Studying the start-up scenario for a pulsed gyrotron with a relativistic electron beam

We present the results of studying the start-up scenario for a high-power pulsed gyrotron operated at the TE53 mode for two variants of the current–voltage characteristic of a three-electrode magnetron-injection electron gun. In the standard variant of feeding the voltage to the first anode from the resistive divider, sequential generation of the TE73 and TE63 modes, and, finally, the operating TE53 mode was observed at the edge of the pulse. The current–voltage characteristic for which only the operating mode is excited is obtained by decreasing the growth rate of the voltage applied to the first anode.