3-D Particle-in-Cell Simulations on a Novel High-Power and High-Efficiency Coaxial Triode Vircator

In order to improve the efficiency and obtain high output power with pure mode, 3-D particle-in-cell simulations are made on a novel coaxial triode vircator. Simulation results show that due to the appearance of the additional cylindrical cathode rod along the centerline, pure TM
₀₁
mode can be obtained in the output region. Simulation results also show that highefficiency and pure TM
₀₁
mode output maintains even for output waveguide radius (equals anode radius) somewhat larger than the cutoff radius of the TM
₀₂
mode (Rc,TM
₀₂
). When the cathode and anode gap keeps unchanged, most optimal structure values can be scaled for models with different anode radius. By careful optimizations, the efficiency can reach 15% at an output power of 1.7 and 2.2 GW, respectively, for anode radii equal 5.6 and 6.6 cm (<;R
_c,TM02
); For anode radii equal 7.6 and 8.6 cm (>R
_c,TM02
), the efficiency is about 13% at an output power of 2.5 and 2.9 GW, respectively. The operating frequencies all are about 3.6 GHz.