Experimental investigation of an l band all cavity axial extraction relativistic magnetron

Experimental results of an L band all cavity axial extraction relativistic magnetron (RM) working at 1.57 GHz is presented. In this 6-cavity RM configuration, microwave from two adjacent cavities is coupled into an axially oriented coaxial sector waveguide through radial slots on the cavities. This configuration is more compact because only three sector waveguides are added outside the magnetron cavity without increasing the radial dimension significantly. Simulation results reveal that this tube could generate a microwave power of 700 MW at the frequency of 1.57 GHz, corresponding to a power conversion efficiency of 50% when employing an electron beam of 350 kV and 4.0 kA. This tube is tested on a compact Marx generator in our lab. In experiment, this tube could generate a microwave power of over 500 MW at 1.57 GHz when employing guiding magnetic field of 0.22 T and input beam voltage of 345 kV and current of 4.8 kA, with a corresponding efficiency of about 30%. Experimental results reveal that this tube is a preferred configuration for a compact relativistic magnetron with relatively high power conversion efficiency.