Abstract:

Summary form only given. Coaxial cavity gyrotrons with axial corrugated insert are able to provide high-frequency microwave power in the MW region. The insert reduces the voltage depression and enhances the mode-selectivity of the cavity. Choosing the insert's radius and corrugation parameters properly, the parasitic modes are more easily suppressed. A major constraint in the design of such resonators is the heating of the structure due to the dissipation of part of the generated RF power of 2-3kW/cm2, whereas for the inner one this limit is up to ten times lower. The EU 2 MW, 170 GHz coaxial gyrotron cavity has been designed using the Surface Impedance Model (SIM) to calculate the ohmic loading of the insert. However, comparisons of SIM results with those obtained by the full-wave Space Harmonics Method (SHM) revealed significant discrepancies in the calculated ohmic loading. In this work, we perform a parametric study of the ohmic loading using SHM and SIM. Possible optimization, by means of minimization of ohmic losses and mode competition, of the EU coaxial gyrotron cavity is investigated.