Multi-cavity Klystron Mutual Role In Programming

The main characteristics of klystrons are high power, high efficiency and high gain. As the end of radar transmitters, klystrons directly impact the available distance of radar. The main military application of radar includes warning, electronic countermeasures etc. In addition to national defense, radar also play important role in communication and microwave heating.Computer-aided design (CAD) is playing a more important role in the design and analysis for klystrons and almost all the design of new developed klystrons would be helped by CAD technology. The design of multi-beam klystrons can be seen as a example of application of CAD. Whether to SBK or MBK, the impact of CAD will be greater. Particularly in improving performance of device, and shorting the development cycle and reducing the cost. Currently several commercial software has been used for the design of SBK and MBK, such as Mafia, Magic, Hfss and Ansys. More important, particle simulation (PIC) also can be analyzed by Magic and Mafia.Beam-wave interaction analysis and calculation of vacuum electron devices is an important part of CAD software, because just in this stage, electronic kinetic energy released, and the energy can be transformed into the microwave energy.From the point of view of integral method of klystrons' beam-wave interaction: it can be divided into distance and time integral theory. Traditionally, we will use respectively the distance integral and time integral method in the section of bunching and output; this is because the steady-state phase of the formula in output section no longer holds. However, in the conversion process, the actual physical process can not be totally true reflected.Viewed from another angle, beam-wave interaction also can be divided into one-dimensional two-dimensional, three-dimensional nonlinear theory. In One-dimensional theory, only the axial movement has been taken into consideration. Because of neglect of the electronic radial movement and the radial field of high-frequency in output gap, the efficiency is obviously higher than the actual value. In consideration of the radial movement, two-dimensional theory would be more accurate, but it is still imperfect. With consideration of the axial, radial, angular movement, three-dimensional theory is the most accurate.In one-dimensional theoretical analysis, this paper uses traditional methods, which is the combination of distance and time integral. In two-dimensional theoretical analysis, this paper will start with klystrons' radial and axial interaction equations with the use of limited thickness of the electronic ring model and will deal with the process of beam-wave interaction based on the principle of time integral. As this paper did not use that traditional method in the analysis of two-dimensional theory, we have successfully avoided the problem when we have to make that conversion between distance and time integral.Combined with these physical parameters of one S-band five-cavity klystrons, we tested our programs of one-dimensional and two-dimensional theory, and results showed that: programs are basically consistent with the actual situation.