The use of higher harmonics for Sub-THz generation in relativistic virtual cathode oscillator

We study the microwave generation regimes with intense higher harmonics taking place in a high-power virtual cathode oscillator (vircator) consisting of a relativistic electron beam with a virtual cathode. It has been shown that the system under study demonstrates the tendency to the sufficient growth of the amplitudes of higher harmonics in the spectrum of current oscillations in the virtual cathode region with the increase of beam current. The obtained results allow us to consider relativistic vircators as promising high power mmw-to-THz sources.