Improved gyrotron cavity with high quality factor

For gyrotrons operating at the second harmonic of the electron cyclotron frequency cavities with high quality factors are needed. Up to now steep output tapers or abrupt output irises are used in order to provide a high reflection coefficient. Such circuits suffer from the problem of strong conversion to unwanted output modes. A promising possibility to achieve a high reflection at the cavity output (and thus a high quality factor) combined with high mode purity is the use of a rounded iris and an optimized nonlinear taper with very low unwanted mode conversion at the output of the resonator.