Sub-Gigawatt W-Band Oversized Surface-Wave Oscillator With 2D-Periodical Slow-Wave Structure of Cylindrical Geometry

We report of the implementation of a strongly oversized W-band surface-wave oscillator (SWO) based on a 2D-periodical cylindrical slow-wave structure (2D SWS). In contrast to the “conventional” SWO with 1D SWS, additional azimuthal wavebeams arise in 2D SWS, which lead to synchronization of the radiation from an intense annular relativistic electron beam with a diameter
${D}$
exceeding the radiation wavelength
$\lambda $
as
${D}/\lambda ~\sim $
10. In the conducted experiments at the SINUS-6 accelerator 0.5 MeV / 5 kA / 25 ns, we obtain stable narrow-band operation with an output power at 120 - 150 MW level. In accordance with the CST simulations, we observe the excitation of the fundamental mode of the 2D SWS, which provides an azimuthally-symmetric structure of the output radiation. For single-direction radiation output, an up-stream Bragg-type reflector is used. Novel additive technology is examined for manufacture of the 2D SWS.