ITER: thermonuclear fusion is on the way

Negotiations concerning the ITER project have succeeded in an agreement: the international fusion experiment will be built in Cadarache, southern France. 10 years of construction work will be necessary, ITER is scheduled to enter into service in 2016. With an outer radius of 6.2 m and a plasma volume of 840 m3, ITER will be more than twice as big as any previous tokamak. ITER is designed to heat its fuel, a mixture of deuterium and tritium, to more than 100 million degrees centigrade for 7 to 15 minutes in order to release 500 MW. Unlike previous machines, ITER is designed to release more energy than it takes in. Most of the energy released by ITER will be in the form of fast-moving neutrons that will interact with the beryllium-coated blanket surrounding the plasma. A big uncertainty with ITER's design is how the important quantity of helium will react with the rest of plasma. Till now in previous fusion experiments the number of fusion reactions that took place was not sufficient to release important amounts of helium and neutrons. The aim of ITER is to demonstrate the feasibility of an industrial use of thermonuclear energy and to provide information on the materials that could be used to design the first industrial reactor. (A.C.)