problems with polywell device design

[jwalding]

I was reading of the Philo Farnsworth devices and link by link found the polywell. It is an interesting device, but in the form that it exist I do not beleive that it will work. I is my understanding that the larger one would be built differently(dodecahedron), but the principle would be the same. I do not beleive that the nature of collisions at the well would be sufficient to create conditions suitable to sustain fusion. I beleive that you will need further heating from pumping with coherent light or possibly microwaves to get it to go critical. The nature of the field being internal to the device is also wrong. Supercooled magnets or otherwise are not going to last in that evironment. Even if water was circulated inside that magrid, it would still overheat is a matter of minutes, or even seconds. Heat liberation seems to have gotten a trivial mention on the website. I do not see any discussion of thermal solutions other than a crude calculation of rejected heat. How will this be dealt with?

[MSimon]

Yeah. That overheated water is a big problem. If only some one could figure out a way to cool it. I have faith some one will figure out how to do it. After all we know that ice is a fact.

[MSimon]

Let me give you the short version. The cooling question has been dealt with on this site since its beginning.

The bigger problem is the first wall problem. Surprised you missed it. BTW that topic too has been extensively covered.

[D Tibbets]

I was reading of the Philo Farnsworth devices and link by link found the polywell. It is an interesting device, but in the form that it exist I do not beleive that it will work. I is my understanding that the larger one would be built differently(dodecahedron), but the principle would be the same. I do not beleive that the nature of collisions at the well would be sufficient to create conditions suitable to sustain fusion. I beleive that you will need further heating from pumping with coherent light or possibly microwaves to get it to go critical...

I may be misreading your post, but the Polywell does not sustain fusion in the sence of criticality or ignition like laser IEC , Tokamaks, or fission reactors. The ions are driven towards (through) the center with independantly applied electrostatic forces. Fusion reations create high velocity particles/ heat, but this does not drive or maintain the reaction directly. The high speed fusion products leave the core (no containment) with very little if any positive effect on the potential well or fusion rate. The tritium and helium 3 and neutrons that are produced with D-D fusion immediatly leave the core (no recirculation). The potential well can contain and recirculate the lower energy deuterium ions (perhaps ~ 50,000 to 100,000 eV in a working reactor(?)) so that they have many thousands of chances to have a fusion collision. The fusion products have kinetic energies of ~ several million eV, so they easily leave the potential well with only one pass- very little chance for additional fusions.
Perhaps an analogy to jet engines is appropriate(?). The compresser is the potential well, while the fuel/ oxidiser is the ions. Adjusting the compresser speed and ion feed determines the reaction rate in the combustion chamber. The hot fusion exaust drives the turbine, producing power that can be fed back to power the compresser- through a machanical link in the jet engine, through generated electricity in the Polywell.

My understanding of the Polywell's potential limitations is the efficiency of electron ( and thus ion) containment through the Wiffle Ball effect and avoidance of real obsticles - like the wire cathode in the center of the classical Hirsch Farnsworth Fusor( or Elmore Tuck and Watson version that is closer to the Polywell operating mode). The ions would hit one of the wires, or be upscattered and hit the outer shell (Magrid in the Polywell ) after no more than ~ 100 flights through the potential well (grid 95-99% transparent). I'm uncertain how many flights through the potential well the average ion would make in the Polywell, but it is in the thousands, if not millions. The electrons leak out through the cusps, so that they last for perhaps 100,000 transits, and I beleive that one of the fundemental criteria for the Polywell is that the ions are contained better than the electrons due to the net negative charge in the well due to excess electrons being continually introduced. The magnetic field contains the electrons sufficiently well (with Wiffle Ball effect) and the resulting negative potential contains the ions (even better than the magnetic field contains the electrons). Since new high speed electrons are constantly shot towards the center to replace the lower energy escaping electrons, there is a potential well or gradient of electrons closer to the center which in turn acellerates and focuses (within acceptable limits) the ions towards the center.*


Dan Tibbets

* Sorry for the rambling, I used the post to again focus and hopefully improve my understanding of the Polywell. I mention the supossed influence of new high energy (and narrow energy range (non Maxwellian)) electrons to stimulate thoughts, or laughs, by much more knowledgable minds concering potential well shape, Maxwellian concerns, etc.

[jwalding]

I have considered the design of the polywell for about two weeks now. I have done some further research in the library and online. I can tell you that this design will not work. It may be possible to go critical for a nanosecond but will never develop into a workable device. Each and every indicator is that this was a stop gap design to allow for temporary fusion so that further research funding could be obtained. In and of itself it is unusable as an avenue to a final prototype. All of the posts that I have read on this site all revolve around the particulars of the polywell. You need a new approach, It is just not going to work. The magnetic field needs to be on the outside of the vessel and not on the inside.

[Betruger]

Can you show, specifically, how you arrived to this conclusion?

[joedead]

Can you show, specifically, how you arrived to this conclusion?

I second that.

[MSimon]

So far as we know from Dr. B's last experiment it has worked for at least 250 uS.

[David_Jay]

I have considered the design of the polywell for about two weeks now.

Well, there you go.

I say we shut down the forum

[jwalding]

First and foremost, the data, what little has been released, has indicated that the #6 design made fusion at a rate almost unmeasureable against background. They could not duplicate due to failure of the device. There is no more proof that they achieved fusion than to say that I could not make a better device. I see it a five distinct problems. Each solvable as individuals, then the resultant improvements placed back into a workable machine that can be turned into a production device. I am of a mind that to create a working prototype would be a wonderful gift for the world, but also be really profitable. I beleive that I have solved two of the problems of five but as of yet am unable to verify. Within the next few weeks will attempt to test one of the five. A few months till I am able to test the second improvement. I promise that I will publish results on this forum as I work through development. Patience is an inventive virtue.

[joedead]

ok...

[D Tibbets]

I have considered the design of the polywell for about two weeks now. I have done some further research in the library and online. I can tell you that this design will not work. It may be possible to go critical for a nanosecond but will never develop into a workable device. Each and every indicator is that this was a stop gap design to allow for temporary fusion so that further research funding could be obtained. In and of itself it is unusable as an avenue to a final prototype. All of the posts that I have read on this site all revolve around the particulars of the polywell. You need a new approach, It is just not going to work. The magnetic field needs to be on the outside of the vessel and not on the inside.

[EDIT] Opps, first paragraph deleted. I basically repeated what I said earlier.

And, Bussard tried external magnets in some of the earlier designs- they didn't work. If MUCH more enegetic magnets are used the area where B=1 and the unavoidable cusps locations may be deep enough inside the machine that external magnets could be used (?).

Dan Tibbets

[KitemanSA]

And, Bussard tried external magnets in some of the earlier designs- they didn't work. If MUCH more enegetic magnets are used the area where B=1 and the unavoidable cusps locations may be deep enough inside the machine that external magnets could be used (?).

Dr. B also said that recirculation was also critical, so the field would also need to be outside the grid. But the field is there to protect the grid. Hmmm.

[Roger]

The magnetic field needs to be on the outside of the vessel and not on the inside.

Good Lord, hes got it. THIS is the solution to what vexes us.

[kcdodd]

This is all wrong, but good news I believe I have solved all our problems. I'll get back to you later on what's wrong and how to fix it.