Metamaterials for Rapidly Forming Large-Area Distributed Plasma Discharges for High-Power Microwave Applications

Electromagnetic metamaterials have broad application potential including new high-power microwave (HPM) sources and anti-HPM devices. In the previous work, we demonstrated that an initial breakdown at one location within a multiresonator unit cell of the single-layer metamaterial emitted vacuum ultra-violet (VUV) radiation that induced breakdowns at the neighboring locations even though the electric field intensities were below the breakdown thresholds. In this paper, we report the results of experimental investigations of single-layer metamaterials deliberately designed to exploit this effect. When illuminated by 26-kW, 9.382-GHz, 0.8-μs intense microwave pulses, breakdown was initially induced only in one small location where the radio frequency (RF) electric fields exceeded the breakdown threshold. In experiments with the metamaterials, the initial breakdown locally occurred in 5-10 ns, after which the VUV preionization effect facilitated the rapid spread of the breakdown across the entire surface within 10-20 ns. In contrast, without a metamaterial, the breakdown remained localized and was delayed by 25-30 ns compared with the metamaterial cases. The experimental results are expected to provide a useful guideline for designing metamaterials in HPM systems.