Relativistic Klystron Theory And Numerical Simulation

The small signal space-charge wave theory of intense relativistic electron beams (IREB) is analysed. The expression of limiting current, the dispersion relation of IREB, the transform matrix of IREB which is in drift tube, and the voltage gain equatio are obtained. After compared with classic Klystron theory, we find out that the space potential voltage of IREB is so large that it can not be ignored in calculation. Because of the potential voltage, the IREB will be lost energy while translating in drift tube. The non-liner self-consistent formulations of ideal annular IREB are obtained, these formulations will be the same as the linear or static equation when we set them into special situation. Although the equations are hard to solve, but we can still drop some unimportant factors, and obtain the harmonic content of modulated IREB current. Base on these, we find out some different characteristics of Relativistic Klystron Amplifier (RKA), the current modulation will be enhanced by it's own pace potential voltage.By using of MAGIC, two kinds of open resonator simulation method are introduced, the advantages and disadvantage are compared. Base on some simple resonator theory, the Q value, R/Q value can be calculated systemically, those methods not only suit for klystron resonator, but also suit for all kinds of complicated cavity. Oneof IREB important characteristics is analysed, pace potential voltage and limiting current are simulated and compared with theory, the results are consistent.By using of the theory and simulation methods above, the inject cavity, buncher cavity and output cavity are analysed separably. With An annual electron beam of voltage 500kV, and current 3kA, average output microwave power 455MW and peak power 1.3GM is observed, bandwidth is 60MHz, the efficiency is 30.3%, the gain is about 36.8dB.and the frequency is 2.85GHz, The amplitude and phase of output microwave is stable. The efficiency is the highest of three cavity klystron.