Experimental studies of an axial vircator with different cathode geometries

This paper describes the numerical study and experimental results of an axial vircator with axial extraction. The microwave source is driven by a Marx generator and excludes any type of pulse forming device between the two subsystems. The main reason for this special arrangement is the final goal to build a compact and robust high power microwave system. The drawback is usually a lower efficiency of the microwave source. The vircator operates with the applied voltages between 300 and 400 kV and the impedance is around 15 Ohms during the process when microwave radiation is generated. The microwave pulse duration is for most cases between 100 to 200 ns. For the experiments described in this paper focus has been on different cathode geometries and on different anode meshes. Results that are given include microwave power, spectral content and mode characteristics. In an attempt to better understand and explain the experimental results particle-in-cell simulations have been carried out in MAGIC.