The magnum opus of alchemy was the Philosopher’s stone, a substance that was able to turn common metals into gold. Unlike alchemists, [Carl Willis] might not be poisoning himself in a multitude of ways, but he did build a Farnsworth fusor that’s capable of turning Hydrogen into Helium.
To fuse Hydrogen in his device, [Carl] first evacuates a vacuum chamber. Deuterium (Hydrogen with an added neutron) is injected into the chamber, and a spherical cathode made of Tungsten is charged to 75 kV. The deuterium gas is heated and confined by the cathode and fuses into Helium. The electrostatic confinement of the plasma isn’t very much different from some old CRT tubes. This isn’t a coincidence – both the fusor and CRTs were invented by the same man.
While no fusion experiments – including some billion dollar experiments – have ever produced a net energy gain, this doesn’t mean it’s not an impressive engineering feat. If you’d like to try your hand at building your own fusor, drop by the surprisingly active research forum. There’s a lot of really good projects to look through over there.