Investigation on “cold” and “hot” characteristics of different configurations of corrugated coaxial slow wave structures

Various configurations of corrugated coaxial Slow-Wave Structures (SWSs) are utilized in O-type Cherenkov oscillators to achieve different goals. This is the reason why a strategy targeting the proper selection of corrugated coaxial SWSs configurations deserves to be further studied. In this paper, high frequency characteristics of different configurations of corrugated coaxial SWSs are calculated and analyzed. The analysis suggests that the coaxial SWSs with corrugations on inner conductor only are characterized by higher coupling impedance and higher growth rate of microwave oscillations, while the coaxial SWSs with corrugations on the outer conductor only are characterized by higher power capacity. Due to the low power capacity, coupling impedance and growth rate, the coaxial SWSs with corrugations on both inner and outer conductors are not suitable for O-type Cherenkov oscillators desired to operate in the quasi-TEM mode. However, if these devices are desired to operate in the TM01 quasi-π mode, the SWSs with both inner and outer conductor corrugations may be a better choice to make it happen.