Measurement of frequency spectrum of submillimeter-wave gyrotron output using Michelson interferometer

Measurements of frequency spectra of millimeter to submillimeter wave range and its application to gyrotron output are described. The results demonstrate that mode competition in the gyrotron between cyclotron fundamental (n=f/fc=1) and its harmonics (n=2,3,4,...) operations occurs in almost all cases, however, auxiliary operations can be suppressed about 30 dB lower than main operation by controlling an electron beam current and applied magnetic field.