#stellarator

A section of NCSX, a fusion reactor so ambitious and advanced for its day that it was cancelled while half-built, in 2008. Each of those massive squiggly copper magnets — of which there were many — had to be held to sub-millimeter precision through many thermal cycles in liquid nitrogen. The vessel is solid inconel. What a beast!

Heyo now that I have a bit of breathing room I'm going to write up a series of posts on the history and physics of the two most prominent kinds of magnetic confinement fusion reactors: stellarators and tokamaks. Check my #fusion tag for more on fusion in general.

Anyway, today I'm going to show you a picture and explain where the names "stellarator" and "tokamak" come from. In Part 1, I'll start getting into some actual physics.

(source)

That's a tokamak on the left and a stellarator on the right. Specifically, the stellarator is Wendelstein 7-X at the Max-Planck-Institut für Plasmaphysik in Germany.

The yellow is hydrogen plasma undergoing nuclear fusion (like stellar plasma in a star!), the blue are the magnets and coils, the black arrows (in the tokamak) and green stripe (in the stellarator) show the path of a magnetic field line within the device. I will explain why the field lines do that in Part 1.

So,

What's with those funny names?

The stellarator was invented at the Princeton Plasma Physics Laboratory in 1951 by Lyman Spitzer, who is also the namesake of the Spitzer Space Telescope. The name is a portmanteau – "stellar" as in "stellar" and "-ator" as in "-ator." As a result, I find it very hard to say "stellarator" without dropping into a 1950's radio announcer voice. As in,

"The boys at Princeton have whipped up a brand new atomic reactor! That's right, their "Stellar-Ator" has brought the power of the stars to the good ol' U S of A, right here in scenic Plainsboro, New Jersey!"

"Tokamak" is a portmanteau of "тороидальная камера с магнитными катушками." First built in 1958 at the Kurchatov Institute in the USSR from concepts proposed by Andrei Sakharov, the United States Atomic Energy Commission was never successful at getting American scientists to stop using the Russian word for the device.