Elasticae and Stellarators

Stellarators are weird-looking fusion devices. The reason is that ions and electrons are better confined when the magnetic field is “twisting” around the centre-line of the device called the magnetic axis. In tokamaks, the vacuum field generated by the evenly-positioned toroidal field coils is somewhat “flat”, as shown on the figure below. In order to generate “twisting”, a strong toroidal plasma current (in red in the figure below) is induced