Collector loading during high frequency power modulation

The high frequency power modulation of cw gyrotrons with an rf-output power up to 1 MW and efficiencies of 35-55 % is limited by collector loading. Two alternative power modulation schemes are commonly applied which show a significant difference in the resulting collector loading. In any case waste power remains in the spent electron-beam and must be dissipated in the gyrotron-collector. Such collectors have strong sophisticated water-cooling systems and the electron-beam strike area is moved on the collector surface by sweeping the magnetic field. The technically less demanding power modulation method unfortunately generates the highest level of collector loading. Different sweep technologies have been developed in order to avoid overheating.