There are two main approaches to realise fusion power on Earth: Magnetic confinement fusion and laser fusion. European fusion research concentrates on magnetic confinement fusion.
The two main classes of magnetic fusion concepts are tokamaks and stellarators.
Tokamak: The tokamak is today’s most advanced and best investigated fusion device design. It is a torus-shaped vacuum chamber surrounded by magnetic coils, which create a toroidal magnetic field.
A second set of coils is centred on the axis, or pole of the torus (the hole in the donut). This poloidal magnetic field adds a vertical component to the magnetic field, which has the effect of giving the magnetic field throughout the vessel a twist. This circulates the particles that have drifted towards the outside of the ring back into the centre, preventing the plasma from escaping.
Stellarator: 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.