Simplified analytic model for improved field calculation inside the coaxial gyrotron cavity

The simple analytical model for calculation of field inside a coaxial gyrotron cavity with corrugated inner conductor is presented. It allows for correct calculations of field all inside the coaxial gyrotron cavity including the region near the corrugated surface. Obtained results are compared with results of the basic surface impedance model (SIM) and with results based on more rigorous methods. It is shown that proposed model is able to provide significantly more accurate results than SIM and almost the same accuracy of results as rigorous full-wave methods. Due to simplicity it is convenient for utilization in different computer codes for simulation of coaxial gyrotron operation and optimization of the coaxial gyrotron cavity. The capabilities of the model are illustrated on the example of a TE_34,19 coaxial gyrotron cavity designed at the Karlsruhe Institute of Technology (KIT, former FZK) for fusion applications.