Reply To: would nuclear energy really be accessible to all?

[jamesr]

nemmart wrote:

I think this is a really interesting question. I don’t understand why one should expect the alpha particles to all go in the right direction, down the axis of the anode. When the excited C12 fissions, I would expect the alpha particles to go shooting out in random directions, with piles of energy. More energy than is in the plasma. Is there a good reason to believe the plasma can capture this energy as opposed to the alpha particle punching through it?

When you run a DPF with deutrium what what percentage of the fusion energy gets captured by the plasma? Does the amount of neutron radiation change with direction?

The alphas for p+B11, or the neutrons in the case of D+D->He3 + n, will of course be emitted in random directions. But the very high magnetic field will cause any alphas to spiral round the field lines with a radius of:

r=mv/qB

where v is the velocity perpendicular to the magnetic field. For a 3MeV alpha emitted perpendicular to a 1GG field the radius is r=2.5E-6m. However the denisty of the plasma where the fusion occurs will mean it will have many collisions before it gets that far and slow quickly to the thermal ion temperature. At 100keV the radius drops to only 4.5E-7m, so the ions are confined easily by the magnetic field in the plasmoid.

Only when the magnetic field collapses creating a large electric field along the axis of the plasmoid are the ions accelerated out in the narrow beam