Nuclear Fusion, Available on eBay

You can buy a lot of things with $40,000: a BMW, a year’s tuition at Carnegie Mellon, a cruise around the world ... but for amateur physicists like Mark Suppes, that kind of money can buy you a nuclear fusion reactor in your own home.

With $35,000 of his own savings and another $4,000 in donations, Suppes took to eBay in early 2009 for the parts he would need to produce nuclear fusion. Coherent laser diodes, neodymium sphere magnets, cryogenic dewars, they’re all on eBay, believe it or not, and according to the fusion-hobbyist site Fusor.net, 38 groups (some teams, most individuals) have created their own working fusion reactors.

Despite the apocalyptic undertones of anything carrying the word “nuclear,” a fusion reactor shares little of the dangers of nuclear fission, a process open to runaway reactions that feed off of the very collisions that they produce. Basically, heavy atoms like uranium are bombarded with neutrons, exploding the atoms and releasing heat that is converted to energy. Those explosions also release other neutrons though, which in turn split more atoms, and if the neutron content of the core is not strictly monitored, the reaction can run wild and cause a meltdown like Three-Mile Island or Chernobyl.

Fusion reactors, on the other hand, need to be constantly refueled, and also need to be kept at very precise conditions for reactions to occur, so they will shut down automatically if the balance is upset. They work by heating up an inert gas (like hydrogen), causing atoms to speed up and crash into each other to form heavier elements (like helium), releasing a ton of energy in the process.

For fusion reactors like Suppes’s in Brooklyn, the presence of free neutrons is the only way to tell that the machine is actually working. Working, though, is not the same as producing net energy. Suppes’s machine, like all fusion reactors ever built by humans (the Sun being a natural fusion reactor), consumes more energy than it produces. The amount of electricity needed to power the magnets that keep the hydrogen core hot and contained far exceeds the amount produced by the handful of fused atoms that reactors of this size can produce.

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