PREDICTED PERFORMANCE OF A DC BEAM DRIVEN FEM OSCILLATOR DESIGNED FORFUSION APPLICATIONS AT 200-250 GHZ

At the FOM Institute (The Netherlands) a free electron laser using a d c beam with depressed collector is being developed for plasma heating, which will be capable of producing 1 MW cw output over an adjustable tuning range of 200-250 GHz. The basic design parameters for the elect ron beam, undulator and waveguide circuit are determined using a 3D no n-wiggle averaged waveguide mode particle interaction code including a c space charge effects. Novel features of the design include using a s tep-tapered two-section wiggler to achieve both the high gain (10) and the required efficiency ( approximately 5%) as well as a rectangular corrugated HE11 waveguide circuit to handle the high average power req uirements. Results are presented on the FEM performance including depe ndence on beam emittance, percentage feedback, and operating frequency .