title: Variation of anode grid surface morphology and its effect on operation of a triode virtual cathode oscillator.
abstract: After repeatedly operation of a triode virtual cathode oscillator, the surface morphology of anode grid is studied by a scanning electron microscope. It is found that there are many quasi-periodic sawteeth formed on the anode grid, which are about 300-500 μm in height, ~200 μm in width, and 150-200 μm in period. The formation of this sawteeth implies that there is possible Rayleigh-Taylor-like instability on the anode grid during the irradiation by high-current relativistic electron beam. These sawteeth enhance the electric field on anode grid, leading to more feasible of anode plasma generation, and more rapidly expansion of that plasma. As a result, the electron transmissivity of anode grid is decreased, the output microwave power of the virtual cathode oscillator is lowered and its operational performance is degraded.
authors.affiliation: College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073, China.
authors.forename: Qifu
authors.initials: Q
authors.lastname: Xu
authors.forename: Dan
authors.initials: D
authors.lastname: Cai
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhang
authors.forename: Xuelong
authors.initials: X
authors.lastname: Zhao
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhao
authors.forename: Guoxin
authors.initials: G
authors.lastname: Cheng
authors.forename: Lie
authors.initials: L
authors.lastname: Liu