Talk-Polywell.org

Radiation shielding... What's this I hear about a 477keV gamma emitted from a boron-10 neutron capture event? That's almost positron annihilation energy. Maybe lithium-6 would be better. The cross section is one-fourth that of boron-10, but it doesn't emit gamma rays. It does, however, produce a tri...

I came up with an idea a while back for an ion turbine engine. It would use the magnetic field generated by the ion current in the acceleration section to substitute for the large permanent magnets that would otherwise be required for the electric motors driving the compressor. This would allow the ...

...I think I hijacked a thread. Let's see... I calculate that on the supercomputer at our school, a 100-year run should take about 1e71 years, give or take a couple of orders. This assumes that adequate RAM is made available and that the initial conditions and boundary conditions (including the beha...

On what scale? Anything bigger than Kn=0.1 or so, provided enough data is available. Of course, you have to make sure the problem is adequately resolved. If you want to avoid having to use a turbulence model, you want a mesh size of maybe a micron or so at the surface, expanding somewhat with altit...

A BFR's magnetic/electric fields are far simpler than the atmosphere and behave in known and measurable ways with decades of practical experience in magnetic and electric fields. Atmospheric modeling is something else. Pfft - it's just the Navier-Stokes equations. Plus species transport, radiative ...

"...the carbon dioxide in the atmosphere would be reduced by half in about fifty years."

Does anyone else think this "carbon-eating trees" idea might be a disastrously bad one?

A couple hundred years? Maybe, if the disaster was external and not sociological. Rome had a lot of knowledge and technology, and if the monks hadn't preserved it (and expanded on it), Europe would have taken a lot longer than it did to re-emerge from barbarism... The people have to WANT to rebuild....

I'm not saying we'll see a total collapse during our lifetimes (or ever - but that's a whole other issue), or that we're anywhere near total understanding and mastery of the physical universe. I'm just saying "singularity" is a bad name for it, and gives a false impression of asymptotic behaviour wh...

There's a finite amount of stuff we can know about the universe, and there's also a finite amount of stuff we can do to it in order to get a useful technological result. Groups of technologies should also show an S-curve, which can be extended by timely scientific advance but not transformed into an...

I don't believe in singularities. I gather from quantum mechanics that the universe is fundamentally finite. If relativity disagrees, I get suspicious. For example, just because we know of no mechanism that can limit the density of a black hole doesn't mean there isn't one. As for technology and tra...

Whatever happened to ECR? Tuned to match the magnetic field near the edge of the wiffleball, it should produce near total ionization right at that depth, right?

So, kind of like an electro plasma conduit from Star Trek...?

Why do you say the electron temperature is uniform? The potential well applies to any charged particles, not just ions. Electrons should be hot at the edge and cool in the core.

Also, didn't they confirm experimentally that the electrons don't thermalize before being lost?

You still couldn't make a space elevator with steel or Kevlar. More mass available cheaper might somewhat relax the constraints on the ribbon strength, but you'd still pretty much need CNT. Besides, the real strength of a fusion drive is with medium and high Isp for fast space travel. Its Isp-T/W pr...

Bah - he was never in real danger. He just couldn't keep his fat mouth shut about what a genius he was, and by extension how stupid you had to be to disagree with him...