Theoretical Study of a Plasma-Filled Relativistic Cerenkov Generator With Coaxial Slow-Wave Structure
The linear and nonlinear theory of a plasma-filled relativistic Cherenkov generator with coaxial slow-wave structure (SWS) is developed. Linear analysis includes the space-charge limiting current, dispersion relations, dispersion curves, and coupling impedance. In nonlinear theory, the electron beam space-charge effect, nonsynchronous interaction, and complex reflection coefficients of the electromagnetic wave at the boundaries of the SWS are taken into account. With the assumption of quasi steady state, the self-consistent equations are numerically calculated using the fourth-order Runge-Kutta method. The effects of the relative phase between inner and outer corrugations, phase and amplitude of the complex reflection coefficient at the boundaries of the SWS, and plasma density on device efficiency are discussed. Efficiencies of up to 37% without plasma and about 50% with plasma density of np = 3-7 times 1011 cm-3 are obtained.
High-Frequency Characteristics of the Axisymmetric TM Modes in a Coaxial Staggered Double-Grating Slow-Wave Structure
The formulas of dispersion and interaction impedances of the axisymmetric TM modes in a coaxial double-grating slow-wave structure (SWS) are obtained utilizing the field matching method, in which the higher order terms of the field in the grooves have been considered. The high-frequency characteristics of lowest two modes-the fundamental mode and the TM01 mode-in the SWS were discussed by adjusting its structure parameters. The calculated results show that the dispersion curve and the interaction impedance are in good agreement with those simulated by the CST-MWS code. In addition, the parameter analysis demonstrates that the rational selection of the position of the beam tunnel and the relative position of the upper and lower gratings are helpful for the development of the traveling-wave tube and the back-wave oscillator to improve the bandwidth and enhance the interaction impedance.
Cherenkov-cyclotron resonance interaction in a high-power plasma-filled backward-wave oscillator.
A possible explanation of high-power microwave radiation from a plasma-filled backward-wave oscillator in the presence of an axial magnetic field has been provided. The increase in power output with magnetic field can be explained by taking into account the simultaneous existence of Cherenkov and cyclotron resonances.