Frequency Tuning in a Gyrotron with a Cavity of Variable Cross Section

We describe an electrodynamic method based on azimuthally asymmetric cavities with a “close-to-circular” cross-section to provide a continuous frequency tuning in subterahertz gyrotrons operating on symmetric modes. A small mechanical change in the rotation angle of the moving “visor” changes the effective volume of the cavity and provides a relatively wide (several percent) bandwidth of continuous tuning of the gyrotron frequency.