Polywell transportation: how small?

If polywell fusion is developed, in what ways will the world change for better or worse? Discuss.

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Postby Roger » Tue Jun 10, 2008 2:34 am

I like the p-B11 resonance peak at 50 KV acceleration. In2 years we'll know.

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Postby djolds1 » Tue Jun 10, 2008 6:41 am

Vae Victis

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Why shut them down? (except for maintenance)

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Postby kunkmiester » Tue Jun 09, 2009 3:36 am

Evil is evil, no matter how small

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Postby Heath_h49008 » Sat Jan 30, 2010 6:42 am


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Postby 93143 » Sat Jan 30, 2010 7:12 pm

Too big for fighters. I doubt you could get net power from p-11B with less than a 10' magrid even with very strong magnets, so very optimistically that's a 14' vacuum chamber. 20' or more is likely, but let's go with 14'.

Now, the neutronicity of a p-11B core is too low to have much effect on the materials, but it does require shielding. Say 6" of water, a bit of 10B, and 1½" of lead. That's 75,000 lbs right there. Then there's the bremsstrahlung, 5% of net power by some estimates. Say 2-5" of lead, so bump the weight to 100,000-200,000 lbs. Then there's the gammas given off by the secondary branch of the main reaction. There aren't that many of them (0.01%) but they're high-energy. Say a foot of lead. (You can forget the water and 10B at this point.) Now your shield weight is up to 450,000 lbs.

You could shadow-shield the pilot's seat, requiring only a few tons of lead, but now the ground crew has to be behind heavy shielding barriers before the reactor is turned on, and no one can be allowed nearby while it's running. Kinda complicates carrier operations, not to mention formation flying, or airshows...

A shadow shield at the reactor would be about 50,000-80,000 lbs, allowing passengers and payload to be safely carried, but this doesn't solve the other problems.

...

Now, you might be able to get a 6 GW core into a 35' sphere. This gives you a complete shielding mass of about 3 million lbs.

Fortunately, at the thrust-to-power ratio achieved by a modern high-bypass turbofan, 6 GW can lift more than twice that weight straight up...

I say use a heat exchanger to dump reactor waste heat into the engine upstream of the main heating element, so as not to have to dump coolant overboard. Range is now limited by how much isotopically-pure protium and boron-11 you can carry...

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Postby Heath_h49008 » Sat Jan 30, 2010 7:23 pm


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Postby Heath_h49008 » Sat Jan 30, 2010 7:44 pm


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