Focus Fusion Google Tech Talk: Eric Lerner of Focus Fusion Society

Aside from the talk being pretty technical and all, I did get an impression of what the major problem might be with this thing. The electrodes could wear out too fast for it to produce much power. He did mention that erosion was a technical problem. I think that it may be THE problem with this thing.

As for using it as a propulsion device, the same applies if the electrodes wear out before much thrust is generated. Given that the electrodes are in contact with very hot plasma, it would appear that there isn't much you can do about it except to slow down the reaction and hope the electrodes don't get too hot. If a way can be found to cool down the electrode, more use could be made of it before it wears out. But it will wear out.

Update:

A few more musings on this subject before I leave it:

The use of Beryllium for the center electrode should help with corrosion. It has a higher melting point and is "transparent" to Xrays. Don't know what that means, but there it is.

It would be really cool if this thing could be put on a small craft and could power it up into space. But it needs to be in a vacuum chamber. There's really no point in reheating anything. If you put it in a vacuum chamber, it would just heat it up inside. Even if you cool the chamber down, you are just redoing what you've already done as far as I can tell. The plasma needs to go straight out the nozzle. To tell the truth, I don't know if that's feasible, even in space.

Now if you could direct it in a controllable fashion, then what? What do you need to keep the plasma output under control? Does that impact the whole idea of using instability, as opposed to controlling it?

Controlling the instability leads to complexity. Then you have to manage complexity.

I still like the idea, though. But I have no idea at all if it could ever work.