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http://epsppd.epfl.ch/Montreux/pdf/P5_078.pdf
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First Wall Problem - Carboran
First Wall Problem - Carboran
Engineering is the art of making what you want from what you can get at a profit.
I Propose that future Hexal and Duodecal magnetic coils and structural supports used in Polywell reactors burning the advanced fuel p + B11, have an outer surface comprised entirely of Lithium 7.
Recently i discovered that the very first nucleosynthesis by man, was performed by Cockcroft and Walton in 1932. It involved
p + Li7 -> alpha + alpha + 17.35 Mev
Although rare, i was also intrigued to discover that a Triple Alpha Process exists in stellar suns.
alpha + alpha -> Be8
Be8 + alpha -> C12 + y + 7.36 Mev
Recently it has become apparent that much is to be gained from working with the fundamental characteristics of the machine, rather than against them. The first wall problem is one such case. Nuclear fusion isnt just about E=mc2, its about alchemy. Could we use the 2.5Mev alpha particles striking our magnet coils, previously seen as a problem to generate fuel ?
p + B11 -> 3 alpha + 8.76 Mev
alpha + Li7 -> B11 ?
I have limited access to journals, and have had trouble finding any information on the Li7 + alpha reaction on the net. Know any sources guys ? It may work, or it may be unstable at the energies involved. I just don't know. Considering 80% of natural Boron is B11 and is largely generated in Stellar Nuclear Synthesis, i really think it could work.
If as Tom L suggested, we run the DC grids at 1.88 MV to simplify E field issues there still would be plenty of energy left to convert the alphas to B11 at the outer perimeter. This could eliminate the complicated helium filtering/Vacuum issues (thats a big one). The fuel could then recirculate back into the core.
Is Li7 + alpha particle nucleosynthesis the answer ? if not, then we can consider other alpha particle nucleosynthesis pathways to eliminate all contamination issues.
Recently i discovered that the very first nucleosynthesis by man, was performed by Cockcroft and Walton in 1932. It involved
p + Li7 -> alpha + alpha + 17.35 Mev
Although rare, i was also intrigued to discover that a Triple Alpha Process exists in stellar suns.
alpha + alpha -> Be8
Be8 + alpha -> C12 + y + 7.36 Mev
Recently it has become apparent that much is to be gained from working with the fundamental characteristics of the machine, rather than against them. The first wall problem is one such case. Nuclear fusion isnt just about E=mc2, its about alchemy. Could we use the 2.5Mev alpha particles striking our magnet coils, previously seen as a problem to generate fuel ?
p + B11 -> 3 alpha + 8.76 Mev
alpha + Li7 -> B11 ?
I have limited access to journals, and have had trouble finding any information on the Li7 + alpha reaction on the net. Know any sources guys ? It may work, or it may be unstable at the energies involved. I just don't know. Considering 80% of natural Boron is B11 and is largely generated in Stellar Nuclear Synthesis, i really think it could work.
If as Tom L suggested, we run the DC grids at 1.88 MV to simplify E field issues there still would be plenty of energy left to convert the alphas to B11 at the outer perimeter. This could eliminate the complicated helium filtering/Vacuum issues (thats a big one). The fuel could then recirculate back into the core.
Is Li7 + alpha particle nucleosynthesis the answer ? if not, then we can consider other alpha particle nucleosynthesis pathways to eliminate all contamination issues.
Purity is Power
I couldn't find (Li, Alpha) cross sections, but I found a table for Energy Excess in Nuclei. I'm not sure I'm reading it right, but it looks like (LI, A) -> B
would convert 2.13 MeV / nucleion to 0.789 MeV / nucleon. That's exothermic and would give off somewhere between 9.4 and 14.75 MeV. Your walls would be hotter than the plasma!
I tried the NNDC, but could not get any data out. Either it is not there, or I wasn't patient enough to figure out how to ask correctly.
would convert 2.13 MeV / nucleion to 0.789 MeV / nucleon. That's exothermic and would give off somewhere between 9.4 and 14.75 MeV. Your walls would be hotter than the plasma!
I tried the NNDC, but could not get any data out. Either it is not there, or I wasn't patient enough to figure out how to ask correctly.
While the Russians were doing that, the Japanese were doing this:
http://ieeexplore.ieee.org/Xplore/login ... ber=534305
http://ieeexplore.ieee.org/Xplore/login ... ber=534305
I like the p-B11 resonance peak at 50 KV acceleration. In2 years we'll know.
I normally research and have a good think about things i post up. The last post was a brainstorm i had late Sunday night. I thought i would post it up before it got corrupted by a week at work.
