W7-X, presently under construction in Greifswald, Germany, is the largest, most advanced stellarator ever constructed and was designed to demonstrate steady-state reactor-relevant operation. The confining magnetic field is provided by a set of 50 computer-designed non-planar superconducting coils and does not require a plasma current.
 

 

The tokamak is the most common fusion research device. The confining magnetic field is generated by currents flowing in the toroidal field coils and, superimposed on this, a smaller field due to a transformer-induced current flowing in the plasma itself. At fusion temperatures, the plasma conducts current as freely as copper.
 

 

Since 1983, JET has been the largest operating tokamak in the world - the human figure on the lower left of the image above gives a sense of the scale of the device! It holds many world records for the best fusion parameters achieved, including that for the most fusion power created in a plasma.
 

 

The future of fusion energy research will rely on the success of ITER, the International Tokamak Experimental Reactor which is under construction at Cadarache, near Aix en Provence, on a 10 year timeframe at a projected cost of €13bn and will operate for circa 35 y.