Controlled thermonuclear fusion at the beginning of a new era

Fusion research has come to a stage at which the newly designed International Thermonuclear Experimental Reactor (ITER) can be build - a machine which will demonstrate the feasibility of generating a significant surplus of energy with a thermonuclear plasma. This machine shall provide the last step towards the first fusion power plant, the construction of which could start in about two decades and would open to mankind the elements deuterium and lithium as a new safe and clean primary energy source. This paper describes the success story of the tokamak-concept of magnetic confinement on which ITER is based. But it also discusses the ongoing research which concentrates on the most critical problems to be solved for the power plant beyond ITER for which a continuously and efficiently operating fusion reactor is required.