The Dutch free-electron maser: 730 kW, 200 GHz

At the FOM Institute for Plasma Physics "Rijnhuizen", The Netherlands, an electrostatic high power free-electron maser is operated at various frequencies. An output power of 730 kW at 206 GHz is generated by a 7.2 A, 1.77 MeV electron beam, and 360 kW at 167 GHz is generated by a 7.0 A, 1.61 MeV electron beam. The lower output power at the latter frequency is due to relatively high losses in the present mm-wave cavity. It is shown experimentally and by simulations that, depending on the electron beam energy, the FEM can operate in single-frequency regime. So far, the pulse length was limited to some 12 /spl mu/S. Nevertheless, many aspects of generation of mm-wave power have been explored, such as the dependency on electron beam current and energy and settings of the mm-wave cavity.