Output-Power Enhancement of Vircator Based on Second Virtual Cathode Formed by Wall Charge on a Dielectric Reflector

A second virtual cathode (VC
₂
) is experimentally developed for the first time in this vircator study, where an axial vircator is simulated by installing a dielectric reflector (DR), whose position is altered from 6 to 18 cm in steps of 2 cm away from the anode. In simulation, the phase space of all electrons indicates that the wall charge on the DR contributed to develop VC
₂
in the downstream region formed by drifting electrons. It is also observed that the main oscillating frequency increases to a higher value when VC
₂
is formed. The simulation and experimental frequencies are in good agreement with and without DR. The proposed VC
₂
interacted with electromagnetic (EM) waves generated from the first virtual cathode (VC
₁
) to amplify its magnitude, and the output power increased from 170 to 688 MW at the optimal position of DR, 10 cm from anode. The distance between VC
₁
and VC
₂
is an important parameter in determining the maximum amplification, which is integer multiples of wavelength for the optimum synergy effect between two VCs. The efficiency of the conventional vircator is 6.07%, which is improved up to 24.60% with DR. This new technique gives an important success in vircator research to use the drifting electrons escaped from VC
₁
to form VC
₂
for power amplification.