The spectrum broadening of excited oscillations in coaxial slowing structure when filling by plasma

The excitation of UHF-oscillations by electron beam in disk loaded coaxial transmission line with combs on inner and external conductors is theoretically investigated. The structure passage channel, where annular electron beam propagates, is fully filled by plasma. The eigenwaves of the plasma filled coaxial transmission line and their dependencies versus plasma density are investigated. It is shown that the plasma has resulted in essentially enhancement of gain and at the same time widens the excited oscillation spectrum.