In fact, I'm assuming and hoping for the sake of his neighbours that he's not actually attempting fusion. If I recall correctly, doing actual fusion with

In fact, I'm assuming and hoping for the sake of his neighbours that he's not actually attempting fusion. If I recall correctly, doing actual fusion with one of these requires deuterium and tritium and produces a crapload of neutrons for which I really doubt he has adequate shielding. Yes and no. The very lowest-energy-threshold fusion reaction is deuterium-tritium, so must research tokamak reactors use that. The JET[1], ITER[2], et al. But tritium is both expensive and excitingly dangerous, (It's an alpha emitter, which is ordinarily harmless, since the alpha particles aren't energetic enough to penetrate skin; but it's a radioactive gas, not a solid, so you can inhale it and get all sorts of amusing cancers) so real amateurs prefer Deuterium-Deuterium fusion, and the kind of fusion reactor that that produce the higher energies needed to accomplish it, known as fusors[3]. D-D fusion does produce neutrons, you are correct. But the PF reactor is a pulsed device, with a tiny coil size: it doesn't make many neutrons, and it produces them for seconds at a time. This guy has been checked out by the NYFD, and they've signed off on the project. If it was a power reactor, neutron emission would be a problem, but it's not, so it ain't. 1: http://en.wikipedia.org/wiki/Joint_European_Torus http://en.wikipedia.org/wiki/Joint_European_Torus 2: http://en.wikipedia.org/wiki/ITER http://en.wikipedia.org/wiki/ITER 3: http://en.wikipedia.org/wiki/Fusor http://en.wikipedia.org/wiki/Fusor