A 130-260-Ghz, 1-Mw Free-Electron Maser for Fusion

We report on design work and testing of several main components of the FOM-Fusion-FEM project. Measurements on the electron gun are presented, showing a uniform beam current profile and a low halo current. A time-dependent simulation study of the interaction between the electron beam and the mm-waves shows that, for proper undulator tapering, longitudinal mode competition results in a quasi single-mode regime. Further, some high power and detailed low power measurements on mock-ups of the waveguide system are presented, showing that the reflection and outcoupling systems perform well.