Firstly thanks Dr Mike for clearing any of my misconceptions up. Promptly, precisely as usual
I knew there would be heat problems, but even i wasn't prepared for that. Interesting enough this means i could of stumbled upon something very useful to small thermal reactors for SSTO/Space propulsion applications. Oh and BTW thanks for scanning that book, that was a nice read. Cheers.
Secondly Roger, i love diamond too. It is my favorite engineering material. I spent alot of time studying chemical vapor deposition and diamond thin film tech. There is nothing in nature like an SP3 bond and im sure it has a big future. I thought it would be a no brainer. Use established methods to coat the coils and reactor with diamond film and we would be sweet. Im afraid it isnt that simple. The particles inside a Polywell reactor are at such high energy a paradigm shift in thinking is needed. The alpha particles wont just atomically sand blast the reactor. It will fundamentally change the reactors elemental composition.
Simon original post mentioned Carboran. You mentioned Diamond. Each containing elemental Carbon.
C + alpha -> Oxygen.
You dont want oxygen in your reactor space just as much as you dont want sputtered heavy metals. It just seems not many people are aware of the magnitude of the alpha problem. Whatever is in your reaction space is going to nucleosynthesize. Things just got alot more complicated. Li7 may present a solution.
Firstly thanks Dr Mike for clearing any of my misconceptions up. Promptly, precisely as usual
I knew there would be heat problems, but even i wasn't prepared for that. Interesting enough this means i could of stumbled upon something very useful to small thermal reactors for SSTO/Space propulsion applications. Oh and BTW thanks for scanning that book, that was a nice read. Cheers. Secondly Roger, i love diamond too. It is my favorite engineering material. I spent alot of time studying chemical vapor deposition and diamond thin film tech. There is nothing in nature like an SP3 bond and im sure it has a big future. I thought it would be a no brainer. Use established methods to coat the coils and reactor with diamond film and we would be sweet. Im afraid it isnt that simple. The particles inside a Polywell reactor are at such high energy a paradigm shift in thinking is needed. The alpha particles wont just atomically sand blast the reactor. It will fundamentally change the reactors elemental composition.
Simon original post mentioned Carboran. You mentioned Diamond. Each containing elemental Carbon.
C + alpha -> Oxygen.
You dont want oxygen in your reactor space just as much as you dont want sputtered heavy metals. It just seems not many people are aware of the magnitude of the alpha problem. Whatever is in your reaction space is going to nucleosynthesize. Things just got alot more complicated. Li7 may present a solution.
Purity is Power
What you really want to know is cross section as a function of energy. It may be that below 1 MeV there are no nuclear reactions to really worry about, or it might be 100 keV. Since we want to directly convert the energy in the particles to electricity anyway, we may be able to slow down enough of the alphas so the first wall nuclear reaction is neglegable. There will still be structural problems from high energy impacts, so diamond coating may well help a lot.
It'd be nice to find the cross section though. Maybe I'll not watch NASA TV during my goof off time today and do a search.
It'd be nice to find the cross section though. Maybe I'll not watch NASA TV during my goof off time today and do a search.
Regarding using boron to coat the grid to prevent alpha spallation, its worth mentioning that all boronization experiments in tokamaks deal with incident particles emerging from the diverter at 100's of eV while alpha's are several MeV so the success of boronization to prevent particle recyling at the diverter of a tokamak will not necessarily imply that it will be effective in prevenmting alpha spallation.
Right, my take was that they got a better behaved plasma thru the coating treatment, which it seems thats what they were trying to do. It seems to have nothing to do with spallation in a Tokamak.jmc wrote: so the success of boronization to prevent particle recyling at the diverter of a tokamak will not necessarily imply that it will be effective in preventing alpha spallation.
I like the p-B11 resonance peak at 50 KV acceleration. In2 years we'll know.
I remember reading a book about the early development of breeder reactors and it mentioned a Zirconium cone underneath the core. The idea was it would disperse any meltdown. On another forum I think I also recall that electrons hitting the screen on a TV cathode ray tube had the equivalent of a 200 million degree temperature. Probably doesn't compare to this situation but I though I'd throw it out there.
CHoff
GOOD NEWS EVERYBODY !
Your right about the cross sections Mike. Its all down to them. I just didnt consider them because at first i couldnt even find the reaction products. I finally found them today have me really, really excited.
