JET development towards pumped divertor operations

The 1991-52 experimental campaign was completed in February 1992. The highlight of this campaign was the preliminary deuterium-tritium experiment (PTE) leading to the first ever production of controlled thermonuclear power in the megawatt range. JET then entered a major shutdown which should be completed by January 1994. The main objective of the shutdown is the installation of a divertor inside the vacuum vessel. It consists of four poloidal coils, of target plates with graphite tiles and of cryo-pumping panels. The divertor magnetic configuration has required the addition of new radio-frequency antennae, new power supplies and new divertor relevant plasma diagnostics. The aim of the divertor programme is to show active control of the impurities in thermonuclear grade plasma regimes for about ten seconds, a key issue for the construction of the International Tokamak Experimental Reactor (ITER)