Development of high frequency gyrotrons

An overview of recent experimental and theoretical progess at MIT on the development of high frequency (>100 GHz) gyrotrons will be given. High power oscillators capable of powers in excess of 100 kW, which could be used as rf sources to heat fusion plasmas, are presently being designed and constructed. The operating characteristics of a 200 kW, 140 GHz gyrotron that achieved peak total efficiencies of 41% and single mode emission will be described. A parametric analysis has been completed that indicates that cw gyrotrons capable of powers in excess of 1 MW and high efficiency are consistent with the technological constraints of the device. The design parameters of 1 and 10 MW, 120 GHz monotrons will be reviewed. A 1 MW, 120-140 GHz pulsed gyrotron is presently being constructed at MIT and should be operational by early 1986. In addition to high power operation, gyrotrons are also capable of generating very high frequencies. The harmonic operation of the MIT gyrotron will be reviewed, and the prospects for generating frequencies up to 1 THz will be described.