magnetic trap for neutrons
http://www.nature.com/nature/journal/v403/n6765/full/403062a0.html
So-called cold neutrons are used for cancer treatment. Cool use of N physics.
I saw that when I started investigating the fusor. But unlike a fusor, I wasn’t sure how you get the neutrons out of the polywell. I guess you want to “leak” them through a cusp? Or are they directional at all?