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Two dimensional (2D) periodic surface lattices PSLs [1-6] have applications in both fast-wave sources [1] and slow-wave sources [4]. Analytical theory and numerical PIC simulations have been used to design an electron beam driven W-band millimeter-wave oscillator, in which a cylindrical two dimensional (2D) periodic surface lattice (PSL) forms an over-sized mode-selective cavity. The 2D PSL consists of shallow periodic cosinusoidal perturbations in both the azimuthal and axial directions on the inner wall of a cylindrical waveguide. Electrochemical deposition of copper on a cylindrical aluminum former was used to construct the 2D PSL. The ratio of the diameter of the cylindrical structure to the operating wavelength is ~5. The performance of this slow-wave oscillator is being measured and will be compared with the numerical simulations.
Work supported by AFOSR awards FA8555-13-1-2132 and FA9550-17-1-0095.
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[4] N.S. Ginzburg, et al., “Theoretical and experimental studies of relativistic oversized Ka-band surface-wave oscillator based on 2D periodical corrugated structure”, Phys. Rev. Accel. Beams, vol. 21, 080701, Aug. 2018.
[5] A.J. MacLachlan, et al., “Volume and surface mode coupling experiments in periodic surface structures for use in mm-THz high power radiation sources”, AIP Advances, vol. 8, 105115, Oct. 2018.
[6] A.J. MacLachlan, et al., “Resonant excitation of volume and surface fields on complex electrodynamic surfaces”, Phys. Rev. Appl., vol. 11, 034034, Mar. 2019.
