W7-X Device

Wendelstein 7-X is a modular stellarator. It produces the confining magnetic field exclusively by magnet coils thus intrinsically enabling steady-state operation. This is in contrast to a tokamak where the poloidal part of the field results from the current driven in the plasma. The fifty non-planar coils provide simultaneously both the toroidal and poloidal field components to achieve the necessary twist of the magnetic field lines. Besides improved mechanical stability and engineering advantages like individual coil testing this allows a wider variety of field structures and ultimately enables the optimization of the magnetic field.

20 planar coils are being used for experimental flexibility, varying the magnetic field.

Wendelstein 7-X coils are equipped with superconducting niobium-titanium wires. The coils will be cooled with liquid helium to the temperature required for superconductivity, i.e. about 4 degrees Kelvin – close to absolute zero.