The objective of this program is the design and development of a millimeter-wave device to produce 200 kW of continuous-wave power at 60 GHz. The device, which will be a gyrotron oscillator, will be compatible with power delivery to an electron-cyclotron plasma. Smooth control of rf power output over a 17 dB range is required, and the device should be capable of operation into a severe time-varying rf load mismatch. The duration of the program is 36 months, to encompass the building and test up to twelve devices. The magnetron injection gun is well understood and allows the user of the extraction anode (as well as cathode temperature variation) to vary the rf power out. At least two design approaches will be taken with respect to the collector, which has to be able to dissipate over 560 kW in underpressed operation. Fabrication and processing of prototype devices will proceed in parallel.