GYROTRONS FOR TECHNOLOGICAL APPLICATIONS

A review is given of the possible uses of gyrotrons in industry. A com prehensive theoretical study of mode selection, mode competition, and resonator design for industrial gyrotrons is performed. It is shown th at the TE02 mode at the second harmonic and the TE03 Mode at the third harmonic are good candidates for the operating mode in an industrial gyrotron. Starting currents for these modes and modes oscillating at l ower harmonics are calculated, and mode competition is examined on the basis of the nonlinear non-stationary theory. It is emphasized that i n industrial gyrotrons, owing to a relatively large length of the cavi ty, it is possible to increase significantly the electron efficiency b y introducing inhomogeneity into the profile of the guiding magnetic f ield in a cavity. The important issue of the negative influence of ele ctron velocity spread on the efficiency is studied quantitatively both for tapered and untapered magnetic fields. This is of interest also f or gyrotrons used for fusion plasma heating and diagnostics.