Reply To: Repowering the electric utility industry

[jamesr]

The way I see it is that you don’t consider the bremsstrahlung x-ray radiated as losses. There will be some other radiative losses that you can’t recover but if the onion works as well as is hoped a significant (>70%) of the x-ray energy in the 10-30keV range could be recovered.

The key issue for getting a reasonable fusion burn in the plasmoids is that the x-ray cooling is not so high as to cool the plasma faster than the fusion energy from the fast He-4 products can be redistributed in the plasma keeping it hot.

The initial tests with DD done so far have shown the radiative losses are not so high, such then the heating during the pinch can get the plasma hot enough for pB11 ignition (but at lower densities).

The next test is to repeat that temperature threshold with higher Z gases where traditionally the Z^2 dependence of the bremsstrahlung would mean the cooling will be much faster.

Todd Rider’s thesis http://dspace.mit.edu/handle/1721.1/11412 and subsequent work, showed that this bremsstrahlung issue effectively rules out all other fusion fuels except D+T, D+D, and D+He-3, and furthermore for nett gain has to be at or near thermal equilibrium. This is partly why I don’t believe any of the other innovative concepts such as polywells will work. However Rider did not take account of the effect of the quantization of electron cyclotron orbits in very strong magnetic fields http://en.wikipedia.org/wiki/Landau_quantization. This limits the transfer of energy from the fast ions to the electrons, and effectively keeps the electron temperature much lower than the ion temperature. Even so it is a tall order to reach the extreme fields needed to reduce the key collision parameter known as the Coulomb Logarithm from the standard value of 15-20 beyond even Rider’s most optimistic value of 5.