Self-consistent Modeling of Terahertz Waveguide and Cavity with Frequency-dependent Conductivity

Ohmic dissipation can lead to excessive wall losses at terahertz (THz) frequencies, while the high-frequency oscillatory motion of conduction electrons tends to mitigate the collisional damping. In this study, a frequency-dependent conductivity is used to model the wall losses on the waveguides and open cavities commonly employed as gyrotron interaction structures. The reduction in Ohmic losses under the AC-conductivity model is shown to be increasingly significant as the frequency reaches deeper into the THz region. Such effects are of considerable importance to THz gyrotrons for which the minimization of Ohmic losses constitutes a major design consideration.