Spectral Characteristics of THz CW Clinotrons

The spectral properties of terahertz (THz) continuous-wave (CW) clinotrons have been studied both theoretically and experimentally. The resonant properties of clinotrons having strong influence on the spectral linewidth have been analyzed both for the frequencies below 150 GHz where resonances are determined by reflections of surface wave, and for THz tubes where resonances are caused mainly by the effect of mode transformations in oversized cavities. The influence of beam voltage ripples in THz clinotron on spectral line broadening has been studied and discussed. The clinotron spectral linewidth of 1.18 MHz has been demonstrated at 346.4 GHz with the output power of 100 mW when the output voltage stability of high-voltage power supply (HVPS) was 5 ppm.