Reply To: EmDrive + Focus Fusion = Space Access for all?

[jamesr]

KeithPickering wrote:

Now I can see how the electrons and ions produced might be captured with nearly 100% efficiency (although this too needs to be demonstrated). But 40% of the energy produced is in the form of x-rays, which are supposed to be captured by the layered foil shell. How efficient is that shell? If it’s only 20% efficient (which is comparable to solar PV cells), the device itself will only capture 68% of produced energy. And that would mean that the effective breakeven point is 47% higher than the theoretical breakeven point.

It may turn out that you can get to theoretical breakeven, but not quite to practical breakeven … or just barely over the line, which would mean that the excess salable energy would be a lot more expensive than assumed.

X-rays are not produced by the fusion directly, so it might be a little missleading to say 40% of the energy is produced in the form of x-rays. They are the result of electrons being deflected by ions and emiting Bremsstrahlung radiation.

The key point for Focus Fusion yet to be shown, as I see it, is whether bremsstralung x-rays will cool the plasma too fast and stop enough of the boron fusing in the plasmoid to release more energy than it took to make it. The plasmoid needs to confine the Helium ions and recycle their energy to keep the Hydrogen-Boron plasma hot for over 50ns (a very long time for an ion with a few MeV of energy). The He 2+ and B 5+ (and any other impurity) ions emit huge amounts of x-rays as they interact with the electrons. According to conventional physics this makes ignition of a pB11 plasma impossible as it will always radiate away the energy faster then the fusion reactions can heat it.

Only if the magnetic field in the plasmoid (assuming the plasmoid does exist in the form postulated) is strong enough for the ‘magnetic field effect’ to restrict the energies of the electrons and so result in a lower electron temperature than the ion temperature can there be any hope of it working. It is this that the ongoing experiments need to demonstrate. If the boron bremsstralung rate is only reduced to say 10 times higher than for hydrogen (rather than the normal 5^2=25 times), then the whole effort is still futile. It is needed to get down to only a few times higher that hydrogen for the plasma.

Only after this burning of a pB11 fusion mix has been demonstrated, I think will engineering the capture of the x-rays to recover their energy to get to the breakeven be worth pursuing.