[itishappy]

It is, it's just rotational instead of mirror symmetry. Check out some of the images further down this page:

https://en.wikipedia.org/wiki/Stellarator

My understanding is that the different sections of the torus experience different forces (inside vs outside due to the varying radii, top vs bottom due to gravity), which the Stellarator design attempts to compensate for by twisting the plasma so that no particular clump spends all of it's time in the same section.

> The basic concept was a way to modify the torus layout so that it addressed Fermi's concerns though the device's geometry. By twisting one end of the torus compared to the other, forming a figure-8 layout instead of a circle, the magnetic lines no longer travelled around the tube at a constant radius, instead they moved closer and further from the torus' center. A particle orbiting these lines would find itself constantly moving in and out across the minor axis of the torus. The drift upward while it travelled through one section of the reactor would be reversed after half an orbit and it would drift downward again. The cancellation was not perfect, but it appeared this would so greatly reduce the net drift rates that the fuel would remain trapped long enough to heat it to the required temperatures.