Looking for a starting point for a 3D simulation and stumbled across this. Have we seen this one before?
http://fti.neep.wisc.edu/static/TALKS/1 ... elroge.pdf
J
PIC Simulation of Polywell
Re: PIC Simulation of Polywell
JohnFul wrote:Looking for a starting point for a 3D simulation and stumbled across this. Have we seen this one before?
http://fti.neep.wisc.edu/static/TALKS/1 ... elroge.pdf
J
I THINK i've seen it before. Thought it was pretty neat, but i'm thinking that at the moment everyone wants experiment to confirm theory.
Sims are cool, but we need real world data now.
I've watched Joel's simulations develop for a few years. It has been interesting to watch the failures and successes as he tried to get the model to match reality.
I don't know how much inside information he has on the actual operation of WB7 and WB8, or how well the model presently matches with actual operation, but Joel's model is probably the best so far.
This appears to be a presentation or outline, rather than a paper, so it is hard to judge its rigor.
It was interesting to me that Joel got his model to predict what happens to cold electrons generated in the machine, and it matched what my intuition told me back when I was working with PXL-1. That closed box machine had some peculiar behavior that caused it to work better than it should in one configuration where large corner cusp losses should have occurred. I thought cold electrons might have been blocking the cusp. Joel shows that cold electrons do wind up there.
Notice his conclusion about the very low leakage of ions at the cusps. Hope he is right.
I don't know how much inside information he has on the actual operation of WB7 and WB8, or how well the model presently matches with actual operation, but Joel's model is probably the best so far.
This appears to be a presentation or outline, rather than a paper, so it is hard to judge its rigor.
It was interesting to me that Joel got his model to predict what happens to cold electrons generated in the machine, and it matched what my intuition told me back when I was working with PXL-1. That closed box machine had some peculiar behavior that caused it to work better than it should in one configuration where large corner cusp losses should have occurred. I thought cold electrons might have been blocking the cusp. Joel shows that cold electrons do wind up there.
Notice his conclusion about the very low leakage of ions at the cusps. Hope he is right.
I can put you in touch with Joel if you want to discuss his work further. He is kind of a private guy.
He seems well connected with Rick. OTOH I have no idea how much of the cat Rick has let out of the bag.
I have seen his stuff on cusp plugging. His current interest is fuel feed. i.e. for D-D the ions (gas fed from the magnets) come out at the right place at the right energy. OTOH the electrons are in the wrong place at the wrong energy.
And the cusp plugging by electrons creates problems for ion injection by ion guns.
Joel also thinks that gas injection will give too many neutrals and possibly ions in the wrong place. Any neutrals that get ionized outside the reaction space are a dead loss because they get accelerated in the wrong direction. Now if you could recover most of that energy with collectors it might not be too bad.
Which says - net power is only the beginning of the problems.
He seems well connected with Rick. OTOH I have no idea how much of the cat Rick has let out of the bag.
I have seen his stuff on cusp plugging. His current interest is fuel feed. i.e. for D-D the ions (gas fed from the magnets) come out at the right place at the right energy. OTOH the electrons are in the wrong place at the wrong energy.
And the cusp plugging by electrons creates problems for ion injection by ion guns.
Joel also thinks that gas injection will give too many neutrals and possibly ions in the wrong place. Any neutrals that get ionized outside the reaction space are a dead loss because they get accelerated in the wrong direction. Now if you could recover most of that energy with collectors it might not be too bad.
Which says - net power is only the beginning of the problems.
Engineering is the art of making what you want from what you can get at a profit.
I'm not sure gas puffing is a major problem in a large machine. If the gas can be puffed towards the center of the machine with a certain amount of collimation, they will ionize to a very large extent before they transit the machine. Even the nonionizing collisions/ scattering would need to travel a significant distance to exit the machine (except for the tiny (?) proportion that are scattered almost straight backwards towards the puffer). In a small machine this was a problem due to escape, and also probably in the spread of the energy of the ions. If it takes x amount of microseconds to ionize 99.99 % of the neutrals and they travel 20 cm during that time, then in a 30 cm WB6 there is alot of energy spread. In a 300 cm machine the energy spread would be proportionatly less. As Dr. Bussard purportedly calculated, in a sufficiently large machine these problems are greatly mitigated. Neutrals formed by recombination is another issue, but you would also have this with ion guns. If the ions have a narrow energy spread (monoenergetic) there would be less low energy ions that presumably would be the most likely to recombine, so I assume the problem is again mitigated (in comparison to a thermalized plasma).MSimon wrote:I can put you in touch with Joel if you want to discuss his work further. He is kind of a private guy.
He seems well connected with Rick. OTOH I have no idea how much of the cat Rick has let out of the bag.
I have seen his stuff on cusp plugging. His current interest is fuel feed. i.e. for D-D the ions (gas fed from the magnets) come out at the right place at the right energy. OTOH the electrons are in the wrong place at the wrong energy.
And the cusp plugging by electrons creates problems for ion injection by ion guns.
Joel also thinks that gas injection will give too many neutrals and possibly ions in the wrong place. Any neutrals that get ionized outside the reaction space are a dead loss because they get accelerated in the wrong direction. Now if you could recover most of that energy with collectors it might not be too bad.
Which says - net power is only the beginning of the problems.
If this holds water, then performance should be significantly improved in the subscale research machines. In full sized power production machines, the tradoffs might make gas puffing more attractive.
Dan Tibbets
To error is human... and I'm very human.
Gas "puffing" is not a very controlled way to introduce fuel. I prefer gas feed.
I tend to agree with most of your points. However, the ions are introduced where ions are cold (near the grid). That means that the electrons from the formerly neutrals are introduced at a point where electrons should be hot.
I tend to agree with most of your points. However, the ions are introduced where ions are cold (near the grid). That means that the electrons from the formerly neutrals are introduced at a point where electrons should be hot.
Engineering is the art of making what you want from what you can get at a profit.