Optimized Vertical Collector Sweeping for High Power CW Gyrotrons Using Advanced Current Waveforms

For high power CW gyrotrons, it is mandatory to reduce the extreme power densities on the collector wall caused by the spent electron beam. A typical measure is the spreading of the electron trajectories using vertical sweeping driven by an oscillating magnetic field. Using a sinusoidal current to feed the sweeping coils has the drawback that the electron beam stays relatively long in the areas of the lower and upper turning points, which causes relatively high peaks of the average power density at these positions. A conceptual study is presented, which tries to mitigate this problem by using advanced current waveforms to speed up the turning process of the electron beam close to the critical areas and to give information to assist in the procurement of a possible sweeping power supply.