Polywell Electrical System

Discuss the technical details of an "open source" community-driven design of a polywell reactor.

Moderators: tonybarry, MSimon

tomclarke
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Post by tomclarke »

93143 -

Agreed.

I am also wondering how the collecting grids are arranged. they must be concentric shells outside the magnets? And ions will hit magnets, but this is relatively small proportion of total, so not a problem (it does not much affect Q since only one chance to hit stuff after fusion, whereas very many before).

Best wishes, Tom

zimdlg
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Post by zimdlg »

Thanks for the explanations MSimon, tomclarke and 93143

Connecting the voltage levels the way you suggested tom and simon also occurred to me. Whoever has the job of setting that circuit up one day is going to have fun. I was unaware of the –ve grid used to slow down the alphas once they past it, now it makes a bit more sense.

Back before we knew the alphas would be coming out in beams
Do the alphas fly out the polywell in beams? Do the beams point out of the cusps? I was under the impression that a portion of the alphas would hit the magrid and be lost. The remaining alphas would be deflected a bit by the magnetic fields around the magrid but would not be affected significantly by them because the alphas are going to fast. Therefore the alphas would fly in all directions but shadows would be cast by the magrid. If they come out in beams collection would be much easier.
the future is near.

MSimon
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Post by MSimon »

The alpha beams depend on the gyroradius being smaller than an individual magnet. i.e. field strength vs. size.
Engineering is the art of making what you want from what you can get at a profit.

tomclarke
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Post by tomclarke »

I make that 20cm for 1T, or 2cm for 10T, for a 2MeV alpha? I am sure the correct figures are etched onto the hearts of many here!

Ok - that makes collector design easier, if they end up collimated into beams as they emerge from the high field regions. Is this known to be true?

93143
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Post by 93143 »

I don't know how coherent a cusp beam will be (it's a high +ve charge concentration passing through a strong, rapidly-varying B field), but according to Dr. Nebel, the alphas do come out the cusps, which is a good start and a lot better than we all thought (no one bothered to calculate the alpha gyroradius, you see). The notional reactor designs use fields on the order of 10 T, so the alphas bounce around maybe 1000 times on average before finding a cusp and exiting that way.

I confirm your 2 cm gyroradius, BTW. Dr. Nebel said 5 cm, which seems to better represent a 3.76 MeV (high-band) alpha in an 8 T field. Either way, the wiffleball confines the ash, poorly, but well enough to prevent magrid bombardment.

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