Just so people understand. Here are the cross sections of the fusion fuels that you are likely to see in a polywell. It is the probabilty of a fusion event taking place at a certain energy. The (linked) graphs energy covers the range obtainable by electrostatic attraction of the Polywells virtual cathode. The graph below cover the energy range that will be produced by the products of the p + B11 reaction -> He @3.46Mev + He @2.46Mev + He @2.46Mev
Fusion Cross Section - alpha + Carbon
I have previously proposed on the forum, using a diamond SP3 coating on the coils and inner structures to protect from sputtering/contamination issues. I grew wary upon this when i realized that the alphas could turn diamond into oxygen. Fortunately it is now appears that the Carbon -> Oxygen reaction has an incredibly low cross section ! The different plots are from diffferent experiments. It is important to consider that the reactor walls and coils will be highly positively charged. This will slow the alpha particle and reduce the cross section further ! It is also important to note that the graph above is just carbon. Carbon in the SP3 Diamond bond could be even more effective !
For people wondering about how on earth we would diamond coat the inside of a polywell, it is already an established commercial enterprise. Its as simple as a Kilowatt microwave source and a vacuum, Backfilled with 99% Hydrogen 1% Methane (CH4) with careful controls.
If you would like a full breakdown of microwave diamond synthesis please read this excellent pdf by Paul W May.
Diamond Thin Films: A 21 century material
Many academics heavily criticize all fusion technology because of the first wall problem. Not only have i shown that diamond excels in dealing with high energy alpha products but i propose that the polywell may have the ability to heal itself and generate its own protective coating of diamond because of its inherent geometry and electrical aspects.
The same high vacuum chamber, the same RF system proposed for POPS ion compression and the same hexal coils and outer walls, switched to a negative potential could generate a protective diamond coating in situ !
I further wish to enhance my proposal by revealing a patent where a machine uncannily similar to an IEC fusion reactor is used to generate carbon allotropes
U.S. Patent 6171451 Method and apparatus for producing complex carbon molecules
Everytime i find a problem with the polywell, i end up finding a solution and then some. I now rest that possibilities exist for the reactor generating its own protective coating in situ. If applied i expect NASA may come knocking on our door before the utilities.
Viva Polywell !
Your right about the cross sections Mike. Its all down to them. I just didnt consider them because at first i couldnt even find the reaction products. I finally found them today have me really, really excited.
Just so people understand. Here are the cross sections of the fusion fuels that you are likely to see in a polywell. It is the probabilty of a fusion event taking place at a certain energy. The (linked) graphs energy covers the range obtainable by electrostatic attraction of the Polywells virtual cathode. The graph below cover the energy range that will be produced by the products of the p + B11 reaction -> He @3.46Mev + He @2.46Mev + He @2.46Mev
Fusion Cross Section - alpha + Carbon
I have previously proposed on the forum, using a diamond SP3 coating on the coils and inner structures to protect from sputtering/contamination issues. I grew wary upon this when i realized that the alphas could turn diamond into oxygen. Fortunately it is now appears that the Carbon -> Oxygen reaction has an incredibly low cross section ! The different plots are from diffferent experiments. It is important to consider that the reactor walls and coils will be highly positively charged. This will slow the alpha particle and reduce the cross section further ! It is also important to note that the graph above is just carbon. Carbon in the SP3 Diamond bond could be even more effective !
For people wondering about how on earth we would diamond coat the inside of a polywell, it is already an established commercial enterprise. Its as simple as a Kilowatt microwave source and a vacuum, Backfilled with 99% Hydrogen 1% Methane (CH4) with careful controls.
If you would like a full breakdown of microwave diamond synthesis please read this excellent pdf by Paul W May.
Diamond Thin Films: A 21 century material
Many academics heavily criticize all fusion technology because of the first wall problem. Not only have i shown that diamond excels in dealing with high energy alpha products but i propose that the polywell may have the ability to heal itself and generate its own protective coating of diamond because of its inherent geometry and electrical aspects.
The same high vacuum chamber, the same RF system proposed for POPS ion compression and the same hexal coils and outer walls, switched to a negative potential could generate a protective diamond coating in situ !
I further wish to enhance my proposal by revealing a patent where a machine uncannily similar to an IEC fusion reactor is used to generate carbon allotropes
U.S. Patent 6171451 Method and apparatus for producing complex carbon molecules
Everytime i find a problem with the polywell, i end up finding a solution and then some. I now rest that possibilities exist for the reactor generating its own protective coating in situ. If applied i expect NASA may come knocking on our door before the utilities.
Viva Polywell !
Last edited by Keegan on Wed May 14, 2008 8:54 am, edited 1 time in total.
Purity is Power