iso + tron.

This machine, a theoretically elegant but practically ugly approach to enriching uranium (increasing the proportion of uranium 235 to uranium 238), was significant for two reasons: Richard P. Feynman worked on it, and it ultimately lost funding to the calutron.

It worked by creating a beam of unenriched uranium ions and then passing this beam through a tunnel with a changing magnetic field. The field would be modulated so that the heavy uranium 238 would form seperate bunches from the lighter uranium 235 ions, and then a magnetic field acting as a switchgate at the end of the tunnel would direct the bunches of uranium 235 ions to one side and the uranium 238 ions to the other side. It couldn't perfectly seperate the isotopes in one stage; the mainly u-235 ions would be run through again and again, filtering out more u-238 ions.

It was a clever approach to enriching uranium, but sadly due to politics and implementation problems lost its funding; many of the people working on it, including Feynman went on to work on the Calutron or later the atomic bomb. If you're making an atomic bomb in your garage, I suggest you use an isotron to enrich your uranium. It's fun and easy if you happen to be an engineer, nuclear physicist, and bongo drummer.