Theoretical And Experimental Study Of The S-band Long Pulse Relativistic Klystron Amplifier

Relativistic Klystron Amplifier (RKA) is one kind of microwave devices with high output microwave power and high efficiency. S-band long pulse intense current RKA are theoretical investigated deeply, and the corresponding conclusions are used to design and guide the RKA experiments. The experimental results are consistent with the theoretical results.The theoretical studies are divided into three parts:1. The dynamics of interaction between Intense Relativistic Electron Beams (IREB) and symmetric mode and asymmetric modes of cavity in RKA is analyzed three dimensionally. The interaction between IREB and asymmetric mode, which leads to the collapse of IREB, is obtained. The input cavity and the output cavity, which work in higher mode with long dimension, are proposed to decrease such influence. The collapse of IREB is controlled and IREB can drift longer. The results of theoretical studies are used in the design and adjustment of cavities in s-band RKA.2. The coaxial output-cavity with large coupling holes is theoretical analyzed based on equivalent principle of field and integral method of Green functions. The resonant frequency and loaded Q value and characteristic impedance of the cavity are solved by three dimensions. The results ared used in the calculation of cavities.3. Space-charge-limited current and energy distribution of annular IREB in coaxial drifting pipe and in cylinder drifting pipe are analyzed. The physical process of reflected electron and self-excited oscillation is described when the long pulse IREB drifts through the gaps of cavities with high electrical field. The structure of uneven mode of cavities in RKA is proposed, and the triaxial output cavity is designed and simulated with particle in cell (PIC), which depresses self-excited oscillation and enhances the efficiency of RKA.The S-band RKA is designed according to above theoretical studies, which is also verified by PIC codes. The geometrical and electrical parameters of cavities are obtained by Mafia code. The structure and the working parameters of RKA are also optimized by PIC code.The experiment includes structural design and parameter adjustment of cavities and antenna, as well as the modulation measurement of electron beams and output microwave. The asymmetric modes of input cavity and output cavity are significantly redued, whose resonance frequency and loaded Q value meet with the design. These structures...