Heating system chosen for ITER
A new, high-frequency ion source has been chosen as the system for heating up the plasma in the test reactor of the International Thermonuclear Experimental Reactor (ITER) project. The experimental fusion reactor, which is to be located in Cadarache, southern France, will attempt to reproduce on Earth the nuclear reactions that power the Sun and other stars. To produce this energy, the reactor will need to heat hydrogen plasma to temperatures exceeding 100 million °C. It is estimated that the reactor could produce, in lasting pulses, fusion power of some 500 megawatts. Developed by researchers at the Max Planck Institute of Plasma Physics (IPP) in Garching, the new heating system uses a high-frequency wave, which is injected into hydrogen gas, thereby ionising some of the hydrogen atoms. The resulting cold plasma, a mixture of neutral atoms, negative electrons and positive ions, flows into the beam source, onto its inner walls. If the surface of the electrode is coated with suitable material, for example caesium, electrons can then be captured by the plasma particles, thus producing the negative hydrogen ions required to heat the beam. The IPP heating system is said to have many advantages over other ion sources. Cheaper to build and basically maintenance-free in operation, the design of the system can also be handled remotely. Further tests will now be carried out on the system to ensure that it can meet the requirements for ITER. 'For IPP this is a great success crowning many years of development work,' said Eckehart Speth, who led the team that developed the new ion source.