor.net/board/viewtopic.php?f=22&t=8509

[happyjack27]

"not using his real name" lol. do you understand how the internet works? I'll go there and use my "real name", "Bart Johnson". And my alter ego "Sally Morrison". And I'm sure i'll be warmly accepted by the community for using my "real name" -s. lol.

[ladajo]

Darn, I thought it would be for spamming the same post across threads and forums.

On a more serious note, that is just silly. The guy is making an honest effort to contribute. It can be annoying sometimes, but it is an honest effort which is more than many.

Like I keep telling my kids (over and over) being a good citizen involves, at the forefront, contributional participation.

[happyjack27]

"silly" is quite the euphemism, imo. "petty" is one word i'd use. the others words i'd use are, shall we say, not as mild.

[Stubby]

i think it is more of the straw and the camel

[ladajo]

Maybe. I dunno, I don't frequent fusor.net. Ironically, when a founder asks, (to wit), 'have any of those Polywell Folks over there done any fusor work and made neutrons?' it woul dappear nor do they so much frequent here.
We have a couple of cross-domainers for sure, but not sure how many in total. I perceive to date, it does not seem to be an abundance.

[KitemanSA]

The distinction between hobbyists and folk interested in a potentially viable fusion energy source?

[mattman]

Hello Everyone,

One of the admins (Paul) was pretty adamant that I use my real name. I really value my privacy, so I told them I could not. I understand where he is coming from.

Richard Hull was extremely nice about it. I realize that virtual communities can sometimes take on the characteristics of real communities.

My goal is add understanding around these machines and to figure out if they will ultimately make energy (I am not sold on that). I think we can work together to do this.