Performance Improvement and System Design in G-band Wideband EIK

A new ridge-loaded cavity structure with unequal-length slots is proposed to improve the bandwidth performance in extended interaction klystrons (EIKs). Based on the transverse-mode overlapping technology, such a structure is well suited to be driven by double sheet beams and exhibits a large efficiency bandwidth product. In contrast to the previously designed ridge-loaded structure, it operates in the longitudinal $\pi $ -mode instead of the longitudinal $2\pi $ -mode and has a larger characteristic impedance and smaller unloaded quality factor. It was designed as the idler cavity for a six-cavity circuit, and the simulation results predicted a maximum in-band output power of 275 W and a 3-dB bandwidth of 3.15 GHz, which expands the bandwidth by 750 MHz compared to the control circuit in the same operating conditions. The corresponding planar double sheet beams electron-optical system is also presented. The beam focusing electrode (BFE) is specifically designed with rod-shaped structure and outstretched structure to enable the two sheet beams to be compressed equally in the broadside direction, and the permanent magnet focusing structure is improved to avoid beam interception. Finally, the beams can pass through the 19-mm tunnel with 100% transmission efficiency, and the matching range of the magnet and electron gun is up to 1 mm.