Talk-Polywell.org

Greetings polywell enthusiasts. I have a web server with the bandwidth to handle the hosting of a FAQ page for polywell. And it is economical for me to maintain for a long time. I've got the start of a FAQ going and I am here to propose its use amongst people here much more informed than I.

I choose media wiki as the frame work for the faq because it seems to be the standard for collaborative editing and administration. I'm new to editing wiki and administrating it.

I think a F.A.Q is important. It allows the ignorant a place to get informed, and the informed the ability to move on to newer more important topics.

Maybe ohiovr.com isn't a good place to put the F.A.Q but its a good place to try things out. Media Wiki is very easy to install and set up. The only thing I cannot get media wiki to do is render equations to png graphics. This is because I do not have shell access to my site and I would need to compile and install LaTex and some support programs. Wouldn't it be nice if talk-polywell.com had shell access, they could host a more effective wiki. Anyway I have a work around for that problem. Open Office has an equation renderer to pdf files and you can grab screen shot of it and it looks nice. Or if you have Linux you can install latex and render equations with that.

You can find the F.A.Q here:

http://www.ohiovr.com/polywell-faq/inde ... =Main_Page

You will need to join as a user to edit the wiki and there is a confirmation email that you'd need to acknowledge for that privilege.

I hope this effort is useful. If I can be of any other help let me know.

spam @ ohiovr dot com

Maybe answering newbie questions over and over isn't a problem after all.

ohiovr wrote:Maybe answering newbie questions over and over isn't a problem after all.

Yeah, it is, and I intend to work on it soon. Thanks for the ping.

Hi KitemanSA I've promoted you to Bureaucrat on the faq. I've started to edit more pages. Hopefully someone can improve my simplistic explanations. But its starting to get fleshed out.

I am pleased to announce that LateX support for the polywell faq page has been implemented thanks to user Tonehog's efforts at creating a wiki extension to take advantage of a service called Texify. At www.Texify.com you can enter in your equations in latex script and it will render it for you. Tonehog made it possible to do this directly inside of the faq page with a <texify> tag.

You can find instructions on how to use it here:

http://ohiovr.com/polywell-faq/index.ph ... %27s_F.A.Q.

ohiovr wrote: ... I've started to edit more pages. Hopefully someone can improve my simplistic explanations. But its starting to get fleshed out.

I would suggest that when you are satisfied that you have done what you can, you copy that FAQ to a topic here on the forum and ask for input here. I am not convinced that those who can best help improve the answer will ever feel the need to go there to browse.

KitemanSA wrote:

ohiovr wrote: ... I've started to edit more pages. Hopefully someone can improve my simplistic explanations. But its starting to get fleshed out.

I would suggest that when you are satisfied that you have done what you can, you copy that FAQ to a topic here on the forum and ask for input here. I am not convinced that those who can best help improve the answer will ever feel the need to go there to browse.

Alright sounds good to me. I've got a few that are really bothersome already. I think it best to keep all that faq work here on this thread. For each Faq related question lets name the issue on each subject line.

http://www.ohiovr.com/polywell-faq/inde ... by_them%3F

currently reads:

literally "deceleration" losses in the German language. It occurs when electrons collide with atomic nuclei. These collisions result in x-ray emissions and lead to a cooling effect on the plasma.

Why does this not effect the polywell much? Well good question! Some one out there could answer it better than me. I suppose it could because that the ions are not accelerated by heating them but rather by the electric fields inside the polywell. Can that be true??

Obviously I haven't a clue as to why this wouldn't happen in a polywell as it has been suggested. After all the device is swimming with electrons, why wouldn't they constantly collide with the ions?

ohiovr wrote:http://www.ohiovr.com/polywell-faq/inde ... by_them%3F

currently reads:

literally "deceleration" losses in the German language. It occurs when electrons collide with atomic nuclei. These collisions result in x-ray emissions and lead to a cooling effect on the plasma.

Why does this not effect the polywell much? Well good question! Some one out there could answer it better than me. I suppose it could because that the ions are not accelerated by heating them but rather by the electric fields inside the polywell. Can that be true??

Obviously I haven't a clue as to why this wouldn't happen in a polywell as it has been suggested. After all the device is swimming with electrons, why wouldn't they constantly collide with the ions?

For a thermal plasma the situation is this: For D-T, if you can keep the impurities low enough, bremsstrahlung is not a big factor, regardless of the concept. This is also true of other fuel cycles involving D, but the constraints on the impurity levels become more stringent and difficult to fulfill. For a (pure!) p-B11 plasma, the bremsstrahlung is greater than the fusion power, so you have lost the game.

