Development of a K-band traveling wave tube based on carbon nanotube cold cathode

In this work, a K-band traveling wave tube (TWT) based on carbon nanotube (CNT) cold-cathode is developed, which achieves a large output power as well as a high power gain. Compared to traditional thermionic cathode TWT, the CNT-based cold-cathode TWT shows significant advantages in fast response speed, miniaturization, integration, and high efficiency. The CNT-cathode of the TWT can emit a current of 9.26 mA, and a high current of 7.80 mA is delivered to the TWT's electron beam tunnel. The maximum current of the collector is 5.90 mA, indicating that the current density of the electron beam in the helix circuit tunnel reaches 750 mA/cm2 and higher, and the maximum transmittance rate in the experiment can reach 92%. The demonstrated CNT-based TWT can output a maximum power of 10.90 W with a power gain of 15.60 dB, and the maximum power gain achieved is 18.97 dB. The above experiment results imply that the CNT-cathode has great potential for application in TWT devices.