3D Computer Modeling of Phase-Locking in a Rinsing-Sun X-Band Magnetron

Summary form only given. The phase-locking in a magnetron usually requires a relatively strong injection signal, typically at a level as high as 10 dB below the output power. It is therefore highly desirable to achieve phase-locking in a magnetron at a much lower power level. This could lead to a range of new applications, among them the element of expensive and bulky-cavity klystrons currently used in particle accelerators, by compact and high efficiency magnetrons. In this study, we propose to inject the locking signal axially into the interaction region in order to reduce the required phase-locking signal level. The process of phase-locking in an X band pulsed magnetron has been investigated using a three dimensional MAGIC code. The magnetron in question has a rising-sun anode with 18 cavities. It has been shown that in the progress of phase locking the injection signal eliminates the initial mode competition and consequently speeds up the start-up of oscillations. It has been found that when the injected signal is sufficiently strong to achieve phase locking, the locking bandwidth is substantially greater than that obtained from the small signal theory; thus in practice a greater bandwidth is obtained using a weaker injection signal. Clearly in the case of phase locking it is advisable to take the nonlinear behaviour of the system into account. A technique of phase measurement based on the time of zero crossings of the time axis by the output signal has been used in order to obtain an accurate measure of the phase difference between the injected control signal and the output of the magnetron