The fusion-FEM: experiments in long pulse set-up

The Free-Electron Maser (FEM) is a high power, wideband, tunable mm-wave source in the range of 130-260 GHz for fusion applications. Without electron beam recovery, the fusion-FEM has generated over 700 kW at 200 GHz in the microsecond scale. Single-mode operation has been demonstrated at various frequencies. A fusion FEM has been completed for long-pulse operation; the energy recovery system, a decelerator and a depressed collector have been installed. in this paper we present results on measurements of the complete mm-wave beam line for long-pulse operation.