Frequency switching in a relativistic magnetron with diffraction output

The possibility of mode switching from one pulse to the next in a 6-cavity gigawatt magnetron with diffraction output (MDO) using a weak (200-300 kW), short (about 10 ns), single frequency RF signal has been demonstrated using particle-in-cell (PIC) computer simulations [1]. This mode switching is possible because of the symmetric nature of the MDO that facilitates the use of any eigenmode as the operating mode. All scenarios of mode switching were considered using common properties of dynamical systems with two stable states separated by an unstable saddle point. In this paper we continue to study the problem of mode switching for a 12-cavity MDO for which we found a splitting of the radiated frequency for each eigenmode owing to its different longitudinal distribution. Since the splitting is realized as a bifurcation from a higher frequency to a lower one as the applied magnetic field is increased, scenarios of frequency switching are considered as in [1] for the TE₄₁-mode whose radiated power is maximal for the MDO under consideration.