Self-excitation of spurious oscillations in the drift region of gyrotrons and their influence on gyrotron operation

Stable operation of gyrotron devices is often limited by spurious oscillations in the drift region where the external magnetic field is nonuniform. Analytical expressions for start-oscillation currents and frequencies of auto-oscillations in gyrotrons with weakly inhomogeneous DC magnetic fields have been published. These expressions are used to calculate the starting currents and frequencies of the spurious oscillations excited in the drift region of a TE/sub 021/ mode gyrotron. The results of numerical simulations are in agreement with experimental measurements of spurious oscillations in our gyrotron. It is shown that self-excitation of these spurious oscillations leads to a sharp decrease in efficiency due to mode competition between desired and spurious modes.<
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