A non-uniform buncher and a depth-tunable collector have been proposed to improve the power capacity and conversion efficiency of the coaxial foilless transit-time oscillator (TTO) in our previous work. Recently, our Ku-band coaxial TTO with low guiding magnetic field is improved by employing them, and the related experimental investigations are carried out on the TORCH-01 accelerator. It is shown that the non-uniform buncher plays a key role in the enhancement of microwave pulse duration. The influences of the collector's depth on characteristics of the device indicate that the conversion efficiency can be improved by optimizing the collector's depth in the experiments. With the diode voltage 460 kV, the beam current 8.7 kA, and the guiding magnetic field of 0.6 T, a radiation power of 1GW with the conversion efficiency of 25% at 14.3 GHz is generated by our improved TTO. The output pulse duration is 26 ns and no obvious pulse shortening is observed. The experimental results demonstrate the abilities of this improved Ku-band device to generate gigawatt-class Ku-band microwave with low guiding magnetic field. Published by AIP Publishing.
展开▼
