Improved foilless Ku-band transit-time oscillator for generating gigawatt level microwave with low guiding magnetic field.

An improved foilless Ku-band transit-time oscillator with low guiding magnetic field is proposed and investigated in this paper. With a non-uniform buncher and a coaxial TM02 mode dual-resonant reflector, this improved device can output gigawatt level Ku-band microwave with relatively compact radial dimensions. Besides the above virtue, this novel reflector also has the merits of high TEM reflectance, being more suitable for pre-modulating the electron beam and enhancing the conversion efficiency. Moreover, in order to further increase the conversion efficiency and lower the power saturation time, a depth-tunable coaxial collector and a resonant cavity located before the extractor are employed in our device. Main structure parameters of the device are optimized by particle in cell simulations. The typical simulation result is that, with a 380kV, 8.2kA beam guided by a magnetic field of about 0.6T, 1.15GW microwave pulse at 14.25 GHz is generated, yielding a conversion efficiency of about 37%. [ABSTRACT FROM AUTHOR]