Microwave Generation Using a Two Spiral Metamaterial Slow Wave Structure Driven by an Electron Beam

We designed a two-spiral metamaterial (MTM) structure which shows a wider bandwidth of double negative permittivity and permeability compared to the well-known split ring resonators [1]–[3] (SSRs) and which can tailor and control the electromagnetic radiation. The two-spiral MTM structure is formed in a waveguide that is below cutoff for TM modes. Particle-in-cell (PIC) simulations with MAGIC [4] demonstrated that a waveguide that is loaded with two axial parallel plates machined with two-spiral metamaterial structures allows two backward modes to propagate in S-band with a pulsed electron beam traveling down the center of the waveguide, midway between the plates. Theory and initial PIC simulations indicate that both Cherenkov and the Cherenkov-cyclotron beam-wave interaction can occur. Microwave generation was studied by varying the operating parameters over a wide range, including the electron beam voltage, beam size, beam current, and magnetic field. This presentation will discuss our most recent results.