Cold test of gyrotron cavity modes using a 3D CFDTD method

Modeling a gyrotron cavity in 3D and time-domain is very challenging due to the open-end features of cavity structure and higher-order mode excitation employed to achieve high efficiency. In this work, a 3D conformal finite-difference time-domain (CFDTD) method has been developed to perform a cold test of a gyrotron cavity. Arbitrarily high order modes can be launched in a gyrotron cavity in time domain to determine the open cavity resonant characteristics. Our preliminary results show that the 3D CFDTD method could provide an alternative modeling tool for designing and validating a gyrotron cavity configuration for further hot tests.