Interaction circuit design and RF behavior of a 236 GHz gyrotron for DEMO

The Demonstration Fusion Power Reactor (DEMO) to follow ITER by 2050 demands high frequency (>230 GHz), high power (in the range from 1 MW to 2 MW) gyrotrons as RF sources for electron cyclotron resonance heating and current drive (ECRH&CD). In the frame of the EUROfusion programme at KIT, the designs of conventional-cavity type and coaxial-cavity type DEMO-compatible gyrotrons are under investigation. In this presentation, the physical design of the interaction circuit of a 236 GHz conventional cavity gyrotron and its RF behavior are presented. The simulation results show a stable single mode RF output power without serious mode competition.