Electron Current Drive by Fusion-Product-Excited.......

[Giorgio]

To distract everyone from the boredoom of the last couple of days here is a good argument of discussion:

Via Physorg:
http://www.physorg.com/news/2011-01-pow ... lasma.html

Researchers at the University of Warwick’s Centre for Fusion Space and Astrophysics and the UK Atomic Energy Authority’s Culham Centre for Fusion Energy may have found a way to channel the flux and fury of a nuclear fusion plasma into a means to help sustain the electric current needed to contain that very same fusion plasma.

And the related Arxiv article.

http://arxiv.org/abs/1009.1041

We present first principles simulations of the direct collisionless coupling of the free energy of fusion-born ions into electron current in a magnetically confined fusion plasma. These simulations demonstrate, for the first time, a key building block of some "alpha channelling" scenarios for tokamak experiments. A fully self-consistent electromagnetic 1D3V particle-in-cell code is used to evolve a parallel drifting ring-beam distribution of 3MeV protons in a 10keV thermal deuterium-electron plasma with realistic mass ratio. Collective instability gives rise to electromagnetic field activity in the lower hybrid range of frequencies. These spontaneously excited obliquely propagating waves undergo Landau damping on resonant electrons, drawing out an asymmetric tail in the distribution of electron parallel velocities, which carries a current.

Happy reading.

[Nik]

Well, that's popped up since I checked PhysOrg this morning !!

It's a neat trick if they can get it to work, and could be very useful, if only as an interplanetary rocket motor...

Of course, however good the simulation, Mr Murphy has yet to have his say...

[D Tibbets]

The EMC2 2008 patent mentions something like this I think. At least with high Z fuels like P-11B, as the fusion alphas leave, the electrons are left behind. At least in principle this could result in these left behind electrons providing most if not all of the needed electron input current.

For this to work, you need something like a Polywell where the fusion ions quickly leave the reaction space. I don't think this would be possible where the fusion ash is retained, like in a Tokamak.

They mention increasing the electron current, though it sounds they are referring to the temperature or eV of the electrons. Or perhaps they are implying some charge separation in the torus that provides some electrostatic confinement of the ions.

Dan Tibbets

[Giorgio]

Of course, however good the simulation, Mr Murphy has yet to have his say...

Couldn't agree more.

At least in principle this could result in these left behind electrons providing most if not all of the needed electron input current.

And this might make a huge difference in BEP calculations for a Polywell type reactor.

Edit: Now also on Nextbigfuture:
http://nextbigfuture.com/2011/01/uk-fus ... clear.html