Polywell Fusion Update: Progress And Hope

 
Dr. Rick Nebel stops by TalkPolywell and shares this:

Here’s what we know and what we don’t know:

1. We don’t have the spatial resolution of the density to see if the cusps are quasi-neutral on the WB-7
2. In one-D simulations the plasma edge (which corresponds to the cusp regions) is not quasi-neutral. Therefore, if the cusps are quasi-neutral it must be a multidimensional effect.
3. Energy confinement on the WB-7 exceeds the classical predictions (wiffleball based on the electron gyro-radius) by a large factor.

Our conclusion is that both the wiffleball and the cusp recycle are working at a reasonable level.

I apologize for the quick physics lesson, but quasineutral just means the plasma has roughly the same number of positive ions and negative electrons, and a “cusp” is where the confining magnetic fields meet, in this case four fields meeting at a point at each corner of the cube the coils approximate. Polywells are run slightly electron-rich to confine and focus the ions, so they are not ambipolar and thus the area on the edge of the plasma is expected to have many more electrons than ions.  Points 1 and 2 are important because significant numbers of ions in the cusps probably doom the concept.

The third item is very good news and offers real hope that the design may scale into a net power machine.

The U.S. Navy has funded testing through the end of 2009, and they appear to be looking at issues we know would have an impact moving forward to a net power sized machine, such as losses to the interconnects.

UPDATE: Thanks to Classical Values and Instapundit for linking!