Operation of a 3 MW, 140 GHz gyrotron with a coaxial cavity

Summary form only given. Experimental results will be presented here for a high power, high frequency coaxial gyrotron. The designed goal for this experiment is to produce 3 MW, at 140 GHz in the TE 21,13 mode with an efficiency of at least 30%. In our experiment the inner conductor extends from the electron gun to the output. The main advantages of the coaxial conductor are: causes rarefied mode spectrum around the design mode; reduces the quality factor of competing modes; volume modes (higher radial index) can be chosen (which increases the output power); and reduces voltage depression.