Special aspects of vacuum systems for fusion experiments

The design of vacuum systems for fusion experiments is governed by the geometry of the apparatus causing limited access to the vacuum vessel. The vessel has to sustain a variety of forces exerted by the magnetic field not encountered in other vacuum applications. Further problems arise from the plasma--wall interaction, from neutral injection, and from high, energetic particle fluxes in divertor chambers. European answers to these tasks will be reviewed from the outline of the experiments ASDEX, TEXTOR, and JET