A novel metamaterial slow wave structure with larger space-charge-limited current

Abstract

This article proposes a new type of metamaterial slow wave structure with larger space-charge-limited current for high-power microwave sources. In order to avoid the anisotropy effect and improve the uniformity of electromagnetic field distribution, the slow wave structure consisted of two all-metal units arranged by a modified method of broadside-coupled complementary split ring resonant (CSRR) geometry. Moreover, the conductor on the periphery of the CSRR has been removed, and a short shift tube was added to the units for the purpose of obtaining larger space-charge-limited current. High-frequency analysis shows that the new slow wave structure has the basic characteristics of metamaterials, including double negative electromagnetic parameters, peculiar dispersion, and high coupling impedance. More importantly, transmission simulation shows that the space-charge-limited current of the structure is at least 12 kA, which is about twice the maximum beam current that the hollow circular waveguide of the same size can transmit, and it proves that the design method is effective and feasible. Applying the structure to a microwave source will achieve the goal of high-efficiency and high-power output.