Talk-Polywell.org

Your responses to the following FAQ?

What major engineering problems would have to be overcome, assuming net power can be produced?

I suspect this may engender several follow-up questions, so don't be shy about laying it on!

Anybody?

Based on discussions around here, most of the uncertainties around building a polywell power reactor deal with plasma dynamics. Magnets of suitable scale and strength have been built for MRI machines. Rocket engines handle heat fluxes at the level required. Electric conversion equipment required is mature enough for the job. Neutron shielding for the magnets isn't expected to be a major problem at the scale expected for a power reactor. Optimal design for fuel injectors needs some work, which I expect is being done in parallel with the plasma studies. Thermal power conversion is old tech, and no surprises are expected for basic direct conversion. Advanced direct conversion that better deals with the energy spread of fusion products is far from a mature tech, but isn't needed for a functional power system.

Is this to say... none?

AFAIK, plasma stability problems are also what is bothering Tokamak systems, so there is extensive research being done into that right now.

Several solutions have been proposed, but there's no practical, reliable solution yet. We're close, but not 100% there.

Stoney3K wrote:AFAIK, plasma stability problems are also what is bothering Tokamak systems, so there is extensive research being done into that right now.

Several solutions have been proposed, but there's no practical, reliable solution yet. We're close, but not 100% there.

Polywells are supposed to be immune to the MHD instabilities due to their convex to the center magnetic fields. Though, confirmation of this would be needed on power plant sized machines.

I'm not sure direct conversion has been demonstrated, at least not on the scales and efficiencies needed. Theoretically it can be reverse engineered from accelerator technology. Efficient conversion of the high voltage direct current conversion to an AC grid may be a challenge. A pulsed machine might have other conversion options (magnetohydrodynamical)

Materials limits, in terms of thermal loads, seem to be well in hand, which is not the case for Tokamaks). Concerns about neutron bombardment should benefit considerably from fission reactors and Tokamak research.

Superconducter performance and related cooling concerns have not been demonstrated in the harsh reactor conditions.

Bremsstrung mitigating processes in P-B11 systems have not been confirmed.

Convincing evidence of the basic physics have been done according to Bussard, but confirmation and communication of this is not publically available. Whether it is real, and whether there are any 'got yous' is unknown (to the public).

Many optimizing details will need to be worked out, even if the basic premise is sound.

Dan Tibbets

Addtiional tasks:

- a control system to keep the system at beta=1 (this will need some sort of diagnostic input and a response system)


Plasma stability should not be an issue. The major advantage Polywells have over toks is that they have good curvature everywhere.

Thermal and neutron loads on the casings are an issue for D-D/T (for p-B11 the fusion products are charged so the magnets swirl them out a cusp). Keep in mind the coil casings have to be conductive and handle big loads. It's probably solvable, but it's an issue.

The major question mark is how losses scale with B. That's really a physics question, though.

I should add-

Vacuum pumping requirements will be extensive, but apparently within current capabilities.

Dan Tibbets