Experimental results with the Dutch free-electron maser

A free-electron maser (FEM) has been built as a pilot experiment for a mm-wave source for applications on future fusion research devices such as ITER, the International Tokamak Experimental Reactor. A unique feature of the Dutch Fusion-FEM is the possibility to tune the frequency over the entire range from 130 to 260 GHz at an output power exceeding 1 MW. Initial experiments have resulted in an output power exceeding 700 kW at 200 GHz and 350 kW at 167 GHz at reduced beam current. Output power, start-up time and frequency correspond well with simulation results. Parameter scans for several settings have given a wide range of interesting data.