Modeling of multifrequency process in lossy structures by using MAGY

Summary form only given. The computer code MAGY developed at the University of Maryland is able to describe the self-consistent nonlinear interaction between electromagnetic fields of an axisymmetric structure and a gyrating electron beam. The code was been used successfully to simulate the operation of both gyro-amplifiers and gyro-oscillators. New applications for gyrodevices require operation at high power and high frequency in overmoded structures. Consequently, multifrequncy processes including sub harmonic bunching can be expected to be important. At the same time suppression of unwanted parasitic modes is critical. One of the most efficient ways for suppression of parasitic modes is coating of the structure´s wall by lossy materials and the inclusion of lossy ceramics. The self-consistent non-linear model in MAGY is based on the generalized telegrapher´s equations for the electromagnetic field and the equations of motion averaged over period of fast cyclotron rotation for the electrons. A problem arises in cases in which the wall has a finite surface admittance. To avoid the divergence of series a new approach was developed. To test the developed approach the electromagnetic fields and its interaction with an electron beam in the beam tunnel containing lossy elements was analyzed. The studied beam tunnel was described completely by Pedrozzi et al., (1998). The results of calculations were compared with experimental data presented in Pedrozzi et al.´s work.