One way to try to get around this limitation is to tailor the electron energy distribution by removing low energy electrons. The most common objection to this path is that it costs energy to maintain a non-Maxwellian distribution. The estimates are that the power recirculated by removing low energy electrons and replacing them with high energy electrons is comparable to that radiated by bremsstrahlung if you just leave the distribution alone.

Advocates seem to think that you can get this recirculating energy for free in a polywell, but the idea hasn't been presented in enough detail to be convincing (at least not to me). Another potential problem in the polywell is the idea that the electrons should be less energetic in the central well, where the fusion is occurring. If it is really possible to maintain T_e << T_i (which I doubt), that will tend to push the bremsstrahlung power back up again.

For a (pure!) p-B11 plasma, the bremsstrahlung is greater than the fusion power, so you have lost the game.

Running hydrogen rich helps.

As to the energy cost of annealing. It need not cost much if annealing takes place at low velocity. Fuel ions are low velocity at the edge. Electrons are low velocity in the center. Will it actually work that way? TBD.

MSimon wrote:

For a (pure!) p-B11 plasma, the bremsstrahlung is greater than the fusion power, so you have lost the game.

Running hydrogen rich helps.

Yes. There is a fuel mix and a temperature that maximizes fusion power, but the conditions that maximize the ratio of fusion power to bremsstrahlung power are somewhat richer in hydrogen and somewhat colder. Unfortunately, the effect is not big enough to help much. A similar issue is the ratio of ion temperature to electron temperature. You would like a high ion temperature to make lots of fusion, but a low electron temperature to limit bremsstrahlung losses. But if T_i > T_e, the ions lose energy by collisions with the electrons. The usual assumption - optimistic but not too unrealistic - is that the only ion energy loss channel is through classical collisions with the electrons, and the only electron energy loss channel is through bremsstrahlung.

Art Carlson wrote:
One way to try to get around this limitation is to tailor the electron energy distribution by removing low energy electrons. The most common objection to this path is that it costs energy to maintain a non-Maxwellian distribution. The estimates are that the power recirculated by removing low energy electrons and replacing them with high energy electrons is comparable to that radiated by bremsstrahlung if you just leave the distribution alone.

I thought high energy electrons would be more of a nuisance with Bremsstrahlung than low energy. So is it some where claimed that the electrons can be maintained at one energy while the ions can be maintained with another energy? Am I reading correctly? Can this be explained to someone educated just a little beyond high school like myself? Also why would running the system hydrogen rich help with reducing Bremsstrahlung?

ohiovr wrote:

Art Carlson wrote:One way to try to get around this limitation is to tailor the electron energy distribution by removing low energy electrons. The most common objection to this path is that it costs energy to maintain a non-Maxwellian distribution. The estimates are that the power recirculated by removing low energy electrons and replacing them with high energy electrons is comparable to that radiated by bremsstrahlung if you just leave the distribution alone.

I thought high energy electrons would be more of a nuisance with Bremsstrahlung than low energy.

This is what I remember from looking at this question many moons ago, but I may not have it right. On the one hand, bremsstrahlung certainly increases with temperature. On the other, the collision cross section goes down rapidly with increasing relative energy, so it might somehow be true that the low energy electrons are especially evil. Any way you cut it, I'm having trouble imagining that there is any way to get really dramatic reductions in bremsstrahlung by tailoring the electron velocity distribution. If there is a minimum value for the bremsstrahlung from a population of electrons with a given average energy, and this minimum is, say, not more than a factor of 2 below that for a maxwellian distribution, then that makes this particular loophole even less attractive. Too much work for too little gain. - Does anybody have a better grip on this question than I do?

ohiovr wrote:So is it some where claimed that the electrons can be maintained at one energy while the ions can be maintained with another energy? Am I reading correctly? Can this be explained to someone educated just a little beyond high school like myself?

Energy exchanging collisions of ions with other ions and electrons with other electrons happen more often than those between electrons and ions. Consequently it can make sense to talk about a system where the electrons have a temperature (i.e. a Maxwellian distribution), and the ions have a temperature, but the two temperatures are not equal. This is always the case to some extent (e.g. in a tokamak), but the polywell, as I understand it, is supposed to carry this to an extreme.

ohiovr wrote:Also why would running the system hydrogen rich help with reducing Bremsstrahlung?

The fusion power is proportional to the product of the hydrogen density and the boron density. But a boron ion has an atomic number of Z = 5, so each boron ion brings with it 5 times as many electrons as a hydrogen ion. Worse yet, the bremsstrahlung radiation is proportional to Z^2, so those more electrons are also radiating more. If you cut back the boron density a bit, and increase the hydrogen density, you don't change the fusion power much, but you significantly reduce the bremsstrahlung.

Thanks Art. May I copy some of your response to the FAQ? I've set the content license to "public domain", fyi.