A stellarator is a device used to confine a hot plasma with magnetic fields in order to sustain a controlled nuclear fusion reaction.
The magnetic field necessary to confine the plasma is completely generated by external coils. It was invented by Lyman Spitzer and the first devices were built at the Princeton Plasma Physics Laboratory in 1951.
The name was given to this early fusion concept because of the possibility of harnessing the power source of the sun.
See also:
Plasma physics, Nuclear fusion, fusion power,
Tokamak, Reversed field pinch, Magnetic mirror, Wendelstein, Large Helical Device