Multiphysics Modeling and Thermal-Frequency Tuning of THz Gyrotron Devices

The interaction process and loss problem of gyro-devices are theoretically investigated. The analysis of interaction process is self-consistently divided into two parts, namely the wave equation and the beam motion. To take the effect of finite wall conductivity into consideration, a perturbation method is utilized to model the losses, in which the propagation constant is modified as a complex number. Based on the nonlinear theory and losses modeling, both frequency-domain single-mode and time-domain multi-mode simulation schemes are proposed, which provides an effective way to optimize the gyrotron operation and instruct the practical design. Using the proposed tools and multiphysics analysis, controllable thermal tuning scheme of a gyrotron is testified by combining the cavity expansion with frequency shift. The results indicate that the thermal-frequency tuning approach has the advantage of high interaction efficiency compared with the conventional voltage and magnetic tuning methods.