The stellarator is also based on a torus-shaped vessel, but relies entirely on meticulously designed coils to generate the helically shaped magnetic field required to contain the plasma. This omits the need for a plasma current and thus removes the need for pulsed operation, making it an ideal concept for a fusion power plant.
The challenge lies in generating the helically shaped magnetic field. These design considerations, along with the costs of realising such intricate designs have made stellerators less common than tokamaks.
The advanced stellarator Wendelstein 7-X has been constructed in Greifswald, Germany. Its magnetic coils are engineering masterpieces, twisted intricately to create the magnetic field required. They are superconducting in order to achieve the large magnetic fields that are required to confine the plasma.