The electron cyclotron heating system for the stellarator W7-X: Status and recent achievements

The status and recent achievements of the electron cyclotron heating system at the stellarator W7-X in Greifswald, Germany are discussed. Three prototype gyrotrons and one from a series of 7 are operable now, one additional is under test. The transmission system is ready up to the stellarator hall; part of it has passed high-power tests (900 kW, 30 min). The test of the multi-beam waveguide is in preparation. At present, optics in front of the stellarator, the antennas, as well as in-vessel components are constructed.