Efficiency enhancement of L-band relativistic magnetron with endcaps

An L-band relativistic magnetron with cathode endcaps is presented and investigated numerically. Cathode endcaps are introduced in the relativistic magnetron to decrease the axial leakage current and enhance the power efficiency. Three-dimensional particle-in-cell simulations are carried out to investigate the effects of the cathode endcaps. The simulation results indicate that when adding cathode endcaps at both upstream and downstream of the interaction space and extending cathode beyond the anode block into the diffraction output (DO), electron leakage current is reduced from above 1 kA to 72 A and the power efficiency increases obviously. The endcaps can not only decrease the leakage current but also bring microwave reflection. Thus, the radius and the location of the endcaps have significant impact on power efficiency, and they have optimum values to make the efficiency highest. Typical optimized simulation results are as follows: working at an applied voltage of 563 kV and a magnetic field of 0.34 T, the relativistic magnetron with diffraction output (MDO) radiates microwave of 2.13 GW at 1.59 GHz, and the corresponding power conversion efficiency is 75.5%.