A Three Double-Gap Hughes-Type Coupled-Cavity Simplified Design Procedure for a Ka-Band EIK

Wide-band high-power sources operating at millimeter and sub-millimeter wave necessitates more efficient devices [1]. SSPAs do not satisfy the stringent requirements so vacuum electron devices are required [2]–[3]. In this paper, a three double-gap Hughes-type coupled-cavity slow-wave structure for a Ka-band EIK is designed. Here, a design technique allowing to reduce the design time of the double-gap coupled-cavity is reported. At first, based on the 3D CST Studio model results, the cold electrical parameters, the coupling coefficient, and the beam-loaded conductance necessary to measure the interaction with the electron beam of the double-gap coupled-cavity are calculated. The
$2\pi$
working mode, for a better coupling coefficient M, is selected. A 1-D large signal analysis with AJDISK tool by performing the double-gap cavity as a single-gap structure is carried out. The large-signal analysis results are in good agreement with the simulated 3D PIC results. Under the optimized beam voltage of 19.55 kV and current of 0.95 A, a peak power value of 11.07 kW and a gain value of 40.44 dB with a 3dB bandwidth of 70 MHz at 35 GHz are obtained. The structure stability and electron beam synchronization are discussed.