Rigorous calculation of energy losses in cavity of ITER relevant coaxial gyrotron

Ohmic losses in coaxial gyrotron cavities with corrugated insert are calculated on the basis of the rigorous singular integral equation (SIE) approach. It is found that SIE predicts significantly lower losses in the corrugated insert compared with the surface impedance model (SIM) widely used before. Calculations are performed in a wide range of corrugation parameters for the cavity of the ITER relevant coaxial gyrotron operating in the TE_34,19 mode at 170 GHz. It is shown that there exist optimal corrugation parameters for which ohmic losses are minimal. They can even be less than those in the smooth insert.