Stellarator

A stellarator is a device used to confine hot plasma with magnetic fields in order to sustain a controlled nuclear fusion reaction. It is one of the earliest controlled fusion devices, first invented by Lyman Spitzer in 1950 and built the next year at what later became the Princeton Plasma Physics Laboratory. The name refers to the possibility of harnessing the power source of the sun, a stellar object.

Stellarators were popular in the 1950s and 60s, but the much better results from tokamak designs led to them falling from favor in the 1970s. More recently, in the 1990s, problems with the tokamak concept have led to renewed interest in the stellarator design, and a number of new devices have been built. Some important modern stellarator experiments are Wendelstein 7-X in Germany, the Helically Symmetric Experiment (HSX) in the USA, and the Large Helical Device in Japan.

Description

Background

Early fusion research generally followed two major lines of study; devices that were based on momentary compression of the fusion fuel to high densities, like the pinch devices being studied primarily in the UK, and devices that used lower densities but longer confinement times, like the magnetic mirror and stellarator. In the latter systems, the key problem was confining the plasma for long times without the hottest, most valuable, particles escaping from the device.